MPD volume vs hardware volume

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MPD volume vs hardware volume

Postby tc-fi » 04 Mar 2014, 16:29

After looking at the code for MPD volume control, it appears to be a very high quality algorithm, including the application of dither. http://git.musicpd.org/cgit/master/mpd. ... Volume.cxx

I’m thinking that MPD volume and digital hardware volume (USB or DAC chip based) should be similar in quality as long as hardware volume is using dither, or dither is applied at some point in the signal path through the chip. Dither is important for 16 bit samples but not so much for 24 bit samples since it affects only the LSB, and for 24 bit samples LSB = -144dB which is below the noise floor of the device.

Another observation is that chip based hardware volume implementations often do not specify much about their volume control processing for example, Tenor TE7022L and ESS Sabre 9012/9018.
http://www.gfec.com.tw/documents/10157/ ... PB-v21.pdf
http://myl8test.files.wordpress.com/201 ... t-here.pdf

Other chips for example, WM8742 provide a lot of detail including selectable dithering algorithms for volume.
http://www.wolfsonmicro.com/documents/u ... WM8742.pdf.

Thoughts?
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Re: MPD volume vs hardware volume

Postby Midnight » 04 Mar 2014, 21:03

The best volume control is the volume knob of an amp :twisted:
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Re: MPD volume vs hardware volume

Postby ACX » 04 Mar 2014, 21:14

From my personal experience, listening to software and hardware mixer while using a M2Tech Hiface2 (XMOS receiver), I found the last one to perform better, although not comfortable to control (it has a non-linear curve). As you said, this could vary from a chipset to another, because of different implementations.
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Re: MPD volume vs hardware volume

Postby tc-fi » 04 Mar 2014, 21:24

An analog control after the DAC is a great option, and its almost essential if one wants to really calibrate their upstream digital volume control.

In my own listening experience I've found that well engineered digital volume controls whether app based or on-chip are as good as analog in terms of SQ. YMMV :)
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Re: MPD volume vs hardware volume

Postby ACX » 05 Mar 2014, 00:39

A good option is also to use a remote controlled digital volume control. There are a lot of DIY kits or assembled packages based on PGA2311 chip, or even better ones.
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