[AnalogEuphoria]

Say you have an amplifier with high gain and it doesn’t allow you much control over the volume pot would digital volume control be better instead? Now if I set the output to something like 3/2V then it’s very small adjustment on the amplifier from quiet to loud.

If I turn the amp up to 80% and send a very low level signal out from the chord mojo for example, degrade the signal?

This would be the optimal setting to allow me to use the knob comfortably.

 

[bigshot]

synesthesia. Now I know what color is the best volume level. I'm painting my volume knob orange.

 

[gregorio]

If I turn the amp up to 80% and send a very low level signal out from the chord mojo for example, degrade the signal?

Very possibly. Unfortunately there’s no simple answer to this question because it depends on a number of factors that aren’t usually obvious. As a general rule of thumb, the ideal digital output level is around 98%.

If I’ve understood what you’ve posted, a -33dB digital volume setting equates to roughly 6bits. In other words, this setting effectively turns a 16bit audio file into a 10bit audio file by removing about 6 of the least significant bits (LSBs). Then you are amplifying that 10bit file with an 80% setting on your amp, which in most/many cases will add more noise and distortion than say a 50% amp setting. In this scenario it is entirely possible (even probable) you could hear a loss of resolution, more noise or distortion. However, this exact scenario is unlikely, it’s likely your DAC is lowering the digital volume in a 24bit environment, Eg. It’s padding the 16bit file to 24bit by adding 8 bits set to zero. In this scenario, loosing 6 of the added 8 zeroed bits cannot have any effect. However, the amp’s high gain setting still could and there are other factors I haven’t mentioned which might.

In addition, on the other side of the coin, a very low setting on your amp can also have detrimental effects with some amps.

There are 3 ways to be sure of what’s going on and whether you’re loosing resolution and/or adding noise:

1. Measure the amp’s output with low digital volume and high amp gain vs high digital output and low amp gain. However, you’ll obviously need measuring equipment for this.

2. Compare the results of a null test for each of the two settings. However, you’ll need an ADC and some free software for this.

3. Do a blind/double blind test of the two settings. However, you’ll need someone to help and it will be difficult to setup this test so the results are reliable.

I know this isn’t a particularly helpful response but at least you have some idea of why there isn’t a simple answer to your question. I can provide advice if you want but it would be almost entirely a guess and the same would be true of anyone else, unless they had done one of the 3 options above with your specific models of DAC and amp.

G

 

[AnalogEuphoria]

Very possibly. Unfortunately there’s no simple answer to this question because it depends on a number of factors that aren’t usually obvious. As a general rule of thumb, the ideal digital output level is around 98%.

If I’ve understood what you’ve posted, a -33dB digital volume setting equates to roughly 6bits. In other words, this setting effectively turns a 16bit audio file into a 10bit audio file by removing about 6 of the least significant bits (LSBs). Then you are amplifying that 10bit file with an 80% setting on your amp, which in most/many cases will add more noise and distortion than say a 50% amp setting. In this scenario it is entirely possible (even probable) you could hear a loss of resolution, more noise or distortion. However, this exact scenario is unlikely, it’s likely your DAC is lowering the digital volume in a 24bit environment, Eg. It’s padding the 16bit file to 24bit by adding 8 bits set to zero. In this scenario, loosing 6 of the added 8 zeroed bits cannot have any effect. However, the amp’s high gain setting still could and there are other factors I haven’t mentioned which might.

In addition, on the other side of the coin, a very low setting on your amp can also have detrimental effects with some amps.

There are 3 ways to be sure of what’s going on and whether you’re loosing resolution and/or adding noise:

1. Measure the amp’s output with low digital volume and high amp gain vs high digital output and low amp gain. However, you’ll obviously need measuring equipment for this.

2. Compare the results of a null test for each of the two settings. However, you’ll need an ADC and some free software for this.

3. Do a blind/double blind test of the two settings. However, you’ll need someone to help and it will be difficult to setup this test so the results are reliable.

I know this isn’t a particularly helpful response but at least you have some idea of why there isn’t a simple answer to your question. I can provide advice if you want but it would be almost entirely a guess and the same would be true of anyone else, unless they had done one of the 3 options above with your specific models of DAC and amp.

G

Thanks this was a very helpful post and the response from the designer was this

"Changing the volume will not affect the sound quality at all, unlike other DACs. This is down to the way the volume control works with the UHD DSP and the fact that Mojo's noise shaper is capable of resolving extremely small signals perfectly. So you will get better sound by running Mojo 2 at 1v or less."

 

[gregorio]

"Changing the volume will not affect the sound quality at all, unlike other DACs. This is down to the way the volume control works with the UHD DSP and the fact that Mojo's noise shaper is capable of resolving extremely small signals perfectly. So you will get better sound by running Mojo 2 at 1v or less."

Interesting response. As in most cases with audiophile manufacturers, it takes some reading between the lines and a fair amount of what they say is contradictory and/or BS because they assume consumers don’t have enough audio knowledge to notice. For example, if they are using noise-shaping as part of the digital volume process, it absolutely must affect the sound quality. This shouldn’t have any audible effect but might do in rare cases depending on exactly what they’re doing with the noise-shaping, what noise-shaping is in the recordings you’re reproducing and how your amp responds to the higher levels of ultrasonic noise this process creates. Some other DACs also use this type of process so that’s another false claim and their Ultra High Definition DSP is most probably pretty much the same definition everyone else uses in their DACs (although I can’t be certain of that).

It’s interesting they state you get better sound out of the Mojo 2 at 1V or less. I can’t see any reason to doubt this claim although it is somewhat strange as many consumer DACs aim for optimal performance around 2V. Also, the “or less” is somewhat troubling, as you go lower you’re going to have more difficulties with the noise-shaping and eventually thermal noise for which there is no solution. So the question is: How much less and does your setting fall within that of range of 1V to whatever?

My guess is that you’re probably just about OK although your high amp setting might be adding a bit more noise than necessary. If it’s not too much trouble to set your digital gain a bit higher and your amp a bit lower, you *might* notice some improvement.

G

 

[Roseval]

In other words, this setting effectively turns a 16bit audio file into a 10bit audio file by removing about 6 of the least significant bits (LSBs).

Does it?
If you have a DAC with a 16 bit register, yes.
If you have a DAC with 24 bits register you can reduce the volume of a 16 bit file with 48 dB and still have the entire 16 bits in the register as you simple shift the sample 8 bits towards the LSB

 

[gregorio]

Does it?
If you have a DAC with a 16 bit register, yes.
If you have a DAC with 24 bits register you can reduce the volume of a 16 bit file with 48 dB and still have the entire 16 bits in the register as you simple shift the sample 8 bits towards the LSB

You seem to have missed the next bit of my post:

“However, this exact scenario is unlikely, it’s likely your DAC is lowering the digital volume in a 24bit environment, Eg. It’s padding the 16bit file to 24bit by adding 8 bits set to zero. In this scenario, loosing 6 of the added 8 zeroed bits cannot have any effect.”

G

 

[Roseval]

Indeed, missed it completely.
Sorry

 

[gregorio]

No problem. Although we’re both wrong in a sense, because we’re talking about just a loss (or lack of loss) in the digital domain. In practice we would effectively loose some of those 16bits because they would be below the noise floor of the DAC.

G

 

[AnalogEuphoria]

Interesting response. As in most cases with audiophile manufacturers, it takes some reading between the lines and a fair amount of what they say is contradictory and/or BS because they assume consumers don’t have enough audio knowledge to notice. For example, if they are using noise-shaping as part of the digital volume process, it absolutely must affect the sound quality. This shouldn’t have any audible effect but might do in rare cases depending on exactly what they’re doing with the noise-shaping, what noise-shaping is in the recordings you’re reproducing and how your amp responds to the higher levels of ultrasonic noise this process creates. Some other DACs also use this type of process so that’s another false claim and their Ultra High Definition DSP is most probably pretty much the same definition everyone else uses in their DACs (although I can’t be certain of that).

It’s interesting they state you get better sound out of the Mojo 2 at 1V or less. I can’t see any reason to doubt this claim although it is somewhat strange as many consumer DACs aim for optimal performance around 2V. Also, the “or less” is somewhat troubling, as you go lower you’re going to have more difficulties with the noise-shaping and eventually thermal noise for which there is no solution. So the question is: How much less and does your setting fall within that of range of 1V to whatever?

My guess is that you’re probably just about OK although your high amp setting might be adding a bit more noise than necessary. If it’s not too much trouble to set your digital gain a bit higher and your amp a bit lower, you *might* notice some improvement.

G

I think it works at 32bit and 104mhz for the noise shaping but I think im just going to use Rothwell attenuators on a cheaper dac because I don't feel its worth all troubleshooting.

 

[gregorio]

If you’ve already purchased the Mojo, there’s no need to change it. Unless you’re noticing an audible problem it’s probably working close enough to optimal not to be causing any audible issues. You could try attenuators on the Mojo, it might make a slight difference (or it might not) and it might make a difference to your amp if your DAC’s output is attenuated. If anything, I’d be looking at your amp and getting one with better adjustments at lower settings.

G

 

[AnalogEuphoria]

Searching around for info about the NAD it does seem to have an unusually high voltage gain at 39dB, maybe that's what's causing the problem with any source plugged in.

 

[KeithPhantom]

Say you have an amplifier with high gain and it doesn’t allow you much control over the volume pot would digital volume control be better instead?

No, I would get a pre-amplifier just for this reason. I’d get one with matched resistor ladders just to not deal with regular volume pots (and their channel imbalances), but the volume change will be still handled in the analog domain, keeping your DAC in its most linear operation.