Question about PCM volume control between 24 or 32 bit DACs.

[jjk1]

Let’s say you have a DAC with an SINAD of 120db until you start engaging the volume control at which point the your operating with a SINAD of 90, to 100db or whatever.
Now let’s say you control the volume with a connected DAC with a an SINAD of 115db at .5v. Instead or put another way, an SINAD of 115db at 1/2 volume or low volume.

Where is the volume control actually happening, and is the optimal SINAD of the final DAC of 120DB maintained if the volume is controlled by the source DAC and the final DAC is maintained at full volume electrically (like pass through)

Elementary questions I’m sure but I just don’t know. I don’t claim to be able to hear much of a difference but it’s a question I really should know the answer too.

Thank you.
JJK

 

[solderdude]

The volume control from a DAC is happening in the digital domain in the processor used inside the DAC IF it has that functionality.

You can also do volume control in the source and leave the DAC at max. volume if it has volume control.

SINAD will be lower when the output level becomes lower. This simply is not because of increased distortion (AD part) but because of the SIN part (SIgnal to Noise).
The noise stays the same, distortion usually is lower and the signal is lower.
So the lower the output signal level the more the SINAD is determined by the noise as the Signal to Noise ratio drops.

One should realize that the self noise of a DAC usually already is far below audible levels (noise you hear is in the recording whenever you hear noise) so inconsequential.

I would not worry in the least about SINAD of a DAC if it was below 100 (at max. level) nor does it say anything about sound quality or 'tone'.

Mathmetical the SINAD will not change much (so in the digital domain) when say 32 bit is used. The DS DAC chips might even do 32bit analog steps but they will simply drown in the analog noise floor.

 

[staticV3]

is the optimal SINAD of the final DAC of 120DB maintained if the volume is controlled by the source DAC and the final DAC is maintained at full volume electrically

WDYM by source DAC and final DAC? Usually, there is only ever one DAC in your audio chain.

 

[jjk1]

WDYM by source DAC and final DAC? Usually, there is only ever one DAC in your audio chain.

Well I have this wiim pro plus with “portable“ PEQ that works on its own analog outputs + it’s digital outputs so Im trying to understand what’s happening with external DACs set to pass through when they measure better “set” at full scale.
I’m not a scientist so conceptually to me this Wiim streamer can be thought of as the perfect “portable preamp virtual workload“
with the potential to let you set your electronics in their most optimal config.
so - just trying to get my facts correct on what’s happening - it’s all transparent to my ears anyway

 

[staticV3]

Please explain your audio chain that includes the WiiM and an external DAC. Preferably like this: A->B->C etc

 

[jjk1]

Please explain your audio chain that includes the WiiM and an external DAC. Preferably like this: A->B->C etc

OK - examples currently


1. source music (internet, cd, tv digits) +Wiim analog out to amplifier preamp - speakers
2. Same source path - Wiim digital output to Oppo headlamp DAC input - set to pass through so its output circuitry is at 2v always right ? - to analog preamp- speakers.
3. Same source path - Wiim second digital output to NAD c510 DAC set to pass through (volume disabled) or at 2v - to analog preamp, or dedicated to another room and used as a full digital preamplifier.
Hence the Virtual machine apology

 

[Nutul]

OK - examples currently

1 - source music (internet, cd, tv digits) +Wiim analog out to amplifier preamp - speakers

1. Same source path - Wiim digital output to Oppo headlamp DAC input - set to pass through so its output circuitry is at 2v always right ? - to analog preamp- speakers
2. Same source path - Wiim second digital output to NAD c510 DAC set to pass through (volume disabled) or at 2v - to analog preamp, or dedicated to another room and used as a full digital preamplifier.

Hence the Virtual machine apology

You appear to not use the DAC in the Wiim at all.

 

[jjk1]

You appear to not use the DAC in the Wiim at all.

im using it’s DAC in esample 1, and a different external DAC in example 2 and 3 - source volume variable and calculated by the Wiim DAC in all 3 examples. What device is swinging the voltage in example 2 and 3 when set in bypass mode and if it’s not the Wiim, does the signal accumulate flaws in the external DAC as a result of volume changes?

 

[Nutul]

im using it’s DAC in esample 1, and a different external DAC in example 2 and 3 - source volume variable and calculated by the Wiim DAC in all 3 examples. What device is swinging the voltage in example 2 and 3 when set in bypass mode and if it’s not the Wiim, does the signal accumulate flaws in the external DAC as a result of volume changes?

I find it hard to follow, but as a rule of thumb, you want to .control the volume in the last step of your audio chain, leaving everything else outputting at 0dB, that is: zero attenuation / 0 amplification; the original audio level.

This is what I'd do in the Wiim => DAC => preamp => amp => speakers setup:

1. Wiim (which acts as a streamer only in this configuration) at max volume / bypass / 0dB
2. external DAC at max volume / bypass / 0dB
3. preamp: this does volume control (attenuation)