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MatthewMK  
#1 Posted : Thursday, February 25, 2010 6:28:46 PM(UTC)
MatthewMK

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Does the digital volume control on the WM8741 degrade the sound quality, like turning down the volume in Windows? Truncating word length etc...?

Regards,
Matt
MatthewMK  
#2 Posted : Friday, February 26, 2010 9:44:06 AM(UTC)
MatthewMK

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I was hoping someone would know this off the top of their head. So to answer my own question, I waded through the WM8741 data sheet. It would appear the the digital volume control does in fact operate on the PCM data, but there is a fine section of dithering and FIR filters afterwords. Also, FYI, the anti-clipping mode is a -2dB attenuation. Not sure if this would even sound bad, but the data signal is altered. I wonder if anyone has listened carefully as the digital attenuation is applied. So for me, it will be analog attenuation after the DAC. Perhaps the Joshua tree.

Regards,
Matt
glt  
#3 Posted : Friday, February 26, 2010 10:35:04 AM(UTC)
glt

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Well, if you believe the theory, the answer is no because you operate at 24 bit and the incoming data is 16 bit. So not until your attenuation is below -48db. Some reference material here: http://hifiduino.blogspo...tal-volume-control.html.
MatthewMK  
#4 Posted : Friday, February 26, 2010 8:17:59 PM(UTC)
MatthewMK

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And perhaps even lower than -48db as the DAC has a 32bit word length. I will be using the Opus as a PC transport, and playing 24 bit material through it, so the plan is to stick with analog attenuation.
Brian Donegan  
#5 Posted : Saturday, February 27, 2010 8:18:11 PM(UTC)
Brian Donegan

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You will get better dynamic range and lower noise from digital volume control.
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