Quality basics: please improve digital volume control

[planetti]

Dear WiiM-Team,

can you improve the quality of the digital volume control implementation? (Do you use e.g 64bit/dithering algorithms?)

The current algorithm seems to be detrimental to sound quality, apart from the numerical bit-reduction. This general improvement would be a gain for all WiiM devices and in the future.

Some users will not recognise, but many (current) users ask for 1:1 bit-perfect, which means that they are not satisfied with the current implementation. This user group may appreciate the WiiM technical quality level.

Perhaps it is possible to add a ISO226 adapted volume level correction at the same time.

Thank you for your efforts!

 

[Brantome]

How does this “detrimental” control manifest itself?

 

[planetti]

I have the subjective impression that the soundstage presentation is "reduced", the sound is "flatter", the instruments are more "diffuse" and a bit "constricted" - when the digital volume in the WiiM app is reduced while volume level is compensated, spdif coaxial out, on headphone and speakers.

 

[hash70]

Dear WiiM-Team,

can you improve the quality of the digital volume control implementation? (Do you use e.g 64bit/dithering algorithms?)

The current algorithm seems to be detrimental to sound quality, apart from the numerical bit-reduction. This general improvement would be a gain for all WiiM devices and in the future.

Some users will not recognise, but many (current) users ask for 1:1 bit-perfect, which means that they are not satisfied with the current implementation. This user group may appreciate the WiiM technical quality level.

Perhaps it is possible to add a ISO226 adapted volume level correction at the same time.

Thank you for your efforts!

Is it not bit perfect?

 

[planetti]

If you do not tick "fixed volume" on 100% and if you use any EQ, the signal is processed and cannot be bit perfect any more.

 

[Brantome]

Is it not bit perfect?

I personally don’t get too hung up on this - to me, bit perfect means that the unit doesn’t make any unwanted changes to the stream, which the WiiM devices don’t. If you want to make changes such as applying PEQ and a volume limit to guard against digital clipping that might occur as a result of applying that PEQ, then you’re making changes to enhance your listening experience.

 

[planetti]

I personally don’t get too hung up on this - to me, bit perfect means that the unit doesn’t make any unwanted changes to the stream, which the WiiM devices don’t. If you want to make changes such as applying PEQ and a volume limit to guard against digital clipping that might occur as a result of applying that PEQ, then you’re making changes to enhance your listening experience.

Every digital processing has an influence on the digital signal, since the information is not the same as the original. Of course, there are algorithms (e.g. sophisticated tricks, filterings, interpolations etc.) which keep the distortion to a minimum or shift to inaudible regions. Depending on the quality of the algorithms and your auditive sensitivity, such processing is detrimental to the original sound.

At low level the digital volume unfortunately looses more than the theoretical dynamics with my actual Wiim devices. With some other gears the effect is not so apparent.

Brantome, perhaps your setup luckily operates with a proper gain design. But in case a setup is running at low digital levels, this effect gets more relevant.

 

[WiiM Support]

Dear WiiM-Team,

can you improve the quality of the digital volume control implementation? (Do you use e.g 64bit/dithering algorithms?)

The current algorithm seems to be detrimental to sound quality, apart from the numerical bit-reduction. This general improvement would be a gain for all WiiM devices and in the future.

Some users will not recognise, but many (current) users ask for 1:1 bit-perfect, which means that they are not satisfied with the current implementation. This user group may appreciate the WiiM technical quality level.

Perhaps it is possible to add a ISO226 adapted volume level correction at the same time.

Thank you for your efforts!

Hi planetti,

Thank you for your suggestion regarding digital volume control. Our volume table is 8-bit, and considering the maximum bit-depth is 24-bit, we employ 32-bit processing for volume control to avoid any loss in precision.

Additionally, we offer a preset EQ mode called 'loudness,' designed to enhance the lows and highs following the ISO226 standards, which might be beneficial at low volumes.

If I've misunderstood your comments, please let me know.

 

[joffy1780]

Hi planetti,

Thank you for your suggestion regarding digital volume control. Our volume table is 8-bit, and considering the maximum bit-depth is 24-bit, we employ 32-bit processing for volume control to avoid any loss in precision.

Additionally, we offer a preset EQ mode called 'loudness,' designed to enhance the lows and highs following the ISO226 standards, which might be beneficial at low volumes.

If I've misunderstood your comments, please let me know.

How does the volume control work when using the analogue outputs, is it a different implementation? @WiiM Support @WiiM Team @RyanWithWiim ?

 

[WiiM Support]

How does the volume control work when using the analogue outputs, is it a different implementation? @WiiM Support @WiiM Team @RyanWithWiim ?

Hi joffy1780,

There is a volume table ranging from 0 to 100 that applies to both digital and analog audio output. Our DAC supports 32-bit input, which we utilize to maintain bit depth. Additionally, intermediate processing is designed to preserve sample value accuracy throughout.

 

[Musician]

Dear WiiM-Team,

can you improve the quality of the digital volume control implementation? (Do you use e.g 64bit/dithering algorithms?)

The current algorithm seems to be detrimental to sound quality, apart from the numerical bit-reduction. This general improvement would be a gain for all WiiM devices and in the future.

Some users will not recognise, but many (current) users ask for 1:1 bit-perfect, which means that they are not satisfied with the current implementation. This user group may appreciate the WiiM technical quality level.

Perhaps it is possible to add a ISO226 adapted volume level correction at the same time.

Thank you for your efforts!

The volume control might have been improved since march.
I dont hear those issues that you mention . And one cant measure any issue either. Vintageflankers measurements of the digital volume regulation ( on PRO ) shows its a very good one, true 24 bit resolution through spdif out.

The volume regulation inside the Ultra ( and my PRO ) is in my opinion even better sounding than using my Mac M1 with an external precisionclock DDC.

Have you set the WiiM app to allow 24 bit and 192 KHz as highest resolution ?

—————

WiiM Pro - Review & Measurements (Streamer)

WiiM Pro - Review & Measurements Hey folks, It is time for my first review of 2023... This one is about a complete objective analysis of the new WiiM Pro streamer. The aforementioned has been recently announced, back in November 2022, and I can see quite a strong hype around it since. That...

www.audiosciencereview.com

Vintageflanker measurements of the digital volumecontrol of the Pro on spdif out:

”Last but not least, a quick world about digital volume implementation. This is what I get when measuring the same 1kHz tone (Wi-Fi In, 44.1kHz) at different levels:”

Fixed: -141.8dB THD+N
≃75%: -138.2dB THD+N
≃50%: -131.5dB THD+N
≃25%: -115.5dB THD+N
≃10%: -99.6dB THD+N

 

[steadyshot]

Which is better in fidelity terms, assuming the same input, from the options below? In my case the only reason I use volume control is that I perceive a slight harshness when it is bitperfect 100% volume fixed. So I slightly reduce the volume, as it avoids that harshness that I hear otherwise. (Wiim pro plus used as a transport)

• Uncheck fixed volume , keep volume limit to 100, and then adjust volume as desired
• Fixed Volume checked but specify volume limit
• Pre gain reduction for the specified input

Another question since I use optical output currently set to 24/96.... Are we sure that there is no extra processing is involved unless the source plays a track of greater resolution than 24/96?

 

[canard]

Which is better in fidelity terms, assuming the same input, from the options below? In my case the only reason I use volume control is that I perceive a slight harshness when it is bitperfect 100% volume fixed. So I slightly reduce the volume, as it avoids that harshness that I hear otherwise. (Wiim pro plus used as a transport)

• Uncheck fixed volume , keep volume limit to 100, and then adjust volume as desired
• Fixed Volume checked but specify volume limit
• Pre gain reduction for the specified input

Another question since I use optical output currently set to 24/96. Are we sure that there is no processing involved unless the source plays a track of greater resolution than 24/96?

your comment raises questions... maybe even joins another thread...
Thread 'Wiim pro plus sounds sharper than before' https://forum.wiimhome.com/threads/wiim-pro-plus-sounds-sharper-than-before.4905/
etc
(maybe onlyoneme, if he read, will have to take out the cosmos ;-) otherwise side measurements on num easier)

 

[steadyshot]

your comment raises questions... maybe even joins another thread...
Thread 'Wiim pro plus sounds sharper than before' https://forum.wiimhome.com/threads/wiim-pro-plus-sounds-sharper-than-before.4905/
etc
(maybe onlyoneme, if we read, will have to take out the cosmos ;-) )

I think that was always an issue (worse on wiim mini) but again because I sparsely tried the 100% volume fixed, due to that phenomenon, maybe there were fw revisions that this was not exhibited . I don't know.

For instance, I saw that a new firmware went out today. Nothing related is mentioned of course, but when I install it I will try again.

 

[canard]

I think that was always an issue (worse on wiim mini) but again because I sparsely tried the 100% volume fixed, due to that phenomenon, maybe there were fw revisions that this was not exhibited . I don't know.

For instance, I saw that a new firmware went out today. Nothing related is mentioned of course, but when I install it I will try again.

there were old episodes with a drc problem even on the fixed level (which joins the following point)....
now remains a major problem for those who use the peq-rc mode, which can of course generate distortion, incredible absence of an "autogain" mode

 

[Musician]

Which is better in fidelity terms, assuming the same input, from the options below? In my case the only reason I use volume control is that I perceive a slight harshness when it is bitperfect 100% volume fixed. So I slightly reduce the volume, as it avoids that harshness that I hear otherwise. (Wiim pro plus used as a transport)

• Uncheck fixed volume , keep volume limit to 100, and then adjust volume as desired
• Fixed Volume checked but specify volume limit
• Pre gain reduction for the specified input

Another question since I use optical output currently set to 24/96.... Are we sure that there is no processing involved unless the source plays a track of greater resolution than 24/96?

Some things to check first:

1. You cant use PEQ with any + values when using fixad 100% volume out , it will have digital clipping.

2. Your external dac dont manage a 100% signal or dont have any headroom. Check If the internal dac of the WiiM also sounds sharper using 100% volume . If its not, the fault is in the external dac.

3. Dont use a fixed output at 24 bit 96 KHz- instead , set the WiiM to the highest resolution possible in the app and turn off any fixed output that has sample rate conversion. Following the source material sample frequency always sounds best.

 

[canard]

It's even more complicated than that if you use ls or hs mode...because you can clip even in negative values (especially in the bass in real life)
may be so brief as misunderstood..but will be there

 

[steadyshot]

Some things to check first:

1. You cant use PEQ with any + values when using fixad 100% volume out , it will have digital clipping.

2. Your external dac dont manage a 100% signal or dont have any headroom. Check If the internal dac of the WiiM also sounds sharper using 100% volume . If its not, the fault is in the external dac.

1. I am not using any eq at the moment and when I was using it was only reductive and had -3db or lower pre gain(in all cases equal to the reduction)
2. Maybe this could be the case for my internal(amp) dac, but I also saw other reviewers and people noticing it (eg. pursuit of perfect sound and others). I remember when I used wiim pro plus as a streaming dac (not transport) this was not an issue, but then again the signal went through my pre amp. When using it as a transport it goes directly to the dac and power amp without being routed to the pre- first.

 

[Musician]

It's even more complicated than that if you use ls or hs mode...because you can clip even in negative values (especially in the bass in real life)

True, especially If one uses higher Q values than 0.7 . It will overshoot and there will be digital clipping If using 100% volume

 

[steadyshot]

3. Dont use a fixed output at 24 bit 96 KHz- instead , set the WiiM to the highest resolution possible in the app and turn off any fixed output that has sample rate conversion. Following the source material sample frequency always sounds best.

I am not using fixed output. I have just selected max output to 24/96 but I have not selected fixed asrc.