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Volume Problem

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blgentry:
I've been using MC for Linux on ARM since MC23 and now with 24.  I've noticed rather low volume pretty consistently.  I thought my older SoundBlaster 24 Live DAC might have wonky volume controls at one point.  So I bought a new DAC.  It had pretty much the same volume and the same need to use the ALSA mixer to turn the volume up upon reboot.

But even with the ALSA volume all the way up, MC through my DAC is about 10 dB quieter than other sources.  It's roughly 10 dB down from FM radio.  Roughly -10 dB compared to my iphone playing via the headphone jack through an RCA to mini cable connected to the same receiver.  At *least* 10 dB down compared to a CD player on the same receiver. 

So what gives?  I turned off Volume Leveling and Adaptive Volume (Peak Level Normalize).  Then I added 6 dB via the Parametric EQ.  That's when I saw it:  MC is turning down the volume with clipping protection.  It took my +6dB and turned it down by about 5.2dB.  It changed as the song played.

OK, well let's see if MC is doing it's job correctly:  I turned off clipping protection and let it do "flat line overflows". Peak levels were consistently reading 140 to 190%.  That should produce some pretty audible clipping right?  It doesn't.  It sounds quite clean and normal to me.

I'm baffled by this.  It seems like MC is underestimating the dynamic range available by a huge amount.  As I said, it sounds about 10 dB too quiet to me.

I guess I could go get a 0 dB sine wave, play it with no DSP applied, and measure the Voltage coming out of the DAC.  I have a funny feeling it would be quite low.  Probably in the 0.1 to 0.2 Volt range.  But that's just speculation for now.

Any ideas? 

Thanks,

Brian.

blgentry:
I've checked quite a few things, but I'm not sure I've checked everything.  Volume protection is off.  I've tried 2 or 3 different devices under Audio Device.

I've tried Internal Volume and System Volume.  As I previously mentioned, I've used the ALSA mixer (alsamixer) to turn the volume up to "0 dB".

Oh and this is on Raspbian if that helps at all.

Thanks,

Brian.

blgentry:
I took some measurements with a multi-meter.  I used a 0dB sine wave recorded as a WAV file as input.  With all volume stuff and eq turned off in DSP Studio I got 0.66V RMS out of one channel of this DAC.

I then moved it to my Mac and set it up the same way.  I got essentially identical readings on the Mac.

So this DAC has somewhat low output, but it's not *that* bad.  By comparison my Schitt Audio Modi 2 puts out around 1.6 VRMS.  The Modi would definitely be louder, but it's not a huge night and day difference.

The receiver I'm using on the Linux/Pi/MC system says it's input sensitivity is 300 mV, or 0.3 V.  This DAC should drive it easily I would think.  But the output seems low with music.  As I said, it's also low compared to a real CD player, a phone plugged in via a converter cable, and even to FM radio.

I'm scratching my head.

Brian.

mwillems:
Are you using the hardware direct sound outputs in MC?  You mention using several different ones, but the one's you mentioned aren't hardware outputs.  In my experience alsa sometimes has a strange relationship with maximum volume (i.e. alsamixer allows turning up a device past 0dB, which for some devices is the only way to get maximum unclipped volume). 

One very easy way to rule it out is to use a different linux music player on the same box and see if you have a similar volume experience; if you do, than you may want to experiment with turning alsamixer up past 0dB because alsa is limiting the max output.  If you don't see the same low volume with a different music player, try using a hardware direct sound output in MC if you haven't.

JimH:
What input are you using on the receiver?  Did you try others?

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