MD: Why MD?

2000-10-25 Thread Timothy P. Stockman


I got started with MD to make compilations of LPs to play in my car.  But
lately, in addition to music, I've been recording interviews with family
members for a genealogy project.  One of my friends at work borrowed my
recorder and mics for a weekend to record some of his relatives and was
hooked.  He claimed that the result sounded as good as NPR (National Public
Radio network) and was so impressed he purchased an MD recorder the next
day!

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MD: Hi speed dubs from computer...

2000-10-23 Thread Timothy P. Stockman


There's no techincal reason that 2x should not be possible, because 96 KHz
S/PDIF sound cards have been avaialble for some time.  Also, most existing
MD transports are capable of up to 5x.  It just hasn't been implemented by
any existing MD model.  I'm sure that once people got a taste of 2x, 4x
would not be far behind...

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Re: MD: WHY?

2000-10-02 Thread Timothy P. Stockman


 I have a Sony MD MZ R 70, and today I have discovered my
 remote control is not working anymore...

The remote is just a resistor ladder.  If you've got an ohmmeter, connect it
to 2 of the pins on the "edge connector" at the end of the remote cable (I
forget which 2, but the other 2 are not connected on the R70 remote).  When
the meter is connected to the proper pins, it will indicate various
resistances when you press keys; the value depends on which key is pressed.
Sounds like your problem is a open circuit.  This test will allow you to
determine if its the remote or the recorder.

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MD: computer to MD - digital vs analog

2000-09-29 Thread Timothy P. Stockman


Lately, there has been some discussion and speculation on MD-L about analog
vs digital for computer to MD transfers.  Below I've enumerated the
technical advantages and disadvantages.

The advantages of analog are:
1) it *always* works
2) easy level adjustments

The disadvantages of analog are:
1) many computers/soundcards have poor internal signal grounding, not to
mention a *lot* of high-frequency hash (which leads to noise) and/or
undersized coupling capacitors (which produces phase shift and poor
frequency response).
2) possible ground problems between the computer and the MD which causes
mains leakage and resultant hum.
3) unreliable connections due to the low contact pressure of the mini-phone
plugs.
4) an extra D/A and A/D conversion.

Digital transfer has the advantages (when it works):
1) No added noise, distortion, phase errors or poor frequency response.
2) No ground problems with optical.  Even if coaxial is used, ground
problems will not cause noise, as with analog.

Digital transfer has the disadvantages:
1) Possible incompatibility problems.  For example, the S/PDIF from the
DIO2448 is not accepted properly by the MDS-PC2.
2) Bad connections or ground problems may cause intermittent dropouts or
pops.
3) Due to lack of  "flow control" on S/PDIF, high CPU activity may cause
dropouts or pops.

For me, the advantages of digital make it worth the hassle.

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Re: MD: Lawyers, Discs and Money

2000-09-27 Thread Timothy P. Stockman


 I've been getting a lot of e-mails from people who don't understand why
they
 can't simply copy the MP3s to MD faster than real time, so I've put
together
 a rather lengthy explanation.

 http://home.sprintmail.com/~dalegreer/Mac-MD/lawyers.html

An interesting account of the history of SCMS, etc.  I disagree, however,
that SCMS limits one to 1X recording.  For example, Sony has a combo CD/MD
that *is* SCMS compliant and transfers to MD at 4X speed.   Current S/PDIF
computer hardware can produce a 96 KHz S/PDIF, so it would theoretically be
possible to construct a SMCS compliant MD machine that would accept this
high speed S/PDIF to record at a little more than 2X.  (Since MD transports
already record in burst mode at 5X speed, it would require redesign of the
chip with the S/PDIF interface, but no other major redesign.)

Right now, we're seeing a wave of USB to S/PDIF hardware.  It ultimately be
a more cost effective and easier-to-use solution to *emulate* this hardware
in the MD recorder itself.  One could also emulate the a USB to serial to
Slink (over the same physical USB cable).  Doing it this way would retain
maximum compatibility with existing hardware and software, but still offer
almost all of the computer transfer advantages of MP3 players, and it would
still be SCMS compliant!


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MD: RM-X69RF question...

2000-09-24 Thread Timothy P. Stockman


Does anyone know where I can get a service manual for the RM-X69RF?  I'd
like to add an extra IR sensor as I plan to put the display module behind a
drop-down door.

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Re: MD: Just got a MZ-R70; love it! Does RM-MZR55 remote work with it?

2000-08-30 Thread Timothy P. Stockman


I have an MZ-EP11 (with LCD remote) and an MZ-R70 (remote with no LCD).
The EP11's LCD remote plug fits the R70 and the controls work, but the LCD
doesn't.   On the 4-pin remote plug, 2 of the pins are for the controls and
2 for the LCD.  My guess is that the LCD pins are not connected in the R70.
I was somewhat disappointed to discover this, because I would have swapped
remotes otherwise.

I don't know for sure, but I believe the remote LCD pins *are* connected in
the R90.

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Re: MD: Speakers

2000-08-29 Thread Timothy P. Stockman


If price were no object, I'd have Martin Logans!

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Re: MD: Digital recordings and track marks...

2000-08-26 Thread Timothy P. Stockman


 But there is no code or signal in S/PDIF that means "new track starts
now."

I don't know how the CD subcode information is translated for S/PDIF
transmission, but the subcode "P" channel on the disc is just that, a "new
track starts now" signal.  It is the CD's version of the "wide spiral
groove" between tracks on an LP.  I've don'e know if the "P" channel makes
it into the S/PDIF data stream, but if it does, then the track start signal
is available.



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Re: MD: forward from CasetteHouse... cheap

2000-08-26 Thread Timothy P. Stockman


 But you have to factor in the shipping and service charge.  That will
raise
 the price somewhat.

I ordered 100 Hi-Space 74 MDs from Casette House a few months ago.  I don't
remember the exact details, but I remember shipping and handling as being
quite reasonable.  They weren't inflating their price that way.

So far, I've used the following batches of MDs and all have worked equally
well:

5  TDK 74 min
40  JVC "Crystal Gold" 74 min
50  HHB 74 min
100  HiSpace 74 min



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MD: CDDA

2000-08-23 Thread Timothy P. Stockman


Not wanting to get into a flame war with Rat, but I stand by my previous
explanation of CDDA.  For those interested, there's some information online:

http://www.howstuffworks.com/cd1.htm

Also, Ken Pohlman's book, "Principles of Digital Audio" has in-depth
explanations of many formats, including CDDA and MD.

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MD: CD-DA

2000-08-23 Thread Timothy P. Stockman


OK, I finally found a page with a good technical expanantion of CD-DA
ripping and the problems involved:
http://www.cdpage.com/Audio_Compact_Disc/daextraction.html

Also some interesting general info on CD, CDROM, MD and DVD here:
http://www.sonydadc.com/pr_handbook.asp

I've got K Pohlman's book somewhere around here.  I'll look and see if he
gives the definitive answer about CD-DA track format.  (He probably does.)

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Re: MD: Sony MD mono workarounds...

2000-08-22 Thread Timothy P. Stockman


 I assume they are being combined before going through the
 MD's ADC

I beleive the ADC outputs a normal stereo signal.  The channels are combined
in the digital domain *after* the ADC, at least on the JE520.

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Re: MD: CD-DA

2000-08-22 Thread Timothy P. Stockman


 Rather, the CDDA is stored with an RF
 encoded carrier wave on the disc.  In other words, it's stored in
 analog.  Different transports will come up with slightly
 different sets of CDDA after reading it.

CDDA is *not* analog!  It is as digital as CDROM, your computer hard drive,
etc.  CDs use a sprial track (similar to an LP) that was originally designed
to be played continuously, not random accessed.  Unlike computer disks,
which have a header on each sector containing the sector number so the drive
can be 100% certain which sector it just read, CDDA contains no such
identifying information in each frame.  As long as you play CDDA
continuously (like an audio CD player does) there's no problem.  Since the
frames are in order on the disc, the data in the resulting audio stream will
be in order.  The problem comes in when one is extracting the digital audio
information to a WAV file.  In this case, the player does not read
continuously but instead reads the data in "chunks".  After each "chunk" it
has to seek back to where it left off before reading the next "chunk".
Since there is no header to unambiguously identify the frame, it seeks back
to *approximately* the same place, reading some overlapping data.  It then
compares the data and discards the overlapping data.  Some CDROM drives are
better at this than others.  A few are very bad, causing the program to give
up, but a few are perfect.  Most are somewhere in the middle.  But as long
as the program can identify the overlap, the resulting WAV file will be a
perfect copy of the audio data.




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MD: Sony MD mono workarounds...

2000-08-20 Thread Timothy P. Stockman


When recording mono from analog, it appears that it would be best to mix to
mono before the signal reaches the MD, then connect only one input channel
of the MD, leaving the other unconnected.  To get the level correct, the
digital record level would have to be set at +6 dB (higher is OK; lower
digital record level coupled with higher analog signal level might cause ADC
overload, which is *not* indicated by the "over" indicators).

Recording mono from digital would require a similar proceedure, done with an
audio editor on the PC: mix to mono and place the resulting mono mix on one
channel of a stereo WAV file and silence on the other channel, then boost
the digital record level 6 dB at the MD.

I see so easy way of making a digital mono recording directly from a CD
player an optical connection.  Maybe one way of fixing it would be to feed
the signal though an S/PDIF receiver, invert the LRCLK signal, then connect
to an S/PDIF transmitter.  This would reverse the left and right channels,
but it might also introduce a 1-sample shift.  Trouble is, it might be in
the same direction as the MD, resulting in a total shift of 2 samples.

That said, I think the effect of the 1-sample-error is fairly minimal in
many cases due to the steep slope of the high freqency rolloff, when viewed
in terms of the "octave" properties of hearing perception.  Also, most
listeners are much more tolerant of a very stable phase error such as this,
than an unstable error such as that caused by tape edge damage on analog
master tapes (for example, Neil Young's "Cinnamon Girl").

Meantime, I'll be eagerly awaiting word on which Sony decks have this
problem, and if (or when) Sony has it fixed for good!

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MD: minidisc on CNNfn

2000-08-17 Thread Timothy P. Stockman


It's nice to hear when MD vs MP3 is treated objectively in the media.

pros:
cheaper media
longer recording time
higher quality recording
wider choice of players
more editing/mix capabilities

I definitely agree with the "pros".  (I think higher recording quality is
based on the 128K MP3's that are widely available in the 'net; MP3 gives
fairly high quality at higher bit rates.)

cons:
double compression

The damage has been done by the 128K MP3 compression.  I think that ATRAC
4.5 or "R" compression makes an inaudible difference after that.

larger than mp3 players

True, but the R70 is really darn small.

needs high-end recorder

(???)  The R70 *is* a recorder.  It even has digital in.  The real con is
that your computer has to have digital out to use it.  Also, it only does 1X
transfer.  Sony *could* change that, though, to 2X if you used 88.2K on
something like a DIO2496.  Or maybe even 4X with USB.

Another point that would eliminate a potential advantage of MP3 is if there
was software to automatically transfer the titles from the MP3 files as they
were being recorded.


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MD: DIO2448

2000-08-15 Thread Timothy P. Stockman


I have had a DIO2448 for about 6 months.  I'm writing this because DIO2448
information is currently on the Minidisc Community page.  The DIO2448 has 6
connectors on the attached bracket: TOSlink in, TOSlink out, S/PDIF coax in,
S/PDIF coax out, and 2 RCA connectors for analog line level output.

The good features of the DIO2448 are:
1) High quality, low distortion, low noise analog output, much better than
many sound cards or motherboard audio.
2) TOSlink and coax digital inputs and outputs.
3) Native support for both 44.1KHz (MD) and 48KHz unlike some 48KHz only
outputs.
4) RCA analog output connectors; much more reliable than mini-phone jacks
due to the higher contact pressure.
5) Up to 24-bits supported.   Machines with ATRAC 4.5 generate 20-bit audio,
ATRAC "R" generate 24-bit audio.  But resolution greater that 16-bits is not
well supported by most PC software.
6) Low cost.  I got mine for $120.

The problems with the DIO2448 are:
1) Digital output not accepted by Sony MDS-PC2.
2) No digital input switching.  The TOSlink, coax and internal TTL header
are all ORed together, so you can only connect a signal to one at a time.

Routing features, may be useful, may be a problem, depeding on your
application:
1) Analog outputs can be switched to monitor the digital output or the
digital input.
2) Digital outputs can be switched to the DAC or to the digital inputs
("loop" mode).
3) No analog input, so you have to use the ADC in the minidisc.

Loop mode does *not* retime or modify the digital audio signal in any way.
Several people have suggested that I connect the S/PDIF header on my CDROM
to the header on the DIO2448 in an attempt to fix the "DIN unlock" problem
that occurs between tracks.  Not only does the *not* change anything, but it
effectively disables use of the TOSlink or coax inputs!

I've been using the DIO2448 for input (from the MDS-PC2) only.  I added a
TOSlink transmitter to my motherboard (16-bit only) and am using that to
transfer from the PC to the MD.





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MD: wish list for Sony et al

2000-08-14 Thread Timothy P. Stockman


I currently have an Sony MDS-PC2 MD recorder and a Sony CRX-120E USB CD
recorder.  This wish list covers both MD and CDR, since one of the things I
would like to see is better software integration.

1) For the MD: USB - USB - USB for both audio and control!  This would solve
a couple current problems:
  a) Sony MDS-PC2 does not accept S/PDIF from Midiman DIO2448.
  b) Eliminate the forest of cables between MDS-PC2 and computer.
  c) Eliminate the need for a sound card with digital I/O.
  d) Eliminate the CAV-50C and a need for an RS232 on the computer.

2) For the CDR: USB drivers that are compatible with other mass storage.  It
currently has *major* compatibility problems with my Iomega Zip 250 USB; I
can't have the drivers for both installed simultaneously.  Microsoft is the
root of this problem, since they don't provide much support for USB mass
storage under Windows 98, so each manufacturer hacked their own
(incompatible) support into Windows.   The goal of USB is to provide a
positive experience for the user: easy installation, hot swapping, etc.
This definitely fails miserably!

3) Integrated software that handles both MD and CDR.  One could start by
merging MD Editor 2 and CD Extreme into a single program.  Some neat
features:
  a) Easy drag and drop track-by-track copying from MD to CD and CD to MD,
all in the digital domain, including titles!
  b) One button "copy entire disk"; CD to MD and MD to CD.
  c) Support for copying to/from MP3 and/or WAV (CD Extreme has this, MD
Editor 2 does not).

One thing that is absent from my wish list is MD Data support via USB.  I
wouldn't complain if they implemented it, but I don't really need it.  I am
very comfortable using CDR for data archiving.


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Re: MD: cheaper optical cables

2000-08-13 Thread Timothy P. Stockman


I bought some Recoton TOSlink cables at Best Buy a few months ago.  They are
very flexable and work great.  The only thing that might be a problem is
that the TOSlink connectors are rather large; they just barely fit the
side-by-side jacks on the DIO2448...

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MD: monoaulizing algorithms...

2000-08-07 Thread Timothy P. Stockman


I will try to check my MDS-PC2 for the 1-sample-out-of-phase error,
providing I can figure out how to get Cool Edit to generate waveforms one
sample out-of-phase.  (I'll have to use a frequncy, say 15 KHz, sufficiently
below the filter cutoff to be unaffected and rotate the two channels to some
phase difference of less than 180 degrees that produces exactly 1 sample
delay.)  I will check using an optical connection from the computer.  Doing
this in the analog domain might pose some interesting problems.  I don't
know if I can get sample accurate phase from the the analog output of the
computer.

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MD: demor-- er, monauralizing algorithms

2000-08-02 Thread Timothy P. Stockman


L+R/2 is almost universally used.  FM broadcast is trasmitted this way for
comptibility with monaural receivers.  The "mono" switch on preamplifiers
does this.  However, this simple, almost universally used transformation
does not provide a perfect mono version of a stereo source.  The reason is
that stereo channels add by *power* acoustically, whereas the electrical sum
L+R/2 adds by *voltage*.  Therefore, when recordings mixed with prominent
material in the center of the sound image, such as vocals, bass, etc.  are
electrically mixed to mono (L+R/2), the sounds in the center of the stereo
will be 3dB higher in the resultant mono mix compared with those at the left
or right edge (known in the recording industry as the "3dB center buildup").

How to solve this?  sqrt(L^2+R^2) is one method.  This method would be
particluarly good for a DSP implementation.   Another method is to rotate
the phase of the channels with an "all-pass" filter so that they are 90
degrees apart and add in quadrature.  This method is better for an analog
implementation.

I'd love to see a deck that implemented the first solution!

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MD: Napster, RIAA

2000-07-30 Thread Timothy P. Stockman


I understand that the RIAA has done some good in protecting artist's and
recording company's rights to profit from their creations, but I really have
gotten tired of hearing them complain about how much money they're losing.
Did they ever stop to compute how much the music consumer has lost?  When I
replace an LP or cassette with a CD, do I get a special deal for the
"upgrade".  No such luck.  They tax all MD blanks, assuming that I will use
them *only* for copying copyrighted material, of which I do some, but I also
make much use of my MD to make voice recordings of my relatives for a
genealogical project.   These are the ways that I have lost money to the
RIAA.  Although I've never had a reason to defeat SCMS yet, but I don't feel
to bad about owning a CO3 (mainly for conversion from/to AES/EBU) or a
digital sound card, knowing that I have the capability to circumvent their
barrier if I even need to.  I don't feel bad about owning a Spressa CDRW,
that does not require audio CDRs to which the RIAA's tax has been added.
(Most of the CD's I write are data, anyway.)  To be honest, I've downloaded
some great tracks from the "starving artists" section of MP3.com because
they have a lot of stuff which is not available at record stores.  Its
somewhat of a production to download, decode and record to MD or write to
CD.  I've never downloaded from Napster, because the vast majority of what
is available there is also available at local record stores (or CDNOW, for
that matter).  I find it easier and achieve better results (than with the
highly variable encoding quality of many MP3s) if I just buy the CD and copy
off the tracks I like.

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Re: MD: whether MD tracks are files

2000-07-30 Thread Timothy P. Stockman


MD shares many of the characteristics of a computer file system.  It has a
freelist.  It has a directory.  One could even consider the track titles to
be sort of a "file name" although it doesn't mind duplicate titles, since
access is by track number.  Data chunks can be stored out-of-order.  MD
allows good editing features.

Contrast this with an audio CD.  It's directory is somewhat primative.
There is no freelist, hence the CDR mis-feature of adding/erasing only at
the end.  CDR has generally poor editing features.  Tracks must be stored
sequentially.   Track titles are not covered by the basic standard, but are
handled by the "CD text" extension, which most equipment and CDs don't
support.

MD is a lot closer to a traditional computer disk file system than CD.
Cassette is easily a poorer file system than CD or MD.  I can still remember
the early days of microcomputers, loading programs from cassettes and/or
paper tape.  How far we've come!

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Re: MD: Mini Disc to CD-R Transfer

2000-07-27 Thread Timothy P. Stockman


I have the hardware one would need hooked to my computer (Sony MDS-PC2 with
CAV50C,  Maudio DIO 2448 (although 2496 is recomened) Sony Spressa CDX-120E
USB CDRW).

The problem is that no unified software exists.  The MDS-PC2 is controlled
by the"Minidisc Editor 2" program, while the Spressa CD recorder is
controlled by the "CD Extreme" program.  The user interface of each program
is very different from the other and there is no easy way to get them to
"talk" to each other.

What I have done to date is to manually play each track from the MD using
the "record" function of CoolEdit to create a WAV file for each track.  Then
drag the WAV files into CD Extreme.   CD Extreme *does* allow you to title
the tracks on the CD, but again, there's no easy way.  I have to use the
Windows clipboard to copy and paste each track title individually.  (MD
Editor 2 allows me to save the entire track list to a CSV file, but CD
Extreme does not allow a "title" file to be imported.)

As you can see, this whole process requires a *lot* of manual intervention.
If Sony is reading this list, here is my wish list:

1) Better software integration.  Merge CD Extreme and MD Editor 2 into a
single program that controls both CDRW and MD.
2) Better MD - computer hardware interface.  Right now I have a sound card
with digital I/O and the CAV50C (supplied with the MDS-PC2) which uses up a
serial port on the PC.  Not to mention all the cables between the 'PC2 and
the PC.  All of this could be replaced by a USB jack on the MD, just like
the one on the Spressa CD recorder!

I know it would be a *big* job, but if someone has the time and would like
to write better PC software, that would solve much of the problem.

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Re: MD: Revolutionary?

2000-07-24 Thread Timothy P. Stockman


 Oh no, I _like_ the clamshell mechanism!

I have an 'R70 (clamshell) and an 'EP11 (slot-in).  The slot-in mechanism
feels a *lot* more solid.  I always feel as if I have to be super-gentle
with the R70.  I wish Sony was offering portable recorders with slot-in.
Especially recorders, because the magnet head assembly makes them even more
fragile than play-only...

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Re: MD: Is 128kbps MP3 bad? MD has loadsa life yet!

2000-07-16 Thread Timothy P. Stockman


 I've found that mp3s of songs with vocals sometimes do not transfer over
to
 MiniDisc well (analog), especially 128k files
...
 at 128, some of the higher
 stuff is muffled, or "combed" or really sharp.

I've noticed some minor problems with 128k MP3, sometimes sort of a "hard"
sounding high end, but 99% of the problems with MP3s are with the source
material (azimuth error on analog source tape, encoding from cheap computer
sound card, etc).  Some of the stuff I've picked up from MP3.com is fairly
well encoded and very enjoyable to listen to.  Mind you, *no* 128k file has
ever sounded as good as a well made CD or even an MD, if care is taken when
encoding, they can sound quite good.  For transfer to MD, I've used an
optical connection from the computer.  I use CoolEdit2000 (Fraunhofer
licensee) to decode the MP3 and play it back.

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Re: MD: mini vs mp3 recorder

2000-07-09 Thread Timothy P. Stockman


I think that solid state memory media *is* the wave of the future.  However,
I do see some drawbacks:

1) Right now, the cost of solid state is very high compared to MD:  $100 vs
$2.50 for the same amount of storage.

2) Right now standalone MD recorders are a mature technology, which means
they're very available at a resonable price.  Standalone MP3 recorders (as
opposed to *players*), are not very common.

3) MD media is a much better choice for archival recording that FLASH
memory.  FLASH uses floating gate technology.  Eventually the charge will
leak off of the floating gates, causing it to "forget", whereas the
recording on MD is more permanent (unless the disk is heated to "record"
temperature).

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MD: Sony MD and CDRW

2000-07-08 Thread Timothy P. Stockman


I just purchased a Sony CRX100E/X2 CD recorder, which has a USB interface.
I also have a MDS-PC2 MD drive connected to my computer.  So far my wish
list includes two general items:

1) The CRX100E/X2's USB hardware interface is just great!  I'd like to see
something like that when Sony gets around to making an MDS-PC3.  It's much
less complicated and less expensive than the cumbersome hardware interface
on the MDS-PC2.

2) I'd like to see some integration of the software.  Right now there are
two separate programs:  "CD Extreme" for the CDRW and "MD Editor 2" for the
MD.  I'd like to see a consistant, single program that could operate both
types of device.

I'd be interested in any opinions concerning the future of MD and CD in
multimedia computing.

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MD: MS stereo microphone

2000-06-29 Thread Timothy P. Stockman


Anyone have any experience with Sony's ECM-MS907?  It's a very reasonalbly
priced mid-side microphone.  I'd be interested to know if they use a
specially manufactured figure-of-8 electret capsule to generate the "S"
signal; I'm not aware of general availability figure-of-8 electret
capsules...  Any of the microphone gurus that read md-l know where to get
figure-of-8 electret capsules?

http://www.sel.sony.com/SEL/consumer/ss5/home/accessories/microphonesfordigi
tal/ecm-ms907_specs.shtml

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MD: Sony MD changer in car on non Sony head unit

2000-05-18 Thread Timothy P. Stockman


 there is an undocumented +12 volt trigger output on the RM-X69RF
controller

I am using this wire successfully in my installation.  I have a classic 1965
Ford Fairlane in which has modern electronics in the original radio case.
Inside the radio, I have a 12VDC DPDT relay controlled by the RMX69RF's
"trigger" output that switches the audio.  Works great!

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MD: amps with digital in/out

2000-05-16 Thread Timothy P. Stockman


Thought I would add this to the discussion:  The amps with digital I/O that
are available now are analog amplifiers with built-in D/A convertors.  Some
of the high-end models use DSP for level, tone/equalization, reverb, etc,
but all eventually convert the signal to analog and pass it through an
analog power amp.  However, there are several companies that are close to
changing that!  They use a DSP to convert the incoming signal to bi-level or
tri-level pulse-width modulated.  The PWM signal switches high voltage
(100V), high current MOSFETs.  The output of the MOSFETs goes through a
passive low-pass filter and then directly to the speakers.  A neat approach,
because the signal remains in the digital domain until the last moment...

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re: MD: compression (correcting a couple errors)

2000-05-02 Thread Timothy P. Stockman


1.  On the VHS SP vs EP discussion:  EP *always* results in inferior quality
compared to SP because the helical tracks *overlap* in EP mode (they do not
in SP), causing a reduced S/N ratio.
2.  On the cellular discussion:  Although normal cellular uses analog FM
audio transmission (non-compressed), the carrier almost always converts it
to digital and use heavy compression between the tower site and the switch.

I think that a formal compression system implies the capability of
expansion.  Sampling at a lower rate throws away information with no hope of
recovery...

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MD: CD/MP3/MD story

2000-04-26 Thread Timothy P. Stockman


It sounds like a radio and nothing like my cd's" this coming from a 15 =
year old female who IMO is not an audiophile at all

As one who spent many years as an engineer at an US FM radio station, I can
say that radio stations work hard to sound bad!  FM radio inherently sounds
very much like a CD, but the typical station feeds the audio through several
thousand dollars worth of processing equipment to screw it up before it gets
to the transmitter.

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MD: analog quality (was Sony Minidisk Recorder with USB)

2000-04-18 Thread Timothy P. Stockman


I find that, even when transfering 128K MP3 to MD, it is best to use digital
I/O so further degradation does not occur.  Analog sound cards often have a
much poorer S/N ratio than the original MP3 file, and they often have
frequency response or phase shift errors at low frequencies due to
undersized coupling capacitors.  The major analog problems are almost never
in the codec chips, but rather are in the supporting circuitry (power
supply, coupling capacitors, circuit topology and ground layout).  Since MP3
intrinsically introduces a different set of problems, the analog problems
get added to the already far-from-perfect MP3 source...  I haven't studied
the MP3 specs enough to know if 16 vs 20 vs 24 bit digital I/O makes a
difference.  But I do know that, given the analog quality of typical sound
cards, digital I/O is definitly better transfering MP3 to MD.

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MD: Salvaging a recording made with levels set too high?

2000-04-14 Thread Timothy P. Stockman


The result you achieve will depend on how much effort you put into it.  If
its a *really* important recording, you can use Cool Edit (or your favorite
audio editor program) to painstakingly find every annoying pop produced by
the clipping and delete the offending samples.  You have to zoom *way* in,
because often you need to delete only a couple samples at each point, but
you have to do this literally hundreds of times.  I spent about a week worth
of free time once restoring a 12 minute song that had quite a bit of
clipping because it was an unbelievably great live performance.

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MD: Mains cable as Speaker cable

2000-04-13 Thread Timothy P. Stockman


The largest improvement, especially at low frequencies, come from low
resistance.  Since the speaker itself is only a few ohms, series resistance
added by small gauge cable and normal connectors will quickly destroy the
high damping factor of modern solid-state amplifiers.  The PA rig I built
several years ago used 12 AWG rubber covered mains cable with 277V
twist-lock power connectors.  (I chose 277V since that power voltage is used
only for industrial lighting and is never present elsewhere so the speakers
would not get plugged into the power mains by mistake, although the woofers
would have withstood this, very loudly! :-)

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MD: dataplay

2000-04-09 Thread Timothy P. Stockman


It's a neat idea.  The small size would be attractive for integration with
palm computing.  But, if the Wired article is right, Dataplay is write-once.
Sounds like a problem to me.  One of the things I like about minidisc is the
ability to re-write if I make a mistake.  Although it sounds like Dataplay
has addressed most all of the other problems of CDR, its apparent lack of
rewritability is a major flaw, so far as I can see.

The only flaw of expanding minidisc into other applications, for instance
palm computing, is that its size is almost to large.  The MDs size is
probably due to the fact that in the early 90s when the format was designed,
the present size is about as good as they could do while keeping the cost
reasonable.  With some effort though, it might be possible to cram a slot-in
MD recorder into a Palm III sized palmtop computer...

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MD: MP3 to Optical Out

2000-04-06 Thread Timothy P. Stockman


I am using a DIO2448 (well, sort of) optically connected to a Sony MDS-PC2.
If you have a motherboard sound system, you will have to use the control
panel to select the DIO2448 as the wave playback device.   After that, the
problem I experienced is that the MDS-PC2 does not lock properly to
DIO2448's signal.  According to M Audio tech support, there is some quirk
with Sony's S/PDIF implementation...  However, the DIO2448 *does* accept the
S/PDIF *from* the MDS-PC2.  Therefore, I am only able to use the DIO2448 for
transfering from MD to HD.  I added a TOSlink transmitter to my
motherboard's codec for transfering from HD to MD.

When you get things working properly, the MD will be able to record
everything that comes out of the WAV audio.  I usually use Cool Edit for
playback from the HD, but have even recorded to MD successfully from Real
Player.

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MD: coax vs toslink...

2000-04-03 Thread Timothy P. Stockman


I think the purists prefer coax to toslink because the slight timing
ambiguity instroduced by the multi-mode fiber can't pass their pico-second
jitter specs.  However, jitter is only important when driving a DAC, and
every "good" DAC has a sophisticated timing recovery circuit in the
receiver.  If everything works as it should there is NO difference in the
signal delivered to the DAC.

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MD: MZ-R70

2000-03-31 Thread Timothy P. Stockman


I just received an MZ-R70 from Minidisco.  The plan is to use this portable
recorder to record interviews with family members for a genealogy project.
The unit is very small, compared to my MZ-EP11, and I find that its
clamshell mechanism feels a bit more delicate than the slot-in mechanism of
the MZ-EP11.  As was noted, it makes a quite audible noise at intervals,
which would prohibit using a "T" mic mounted on the jack.  I'm planning on
using a couple "tic-clip" mics with long cables, so this shouldn't be a big
problem.  (The MZ-EP11 is comparatively rather quiet.)  The MZ-R70's
front-panel buttons are much easier to operate than those on the MZ-EP11.
Interesting to note: the MZ-R70 has 2 headphone jacks, one next to the
line-in and mic jacks and another as part of connector for the remote.  The
jacks are color coded: black for headphones, white for line/digital in and
red for mic in.  One nice touch on the MZ-R70 LCD display is a 10-segment
level meter (with 1-second peak hold) which operates during both record and
playback.  As usual with portable Sony recorders, the MZ-R70 requires one to
press the annoying "END SEARCH" button when recording.

All told, this recorder looks like an good deal for a rather low price.
Now, does anyone know a good source of Mogami 2697 cable to make microphone
cords?

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MD: portable recorder recomendation?

2000-03-26 Thread Timothy P. Stockman


Hi,

I'm looking for a portable MD recorder for my sister to use for recording
interviews with my relatives for a family genealogy project.  She's not
gadget-phobic, but I'd like to keep operation as simple as possible so she
can put her thought into the interview, not the recorder.  I think the
following features would be nice:

1) NO END SEARCH.  Since I'll be "cleaning up" the raw recordings she makes,
I'd rather that she doesn't record over anything.  This probably rules out
Sony...
2) Manual record level from the microphones, which I'll set before send the
recorder to her.  MD has *plenty* of dynamic range, so I can get away with
setting it plenty low to avoid overload.
3) Long record time.  Don't know whether she'll prefer alkalines or
recharagables, but this is much more important than small size, so a unit
that has multiple cells or even an external pack (if the whole thing could
fit into some sort of bag, if it could be operated without removing it from
the bag) would be OK.

My plan is to use 2 clip-on mics, one for her and one for the interviewee.
I would set up the recorder to record her on one channel and the other
person on the other.  That way I'd have a good opportunity to balance
things.  I'd do the clean-up with Cool Edit 2000, then transfer the
resulting mono back to MD.

Any recomendations?

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RE: MD: CD-rom to soundcard?

2000-03-21 Thread Timothy P. Stockman


 do you have to digitally connect your cd-rom drive to your
 soundcard to make
 use of the digital out on the soundcard?

Here's my experience with a Samsung 40X CDROM and an M Audio DIO2448.  The
Samsung does have an S/PDIF (TTL level) header, but the problem is that it
does not produce a valid signal unless the drive is playing an audio CD.
This causes glitches when the drive starts playing or seeks to a new track.
The sound card *does not* remove these glitches.  The only way to dub from
the CDROM via S/PDIF to the MD is to play the last few seconds of the
previous track and start recording at the beginning of the desired track.

There is reportadly a real-time CD ripping plug-in for winamp.  CD ripping
is *not* a trivial task, since the CD data format and CDROM drives were not
designed to do it reliably.  The performance you achieve will be highly
dependent on the drive model and CPU speed.

A standard CD audio drive with digital output is still by far the best
way...

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MD: MDX-65RF

2000-03-19 Thread Timothy P. Stockman


Hey, the display looks exactly like the one that comes with the RMX-69RF!
I've got 3 regular MDX-65s in the trunk (with a XA-C30 switcher) that are
controlled by an RMX-69RF.  With this arrangement, I could expand up to 7
changers (any combination of MD or CD) by cascading up to 2 more XA-C30s.
What I'd really like to add, though, is a Unilink digital radio to receive
the satellite broadcasts that will begin in North America this year.  Don't
know if they planned this far ahead when they made the RXX-69RF...

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MD: Why USB?

2000-03-17 Thread Timothy P. Stockman


I'm glad the MD - USB thread has proven to be a lively topic of
discussion!  You'll get no argument from me that USB is not technically the
"best" interface.  However, it might turn out to be the very popular for
these reasons:

1) USB is available on the motherboard of almost every new computer these
days and there are a wide variety of USB peripherals.  It is multi-drop
(unlike serial RS232) and *designed* from the start to be two-way (unlike
the printer port).  It is cheap (unlike SCSI).

2) There are many advantages over current methods of digital transfer
(TOSlink/SPDIF/ControlA1).  Although TOSlink/SPDIF can theoretically hand
high speed transfer, there is no readily available hardware for faster than
96K (2x).  TOSlink/SPDIF is uni-directional, so you need 2 cables to go both
directions.  TOSlink/SPDIF has no "flow control" or retransmission; one has
to be careful of buffer overruns/underruns with Windows.  TOSlink/SPDIF does
not handle deck control; you must use a separate ControlA1 (or other more
primative) interface.  Beside handling all these functions in one cable, USB
would also supply the modest power requirements of a portable MD recorder!
So it would essentially replace 4 cables to the MD with one cable, certainly
an important point when considering the compact size of a portable MD
recorder.

3)  It would be a simple, incremental improvement from the manufacturing
point-of-view.  This is important, because no manufacturer wants to incure
the possibility of out-of-control costs associated with a more open-ended
design project.  Adding USB capability to a portable MD recorder would be a
fairly "contained" design effort, constrained to the single chip that
implemented the USB interface.  No transport modifications would be required
to implement high-speed transfer, since the MD transport in most machines
can already run at 5X speed.

I know USB is not the ultimate in terms of performance, but it could be the
most cost-effective.  Judging from what I've seen on MD-L, cost is a *big*
incentive.

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MD: JB940

2000-03-11 Thread Timothy P. Stockman


The 5 hour mode that everyone has generated such interest is indeed a neat
feature, but the feature that is most inseresting to me is the ability to
change the level of already-recorded tracks.  I'm guessing that this feature
uses an entry in the UTOC for each track that specifies how much the to
shift the level *during playback* of that track, without actually changing
the audio on the disc.  This idea was mentioned once a while back by someone
on the md-l.  Is anyone still interested in this level-shift feature?

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MD: Sony JB940 info...

2000-03-08 Thread Timothy P. Stockman


http://www.video-direct.com/news/preview3-7/mdsjb940.html

Sony MegaStorage® CD Changer Control

CD Text and Custom FileT Transfer from CD Via Control A-1 II

Coaxial and Optical Digital Inputs and Outputs

Long Play Mode - Captures up to 5 hours, 20 minutes of stereo music on a
single 80-minute MiniDisc

Scale Factor Edit - Enables you to adjust the volume of MiniDisc tracks even
after they're recorded. Equalizes tracks recorded from different sources

Disc and Track Titling Through PC Keyboard

Playback Pitch Control

ATRAC Type "R"

I wonder how they implemented "long play mode", by using a low sample rate?
I also wonder about scale factor edit.  Does it actually rewrite the entire
audio track or does it make a change in the UTOC which then gets applied to
the track during playback.  I'll be on the edge of my seat awaiting the
answers!  Hope someone gets one soon so they can give us a report...

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Re: MD: Sony USB 2nd try?

2000-03-06 Thread Timothy P. Stockman


Here's an interesting thought.  If someone *does* buy the Sony USB adapter,
could they pry it open and let me know the numbers on the chips.  Might be
that the codec chip has an S/PDIF output pin (fairly likely with modern
codecs).  Its less likely to have and S/PDIF input pin.  If Sony has used
their own chips, documentation might be hard to come by.  But they used a
NEC microprocessor in the CAV-50C interface, so maybe their latest trend is
to move away from designing their own chips for everything.

One other comment: S/PDIF I/O is, in general, less of a design hassle than
analog I/O.  The only reason it is currently more expensive is
economy-of-scale.  If manufacturers roll out S/PDIF sound cards in the
quantity they do with analog sound cards, the price will go *way* down,
becuase S/PDIF is actually *simpler* from the manufacturing standpoint.

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Re: MD: Sony's new Internet Audio Recording Interface

2000-03-03 Thread Timothy P. Stockman


 Is S/PDIF hard to generate?

Computer audio chips tend to send/receive it right with pins on the main
sound chip and CD/MD equipment also tends to have it integrated at the chip
level (this is the most economical way to do it).  So my guess is that it's
no big deal, if Sony has designed a special chip.  Alternatively, Crystal
Semiconductor makes generic S/PDIF transmitter receiver chips.

 Make it run at a special 4X or 8x S/PDIF rate, so that a portable
 MD player could compete in downloading convenience with an MP3
  player.

4X is no big deal if Sony designs their own chips (both in the interface and
the MD).  So far as I know, the highest speed that the Crystal chips run at
is 96K (there's not a big market for higher speed yet), which would at least
handle the 88.2K rate for 2X transfer.  I think the fastest USB transfer
rate would limit things to 4X or so...

I'm hoping that the USB - MD interface is so successful that Sony starts
putting it into new recorders at the chip level.  That would allow them to
produce USB-enabled MD recorders for little more than the price of the USB
connector!  If they did it at the chip level, maybe they could (in the
future) revive MD data, so you could make the MD recorder do double duty.
(Although MD data disks are expensive right now, its only because the market
is extremely small compared to the audio market.  If there was a large base
of MD data equipment; they price would come down.  As a matter of fact,
since there's no "SCMS tax" on data disks, it could go even lower!)


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MD: Ken Pohlmann Principles of Digital Audio 4th ed...

2000-03-03 Thread Timothy P. Stockman


"Priciples of Digital Audio - 4th", considered by many to be the "bible" of
digital audio theory, is now available.  My copy, which was pre-ordered at
BN.com, arrived yesterday.  The latest edition is up to 736 pages, and
contains an entire chapter on MD, as well as chapters for CD, DAT, DVD, PC
audio and digital broadcasting.  I've not had a chance for detailed reading
yet, but it seems to bring together a *lot* of basic theory together in one
place.  Maybe not enough to actually build the devices it talks about, but
certainly plenty of information to conduct an intellegent conversation with
those who do build the stuff.

All in all, a great reference book!

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Re: MD: Micro keyboard for titling

2000-03-02 Thread Timothy P. Stockman


There is your answer ... MD connected to a Palm Pilot

I have a Palm III and various MD equipment.  At this point, the *only*
common connection is IR, specifically, the Palm with send/receive IR and my
JE520 and MDS-PC2 will receive it.  The Palm will send/receive RS232 and,
with the addition of the CAV-50C RS232/Slink interface, so will the MDS-PC2.
But I think it would be better to concentrate on the portables, rather than
these home-type decks.

I think the best solution for *existing* portable MD would be a cable that
connected the RS232 hotsync on the Palm to the 4-pin remote connector on the
MD.   Two of the 4 pins are control, which is normally implemented by a
resistor ladder and pushbuttons, but I've seen PC interfaces that use CMOS
analog switches.  The other two are data from the MD to the LCD (or the
label printer).  Looks like an opportunity to use a PIC single-chip
microprocessor to make the connection.

I'm sure that it would be possible to write a Palm program similar to the PC
program Sony supplies with the MDs-PC2.  Might make me think of replacing my
MZ-EP11 player with a portable recorder!

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MD: crossfade between tracks (was: My Diamond Rio Experience)

2000-02-23 Thread Timothy P. Stockman


could shock memory be replaced with the ability to eliminate silence and
have a good transition between songs? Like those CD changers that take 5 to
10 seconds to change disks, can you set them to record some in memory so by
the time the disk has to change, you could have gapless playing?

Sony megadisk CD changers will do crossfade transitions if you have two
changers.
The Sony MDX65 car changer does disc change without interruption (but not
crossfade) using the shock memory.

I'd like to see a crossfade feature that works regardless of whether the
tracks are
on the same disc, different disc in the same changer or different disc in a
different changer.
Given a sufficient amount of RAM, it doesn't look like it would be a big
deal...  In an
ideal implementation, it would be user adjustable, say from a uniform 5
second gap
between tracks to a 5 second overlap.


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MD: MD USB summary...

2000-02-22 Thread Timothy P. Stockman


First, a quick thanks to all who have taken part so far in this thread.
Much of the discussion has centered aroung the obvious fact that an MD with
a USB port starts to look similar to an MP3 player to the user.  This is
indeed true, but my original reason for proposing USB for MD was to
eliminate the many problems of S/PDIF / TOSlink / Control-A1.  So far as I
know, the software for making automatic MD compilations from CD/WAV/MP3/RA
is limited to non-existant.  I feel this is mostly because there are too
many competing "standards" for deck control and, to a lesser extent, because
S/PDIF is somewhat problematic due to poor adherence to the EIAJ standards
and due to its lack of flow control.

Already, I use RealAudio and MP3 as a substitute for the radio.  This gives
me access to a much wider variety of programming than is available
over-the-air.  It would be great to have software that allowed me to do
unattended "timer" recordings of streaming audio feeds.  This would allow me
to listen to some of what's available on the Internet when I'm away from the
computer, for example driving in the car.

It's my feeling that USB on MD is a small step in the direction of
unification and standardization that would advance the development of
hardware and software which would allow people to use MD in ways that we
haven't even though of yet.  A totally different solution on the horizon at
this point is dedicated Internet audio appliances (http://www.kerbango.com 
http://www.penguinradio.com), but we'll definitely be at the vendor's mercy
when it comes support (or lack thereof) for interfacing with MD.  In
summary, I believe that USB on MD would be an simple, inexpensive and
reliable method of connecting an MD to a PC that would greatly expand the
usefulness of the MD audio medium.

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Re: MD: Stop press: The Cassette is back!

2000-02-22 Thread Timothy P. Stockman


Wow! A $200 cassette!  Do you want fries with that?

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MD: CDROM digital output

2000-02-21 Thread Timothy P. Stockman


I've received more than one suggestion that I run the CDROM's digital output
through my sound card and somehow the digital output from the sound card
will be valid when the CDROM is not playing.  I have a DIO2448, which does
have a header for the CDROM's digital signal.  Running it though the sound
card makes no difference.  To get the CDROMs signal to the TOSlink output on
the card, the card must be in "pass through" mode, where it is routing one
of its digital inputs to the digital outputs.  In this mode, the output is
not valid unless the input is valid.

The basic problem that seems to be confusing everyone is that the S/PDIF
signal is a *synchronous* signal where the clock and data are encoded onto
the same signal.  (The technique they use is called Manchester encoding.)
The clock must be extracted at the receiving device using a
phase-locked-loop.  This has two problems:

1) The PLL has a finite lock time, so you end up missing the first several
samples before lock occurs.  Remember, this is *synchrounous*, unlike normal
RS232, which is asynchronous acquires sync on every byte.
2) The extracted clock may be unstable, depending on the data.  Certain data
patterns are worse than others.  Stability is improved by increasing the
lock time.  Good receivers use a two speed lock algorithm: high speed when
acquiring lock and slow speed to improve stability, once lock is acquired.

There is no magic that the soundcard can do to acquire lock that the MD
cannot do.  The damage caused by interrupting the S/PDIF stream is
irreversable.  The bottom line is: it takes a finite amount of time to
re-acquire lock, regardless of whether its a sound card, an MD, a DAC or
whatever...

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MD: USB - MD

2000-02-21 Thread Timothy P. Stockman


I just thought of one more advantage if the MD had USB from transfering
digital audio the PC:  flow control.  The data flow on the USB can be
throttled by the sender or the receiver.  S/PDIF, OTOH, *must* continue
uninterrupted.  If you get a buffer overrun/underrun, too bad, it'll put a
skip or a dropout in the audio... For S/PDIF to work, you have to have
plenty of excess CPU speed.  I also find it helps to close all unnecessary
programs.

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MD: MP3 - MD

2000-02-19 Thread Timothy P. Stockman


With my new computer and MDS-PC2, I've been making compilations of MP3s on
MD for the past couple weeks.   While the "playlist" method using winamp or
Real jukebox will produce satifactory results, I've been using Cool Edit
2000 to play back songs one-at-a-time.  This has allowed me to catch and
correct problems with the MP3 files, generally level-related, although the
occasional file has had a DC offset problem.  One problem I have noted with
Cool Edit is that it "remembers" the value of the last sample that was
played, so if you play a bit of the file as a test, then stop playback, it
will produce a pop when it is restarted at the beginning unless silence is
played first.  I've been using a TOSlink connection from the PC to the MD,
with excellent results.

My impression is that, while MP3 encoding produces more audible artifacts
than ATRAC, one can achieve very satisfactory results from well encoded MP3
(128Kb) files.  The most frequent problem with MP3 files seems to be
clipping from excessive "overs" resulting from too-high levels.  Second on
the problem list is aliasing, probably caused by doing A/D conversion on a
computer sound card with a poor anti-alias filter.  I've heard some really
good sounding (and also some really bad sounding) MP3 files, so my guess is
that a lot of the flaws often attributed to poor MP3 sound is really the
result of poor encoding practices.

In summary, I feel that the MP3/MD marriage will bring me a lot of musical
enjoyment by allowing me to hear a lot of great music that I would otherwise
not be exposed to.

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MD: MDS-PC2 bugs

2000-02-19 Thread Timothy P. Stockman


Here's a problem I've noticed periodically with the MD Editor 2 program that
is bundled with the MDS-PC2.  Sometimes when adding tracks to an MD that
already has a few tracks, some of the titles on the pre-existing tracks get
screwed up *on the MD edit window* but not on the UTOC.  I think this is
because only writes new titles to the MDS-PC2s RAM when you make changes.
So ejecting and re-inserting the MD fixes the display.  Boy I caused my
heart to skip a beat the first time!  But I've learned that it can safely be
ignored...

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MD: Sony MD-Cam - 650MB - 4.5 hr audio!

2000-02-18 Thread Timothy P. Stockman


Video Direct is now selling the Sony MD Camera with the new 650MB MD drive.
Among other things, it will record 4.5 hours of audio!
http://www.video-direct.com/sony/mddiscam/mddiscam.html

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MD: MD - PC connection

2000-02-17 Thread Timothy P. Stockman


In my previous post (about the Sony commercial), I made the observation that
transfering between PC and MD is extremely problematic at this point (1X
transfer via S/PDIF or analog, titling via Slink, IR, etc).  This response
seemed somewhat interesting:

 better use a USB or FireWire

Adding a USB connector to an MD deck is a great idea, especially one such as
the MDS-PC2, which is made *specifically* for connection to a PC.  I believe
the high-speed mode on USB is 12Mbit/s, which is enough to transfer audio at
a little better than 4X!  Given that the most MD current transport
mechanisms are designed to run at about 5X when filling/emptying the buffer,
this looks like an easy change for the manufacturers to implement by simply
designing a data coder/decoder chip with USB pins on it.  Basicallly, the
rest of the deck design would remain unchanged.  2X and 4X CD - MD decks
(that use standard MD transport mechanisms) are already a fairly common...
The USB connector is physically small, so it would work great on a portable
MD recorder and given the modest power requirement of modern MD portables,
the USB could probably power the MD as well as transfering audio, titling
and remote control.  Wow, this would certainly cut down on the forest of
wires I've got with my MDS-PC2!

FireWire is a possiblility, but its not near commonplace as the now
ubiquitous USB connectors on new computers, and while its extremely high
transfer rate would be nice, it would require extensive design changes, such
as higher-speed MD transports, etc, to exploit its high speed.  Maybe down
the road...

Man, I'm excited just thinking about the implications of USB!  Now this
would make MD a *clear* winner over the MP3 players!  Sony, let me know if
this type of thing is in the works; I'm ready to buy it now...




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MD: Sony MD commercial

2000-02-15 Thread Timothy P. Stockman


I've seen the Sony MD commercial on MTV serveral time now selling MD as a
way to record music from the Internet.  While I think it's great that we're
finally seeing MD ads, I wonder if this is really the right approach.  I am
a big supporter of MD, specifically Sony (I have a JE520, an MZ-EP11, an
MDS-PC2 and 3 MDX-65s), but it seems to me that its *more* difficult to
record MP3s to MD than it is to, for example, a Rio.  It takes longer, since
the MD has to be recorded at 1X; the titles don't transfer automatically,
etc.  I'm afraid these commercials might backfire if MD newbies are
disappointed when they find out that MD is actually not the best format for
this specific application.

Sony *could* have addressed some of these issues:

1) There are digital soundcards that will support 88.2KHz, so 2X transfers
would be possible today if  it was supported by the firmware in the MD
recorder; the hardware already mostly supports it!  Not much PC support for
higher than 96KHz yet, but that may change with DVD-computer integration; I
think AC-3 uses 192 or 384K, so theoretically 4X and 8X would be possible as
newer soundcards become available.

2) Some PC software to make things easier.  Drag-and-drop hard disk to MD.
Maybe somehow integrate a CD ripper into it, so that you could just do
drag-and-drop beween the CDROM, MD, or HD.

3) Right now, the digital audio goes via TOSlink and the control goes via
control-A1 (which portable recorders don't have).  Maybe they could figure
out a clever way of embedding deck control into the user bits of the
TOSlink.  That would certainly make it a *lot* simpler to set up...

Any thoughts about this?



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Re: MD: Digital out ...

2000-02-09 Thread Timothy P. Stockman


Adding digital out *may* be as simple as adding a TOSlink transmitter *if*
the data decoder chip has an S/PDIF output pin.  Most modern ones do.  If
not, it will involve adding a digital audio transmitter chip, like the
CS8401, to take the serial data/bit clock/frame sync signals from the output
of the data decoder and encode them into S/PDIF.  I've done it both ways in
home CD players, where there's tons of room to add the extra parts, but I
wouldn't want to try it in the cramped quarters inside a portable MD unit...

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MD: S/PDIF channel status user bits

2000-02-07 Thread Timothy P. Stockman


Just wondering if anyone knows of a program to display the contents of the
channel status and user bits from an S/PDIF data stream?  I've got an M
Audio DIO2448 soundcard (CMI8738 chip).  One alternative I may investigate
is connecting the "C" (channel status) and "U" (user bits) pins from a
CS8414 receiver chip to the 'scope to get a rough idea of what's there.

Also, does anyone have access to the EIAJ standards that describe S/PDIF?
Some information about the channel status bits is available in Crystal
Semiconductor's now (in)famous AN22...  Does anyone know how much of this is
implemented by average consumer equipment?  Are there any extensions?  Is
there any infomation about the user bits?

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Re: MD: SLINK for interfacing with MD

2000-02-01 Thread Timothy P. Stockman


Sony makes an RS232 - control-A1 convertor, the CAV-50C.  Its a very small
box with an attached 1 foot cable terminated in a DE-9F, which plugs into
the serial port.  It requires no external power; it is powered by DTR from
the serial port.  It comes with the MDS-PC2.  Maybe you could order it
separately directly from Sony.

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MD: MDS-PC2 review (long)

2000-01-30 Thread Timothy P. Stockman


This review is in two parts:  (1) the MDS-PC2 deck and (2) the PC Interface.

Physically, the front panel of the MDS-PC2 is slightly larger than a
half-height 5.25 floppy drive.  Along the left side is (from top to bottom)
the Power button (standby/operate), the IR sensor for the remote, a
mini-phone jack for headphones and the Input selector (analog/optical
1/optical2).  Buttons on the right side are (top to bottom) are Eject,
Play/Pause, Back, Forward, Stop and Record.  The front panel Back and
Forward buttons operate like those on a portable.  That is, pressing quickly
causes it to skip to the next/previous track (the | and | functions),
while holding the button down gives foward and rewind (the  and 
funtions).  However, the buttons on the supplied remote are like a normal
home deck.  That is, there are four separate buttons: |  |.
Also on the front panel is a 1-line flourecent display, similar to the
displays on normal Sony home MD decks. The case is surprisingly deep.  On
the rear panel is a non-detachable mains cord, two mini phone jacks wired in
parallel for the Control A1, a TOSlink optical output, 2 TOSlink optical
inputs and 4 RCA jacks for the analog line inputs and line outputs.

The deck itself is electrically very similar to the JE520 in my stereo
system.  It uses ATRAC 4.5 and produces 20-bit digital output.  The front
panel controls are very limited (there's no menu button, for instance), but
all of the controls that I have come to expect on a home minidisc deck are
available on the supplied IR remote.  Operating the MDS-PC2 from the remote
is almost identical to operating the JE520.  Most features I tried operated
flawlessly, however the A-B erase mode (which I use to trim off the excess
recording at the start of the song) seemed to crash when I tried to move the
"B" edit point forward a frame with the | button.  While not essential for
playing discs, the remote is needed when recording if it is necessary to
access the level meters (with the display button on the remote) or adjust
the record level.

The computer interface is a small box labeled "Vision Touch CAV-50C".  It
has an attached 1 foot cable with DE-9F for connection to the computer's
serial port and a single mini-phone jack for connection to the Control A1
cable from the deck.  It contains an NEC 78082GA26 single chip CPU, a Maxim
3221 RS232 interface and various other parts.  It requires no external
power; it is powered by the DTR line from the computer.  The interface only
works with a normal PC-type serial interface; it will not work with
high-speed PCI serial cards.

The installation instructions suggest using analog audio connections to the
computer.  At first I thought this strange, but given the experiences I've
had the past few weeks, I can see that they do this because they can be sure
it will work.  I have been unsuccessful with connecting the S/PDIF output
from my Samsung SC140 CDROM because it, like most other CDROM drives, only
outputs valid S/PDIF data when playing, not during stop, pause or seek.
This is unusable with Sony's drag-and-drop software.  The digital inputs on
the MDS-PC2 seem also seem to have a problem accepting 16-bit S/PDIF from my
M Audio DIO2448 sound card, although the DIO2448's S/PDIF input does accept
the MDS-PC2's output (at least 16-bits of it; Cool Edit 2000 is prone to
skipping (probably needs something faster than my 433 Celeron) if I use it's
32-bit mode, which is necessary to completely capture to 20-bit output of
the MDS-PC2).  The MDS-PC2 *does* accept the 16-bit S/PDIF from the CS4299
codec on the computer's motherboard.  Sound confusing?  That's probably why
Sony recommends analog!

The PC software comes on a CDROM along with a label making program and a
user operation manual in PDF format (the only written instructions that come
with the software are the installation instructions).  Installation is very
simple, just insert the disk and click on the install buttons.  Operation is
fairly intuitive.  Upon starting the MD program, you are presented with a
"remote control" bar that has title readout, running time, and play, stop,
next track previous track buttons.  There's also a unit select drop down box
on the left that allows you to select the device you're controlling: the MD
deck, the CDROM drive (PC CD) or an external CD player (via Control A1).
For more complex functions, there's a drop-down button on the right that
brings up an "edit" menu bar with, from which you can select the MD edit
window, an edit window for an external CD player,
an edit window for the CDROM player, an edit window that has the external CD
and the MD for drag-and-drop copying from CD to MD and an edit window with
the CDROM and MD for drag-and-drop.  Some may find mildly annoying the fact
that *all* windows in the program are fixed size and cannot be resized, but
usually it's not a problem.

Hands down, the best feature of the MD edit window is the track titling
feature.  When a minidisc is inserted, 

MD: CDROM - stable S/PDIF

2000-01-29 Thread Timothy P. Stockman


A question and an observation...

Can anyone recomend (or point me to) which CDROMs have an S/PDIF output that
is stable during pause, seek, etc.

I think that stable S/PDIF is necessary regardless of whether the CDROM is
connected to an MD recorder or a sound card.  The S/PDIF receiver chip (the
most popular are Crystal CS8412  CS8414) has a PLL to extract the clock
signal, which requires a finite amount of lock time.  It *does not* lock on
the first frame!

That said, I have to give poor marks to the S/PDIF inputs on the Sony
MDS-PC2.  They are unable to lock to the S/PDIF from an M Audio DIO2448 and
they MDS-PC2 requires longer than it should to lock to to CDROM's S/PDIF
after it glitches.  This may have to do with the fact that it tries to lay
down (multiple) track marks when the S/PDIF lock is shaky.  (M Audio tech
support did finally get back to me, stating that Sony products were known to
have problems sometimes with accepting S/PDIF from non-Sony.)



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MD: Samsung CDROM to Sony MDS-PC2 problems...

2000-01-28 Thread Timothy P. Stockman


Well, I took time this evening to connect a TOSlink transmitter to the
S/PDIF output of the Samsung CDROM drive so I could try the drag-and-drop CD
to MD feature in the Sony MDS-PC2's PC software.  The problem I encountered
is that the Samsung CDROM does not output S/PDIF unless the drive is
playing.  During stop and pause on the CDROM drive, the MDS-PC2 gives "DIN
unlock", and it glitches briefly when seeking from track to track.  This
behaviour of the Samsung drive (not continuing to output valid S/PDIF at all
times) makes the S/PDIF output somewhat useless, because no matter what it
is connected to, some time will be required to acquire lock, thus you'll
always miss the beginning of playback.  I have heard some mention that this
is a common problem with the S/PDIF output of CDROM drives.

One way that the drag-and drop software could partially get around this
problem is to play the last few seconds of the preceeding track after each
seek (with the MD in record-pause) to allow the MD recorder a chance to lock
up.  Then it would start the MD recording at the instant playback reached
the desired track.  This would work for eveything but the first track.
Right now, I see no way to cleanly get the beginning of the first track.
Doing this would not, so far as I can see, create any new problems.  (Sony,
are you listenning?)

I should note that the Sony setup instructions intend for you to do the dub
using *analog*, possibly for this very reason.  I don't think I'd want to do
the dub through a typical computer sound system, the way they suggest,
because of the big-time audio degradation (compared to a digital dub).

Does anyone here have experience with using the digital audio output of a
CDROM drive?  If so, what have you found?

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MD: CDROM to MDS-PC2 (pre-roll)

2000-01-28 Thread Timothy P. Stockman


I've been thinking a bit more about the idea of having the CDROM drive play
the last few seconds of the preceding track to allow the MD recorder a
chance to lock up after a seek.  The industry (especially video) name for
this is "pre-roll".  Professional video tape editing equipment *always*
prerolls the tapes, so that they are running stable, at speed, locked to
each other, then it switches to record mode at the edit point.  I used to
have a pair of JVC home VCRs that did this to produce clean, frame accurate
edits.  (In the case of the MD recorder, it could be placed into
record-pause during pre-roll, since it will start recording instantly due to
its RAM buffer.)

Sony could make pre-roll an option (or even an adjustable parameter) in the
PC software.  This would certainly fix the problems caused by the S/PDIF
drop-outs during seek, except for the track 1 or the CD.  I know that the
Red Book standard mandates that the first 2 seconds of the CD are reserved
for the TOC and such, so in fact, it would be possible to pre-roll track 1
*if* the CDROM drive would allow it.  The non-audio TOC data would make a
really loud noise, but the MD wouldn't start recording until the start of
the first track.

My personal preference, even if they couldn't figure out a way to pre-roll
track 1, would be to pre-roll after seeks to all other tracks.  The way it
is right now, it glitches after a seek regardless of the track number.  This
way, it would at least work properly for all tracks except track 1.

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MD: bit-for-bit copy via S/PDIF (was Linux S/PDIF soundcard)

2000-01-26 Thread Timothy P. Stockman


This is a more complex than it sounds... There are a couple factors that can
affect the bit accuracy when going, for example, from a WAV file to MD via
(or vice vesa) via SPDIF.

1) Dropped samples due to system activity.  My experience is that a bunch
get dropped at the same time, causing a "skip".  I usually try to close all
programs other than the record/playback program.
2) Hardware/software resolution.  From what I see on the 'scope, the MDS-PC2
always puts out 20 bit resolution.  The motherboard S/PDIF always outputs 16
bit.  The DIO 2448 can output/input16 or 24 bits.  Most all software will do
16 bits.  Cool Edit 2000 has a 32 bit mode that can be used with the DIO to
get 24 bit resolution, but it's fairly processor intensive and prone to
skipping.  Maybe this will change when my memory upgrade comes...
3) Digital Signal Processing in the soundcard.  I know that this is present
in high-end cards like the ZA2 (which disables it unless you ask for it).
Don't know whether the 3D processing some cards do is applied to the digital
bitstream or the analog.  My guess is that it only affects the analog,
because it would require a lot of DSP horsepower.

Of all these, I would say that (2) is hardest to detect, unless of course,
you monitor the bitsream with a 'scope.

There are also a *lot* of other factors that affect the sound quality, if
you do *any* manipulation (editing) while the sound file is on the computer.
For further reading, I direct you to http://www.digido.com (which I'm not in
any way affiliated with; I just happen to think he really knows his stuff).

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MD: bit-for-bit (cont'd)

2000-01-26 Thread Timothy P. Stockman


Of course, this biggest reason, as has been mentioned, is that the ATRAC in
the MD prevents the MD from playing back a bit-accurate copy of what was
recorded.  But I'm assuming that modern ATRAC algorithms are fairly good.  I
don't think one can make that assumption on a wholesale basis, for example,
about a sound card that truncates a 20-bit signal to 16-bits.  (The proper
way to shorten word length is to apply dither *before* truncation.)

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MD: DIO2448 - MDS-PC2 problems...

2000-01-25 Thread Timothy P. Stockman


After a *long* evening of work, I accomplished my first *digital* transfer
from Cool Edit to the MDS-PC2.  I have so far been unsuccessful at
transfering from the output of the DIO2448 to the MDS-PC2; I get
intermittent "DIN Unlock" when there's any audio.  (It seems to lock to
silence OK, but how useful is that?)

I found that the codec on the computer's motherboard, a CS4299, had an SPDIF
output on pin 48.  A TOSLink transmitter, a little microsoldering to the pin
on this tiny chip (about 1/4 the size of a postage stamp) and I was in
business!

I must note that I have hooked a Midiman CO3 format converter to both the
DIO2448 and the motherboard output.  Both give a continuous "source valid"
indication.  The CO3 has a CS8414 (it's the 96KHz version of the CS8412)
digital audio receiver, so I connected a scope to the data output (pin 26)
triggered from frame sync (pin 11).  (This suggestion comes from Bob Katz
http://www.digido.com/bitscope.html )  I got a very stable display,
regardless of whether I was looking at the DIO2448 or the motherboard
digital output.

Could it be that the DIO's clock rate is off to far for the MDS-PC2?   Or
does it's output have some screwiness in the subcode bits that is tripping
up the 'PC2?  Anyway, now that I have some evidence that the 'PC2 is
functioning properly, I'll go back to M Audio customer support.

I'd be interested in knowing if anyone else has experience with either the
DIO2448 or the MDS-PC2...

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MD: MDS-PC2 first impressions...

2000-01-20 Thread Timothy P. Stockman


 === The original message was multipart MIME===
 === All non-text parts (attachments) have been removed ===

I purchased an MDS-PC2 a couple months ago.  Up until today, I have been =
using it in stand-alone mode (no PC), because its software would not run =
on my NT machine.  It has proven to be a fine unit, even without a PC, =
over the past couple months.

 Today I got a second PC (HP Brio BA200) running Windows 98 with an M =
Audio DIO 2448 digital audio card.  I installed the Sony MD Editor 2 =
program (that came with the MDS-PC2) and the DIO driver.  An interface =
is supplied with the MDS-PC2 allowing its Control A1 jack to connect to =
a COM port on the PC.  A single 1-meter TOSLink cable is supplied with =
the MDS-PC2 (no cables are supplied with the DIO 2448), which was not =
long enough for my installation.  Anyway, 2 are needed, so I purchased 2 =
Recoton 6-foot cables.  (Note: the TOSLink connectors were almost to =
large to fit the closely spaced connectors on the DIO.)

After setup, I started up the MD editor and it asked me to select the =
COM port (more about that in a bit).  I then pressed play and it worked! =
 All in all, a fairly painless installation.

There are 2 unresolved issues at this point.  One is the COM port.  The =
BA200 only has 1 com port on the motherboard (COM1).  Since I have other =
devices (a Palm Pilot, etc), I ordered a 2-port add-on card.  The BA200 =
has no ISA slots, only PCI, and ports on the PCI serial card (Boca =
IOP652) were not recognized by the Sony program, so I have to use COM1.  =
The second issue is that, although there was a header on the DIO for TTL =
S/PDIF from the CDROM (and also onthe Samsung 40X CDROM drive that came =
installed in the Brio), there was no cable supplied with the card, so =
I'll probably have to make one.  (I haven't installed my CD ripper - =
CDWorx yet.  A assume I'll be using it to go from CD to WAV.)  The DIO =
does have an internal header for the analog audio from the CDROM.  Maybe =
I'll just move the analog cable from the Brio motherboard audio to the =
DIO, but it seems such a waste to use analog when all I need is a =
digital cable.

I only played around briefly with the Sony MD Editor program, but it's =
operation looks to be fairly intuitive.  Sony supplies a fairly =
comprehesive manual in PDF format, which has answered all my questions =
so far.  I've been busy installing other software on the machine, =
including Adobe Acrobat (so I could read the manual) and Cool Edit 2000. =
 I had to phone Syntrillium, as my previous registration was only good =
for Cool Edit 96, but for an update fee of $29.95 (charged to my credit =
card) they emailed the new registration, which I received in 5 minutes.

One last recomendation I can give is to invest in some really good =
speakers; most "computer" speakers are not very good.  I've been using a =
pair of Proton 301's for many years (biamplified 2" cone tweeter 5 =
watts, 5" sealed woofer 20 watts, no sub).  The response is =
astonishingly flat between 100-2 Hz with none of the ringing =
characteristic of some dome tweeters.  The 301's use a 6dB shelving =
low-end boost to get good response to 100 Hz, so it drops of rapidly =
below 100 Hz.

I'll write a bit more after I've had a chance to use the program for a =
while.=20

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Re: MD: Questions re: Audio Outputs on Denon Deck

2000-01-04 Thread Timothy P. Stockman


  1.  What is meant by "balanced" vs. "unbalanced"

The unbalanced RCA connector is S/PDIF digital.  The center pin is "hot" and the 
outside
of the connector is ground.  The signal is connected between "hot" and ground.

The XLR connector is AES/EBU digital.  The signal is between pin 2 and 3 (neither is
grounded) and pin 1 is ground.

  2.  If I want to use the RCA plug digitial output
 The miniplug input is optical, so you need something to convert the
 RCA coaxial electrical information into optical information for use with
 fibre optic cable. One such device which does this is the Midiman CO2.

Midiman also makes a model CO3, which has RCA (coax) and TOSlink S/PDIF as well as XLR
AES/EBU.  It has the added advantage that it allows one to tweak the SCMS bits, when
appropriate.  (This is often necessary when converting AES/EBU to S/PDIF, since AES/EBU
does not define SCMS.)

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MD: Intertrack noise...

1999-12-01 Thread Timothy P. Stockman


Intertrack noise on CDs or MDs can be caused by

1) DC offset on the original *digitally transferred* recording.
   This causes a "pop" regardless of where the edit point is placed.
   The best way to fix this is to use the "Remove DC offset" checkbox
   in the "normalize" function of Cool Edit.

2) ADC noise in a computer sound card for *analog* transfers.
   Cheap soundcards may have poor anti-alias filters, so the noise
   might be caused by alias components.

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MD: digital soundcard...

1999-11-15 Thread Timothy P. Stockman


I just found a distributor called "Doctor Audio"
http://www.doctoraudio.comselling Midiman
DIO 2448 for $119!  Looks like it might be the
perfect way to hook MD to the computer.
Anyone have any experience with this card or
with Doctor Audio?

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MD: MDS-PC2 has arrived!

1999-11-11 Thread Timothy P. Stockman


I received the Sony MDS-PC2 from Video Direct.
I'll have a detailed review after I use it a bit.  This
information is for computer interface hackers...

Included with the MDS-PC2 is a Sony CAV-50C
RS232 - Control A1 interface.  I opened the
interface to find the following major components:

NEC 78082GA26 microprocessor with 5 MHz xtal
Maxim MAX3221 RS232 transceiver
Appears to be powered by the DTR and one other line,
connected through steering diodes and a 3 terminal regulator.

The CAV-50C says "VisionTouch" on its label, which
leads me to believe that it is also used in Sony's Home
Theater control system...

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MD: Sony XA-C30 with 3 MDX-65 changers...

1999-11-07 Thread Timothy P. Stockman


For the past week I have been using a car system
with 3 MDX-65 changers and an XA-C30 source selector
box.  The XA-C30 is mounted in the trunk along with the
changers.  Previously, my single MDX-65 was powered
through the Unilink cable, but I had to run an unswitched
battery line back to the trunk to power the XA-C30.  The
XA-C30 also requires a power ground connection which
I fastened under a convenient screw in the trunk.  Sony
seems (wisely) to have used the shield in the audio cables
for the ground that powers the analog circuitry to prevent
noise from being introduced by the power ground.  I bought
3 1-meter (Sony RC-61) Unilink cables to connect the XA-C30
to the MDX-65 units.

Upon auto-detecting the XA-C30, a single digit (identifying
the changer) appeared to the right of the "MD" on the display.
In normal mode, the system will play through all tracks on
all discs in MD1 in order, followed by MD2, then MD3 and
it will then go back to MD1.  The disc "+" and "-" keys
function much as expected: MD2 disc 1 follows MD1 disc 6.
However, it does *not* use the RAM buffers to provide
uninterrupted play when switching changers as it does when
switching discs in the same changer.  This proved to be a major
disappointment for shuffle mode 3 (where it picks random
tracks from all available changers), causing about 10 seconds of
silence while the display says "LOAD" between *every* track.

The advantage of using multiple MD players is that one can have
much more music "on-line" at a given time; great for long trips!
However, in my opinion, the 10 second interruptions make shuffle
mode 3 rather annoying; so having multiple changers is *not*
that useful if you plan to use shuffle mode.  Luckily, most of my discs
are compilations that I recorded, so lack of shuffle is somewhat
tolerable, just disappointing.

Perhaps someone at Sony watches this list and will improve the software
to fix shuffle mode 3 in future releases.  My guess is that it would involve
buying a new head unit (BTW I'm using the unilink control part of the RF
adapter with the audio feeding directly into "aux" inputs on my radio) and
maybe a new switching unit...

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MD: digital clipping indicators...

1999-10-13 Thread Timothy P. Stockman


There has been some discussion of digital clipping
and how the "over" indicator behaves.  While this
depends on the actual implementation, here are
the important issues:

On record, the "over" indicator should indicate when
the maximum sample value has been exceeded.

Since it is impossible to record a value greater than the
maximum sample value, there should never be any
true "over" during playback.  However, some equipment
infers that 3 contiguous samples of the maximum value
are almost always caused by an "over" during record.
That is, it infers that the middle sample of the 3 must
have been "over". 

That stated, it should be pointed out that consumer
equipment is often not this rigorous when it comes to
level indication.  However, I should also point out that
occasional "overs" are almost always inaudible.

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MD: MDS-PC2 ordered!

1999-10-08 Thread Timothy P. Stockman


I just ordered an MDS-PC2 from Video Direct,
in Florida (800) 368-5020 for $289 + $15 shipping.
They inform me that they expect to receive a batch
of them from Sony in 10-15 days, so I should receive
it mid to late October. 

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MD: In car changer, shuffle mode

1999-09-12 Thread Timothy P. Stockman


I've got a Sony MDX-65.  It starts the disc change while
the end of the current track is playing so that there is no
pause in the audio.  And at normal level...

I'll be installing a 3-unit Unilink switcher and 2 more MDX-65s
shortly, so I can let you know about the multi-changer shuffle
mode, if there is any interest.

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MD: : Re: Digital Recording: why is volume low?

1999-09-08 Thread Timothy P. Stockman


 When digital dubbing, it's important not to record the signal any higher
 than the "0" mark or you'll get clipping and distortion (when making a
 digital recording--analog things like cassette decks let you go over the "0"
 a tad before you start to hear distortion).

Whilst I agree with this statement totally, in principle, it does seem that
somehow the Sony engineers have allowed for accidental excursions over the
0dB mark.

"0" indicates the largest number that can be expressed, and the "over" indicator
means that you've exceeded that number, so clipping *will* occur.  In all but
the most stringent listening environments, occasional clipped peaks are almost
impossible to detect.  Most would have a difficult time hearing even moderate
clipping on a portable unit with "fold-up" headphones or ear buds.

But be aware that clipping *does* occur every time the "over" indicator lights,
so one should consider whether the resulting distortion will be masked by
noise and distortion in the source material or playback environment.

Solutions to the problem of not-enough-headphone-level include outboard
amplifiers, changing to a unit that has higher output voltage (usually one with
more available battery voltage) and changing to more sensitive headphones.


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Re: MD: Subject: RE: What is a plug in power mic?

1999-09-01 Thread Timothy P. Stockman


 1. Could using a regular dynamic mic really damage my 702?  Before
 I saw the warning in the manual, I tried a regular mic and it seemed to
 work OK (but occasionally there was a lot of static -- could the power
 supplied by the 702 have built up somewhere and then discharged, causing
 the static?)

A dynamic microphone has a small coil of wire attached to the diaphram.
This coil moves through a strong magnetic field to generate the output
voltage.  This coil will obviously conduct DC current, and will present
a much lower resistance DC path than the FET, so the 702 will supply
much higher-than-normal current, which will certainly shorten the battery
life even if it doesn't damage things.  The static probably is the result of
small changes in resistance during slight movement of the plug which normally
would not cause a problem, but because of the high current, they create
enough voltage change to hear.

Bottom line: pay attention to the warning!  If you want to use a dynamic mic,
place a capacitor, say 47 uF/16 V in series with the hot lead (+ to the 702,
- to the mic) to block the DC.

 2. Is it OK to use an electret mic that takes a battery?  I'd think that
 with the battery in, it would "look" like a regular dynamic mic to the
 unit, so would present the same danger that the manual warns against.
 I'd also think that with the battery out, there would be an open circuit
 so the FET wouldn't be powered.

Should work OK, because most mics with the battery in the plug have
a series capacitor to keep the DC out of the recorder input.  The best
way to use such a mic however, is just to cut off the plug (containing the
battery) and replace it with a normal (non-battery) plug that fits the recorder.
Since the recorder already has the circuitry for powering the mic, you'll
eliminate the duplicated circuitry in the battery plug.

BTW-- The power circuitry for electret mics generally consists of a series
capacitor (47 uF/16 V, + to the mic, - to the input stage of the recorder) to
block the DC.  A small resistor 1.5K to 2.7K is connected from a DC
voltage source to the mic to provide power.


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MD: Subject: RE: What is a plug in power mic?

1999-08-31 Thread Timothy P. Stockman


The discussion of electret microphones here is mostly correct
in that they are a type of condensor microphone and that they
require an excitation voltage, usually between 1.5 and 10 VDC.

All capacitor mirophone capsules are inherently very high
impedence devices, so high that they cannot drive the connecting
cable.  Therefore, a preamplifier (in the early days a vacuum tube,
but more recently a FET) is placed in the microphone case to
drive the cable.

A normal condensor microphone requires a fairly high excitation
voltage, so often a small switching power supply is also placed
in the microphone case to convert the "phantom" power supplied
via the cable to high voltage for capsule excitation.

Electret microphones have permanently charged capsules, made
by heating a special dialectric material while it is in a strong
electrostaic field, so there is no need for high voltage excitation
(and the required switching supply).  The excitation voltage for an
electret microphone powers the FET amplifier.  An electret, in
practice, is a very simple and elegant microphone... It is made up
of just the capsule and a FET transistor.

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MD: Analog input on JE520

1999-08-23 Thread Timothy P. Stockman


I have done more experimentation regarding the analog input
levels on the JE520.  I have come to the conclusion that the
"over" indicators do not accurately report ADC clipping if
the input gain is set to less than 0.0.  In fact, in most cases,
no amount of input signal will light the "over" indicators at
negative gain settings, however, severe clipping may result
in the ADC.  Positive input gain settings result in some loss
of ADC resolution; +12.0 dB (the maximum allowed) causes
a loss of 2 bits.  Therefore, optimum results are obtained by
setting the input gain to 0.0 and controlling the level externally.

That said, there should be little reason to use a negative gain
setting under normal circumstances, since the gain between the
analog inputs and the ADC is fixed requiring a *very* hot
input to overload the ADC.  Therefore, the most common
situations will require a positive gain adjustment causing slight
loss-of-resolution (almost inaudible).

When recording from vinyl, I am using a PS Audio IV preamp
which has a line output amp (after the level control) allowing
it to put out a hot enough signal to overload the JE520's ADC.
I obtain the best results by setting the JE520's input gain to 0.0
and using the level control on the preamp.  However, switching
off the line amp and boosting the level on the JE520 produces
acceptable results.

The moral of this is to beware of ADC clipping if the JE520's
input gain is set below 0.0, because the over indicators will be
unreliable in this case!


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MD: JE520 analog input level...

1999-08-18 Thread Timothy P. Stockman


Perhaps I should have been more clear.

The underlying issue I was getting at is: what is the
resolution of the A/D converter on the JE520 and
how is that affected by adjusting the record level
*after* the signal has been converted to digital?

Let's say you increase it by 12 dB.  I think that means
you end up with two less bits of resolution that if you'd
have increased the level by 12 dB *before* the A/D.
My observation to date is that this effect is fairly
subtle on most program material.

Let's say you decrease it by 12 dB.  Does the A/D
have enough headroom to sample a signal that's 12 dB
hotter than normal?  My observation is that the A/D
*does* clip in this situation; the loss of dynamic range
is clearly audible on just about any material.

My point is this:  it seems that to get optimum performance
out of the A/D, it seems best to put a potentiometer at
the analog input of the deck.  BTW -- If you use a
pot with a conductive plastic element, this will minimize
any degradation.  In my opinion, such a setup would
be far better than operating the A/D at a non-optimum
level.

Digital record level adjustment seems to be the wave of
the future; it's less expensive for the manufacturer since the
hardware to do it is already there.  It's a firmware issue.
I'm not so sure that the end user, who just wants to turn
a knob to adjust the level, can understand the tremendous
potential for negative effects without first having an understanding
of the technical aspects of digital audio.

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MD: JE520 analog input levels...

1999-08-17 Thread Timothy P. Stockman


Here are some questions and observations regarding analog
recording on the JE520.  Does anyone know what tradeoffs
are involved in using the analog input level adjustment on the
setup menu?

I don't think there's any way on the JE520 to adjust the
input level to the A/D converter, so it would seem that
one looses resolution when a low-level signal is applied
and boosted with the adjustment in the setup menu.
OTOH, the converter may be overloaded when a
high-level signal is reduced with the setup menu level
adjustment.

My experience to date is that it is best to adjust the input
level with an external pot so that the setup level adjustment
can be left at 0.0.  Using the setup menu to boost the level
doesn't seem to leave many sonic artifacts, but I haven't
tried "difficult" material (like low level solo piano).  Using the
setup menu to cut the level seems to be the kiss of death,
because I think that the A/D gets overloaded.

Given that one usually likes to maximize the level on the disc
to make the best use of the available disc (is this indeed true
with ATRAC encoding?), does it make sense to ever adjust
the record level setup to less than 0?

Does anyone know exactly where in the digital signal path
the record level setting is applied?  A flow chart, showing
the order of processing steps along with word length (# bits)
and sample rate (1x, 2x, etc) would be very helpful...

Unless I hear a reason not to do so, I'll continue to leave the
setup level adjustment at 0.0 and make the adjustment with
an external pot.

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Re: MD: RM-X69RF

1999-08-16 Thread Timothy P. Stockman


 How is the RM-X69RF controller supplied? Is it supplied with the RF block
 (which feeds the FM car radio) built into the controller circuitry or as a
 separate block, apart from the controller box, which just receives power
 from the controller box and the signal from the changer?

It is in one small metal box 5" x 4" x 1 1/4" with the following connectors
on one of the 5" faces: L audio in (RCA), R audio in (RCA), wired remote in
1/8 phone, Unilink, LCD display.  On the opposite face: power (4 pin Molex),
antenna (Motorola jack on a cable), RF to receiver (Motorola plug on a cable).

The LCD module is 4 1/2" x 1 1/4" x 3/4", at the end of a 5 foot cable that can
be detached at the main unit.  It consists mostly of a large backlit display, a
single "power" button that initiates (or suspends) playback, an IR detector for
the wireless remote and a "paper clip" CPU reset button.

To use it without the FM modulator, simply do not hook up the antenna and
RF cables.

  Also, how do some car radios open up the line-input when the auxiliary
 source is started? Does this involve any special wiring to cause this
 trigger and can this controller provide that special trigger arrangement for
 these radios?

Various radios work differently, but the RM-X69RF has an undocumented
"amp turn-on" lead (the red/blue wire from the power Molex connector) that
goes to +12V when playback is initiated.  I guess you *could* just use it with
an amp (no radio) if you put a volume control between the changer and the amp.

Good luck!


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Re: MD: RM-X69RF...

1999-08-15 Thread Timothy P. Stockman


The RM-X69RF can indeed be used as "just a controller"
by connecting the RCA outputs of the MDX-65 to another
device.  Here's the catch:  due to the way the MDX-65 gets
its analog ground, you have to at least connect the shield of
one of the RCA's on the MDX-65 to the shield of the RX-X69RF
RCA (either channel will work and the center pin need not be
connected).  This requirement MAY already be taken care of
since the radio and the RM-X69RF have the same ground; it
was not on the powered speaker.  My guess is that this so that
the MDX-65 analog circuitry gets a "clean" ground, rather than use
the "dirty" power ground in the Unilink cable.  This probably helps
eliminate electrical noise from the various motors in the MDX-65.

I've got an XA-C30 3-input Unilink switcher on the way from
Sony (had to order it direct since no dealers seemed to know what
it was).  If anyone's interested, I can report how this affects the
situation when multiple changers are hooked up to the RM-X69RF
in controller-only mode.  My guess is that they still require the
analog ground (separate from the Unilink cable)...


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MD: MDX-65 problems...

1999-08-11 Thread Timothy P. Stockman


I'm having problems playing discs in an MDX-65 changer.
I have it connected to a RM-X69RF controller.  Right now
its sitting on the workbench running from a 12VDC bench
supply.  The audio output is connected to a powered speaker.

When it is running, the display indicates normal operation.
I can see the track numbers and time, etc.  The problem is
that I get no audio output.  The discs in the player were
recorded in mixed mono/stereo (mostly mono) and play
back fine on my JE520 and MZ-EP11.  I've checked the
obvious like the digital/analog switch in the analog position.
This may be a clue: when I look at the TOSLink connector,
there is no visible light (even with the switch in digital).

I've had this problem with 2 units now (the first I exchanged
as defective).  Can anyone offer me any suggestions or
let me know their experiences with the MDX-65?

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