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Topic: Volume control pipeline (Read 6982 times) previous topic - next topic
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Volume control pipeline

I'm looking to debunk or confirm an unfounded assumption I've made "logically" from the moment I began using my computer as primary source of music (which was about ten years ago).

Currently, there are four independent volume controls between a file and my speakers, namely:

- foobar's volume control
- Windows volume control
- some odd-looking knob control in the RealTek control panel
- the volume control on my amp

Already having a decent background of graphics editing, my old reasoning was this: if downscaling a graphic from a larger source is always better than upscaling from a smaller, surely this is the same for audio, and I should never downscale with an earlier control, then pump back up with a later control.

I never actually tested this assumption, and ever since, I have them all maxed, and control exclusively via the amp, the final control.

So theoretically speaking, is that actually accidentally sensible or just silly myth?

Volume control pipeline

Reply #1 –
I've always viewed the software volume controls as having a max level of unity gain (or '0'), in other words, there is no volume 'boost,' only a volume attenuation when you move the slider. I don't know how the amp volume knob works, though.
I may be wrong.

EDIT: But I'm quite certain that moving the volume slider beyond 100% in VLC is a volume boost. (even though you didn't mention VLC, I just thought I'd point that out)

Volume control pipeline

Reply #2 –
Quote
Already having a decent background of graphics editing, my old reasoning was this: if downscaling a graphic from a larger source is always better than upscaling from a smaller, surely this is the same for audio, and I should never downscale with an earlier control, then pump back up with a later control.
True!     

I was about to say the same thing as tropicalfish.  I believe all 4 of these are attenuators.  When it comes to "resolution", it doesn't matter if you attenuate digitally or in analog.  Some people worry about the "lost bits" when you attenuate digitally, but this "detail" is also lost with analog volume reduction....  The same is true with digital images...  When you scale-down an image digitally (or with lenses & film in the darkroom), the picture gets smaller but it still looks sharp, unless you re-magnify. 

Here's the thing...   Assuming you're using an analog connection, the noise from your soundcard is usually constant (it does not not get reduced when you turn down the digital volume controls).  So, it's best to keep a strong signal coming out of your soundcard for a strong signal-to-noise ratio.  Then, use the volume control on your amp.  When you turn-down the amps volume knob, the noise (from the soundcard) gets reduced together with the signal and you maintain a strong signal-to-noise ratio (except for whatever noise is generated inside the amp.)

Volume control pipeline

Reply #3 –
Quote from: dhromed on
Already having a decent background of graphics editing, my old reasoning was this: if downscaling a graphic from a larger source is always better than upscaling from a smaller, surely this is the same for audio, and I should never downscale with an earlier control, then pump back up with a later control.


Most of those are just adjusting the gain of the output stage of your sound cards amplifier.  You can usually tell which ones are controlling the analog volume and which the digital by rapidly changing the volume.  Digital adjustments will lag changes in volume since your PC buffers output a little to avoid skips during high CPU use, while analog ones will be instant (although depending on your card, OS and application the digital volume might be very fast too).

Volume control pipeline

Reply #4 –
I've found that some soundcard/onboard sound control panels reach unity gain around 70-75% on the sliders.  You will have to play around with your systems to figure out if this is true for you.
"You can fight without ever winning, but never win without a fight."  Neil Peart  'Resist'

Volume control pipeline

Reply #5 –
Quote from: dhromed on
- Windows volume control
- some odd-looking knob control in the RealTek control panel
Depending on which RealTek control you mean, these may be equivalent; in my experience Windows' Stereo Mix is often equivalent to the sound card's master volume. That said, one or both often have Wave controls too, just to add to the confusion!

Volume control pipeline

Reply #6 –
Quote from: dhromed on
I'm looking to debunk or confirm an unfounded assumption I've made "logically" from the moment I began using my computer as primary source of music (which was about ten years ago).

Currently, there are four independent volume controls between a file and my speakers, namely:

- foobar's volume control
- Windows volume control
- some odd-looking knob control in the RealTek control panel
- the volume control on my amp


I don't know about foobar but with some music players, the player's volume control, the windows volume control, and one of the knobs on the audio interface's control panel could all be the same control.

One way to test this out is to move one of the three controls and see which other ones move in synch.

Quote
Already having a decent background of graphics editing, my old reasoning was this: if downscaling a graphic from a larger source is always better than upscaling from a smaller, surely this is the same for audio, and I should never downscale with an earlier control, then pump back up with a later control.


In general, all volume controls are themselves attenuators. There may be a gain block that is associated with them.  Usually the attenuator precedes the amplification.

In a few rare cases such as professional mic preamps the gain control may actually internally change the gain of the amplifier. The trade off here is that it is difficult or impossible to reduce the gain of an amplifier to zero. It's far easier to have an amplifier with some amount of fixed gain and use a separate attenuator to control over-all gain. Attenuators may have no problem reducing gain to very close to near-infinite amounts of attenuation, but in the real world they may have a little leakage.

Quote
I never actually tested this assumption, and ever since, I have them all maxed, and control exclusively via the amp, the final control.


The relevant question is what sort of audible artifacts that you are getting. I'm not talking about fear and inference, I'm talking about real audible bad effects. There may be none. 

The usual rule is to get the signal up to a reasonably high level (sometimes called line level) as soon as possible in the chain of components and keep it there as close as possible to the final load.  Line level is usually on the order of  from 1/3 of a volt to 6 volts with around 1 volt being the most common.

In most systems this means that all volume controls should be set as high as possible without causing clipping, and that the only user-accessible volume control be associated with the input to the power amp. Of course this might not be convenient. As soon as you have a system with 2 user-operable volume controls in series, there is plenty of opportunity for them to be used in sub optimal ways. The worst case is usually when the first volume control is set low, and the second volume control is set high to overcome the low setting. Then the high setting of the second volume control increases any noise that is added in the intervening stages of amplification.

In audio production systems where we try to ensure the highest possible sound quality, the main system volume control is often an analog attenuator at the input to the system's power amp or active speakers. Any other volume controls are left near or at their maximum setting, again consistent with avoiding clipping.

Quote
So theoretically speaking, is that actually accidentally sensible or just silly myth?


The thing is that theory shouldn't rule our lives - what works well in actual use is always of the essence.  Most better audio gear has enough dynamic range that suboptimal settings within bounds cause no audible difficulties. Remember that any theoretical goodness you manage to scrape together can easily get lost in the speakers, headphones, and listening environment.

So, if you are hearing hiss all the time you should pay attention to perfecting up your gain structure, and if you aren't you should move on to more entertaining pursuits.

Volume control pipeline

Reply #7 –
Quote from: dv1989 on
Quote from: dhromed on
- Windows volume control
- some odd-looking knob control in the RealTek control panel
Depending on which RealTek control you mean, these may be equivalent


Ah, but both are present. The main EQ in the RealTek panel just shows a skinned version of Windows' default volume controls, plus a nice* graphical-looking round knob that you can drag. I'm really not sure why it exists, but it's there.



*) sarcasm! It actually looks quite crappy. You know how it is.

Volume control pipeline

Reply #8 –
Quote from: Arnold B. Krueger on
I don't know about foobar but with some music players, the player's volume control, the windows volume control, and one of the knobs on the audio interface's control panel could all be the same control.


Perhaps I should have made it more explicit: all the controls I describe are totally independent. The soundcard's own control panel contains a copy of Windows' volume controls, and these are indeed the same, so I didn't mention it.


Quote from: Arnold B. Krueger on
The relevant question is what sort of audible artifacts that you are getting. I'm not talking about fear and inference, I'm talking about real audible bad effects. There may be none. [...] The thing is that theory shouldn't rule our lives - what works well in actual use is always of the essence.


I'm not getting any articfacts at all, really, so I don't have a practical issue. Theory does help with understanding the general case, and the idea was nagging me a bit. A motherboard that suffers from buzz, like all of my previous computers, might have benefited from more modest volume in Windows and letting the amp do the work. That may not make theoretical sense either, but those computers are gone now and I can't experiment. The only noise I get now is a perfectly smooth white noise, and only when I open up the amp beyond levels I consider far too loud.


Thanks for the info, everybody!

Volume control pipeline

Reply #9 –
Quote from: dhromed on
Quote from: Arnold B. Krueger on
I don't know about foobar but with some music players, the player's volume control, the windows volume control, and one of the knobs on the audio interface's control panel could all be the same control.


Perhaps I should have made it more explicit: all the controls I describe are totally independent. The soundcard's own control panel contains a copy of Windows' volume controls, and these are indeed the same, so I didn't mention it.


Newer versions of Windows allow per application volume settings as well as a master volume.  In this case the mixer just multiplies the application volume times the master volume to get the actual volume applied.

Volume control pipeline

Reply #10 –
I know this topic is old, but i'd rather reply to it than create one more duplicate thread around here. I hope that's alright. If not, i'd appreciate it being spun off.

I'm confused.  It was said earlier in this thread that the reason to keep the soundcard volume up is that it masks the sound of the card's own noise. This noise remains a constant regardless of your gain setting. Well, amplifiers and all other equipment have noise as well. That's what a signal-to-noise ratio represents, right? So why doesn't this apply to the amp as well even if it's an analog controll?

I've also read that the digital volume control reduces the bits as and thus the information  as well, so it's better to keep your soundcard volume at max and adjust the analog volume control on your analog preamp. Is that true? Does it matter in practice?  Besides, few people want their bits reduced. ^>.>^

If the above is true, how it is handled in digital pre-amps like those made by Theta Digital and Meridian, or even outboard pro/portable D/A converter like the MOTU traveller, M-audio usb D/A etc or any D/A with a volume control? Is the attenuation just placed after the D/A inside the unit? Might some higher end soundcards do that as well?

Thanks.

Music lover and recovering high end audiophile

Volume control pipeline

Reply #11 –
Quote from: BearcatSandor on
I'm confused.  It was said earlier in this thread that the reason to keep the soundcard volume up is that it masks the sound of the card's own noise. This noise remains a constant regardless of your gain setting. Well, amplifiers and all other equipment have noise as well. That's what a signal-to-noise ratio represents, right? So why doesn't this apply to the amp as well even if it's an analog controll?


I don't understand this question.

Quote from: BearcatSandor on
I've also read that the digital volume control reduces the bits as and thus the information  as well, so it's better to keep your soundcard volume at max and adjust the analog volume control on your analog preamp. Is that true? Does it matter in practice?  Besides, few people want their bits reduced.


If you soundcard uses digital volume, probably.  To your second question, probably not, since I think digital volume control is fairly rare. 

Quote from: BearcatSandor on
If the above is true, how it is handled in digital pre-amps like those made by Theta Digital and Meridian, or even outboard pro/portable D/A converter like the MOTU traveller, M-audio usb D/A etc or any D/A with a volume control? Is the attenuation just placed after the D/A inside the unit? Might some higher end soundcards do that as well?


I think pretty much every dac and sound card does that. 

Volume control pipeline

Reply #12 –
Thanks for the answers. As to the first question:  The idea is that a sound card creates a steady level of noise. Therefore you want your volume up to mask that noise, because the noise is the constant and the volume is the variable.  Doesn't every piece of equipment you have create noise? Is it just that the audibility of the self-made noise of an average preamp is so low that it does not matter?  In other words, if everything has a s/n why would this only apply to sound cards?
Music lover and recovering high end audiophile

Volume control pipeline

Reply #13 –
Quote from: BearcatSandor on
Doesn't every piece of equipment you have create noise? Is it just that the audibility of the self-made noise of an average preamp is so low that it does not matter?  In other words, if everything has a s/n why would this only apply to sound cards?


Yes every piece of equipment generates noise, and no it doesn't apply only to sound cards.  SNR will often be maximized at extremely high volumes, at least if nothing distorts/saturates/clips.

Volume control pipeline

Reply #14 –
Quote from: BearcatSandor on
The idea is that a sound card creates a steady level of noise.


The sedond idea is that your soundcard is sufficient, which is to say that it plays music well, even if everything isn't exactly optimal.

Quote
Therefore you want your volume up to mask that noise, because the noise is the constant and the volume is the variable.


The input to the sound card is typically from the digital music source. Yes, any noise that is natually added along the way has its signficiance minimized if the music signal is as large as is reasonbly possible.

The relevant question is how much do you need to maximize levels in order for you to enjoy the music.

Quote
Doesn't every piece of equipment you have create noise?


Of course, but very often the noise added to the music is minor or even irrelevant compared to the noise that is already part of the music.

Quote
Is it just that the audibility of the self-made noise of an average preamp is so low that it does not matter?


Yes, in a good modern system any self-noise that is added along the way is not bothersome, or even noticable.

Quote
In other words, if everything has a s/n why would this only apply to sound cards?


It doesn't. Often, the major source of the noise that you may hear is the recording itself, and there is nothing an ordinary listener can do about that.

Volume control pipeline

Reply #15 –
Thanks for the responses all. Ok, i think i'm cleared up on the noise issue, but i'm still confused on the "resolution reduction" issue.

There are 3 ways to adjust volume on my system: the hardware mixer on the sound card, the software volume control on the player and the volume knob on my integrated amp.

I was told by someone (not on this board) that you always want to leave the volume on the sound card at max. This is because when you reduce the volume on the sound card you are lowering the bit rate. So, turning down my volume on my sound card i'm reducing my bit rate from 24 bits to 14-bits or something if i play music softly.  This is because sound cards don't work in floating point numbers.  The volume control on the software player does work with floating point numbers so it is able to adjust, for that and not reduce the data rate. How/what it adjusts he never said. Does it dither or something?

It just feels like what i was told is wrong but i don't know why.  Why would a sound card not be able to work in floating point numbers? If the volume attenuation in the sound card is done after the d/a then none of that matters right? Then it's an analog control just like my integrated amp has. Does the integrated amp reduce resolution a non-digital way when you turn it down?

I'm not wanting to adjust the volume of my amp because it has no remote, it's across the room, and i have the level on it set as a max level to protect my ears just in case i hit the wrong keys and my computer's volume (player or sound card control) hits 100.

So, for max fidelity which is it better to adjust the volume on? The software player or the sound card?
Does it matter?
Is what i was told about the resolution reduction b.s.?

When we talk about "resolution" like this what are we really talking about? The bit-rate? The bandwidth? Adding/removing compression?

Thanks folks, i'm still learning new things and unlearning others.

You can talk to me like an idiot.  As a recent audiophile, i only *thought* i knew things about all this and i made a lot of assumptions along the way.

Thanks
Music lover and recovering high end audiophile
 

Volume control pipeline

Reply #16 –
Just addressing the concern about the reduction in resolution (quantization error) and completely ignoring the noise generated by the hardware components involved, depending on how loud you plan on listening to the sound card set to a low level, the ambient noise of your listening environment may dominate the noise resulting from a reduction in resolution.