Does Foobar's Volume Control Degrade Sound?
Jan 20, 2005 at 5:14 AM Thread Starter Post #1 of 29
Zoide

Zoide

Headphoneus Supremus
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Is there any degradation of sound if I use the Foobar volume control?
I'm guessing it's just some 32-bit domain digital lowering, which shouldn't harm things, but since I've heard so many horror stories related to not using Kernel Streaming b/c of Kmixer...
 
Jan 20, 2005 at 2:43 PM Post #2 of 29
I'm not sure how Foobar implements their volume control, but if it's done at 32 bits and applies dithering (I know this is an available option) I wouldn't worry about it. By the time you go from 32->16 bit resolution, you have reduced the amplitude by 96dB which is equivalent to the SNR of redbook. This is over-simplified, but demonstrates that there isn't a whole lot to worry about.
 
Jan 20, 2005 at 2:53 PM Post #3 of 29
the volume control in foobar2k isn't the traditionanal volume control. it only attenuates the sound. in other words, it doesn't provide any amplification that could potentionally degrade the sound.
in my setup, i use the volume control and set it to -8db to reduce clipping. for actual volume control/amplification on rely on my headphone amp.
 
Jan 20, 2005 at 5:45 PM Post #4 of 29
Sounds like a good volume control then. I was just worried that it would reduce the dynamic range, as I've understood happens in other contexts (ie. if you connect an amp to the iPod's headphone out, lower the iPod's volume a lot, and raise the amp's a lot, then the sound i shorrible).
 
Jan 20, 2005 at 8:09 PM Post #5 of 29
Quote:

Originally Posted by Zoide
... as I've understood happens in other contexts (ie. if you connect an amp to the iPod's headphone out, lower the iPod's volume a lot, and raise the amp's a lot, then the sound i shorrible).


Is this from personal experience, or is what you're hearing anecdotal? The digital attenuator in the iPod works exactly like the attenuator in Foobar. Exactly alike.

(Yes, I know Foobar has an intermediate 32 bit stage, but once you requantize to 24 bits, the result is identical to a 24 bit integer hardware implementation, assuming no dither -- and dither at 24 bit is way beyond the threshold of audibility.)
 
Jan 20, 2005 at 10:13 PM Post #6 of 29
Quote:

Originally Posted by Wodgy
Is this from personal experience, or is what you're hearing anecdotal? The digital attenuator in the iPod works exactly like the attenuator in Foobar. Exactly alike.

(Yes, I know Foobar has an intermediate 32 bit stage, but once you requantize to 24 bits, the result is identical to a 24 bit integer hardware implementation, assuming no dither -- and dither at 24 bit is way beyond the threshold of audibility.)


If this is so why have some reported best SQ out of the iPod at a little less than max volume? (FYI, I have no experience, nor an iPod, just curious.)
 
Jan 20, 2005 at 10:25 PM Post #7 of 29
Quote:

Originally Posted by IstariAsuka
If this is so why have some reported best SQ out of the iPod at a little less than max volume? (FYI, I have no experience, nor an iPod, just curious.)


I imagine that full volume might drive certain amplifiers into clipping, or at least out of their linear range.
 
Jan 20, 2005 at 10:31 PM Post #8 of 29
Quote:

Originally Posted by IstariAsuka
If this is so why have some reported best SQ out of the iPod at a little less than max volume? (FYI, I have no experience, nor an iPod, just curious.)


Placebo effect? Clipping caused by using the equalizer?

Come to think of it, it is possible that the iPod designers are doing volume control in software, rather than using the DAC's internal 24-bit volume control. If the volume was implemented in this manner, it could be a 16-bit volume control, in which case it could be audible. Putting the iPod at a little less than max volume would cause additional quantization errors (i.e. added distortion). Some people might like this effect and think it sounds "better."
 
Jan 20, 2005 at 10:46 PM Post #9 of 29
The problem with determining how good Foobar's vol control is the impossibiliby of doing A-B comparisons. One can't A-B max volume vs. lower volume just because of the actual volume difference, which will cause perceived sound quality differences.

I can get close by using my EVS ultimate "nude" attentuators. I set the overall end volume to be the same, but create this volume by using Foobar vol control mostly vs. using EVS mostly. In this sort of test, Foobar vol control does not seem worse than the EVS, which is a fantastic volume control..
 
Jan 20, 2005 at 11:41 PM Post #10 of 29
so should i keep my foobar set to -8 and use my cmoy to control volume then? ive been keeping it at 0 and havent noticed any problems
 
Jan 20, 2005 at 11:44 PM Post #11 of 29
Hmm.... I'm currently using the Foobar volume control at -18.00 dB, and my amp's volume pot is only slightly above 9 o' clock. Maybe I should ask Xin to lower its gain.
 
Jan 21, 2005 at 1:27 AM Post #13 of 29
Well, at least with columns UI it tells you in the bottom right of the window, in the status bar.
 
Jan 21, 2005 at 1:33 AM Post #14 of 29
Quote:

Originally Posted by Zoide
Well, at least with columns UI it tells you in the bottom right of the window, in the status bar.


It says so there in the default UI too.
 
Jan 23, 2005 at 9:49 PM Post #15 of 29
Quote:

Originally Posted by jefemeister
I'm not sure how Foobar implements their volume control, but if it's done at 32 bits and applies dithering (I know this is an available option) I wouldn't worry about it.


Actually, all processes are done at 64-bit float, and are dithered down in the output stage to whatever settings you have in Playback.
 
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