Audirvana volume control - need explanation

[mkrzych]

Hello,

I am on Maverick connected via USB to my DAC. Integer Mode is ON and volume control is set up only to be used with DAC on A+ preference pane. I am using late 2008 Macbook Unibody.

 

However, I can still change volume control in Audirvana?! It is normal or something is wrong? When I use optical control is disabled at all, but in this case I can understand it. So, why I am still able to use volume control on A+ and if used, how it works - in digital domain, if so, does it means that after any change it may loose bit precision (like 25% meant ~2 bits), am I right? I don't want to use software volume control, only that one which is provided by my DAC.

[wgscott]

I may be wrong, but my understanding is that you would see this connected via USB if your DAC has either a physical volume control knob or at least the internal circuitry compatible with volume control that is accessed by USB. (In other words, the USB is serving two functions simultaneously -- transmission of unattenuated (hopefully bit perfect) audio data, and transmission of the volume knob control signal.) In principle, this could be done either within the digital domain, like with the NAD M51, or in the analogue domain, like many DACs that have a variable output-stage (passive buffer or pre-amp). The A+ software is only driving that volume control, not implementing it. Whether this involves sonic degradation is therefore dependent entirely upon your DAC. I have noticed a clicking noise during volume readjustment on some systems.

 

In the case of toslink, there is no ability to control the DACs volume control circuitry from the computer. It only transfers the unattenuated (hopefully bit perfect) audio data.

[mkrzych]

I may be wrong, but my understanding is that you would see this connected via USB if your DAC has either a physical volume control knob or at least the internal circuitry compatible with volume control that is accessed by USB. (In other words, the USB is serving two functions simultaneously -- transmission of unattenuated (hopefully bit perfect) audio data, and transmission of the volume knob control signal.) In principle, this could be done either within the digital domain, like with the NAD M51, or in the analogue domain, like many DACs that have a variable output-stage (passive buffer or pre-amp). The A+ software is only driving that volume control, not implementing it. Whether this involves sonic degradation is therefore dependent entirely upon your DAC. I have noticed a clicking noise during volume readjustment on some systems.

 

In the case of toslink, there is no ability to control the DACs volume control circuitry from the computer. It only transfers the unattenuated (hopefully bit perfect) audio data.

 

I thought that if I set up A+ to use "Only DAC volume" in pref pane the slider for changing volume control on Mac OSX will be disabled, similar like when I am connected via toslink. I do not want to change volume in software, my DAC has physical knob for it. So why I am able to move that software slider? Is it normal with USB DACs even they have physical volume pot?

 

When you have noticed clicking noise, when changing volume on A+ or on DAC when using its volume knob?

[Nico]

I connect my DAC via Firewire and "Only DAC volume" shows no volume slider. Everything is as it should be (at least with FW).

[mkrzych]

I connect my DAC via Firewire and "Only DAC volume" shows no volume slider. Everything is as it should be (at least with FW).

 

I don't have FW, asking for USB

[pdvm]

I have a USB dac with volume knob, so no volume slider in A+2 here.

[unsleepable]

Some DACs allow changing the volume through USB, even though the DAC itself doesn't feature a volume control. As said in a previous post, this is because the DAC reports back to the computer that it accepts volume control orders through USB HID.

 

I don't know if it's the DAC chip or the USB controller that handles these orders. But if the DAC doesn't feature a volume control, the volume will be attenuated in a crude manner—pretty much by chopping bits off.

 

For example, the irDac. It's a line-level only DAC and doesn't feature a volume control. Still, when you connect it to a computer on USB it's possible to set its volume.

 

Typically, you want to keep this volume at its maximum setting. Although it's not like reducing it a bit will deteriorate the sound quality—or that it will be audible if it does. But if you attenuate it much, the loss of detail may become apparent.

[pooger]

 

Typically, you want to keep this volume at its maximum setting. Although it's not like reducing it a bit will deteriorate the sound quality—or that it will be audible if it does. But if you attenuate it much, the loss of detail may become apparent.

 

This will depend on what bit depth your DAC is sending to your computer. A+ displays the bit depth and sampling rate it's receiving towards the lower right of its display. If your DAC chip outputs 32 bits, then you can attenuate by up to 48 db without losing any information in 24 bit files.

 

Ideally, with analog volume control, it's best to have your volume up almost all the way--otherwise, you are just throwing away gain and upping the noise floor. Some power amps have adjustable gain settings that can allow for trimming the overall system gain this way. (This is not a volume control on the amp, which just attenuated some of the signal going into the amp.) most systems have more gain than ideal. Using the digital volume can allow you to run the system at less overall attenuation in the analog domain, and this will improve s/n.

[mkrzych]

Some DACs allow changing the volume through USB, even though the DAC itself doesn't feature a volume control. As said in a previous post, this is because the DAC reports back to the computer that it accepts volume control orders through USB HID.

 

I don't know if it's the DAC chip or the USB controller that handles these orders. But if the DAC doesn't feature a volume control, the volume will be attenuated in a crude manner—pretty much by chopping bits off.

 

For example, the irDac. It's a line-level only DAC and doesn't feature a volume control. Still, when you connect it to a computer on USB it's possible to set its volume.

 

Typically, you want to keep this volume at its maximum setting. Although it's not like reducing it a bit will deteriorate the sound quality—or that it will be audible if it does. But if you attenuate it much, the loss of detail may become apparent.

 

Thank you. One thing I've noticed when using USB where the volume slider IS available it sounds louder than when I connected over toslink and volume slider in A+ IS NOT available. Why?

[unsleepable]

I honestly don't have a clue why, using the same software and settings and without attenuation, you get louder sound on TOSLINK than on USB… Could it be related to your DAC?