Hi all,
Over the last few months, I had wondered about digital recording
levels. This interest original surfaced when I bought the Sony JB920
and found that you can change the digital recording levels. I
always thought bits were bits and adjusting digital input levels
doesn't make sense to me.
Then when I bought the Sound Blaster Live Value editionn with the
Hoontech daughter board, I noticed you can change the digital
recording levels in the computer. Again this seemed a bit odd to me.
Recently I borrowed a Stereophile TestCD from a friend to test the
db levels displayed on my JB920 and then into my computer.
Here is the list of equipment used for this test:
Sony CDP-CX55 CD Changer with digital output
Sony JB920 MD Deck
Sound Blaster Live - Value with Hoontech daughter board. Taking
coax digital from the Sony JB920 into the computer.
Sound Forge XP software for recording and showing db levels in the
computer
Generic AMD 233Mhz Windoze 95 PC.
Sound Blaster Live - Value edition with Hoontech digital I/O daughter
board.
-----------------------------------------------------------------
When I play a track on the test CD (track 4 - Pink Noise at -20db
L+R), I expected to see a db level around -20db on my Sony JB920
deck. Nope. The db level was around -12db to -9db.
When I looked at the level then in the computer, when I have the
record level slider set at max for the SPDIF-In, the db level inside
the computer is about -6db.
Note: My Windoze 95 machine has a record fader for the SPDIF-In.
It is gradutated as follows:
SPDIF-In
-[**]-
- -
- -
- -
- -
- -
- -
The fader has a visible 7 level reference mark, and the 'block
cursor' that you drag to adjust the level can go smoothly from the
top (as shown above) to the bottom.
For the sake of discussion, I will label the above as follows:
(please note my computer does not display these numbers)
SPDIF-In
-[**]- 13
12
- - 11
10
- - 9
8
- - 7
6
- - 5
4
- - 3
2
- - 1
Max input level is 13 above and min. is 1.
When I have my input set to 13 as shown above, the computer sees
about -6db.
When I move the fader to say 8 above, the db level according to
Sound Forge is about -10 to -12db, or close to the JB920 meter.
When I move the computer input fader to say 5 above, the db level is
about -20db.
My questions are as follows:
1) Why is the db level mismatched between the CD reference CD and
my Sony deck JB920?
2) How is the db level being affected in recording? I thought
bits are bits?
Any help you can provide on this discussion would be appreciated.
Jerry
----------------
Jerry Jelinek at work via OS/2 [EMAIL PROTECTED]
http://junior.apk.net/~centaurs - My Favorite Web Links
"..both IBM and Microsoft insist that the 'desktop platform of the
nineties' will be a 386 or 486 PC with at least 4MB of memory and
a 60MB hard drive, running the 32-bit OS/2 version..."-PC World Jan. 90
-----------------------------------------------------------------
To stop getting this list send a message containing just the word
"unsubscribe" to [EMAIL PROTECTED]
