Topic: M-Audio Audiophile 2496 Issue

[taylorc]

Issue: Cannot get a pure/exact digital transfer

Comparing:

Downloaded shn> wav copy of show A (100% accurate)
-to-
DAT> M-Audio Audiophile 2496> PC copy of show A

Results:

1. Transferred copy distorts at higher volumes before the dl'ed original version does
2. The physical appearance of the transferred copy's soundwaves' graphics lose their texture before the original copy does

Using: Win XP, DA-20, 75ohm coax, Latest Driver, Sound Forge7.0, Samplitude6.0, EAC, CDWav

Attempted solutions: Mulitple PCI slots, unsuccessful communication with and return to M-Audio, tweaking of settings, etc.

Any input?  If I need to provide more information, please ask...

[plucks]

Is SF set to the same sample rate as the DAT that you are transferring?  

[Uncle Jimmy]

I use a similar set-up, and i think you may be right. Try checking for inadvertent downsampling (was the original in 20-bit, like my A/D throws).

UJ

[nic]

are you sure that the person who transferred the copy you downloaded didnt do any mastering?
this is always possible.

I use the Audiophile 2496 and all of my digital transfers come out clean and pure everytime

[Uncle Jimmy]

luvean,

   what software do you use to capture the signal? also, how do you test that your copies are bit-perfect? (you didn't actually mention that, so I'm just taking a shot.)

UJ

[nic]

I use Soundforge 6.
the Audiophile 2496 is a KNOWN bit-perfect card with a DC offset of 0

[Uncle Jimmy]

OK, but for some reason i thought that recording through, say, CDWav was not bit-perfect. Is it necessary to use something like Soundforge? If not, OK. If so, what is it about SF that makes it better at sound capture than CDWav?

Also, how is it KNOWN to be bit-perfect? Any documentation or the like? Or is that just something you heard and believed?

Thanks,
UJ

[taylorc]

I get the same results with any transfer.  Any high frequencies have a "lossy" effect.

My specific comparison has been done with Phish 4.5.98 641>Sax>P1.  I have it in numerous versions: PCP CD-R, DAT, shn (that I've used to compare).

All signs indicate that the card is good and installed/setup properly.  DAT's play fine through the DA-20 I use for transfers.  Just wondering if something on my PC is conflicting with the card?...

[nic]

I dont see how recording through CDWave would not be bit-perfect.
as for why I use SF, personal preference...I use CDWave for tracking.

there have been numerous tests over the years showing that the Audiophile 2496 is bit perfect in the 16bit realm...24bit is somewhat a different story.

[Uncle Jimmy]

I dont see how recording through CDWave would not be bit-perfect.
as for why I use SF, personal preference...I use CDWave for tracking.

But you don't know the technical details of why it is bit-perfect?

there have been numerous tests over the years showing that the Audiophile 2496 is bit perfect in the 16bit realm...24bit is somewhat a different story.

Can you link to these tests, or tell me who performed them, or anything like that? At a sample rate of 44.1 or 48 thousand samples (16 bits each? 20?)  per second, it's hard for me to believe that  the transfer is perfect on the fly, with little time for error correction, without some kind of evidence.

Case in point, sometimes it takes longer than real time to overcome errors in EAC, for those specific bits. An audio transfer is one direction only and does not have the benefit of reading the same sample 8 or 16 or 32 times to determine what it might be.


Thanks for the discussion,
UJ

[nic]

well, honestly I dont have the time to redig through old DAT Heads digests(I remember seeing tests on the Audiophile 2496 back in 2000/2001 before I originally purchased mine)

as for CDWave, no, I'm not a programmer, so I dont know the internal workings/functions it is using. that said, I would seriously doubt that CDWave is NOT bit perfect based on the personal and community recomendations to use it(and knowing how anal these people are with regards to being bit-perfect and such...)

you are confusing dat> hd transfers with eac....extracting data from a cd is inherently risky and prone to errors, that is why EAC has the error corrections.
as for transfering dat> hd there is much less of a chance of errors being introduced. the reason why some cards are not bit-perfect is that they resample on the fly regardless of incoming signal. this is bad...the Audiophile 2496 does NOT do this UNLESS you have the cards mixer controls set up incorrectly.
when transferring dat> hd you need to make sure the sample rate is matched in 3 places: the dat, the transfer card and the recording software.

from above you posted that your ADC outputs 20bit...which ADC are you using? if recording to DAT through s/pdif the ADC should only be outputting 16bits(it may process internally at 20bits, but it then either dithers or use some other noise-shaping algorithm to output 16bits)

for your transfers have you checked to see if your PC environment is creating a DC offset? this could help explain why the transferred audio different visually and sonically from the dat.

[Uncle Jimmy]

OK, well, I can go look at DAT-heads myself now that you have mentioned it.

As for CDWav, it is used "by the community" as an accepted way to trim or track out .wavs because it always splits on sector boundaries. I have not seen too many people suggest that it be used as a recorder, just that it has that capability if you don't have SF or Wavelab or whatever.

Why is there less chance of errors during a transfer, and how does it correct if there are errors? How does it even know?

I use a Gram-Patton (sp?) ADC-20. I am relatively new to that, so it may very well only process 20 bits internally, but i'd have to check instead of assuming that i know something that i really do not.

How do I check for a DC offset?

I'm not trying to be argumentative. It just doesn't seem that there is much hard evidence so far, although you do seem to be quite experienced with your own set-up.

I do appreciate the tip on the sample rates, although that is a macro-type problem that usually resuls in severely distorted, unnatural sounding audio, rather than the second order effects of some peaks clipping early.

One more thing, how would the settings be set up wrong vs right on the card for resampling on the fly? Specifically? Just the internal vs external clock? if that is the case, then CDWav isn't bit perfect at all, as it will not record with an external clock signal.

UJ

[nic]

with dat> hd transfers, if you notice a error in the waveform that isnt on the dat, you simply retransfer..the error could be anything from a dropped sample to a missplaced sample.
not sure how to check for DC offsets in anything but SoundForge. in SF, in the record dialouge there is a checkbox for checking DC Offset and a button underneath to correct any DC offset it finds.
DC Offset sounds more likely to be the culprit of the problems originally described at the top of this thread

[Uncle Jimmy]

OK, thanks. One last thing...

  If there IS an error in the waveform, doesn;t that mean that the transfer was not bit-perfect, by definition? It would be pretty inconvenient and quite inexact if the only way to check the "bit-perfectness" was to listen to the DAT and then look at/listen to the waveform.

Can anyone else jump in here and add some knowledge? I think we have hit the rail on actual knowledge of the subject and are cruising into pure speculation.

UJ

[nic]

fyi, most errors are caused by the tape itself and the s/pdif cable between the dat and the card