Re: MD: 24 bits/MD standard

[Ralph Smeets]

[EMAIL PROTECTED] wrote:

 But aside from that, you seem to be confusing sampling rate with bit depth.
 Faster processors can certainly up the sampling rate--just speed up the
 clock; increasing the bit depth is all about good old analog electronics
 design expertise and much more difficult/expensive.
 
 -Alex

I'm sure I didn't confuse sampling rate with word size. I'm talking about the
converter, you know, the little IC that does the conversion.

A studio ADC is more expensive due to several reasons. One of them is a good
design. But you'll probably find "exactly" the same design in home equipment.
The second more important is the selection of components. By selecting
components manualy, you'll get components that match. Ie, all resistors have the
same variation (ex -4%) and not some random (ie somewhere between -5% and +5%)
variation which is different for all components.

The point I try to make is the fact that it is possible to build a cheap 24 bit
AD converter that is just a little bit worse than a studio 24 bit AD converter
which costs a factor 100 more.

Cheers,
Ralph - who just came back from holidays
-- 
===
Ralph SmeetsFunctional Verification Centre Of Competence -  CMG
Voice:  (+33) (0)4 76 58 44 46   STMicroelectronics
Fax:(+33) (0)4 76 58 40 11   5, chem de la Dhuy
Mobile: (+33) (0)6 82 66 62 70 38240 MEYLAN
E-Mail: [EMAIL PROTECTED]  FRANCE
===
"For many years, mankind lived just like the animals. And then some-
thing happened that unleashed the powers of our imagination: We learned
to talk."
-- Stephen Hawking, later used by Pink Floyd --
===
-
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]

Re: MD: 24 bits/MD standard

[Alex LeVine]

 
 Date: Thu, 19 Aug 1999 16:15:27 +0200
 From: Ralph Smeets [EMAIL PROTECTED]
 Subject: Re: MD: 24 bits/MD standard
 MIME-Version: 1.0
 Content-Type: text/plain; charset=us-ascii
 Content-Transfer-Encoding: 7bit

 [EMAIL PROTECTED] wrote:

 of BS; meanwhile 24 bit in could just truncate at 20 or 18. (The second
 thing I wonder is if these 24 bit converters are for real, since stand alone
 24 bit ADC units cost thousands of dollars, and the new Sony MDs with 24
 start at under US$300.  But that's a whole nuther issue.)

 What are the specs of those 24 bit converters that cost thousands of dollars?
An
 audio AD converter just needs to be 44.1 kHz. That's rather slow for a ADC.
Note
 that if you use 8 times oversampling at the front-end, your AD converter runs
on
 44.1*8 Khz ie, 352kHz.

 I know a 200 Mhz 24 bit ADC costs loads of money but a ADC that doesn't even
run
 on 1Mhz? They are normally very very cheap.

 Cheers,
 Ralph - Who's glad the ugly German is back!

Ralph-

Professional studio 24 bit A/Ds (and DACs) tend to have specs of 115-120 dB
Dynamic Range and S/N of 108dB.  The reason they are so damn expensive is
because when you have that kind of dynamic range, you have to be very
careful about various physical limits of electric signals before you convert
them, i.e. the analog section, power supply etc. needs to be of the lowest
noise possible, which means premium parts.  At 24 bits (even at 20) you
actually begin to run into the inherent thermal noise within resistors which
cannot be eliminated, and this is why the S/N ratio doesn't match the
Dynamic Range for higher bit rate converters (we can hear information
sitting well below the thermal noise level).

But aside from that, you seem to be confusing sampling rate with bit depth.
Faster processors can certainly up the sampling rate--just speed up the
clock; increasing the bit depth is all about good old analog electronics
design expertise and much more difficult/expensive.

-Alex

_
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com

-
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]