Reducing DAC volume doesn't necessarily decrease bit-depth of audio data.

[Sokel]

What you see is a line that goes down exactly with the volume, this means the absolute level of the noise/distortion remains constant.

Let's see real world (attenuated at the DAC side not generator level,as a user would normally do) :

-2db of attenuation 104.8 SINAD

-30db of attenuation 75.1 SINAD

Edit:values added.

 

[Hayabusa]

Let's see real world (attenuated at the DAC side not generator level,as a user would normally do) :




View attachment 276344

-2db of attenuation



View attachment 276345

-30db of attenuation

if you would scale the 30dB plot back to absolute level you see the noise and distortion components stay at the same level..
Why did you scale back the -30dB signal to 0dB?

 

[Sokel]

if you would scale the 30dB plot back to absolute level you see the noise and distortion components stay at the same level..
Why did you scale back the -30dB signal to 0dB?

The measurements is in dbr so already relative to absolute level you can see that in settings that's why I posted the whole screen.
In dbFS the harmonics would be waaaay down but the overall SINAD would the same or very near,I'll make one that way too later (now I'm drinking my coffee with music).

 

[Sokel]

if you would scale the 30dB plot back to absolute level you see the noise and distortion components stay at the same level..
Why did you scale back the -30dB signal to 0dB?

Forgot I can do it from the saved ones in history.here we go:

-2dbdbFS 104.8 SINAD

-30dbFS 75.2 SINAD

Both.

Don't ask me to interpret,I'm too newbie for it

 

[piaseczek]

Forgot I can do it from the saved ones in history.here we go:

Could you add an attenuator and repeat measurements?
I don't recall if anybody made such a measurements - great value added.

 

[Sokel]

Could you add an attenuator and repeat measurements?
I don't recall if anybody made such a measurements - great value added.

Amir does it all the time lately,it's the SINAD vs level one (on device's side),the one with the time on the X axis).
Attenuator,you mean something like a pre?

 

[piaseczek]

Attenuator,you mean something like a pre?

I mean fully passive attenuator, e.g. -20dB made from low value resistors not to increase noise of the DAC. In theory it should not worsten the SNR/SINAD and solve the issue of gain mismatch in many systems based on DAC connected directly to a power amplifier.

E.g. ready made one, jts ma-123 (very low input impedance):

JTS: MA-123

Adjustable attenuator for balanced microphones For matching the microphone signal to mixers or preamplifiers Attenuation: 10 dB, 20 dB, 30 dB Also suitable for microphones with phantom power Meta...

www.jts-europe.com

Nice discussion in the rme forum:

Level mismatch solutions - fixed and variable attenuators (Page 1) — Tips & Tricks — RME User Forum

Level mismatch solutions - fixed and variable attenuators (Page 1) — Tips & Tricks — RME User Forum —

forum.rme-audio.de

 

[Sokel]

Ok,got it.
I don't have a ready one at hand as I normally use a traditional pre (old one) but i must have resistors to built one.
I will update at some time,I'm curious too.

 

[piaseczek]

I would say that universal values for -20dB attenuator are: 2 x 2k and 450ohm. Lower impedance than most of potentiometers and high enough not to stress (much) analogue part of the DAC.

Here is the online calculator:

Voltage divider - loaded and open-circuit dB calculator damping volts potentiometer circuit impedance damping pad decibel dB voltage attenuator impedance bridging matching - sengpielaudio Sengpiel Berlin

Calculations: voltage divider circuit calculator dB - loaded and open-circuit damping potentiometer circuit impedance damping decibel dB attenuator impedance bridging matching - Eberhard Sengpiel sengpielaudio

www.sengpielaudio.com

 

[notsodeadlizard]

This discussion is completely incomprehensible because it has been proven that 16 bits of CD quality is enough, lossy compression is no different from lossless compression, so listen to your mp3 and don't torture yourself with such difficulties.
Or does "objectivism" mean something else?

^_^

 

[antcollinet]

This discussion is completely incomprehensible because it has been proven that 16 bits of CD quality is enough, lossy compression is no different from lossless compression, so listen to your mp3 and don't torture yourself with such difficulties.
Or does "objectivism" mean something else?

^_^

Take your strawmanning elsewhere please.

 

[BDWoody]

This discussion is completely incomprehensible because it has been proven that 16 bits of CD quality is enough, lossy compression is no different from lossless compression, so listen to your mp3 and don't torture yourself with such difficulties.
Or does "objectivism" mean something else?

^_^

Troll much?

 

[antcollinet]

Forgot I can do it from the saved ones in history.here we go:


View attachment 276352

-2dbdbFS 104.8 SINAD

View attachment 276353

-30dbFS 75.2 SINAD

View attachment 276354

Both.

Don't ask me to interpret,I'm too newbie for it

What DAC is that? Do we know how it is implmenting the volume control? (It starts with a less than SOTA SINAD in the first place)

What is more significant though is the dramatic *increase* in 3rd and 5th harmonic of the attenuated signal, so the two harmonics are actually HIGHER absolute level than in the non attenuated signal.

This is not what I would expect, and suggests a non ideal implementation of the digital volume control.

 

[Sokel]

What DAC is that? Do we know how it is implmenting the volume control? (It starts with a less than SOTA SINAD in the first place)

What is more significant though is the dramatic *increase* in 3rd and 5th harmonic of the attenuated signal, so the two harmonics are actually HIGHER absolute level than in the non attenuated signal.

This is not what I would expect, and suggests a non ideal implementation of the digital volume control.

The known Khadas which Amir has tested.
Of course my measurement (at -2db) is some 5db worst than Amir's SOTA analyzer,that's more than expected as I insist measuring everything as-is,sitting on the rack (for this one 6 meters cable is involved but still gets decent for a 13 yo ADC).
The VC is also the known internal ESS digital implementation.
If you want to change something in the measurement tell me,I have everything handy now.

 

[antcollinet]

The known Khadas which Amir has tested.
Of course my measurement (at -2db) is some 5db worst than Amir's SOTA analyzer,that's more than expected as I insist measuring everything as-is,sitting on the rack (for this one 6 meters cable is involved but still gets decent for a 13 yo ADC).
The VC is also the known internal ESS digital implementation.
If you want to change something in the measurement tell me,I have everything handy now.

Thanks.

I can't suggest a change in measurement. I can't understand where the absolute increase of 3/5th harmonics is coming from. Perhaps someone more experienced with how the ESS DACs VC works can explain possible causes.

(I would expect the harmonic distortion comes from the analoge electronics after the DAC chip. However, if that were the case, I'd expect the absolute levels of HD to be proportional to the attenuated level of the output signal (Like it is for 2nd and 4th). Increased absolute HD suggests to me that it is being added by the volume change in the digital domain - but I also don't see how this could happen)

 

[piaseczek]

The VC is also the known internal ESS digital implementation.

In well-implemented DAC digital volume control measurements should look like that:

Topping D90SE Review (Balanced DAC)

Merry Xmas Amir What is type of USB port at the back of this Topping D90SE DAC. Thanks. Type B. Topping includes the cable with the unit. Thanks for reaching out. Much appreciated. Which would be the preferred or better input to use on this Topping D90SE DAC? USB or Coax?

www.audiosciencereview.com

The harmonics are gone in the noise.

 

[Sokel]

Thanks.

I can't suggest a change in measurement. I can't understand where the absolute increase of 3/5th harmonics is coming from. Perhaps someone more experienced with how the ESS DACs VC works can explain possible causes.

(I would expect the harmonic distortion comes from the analoge electronics after the DAC chip. However, if that were the case, I'd expect the absolute levels of HD to be proportional to the attenuated level of the output signal (Like it is for 2nd and 4th). Increased absolute HD suggests to me that it is being added by the volume change in the digital domain - but I also don't see how this could happen)

Just for the fun of it I did a loopback of the E-MU to see,first with it's crappy analog pot from the headphone amp and then just attenuating it by windows mixer (all ASIO).

at -4db

at -30db crappy pot

at -30 by windows mixer.

Fell free to comment,suggest other measurements,etc.

 

[antcollinet]

The VC is also the known internal ESS digital implementation.

How are you accessing the internal ESS VC with the Kahdas? If it is the Khadas 1, then it has no volume control on the board.

 

[Sokel]

How are you accessing the internal ESS VC with the Kahdas? If it is the Khadas 1, then it has no volume control on the board.

Not if you have Ian's ESS controler (which I do),it comes handy as you can control everything (I don't use it's VC,I have a pre,I bought more for the display and the other features).

 

[Sokel]

In well-implemented DAC digital volume control measurements should look like that:

Topping D90SE Review (Balanced DAC)

Merry Xmas Amir What is type of USB port at the back of this Topping D90SE DAC. Thanks. Type B. Topping includes the cable with the unit. Thanks for reaching out. Much appreciated. Which would be the preferred or better input to use on this Topping D90SE DAC? USB or Coax?

www.audiosciencereview.com

The harmonics are gone in the noise.

I agree and I urge anyone to test for themselves in real life conditions,Multitone Analyzer is free (thank's to @pkane) and all you need is an half-decent ADC to get an idea.