Guide for Managing Volume and Headroom on the WiiM Mini (Measurements)

[staticV3]

This is a small excursion into volume and EQ headroom on the WiiM Mini (and by extension, likely other WiiM products).

WiiM Mini Firmware: 4.6.805929
WiiM Home Version: 3.5.1

For all tests, I used a -1dBFS Measurement Sweep, exported from REW and played back directly via the WiiM Home App.

Part 1: Optical (Digital) output

• Blue: Raw sweep measurement, EQ disabled, Volume limit 100%, Volume 100
• Pink: 1kHz +1dB Q1.41 Peaking filter enabled -> no clipping, but zero headroom
• Red: filter gain pushed to +3dB -> hard digital clipping (+2dBFS)
• Green: WiiM volume reduced to 94/100 -> -2dB volume reduction gives +2dB more headroom ->+3dB Peaking filter now played back clean

• Green/Pink: same as before
• Blue: +12dB Peaking filter compensated by setting volume to 68/100 -> no clipping
• Orange: 2x +12dB Peaking filters (+24dB total gain) compensated by setting volume to 38/100 -> no clipping

Here's the WiiM's volume curve:

Notes:

• Volume only changes every third (sometimes fourth) step
• Range 100-50: 1dB steps
• Range 49-29: 2dB steps
• Range 28-16: 3dB steps
• 15 and below: inconsistent steps (1.45->1.7->2.1->2.75dB)

• Orange: +24dB Peaking filter, Volume Limit 100%, Volume 38/100
• Blue: +24dB Peaking filter, Volume Limit 38%, Volume 100/100

The two traces overlap exactly -> Volume Limit 100% + Volume 38/100 = Volume Limit 38% + Volume 100/100

This means it doesn't matter whether you change the volume or set a volume limit: either one will result in the same playback volume and EQ headroom.

The selected volume limit will become your new baseline max vol value, but the volume curve behavior will otherwise stay exactly the same.
E.g. 38% Limit with Volume 38/100 will result in -24dB baseline plus -24dB reduction according to volume curve -> -48dB total volume.


Part 2: Aux (Analog) output

Here, I've scaled all measurements so that 0dB SPL = 2.0Vrms (effectively 0dBFS).

• Red: Raw sweep measurement, EQ disabled, Volume limit 100%, Volume 100, 2Vrms setting
• Green: +0.5dB Peak filter -> no clipping, 0.5dB headroom left
• Blue: +1.0dB Peak filter -> no clipping, zero headroom left
• Orange: +2.0dB Peak filter -> digital clipping (+1.0dBFS)
• Yellow: +3.0dB Peak filter -> strong clipping (+2.0dBFS)

Here's the measured output voltage of each Aux Out Level that you can configure in the WiiM Home App, with the effective volume reduction:

You'd expect the Aux Out Level to function similar to the other two volume controls, but alas:

• Magenta: Volume 100/100, 2Vrms setting with +6dB Peaking filter -> heavily clipped (+5dBFS)
• Red: Aux Out Level reduced to 1Vrms -> identical clipping, but at 5.5dB lower volume
• Green: Aux Out reset to 2Vrms, but volume set to 86/100 -> clipped filter recovered

Ergo, the volume reduction which results in the different Peak output voltages selectable via Aux Out Level is applied after the DSP step and does not increase headroom.

One more example:

• Purple: 2Vrms setting, 70% Volume limit, Volume 100/100 with +23dB Peaking filter -> heavy clipping (+23dB filter -1dB sweep amplitude -10dB Volume limit = +12dBFS)
• Mint: Ditto, except Aux Out Level set to 500 mVrms -> -12dB volume on top should provide 12dB extra headroom, therefore 0dBFS Peak amplitude and clean filter response, but instead the filter response is clipped as before, just with 12dB lower volume
• Yellow: Aux Out Level reset to 2Vrms, but Volume Limit reduced to 42% -> 12dB reduction now provided by Volume limit instead of Aux Out Level -> 12dB headroom recovered and filter can be cleanly played back.

This should hopefully give you enough information to manage your Mini's volume and headroom in a smart way.

I don't have other WiiM products to test, but I imagine they'll perform largely the same.


One last note:

If you have a finished PEQ preset but don't know the total Peak gain and hence what volume limit to choose to avoid clipping, then head on over to squig.link (or one of the dozens of custom squig.links) and click on Equalizer (next to Brands and Models).

Here you can copy your PEQ parameters over from WiiM Home. Both Peaking and Shelf filters are supported and you can change the number of filters with the Plus and Minus buttons.

Don't mind what earphone or target is selected, just punch in your parameters.

When you're done click on Export, and the first line in the downloaded .txt file returns the necessary Pre gain required to apply your preset without clipping:

You can use this value as-is, or add some margin on top to account for inter sample overs etc.

So, say I want to apply the above preset but leave some margin, therefore apply a -6dB preamp.

Have a look at the Volume Curve posted earlier and you can see that volumes 82-84 correspond to -6dB reduction, so best to set the Volume Limit to 82, 83, or 84% (doesn't matter which).

Say also that I'm using a vintage Integrated Amp which can't handle input signals above 0.5Vrms very well.

I can go back to the table above, check that to go from 2Vrms to 0.5Vrms requires 12dB of attenuation in addition to the -6 from before, ergo -6-12=-18dB which corresponds to volume 47-49/100 -> set the Volume Limit to 47, 48, or 49%.

This now ensures that the PEQ preset is applied without digital clipping (-4.4dB), there's some extra margin (-4.4 -> -6.0dB), and the entire thing is clamped to 0.5Vrms max (-6.0 -> -18dB).


Happy listening!

 

[jareinertson]

This is a small excursion into volume and EQ headroom on the WiiM Mini (and by extension, likely other WiiM products).

View attachment 511790

WiiM Mini Firmware: 4.6.805929
WiiM Home Version: 3.5.1

For all tests, I used a -1dBFS Measurement Sweep, exported from REW and played back directly via the WiiM Home App.

Part 1: Optical (Digital) output

View attachment 511797

• Blue: Raw sweep measurement, EQ disabled, Volume limit 100%, Volume 100
• Pink: 1kHz +1dB Q1.41 Peaking filter enabled -> no clipping, but zero headroom
• Red: filter gain pushed to +3dB -> hard digital clipping (+2dBFS)
• Green: WiiM volume reduced to 94/100 -> -2dB volume reduction gives +2dB more headroom ->+3dB Peaking filter now played back clean

View attachment 511796

• Green/Pink: same as before
• Blue: +12dB Peaking filter compensated by setting volume to 68/100 -> no clipping
• Orange: 2x +12dB Peaking filters (+24dB total gain) compensated by setting volume to 38/100 -> no clipping

Here's the WiiM's volume curve:
View attachment 511791

Notes:

• Volume only changes every third (sometimes fourth) step
• Range 100-50: 1dB steps
• Range 49-29: 2dB steps
• Range 28-16: 3dB steps
• 15 and below: inconsistent steps (1.45->1.7->2.1->2.75dB)

View attachment 511795

• Orange: +24dB Peaking filter, Volume Limit 100%, Volume 38/100
• Blue: +24dB Peaking filter, Volume Limit 38%, Volume 100/100

The two traces overlap exactly -> Volume Limit 100% + Volume 38/100 = Volume Limit 38% + Volume 100/100

This means it doesn't matter whether you change the volume or set a volume limit: either one will result in the same playback volume and EQ headroom.

The selected volume limit will become your new baseline max vol value, but the volume curve behavior will otherwise stay exactly the same.
E.g. 38% Limit with Volume 38/100 will result in -24dB baseline plus -24dB reduction according to volume curve -> -48dB total volume.


Part 2: Aux (Analog) output

Here, I've scaled all measurements so that 0dB SPL = 2.0Vrms (effectively 0dBFS).

View attachment 511794

• Red: Raw sweep measurement, EQ disabled, Volume limit 100%, Volume 100, 2Vrms setting
• Green: +0.5dB Peak filter -> no clipping, 0.5dB headroom left
• Blue: +1.0dB Peak filter -> no clipping, zero headroom left
• Orange: +2.0dB Peak filter -> digital clipping (+1.0dBFS)
• Yellow: +3.0dB Peak filter -> strong clipping (+2.0dBFS)

Here's the measured output voltage of each Aux Out Level that you can configure in the WiiM Home App, with the effective volume reduction:
View attachment 511805

You'd expect the Aux Out Level to function similar to the other two volume controls, but alas:
View attachment 511792

• Magenta: Volume 100/100, 2Vrms setting with +6dB Peaking filter -> heavily clipped (+5dBFS)
• Red: Aux Out Level reduced to 1Vrms -> identical clipping, but at 5.5dB lower volume
• Green: Aux Out reset to 2Vrms, but volume set to 86/100 -> clipped filter recovered

Ergo, the volume reduction which results in the different Peak output voltages selectable via Aux Out Level is applied after the DSP step and does not increase headroom.

One more example:
View attachment 511793

• Purple: 2Vrms setting, 70% Volume limit, Volume 100/100 with +23dB Peaking filter -> heavy clipping (+23dB filter -1dB sweep amplitude -10dB Volume limit = +12dBFS)
• Mint: Ditto, except Aux Out Level set to 500 mVrms -> -12dB volume on top should provide 12dB extra headroom, therefore 0dBFS Peak amplitude and clean filter response, but instead the filter response is clipped as before, just with 12dB lower volume
• Yellow: Aux Out Level reset to 2Vrms, but Volume Limit reduced to 42% -> 12dB reduction now provided by Volume limit instead of Aux Out Level -> 12dB headroom recovered and filter can be cleanly played back.

This should hopefully give you enough information to manage your Mini's volume and headroom in a smart way.

I don't have other WiiM products to test, but I imagine they'll perform largely the same.


One last note:

If you have a finished PEQ preset but don't know the total Peak gain and hence what volume limit to choose to avoid clipping, then head on over to squig.link (or one of the dozens of custom squig.links) and click on Equalizer (next to Brands and Models).

Here you can copy your PEQ parameters over from WiiM Home. Both Peaking and Shelf filters are supported and you can change the number of filters with the Plus and Minus buttons.

Don't mind what earphone or target is selected, just punch in your parameters.

When you're done click on Export, and the first line in the downloaded .txt file returns the necessary Pre gain required to apply your preset without clipping:
View attachment 511808

You can use this value as-is, or add some margin on top to account for inter sample overs etc.

So, say I want to apply the above preset but leave some margin, therefore apply a -6dB preamp.

Have a look at the Volume Curve posted earlier and you can see that volumes 82-84 correspond to -6dB reduction, so best to set the Volume Limit to 82, 83, or 84% (doesn't matter which).

Say also that I'm using a vintage Integrated Amp which can't handle input signals above 0.5Vrms very well.

I can go back to the table above, check that to go from 2Vrms to 0.5Vrms requires 12dB of attenuation in addition to the -6 from before, ergo -6-12=-18dB which corresponds to volume 47-49/100 -> set the Volume Limit to 47, 48, or 49%.

This now ensures that the PEQ preset is applied without digital clipping (-4.4dB), there's some extra margin (-4.4 -> -6.0dB), and the entire thing is clamped to 0.5Vrms max (-6.0 -> -18dB).


Happy listening!

Thank you!

 

[VintageFlanker]

Stunning job, @staticV3 !

 

[90sNintendoKid]

@staticV3, may I please ask how you created the graphs? Did you use a soundcard as an input in REW?

 

[staticV3]

@staticV3, may I please ask how you created the graphs? Did you use a soundcard as an input in REW?

The Aux output was fed into a UMC22. The Toslink output into a HiFime UR23.

EXCL input was used in REW and measurements were made using "Playback: From file" in the Measure dialog.

 

[90sNintendoKid]

The Aux output was fed into a UMC22. The Toslink output into a HiFime UR23.

EXCL input was used in REW and measurements were made using "Playback: From file" in the Measure dialog.

Thank you, in my opinion this is an awesome guide.

Did you use a converter for 3.5mm aux output to trs on the umc22?

 

[SlowJim]

Brilliant, thank you for sharing.

 

[staticV3]

Did you use a converter for 3.5mm aux output to trs on the umc22?

Nope, straight into the TRS Line input one to one.

You just have to play the sweep on only one channel so that it isn't cancelled out by the differential input

 

[90sNintendoKid]

Nope, straight into the TRS Line input one to one.

You just have to play the sweep on only one channel so that it isn't cancelled out by the differential input

Thanks, I'm going to research and experiment with this with my Wiim Ultra and Minidsp 2x4 HD and Minidsp DDRC8A to investigate if I get clipping etc post EQ.

 

[staticV3]

Thanks, I'm going to research and experiment with this with my Wiim Ultra and Minidsp 2x4 HD and Minidsp DDRC8A to investigate if I get clipping etc post EQ.

On WiiM products other than the Mini, you get an additional per-source gain control of -12 to +12dB, so that's something I wasn't able to test.

If you could test whether it works like the Volume Limit control (pre EQ), or whether it works like the Aux Out Level control (post EQ), that'd be awesome!

 

[1066]

‘Digital clipping’ when using WiiM equalisation, another thing to stress about ;(

So does this mean when using optical output and peq from WiiM, not to use more than +3db peq if WiiM volume set to 90%?

Or just avoid all positive values in WiiM peq and turn on fixed output volume in WiiM app?

 

[staticV3]

So does this mean when using optical output and peq from WiiM, not to use more than +3db peq if WiiM volume set to 90%?

WiiM volume set to 90% means you have 4dB of headroom to apply boost filters.

Or just avoid all positive values in WiiM peq and turn on fixed output volume in WiiM app?

That's another approach, but there's no strict need to limit yourself to only Cut filters, as using the Volume Limit as Pre gain is a valid and functioning solution.

 

[1066]

So when WiiM roomfit makes its calculations and implements +4 to +5db in a couple of places (see screenshot) it will digitally clip on optical output at those two frequencies if left at 100% WiiM output volume?

 

[DanielT]

Thanks @staticV3 , very good test you did.
I will use those volume settings (in relation to gainsetting) in practice.

This function, which is available as a setting in WiiM's RoomFit:

Non-Boost Mode

This setting ensures that the sum of all correction values does not exceed 0 dB, preventing distortion and clipping caused by excessive boosting.

Introducing RoomFit™ Settings

TABLE OF CONTENTS Target Curve Frequency Range Max Gain Min Gain Max Q Non-Boost Mode Built-in Mic Compensation External Mic Calibration Subwoofer Calibration Moving Mic Measurement (Beta) Smoothing Multiple Measurements (Beta) ...

faq.wiimhome.com

Does this refer to the signal out of WiiM if RoomFit is set to Boost Mode? What you showed in your test can happen? Am I interpreting it correctly?

 

[staticV3]

Does this refer to the signal out of WiiM if RoomFit is set to Boost Mode? What you showed in your test can happen? Am I interpreting it correctly?

I did not test RoomFit, only the PEQ behavior with arbitrary EQ parameters.

From my understanding, Non-boost mode is supposed to generate PEQ parameters with maximum gain <0dB.

If you are using your own EQ parameters, or parameters generated by RoomFit with Non-boost mode disabled, then digital clipping is possible and my thread shows how to prevent it.

 

[DanielT]

So when WiiM roomfit makes its calculations and implements +4 to +5db in a couple of places (see screenshot) it will digitally clip on optical output at those two frequencies if left at 100% WiiM output volume?

Gain settings in relation to volume, what the limits are, you can see in staticV3s post above. But I don't really know how different Q + gain settings together affect when clipping occurs.