[IanS]

This is likely a dumb newbie question, but how is it that the volume level of a song can change across 2 sources that both use SPDIF digital output into the same amp?

When I rip a song to FLAC on my PC (EAC/FLAC/Foobar2k) and use the digital coax output from my audio card, it plays at a much lower volume than the same song from my CD transport. How can this be if its just streaming bits from the song?

Is one of the software pieces chaning the bits and adjusting the volume? Or my sound card?

 

[lan]

On your PC, there must be some volume control somewhere lowering it.

 

[Budley007]

Click on your mixer. (or that little speaker in the system tray)
There should be separate sliders for CD output and Wave output. If they're set at different levels, then there's your culprit.

 

[IanS]

Quote:

Originally Posted by Budley007 Click on your mixer. (or that little speaker in the system tray) There should be separate sliders for CD output and Wave output. If they're set at different levels, then there's your culprit.

I cannot find a 'Volume' control anywhere on my 98se system. The 'Start->Programs->Accessories->Entertainment->Volume Control' is a dead link. And there is nothing in the 'Multimedia' panel either.

But shouldn't a WAV file over SPDIF go out unprocessed? Shouldn't it be a bit-perfect replica of what was on the hard drive, which according to EAC is a bit-perfect replica of what was on the original CD?

I see that Foobar2000 has 'Volume Control' under 'Active DSPs'. But even when I remove it from the Active DSP list, it still goes into my amp at a lower volume than from my transport (a NEC CDR-602 SCSI CD-ROM reader with no DSP inside).

I can understand why the quality might not match, as I still have a crap audio card (the default audio with my VIA EPIA M10000), but why shouldn't the volumes match?

 

[breez]

Quote:

Originally Posted by IanS I cannot find a 'Volume' control anywhere on my 98se system. The 'Start->Programs->Accessories->Entertainment->Volume Control' is a dead link. And there is nothing in the 'Multimedia' panel either.

Try Start - Settings - Control Panel - Multimedia or just double click on the loudspeaker icon on the bottom right corner.

Quote:

But shouldn't a WAV file over SPDIF go out unprocessed? Shouldn't it be a bit-perfect replica of what was on the hard drive, which according to EAC is a bit-perfect replica of what was on the original CD?

No, because the sound data is getting through the mixer which may attenuate the signal.

 

[sgrossklass]

Quote:

Originally Posted by IanS But shouldn't a WAV file over SPDIF go out unprocessed? Shouldn't it be a bit-perfect replica of what was on the hard drive, which according to EAC is a bit-perfect replica of what was on the original CD?

It should, but in many cases is not. What you've seen happens exactly when the digital output is derived from the signal as it comes out of the card's DSP, and of course digital volume control may already have been used then. (Along with resampling, if necessary - think old-style AC97 with 48 kHz fixed.) I've read the Terratec 512i (FM801 based) also suffers from such a problem. As far as barefoot AC97 codecs on motherboards are concerned, I guess either the southbridge has an integrated DSP or it's all done in software.

 

[rincewind]

If I were you, I'd be wondering which of your sources is outputting the "standard" volume!

Get a third (or more if possible) digital source and try listening to see what levels they put out.

If each puts out a different volume, with all the "bell and whistles" available turned off (so as not to attenuate/play with any signals) then I guess it proves that some manufacturers have different ideas on what "standard" SPDIF should to.

But I expect one of the sources to be an odd-one-out and be playing non-standard, and the rest to be identical (if we can put any trust in digital audio "standards")!

 

[IanS]

breez: I went into 'Add/Remove Programs', and I realize now that I haven't even installed the Windows multimedia Volume Control! That's why I cannot find it anywhere. Maybe the VIA software kicked it out?

sgrossklass: I suspect you are on the right track. The VIA AC'97 processing must not be passing out the raw PCM stream.

rincewind: I have tried a 3rd source (another transport), and it mimics my other transports volume level. What I need to do now is get a quality sound card (a USB Waveterminal U24 would be perfect) and compare its output to that of my transport.

Thanks for all the help.