[alsa-devel] What does 0dB refer to? (Logitech USB Speakers)

Rene Herman rene.herman at keyaccess.nl
Sat Apr 12 23:16:11 CEST 2008

On 12-04-08 21:32, Rene Herman wrote:

> On 12-04-08 15:35, Lennart Poettering wrote:
>> On Sat, 12.04.08 12:15, James Courtier-Dutton (James at superbug.co.uk) 
>> wrote:
>> My I thus assume that we can say that for all but the last element in
>> the series 0db means avg input power equals avg output power, and for
>> the last one 0db means max? That would fit on what you are saying but
>> also match my usb speakers, not depending on the existance of a
>> "Master".
> If we add in ISA cards, it's not a very generic assumption at least. For 
> example on my cs4236, "master" is -94,5 to +12 dB with 0dB at "87" in 
> the integer scale.
> It's a "Master Digital Gain" -- not sure what that "digital" implies as 
> it very much seems to be positioend in the post output mixer analog path...

Mmm, no, this control seems to be divided into two parts in hardware, with 
-60 dB to 0 digital attenuation pre DAC and -34.5 to +12 dB analog post DAC. 
Odd, but anyways... 0 is still the "correct" default.


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