Volume scaling
- Thread starter Pikouchou
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hgo58
Major Contributor
No, it's not.
It has been requested before.
Note that there is not a 1 to 1 between the current volume percentage values and dB.
The values would be from -40 to 0 dBFS.
dBFS = 20*log10(volume/max-volume)
Here's the Volume vs optical output dBFS (peak) level relationship I measured on my Mini a few days ago:
Note that this was measured with "Volume Limit" set to 100 and "Fixed Volume Output" disabled.
hgo58
Major Contributor
How was that measured?
The 0% shall be minus infinity and 50% shall be -6 dBFS.
I don't know if the current volume percentage is actually a linear scale based on the digital volume value, so hard to say if it matches.
You values don't seem to match anything related.
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With a 0 dBFS (peak) 1kHz sine tone playback (24bit wav file), measured with REW at the WiiM Mini optical out into my RME Babyface optical in (S/PDIF mode, using optical in as clock source).
I've also measured the exact same volume steps on the Mini analog Aux output into RME analog in.
Sure, but -240dBFS is minus infinity for all practical purposes.
Yes, I've noticed on the forum it was stated several times that each 1% decrease in volume is -0,6dB in output.
This never made sense to me because having such a linear scale would mean that 0% volume would be only -60 dBFS, so I doubted this a bit from the start.
Then in this post I made some measurements that show that compensating for a +12dB EQ boost required setting volume at about 60%, which also doesn't match this -0,6dB/% rule.
This made me want to measure the volume steps which gave the above result.
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slartibartfast
Major Contributor
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Didn't someone find that the the dB per volume unit varied at different points of the scale?
hgo58
Major Contributor
The correct scale for dBFS is the one I gave above.
dBFS = 20*log10(volume/max-volume)
The other calculations are for analog values and may vary depending on what is measured (voltage, power, etc).
Fully Functional
Member
On a very prosaic note, this feels like it makes sense but i have an amp that does this and it does my head in...
From -80 aka silent to 0; i know enough to know that -40 is not '5' on a volume dial of 1-10 but sometimes i just want to know where i am in terms of power/volume(ish).
(and it has a freely rotating/infinite dial so there's no start stop place you can take as reference
)
From -80 aka silent to 0; i know enough to know that -40 is not '5' on a volume dial of 1-10 but sometimes i just want to know where i am in terms of power/volume(ish).
(and it has a freely rotating/infinite dial so there's no start stop place you can take as reference
)
The volume limiter doesn't follow the same pattern as the volume control.
I don't think there's anything right or wrong when it comes to volume control. It's not the inversion of digitisation, but just what feels practical.
hgo58
Major Contributor
The reason to use the dBFS for the sound volume, instead of percentage, is because it provides a logarithmic scale that aligns well with human perception of sound levels.
I think both works fine but would prefer the decibel if I could.
OK, I think we're in agreement again. If one decides to provide a "proper" dBFS scale (like I'm e.g. used to from my Lyngdorf amp) then it has to be, well, the proper scale, of course. Due to the fact that it's logarithmic, it does comply well with human perception, indeed.
If you have a rotational knob for adjusting the volume setting then a linear ratio between the angle and the dBFS scale does make some sense, but there's no hard and sound rule enforcing this. In the past, analogue volume pots have been used with varying logarithmic scaling and some liked it better one way, some the other way. Personally, a direct relation between rotational angle and dBFS reading is what I would actually prefer.
If there's just a scale from 0 to 100 (or to 50 or to 64 or to whatever) this does not imply how these values are mapped to a dBFS scale. If it was a linear relationship, it could be given in dBFS straight away.
Wouldn't be a bad thing.What's common for both is the min audible value which is around -60 dB.
dBFS values above are RMS, add +3dB for sine peak level. These are the measurements that I based the above table on.
Note that I got the same relative values when measuring the analogue Aux output, and I found also that both the Volume control and Volume Limit use the same steps. This is a WiiM Mini with latest FW, I didn't measure any other WiiM device.
IMHO it would be great if there was an option in WiiM Home App to display output level in dBFS.
Something along these lines (a quick and dirty mock-up in MS Paint
):
This is not the truth, at least not for the Ultra for example where 90% volume limiter is exactly -6 dBFS but 90% volume control is -3.18 dBFS. I use the convention where full scale sine signal RMS level is 0 dBFS.
hgo58
Major Contributor
Hmm. The 50% shall be at -6 dBFS, not 90%.
I don't own the Ultra so can't say much about it.
As I said, my measurements are for the Mini.
It definitely makes things more complicated if different WiiM devices use different volume curves.
@WiiM Support Would it be possible to provide an official mapping table between Volume / Volume Limit and dBFS for each WiiM device?
Also, have you perhaps considered adding optional dBFS level indication to Volume / Volume limit? Like in this example:
That would make things much more convenient - especially when dealing with positive gain PEQ. Thanks!
Here are my WiiM Mini measurements showing this (WiiM Mini Optical output into RME Babyface Optical input):
Note: When I measured Output Volume levels the "Volume Limit" was kept at 100%. Conversely, when I measured "Volume Limit" levels the Output Volume control was kept at 100.
These are the results of the analogue Aux Out (at 2Vrms output level setting) into RME Babyface Hi-Z unbalanced input, in dBV:
Notice that the relative level steps on the Aux Out are identical to the optical output:
- Vol 99 is -1dB compared to Vol 100 [5,1dBV - 6,1dBV = -1dB]
- Vol 70 is -10dB compared to Vol 100 [-3,9dBV - 6,1dBV = -10dB]
- Vol 50 is -16dB compared to Vol 100 [-9,9dBV - 6,1dBV = -16dB]
- etc...
Still, the mapping is not linear so having an option to actually see the output level in dBFS would be very useful.
Ideally dBFS level display would be controlled by a toggle switch, so those needing it could enable it, while others could hide it.
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