[linux-audio-dev] db gain controls.

[David Kastrup]

Lee Revell <rlrevell at joe-job.com> writes:

> On Fri, 2005-12-23 at 03:00 +0100, David Kastrup wrote:
>> James Courtier-Dutton <James at superbug.co.uk> writes:
>> 
>> > Hi,
>> >
>> > I have a question for some audio professionals out there.
>> > What is the smallest sensible gain control step in dB.
>> > Is it 0.5dB ?
>> > I am asking, because if one is using a digital gain control in a 24bit
>> > fixed point DSP, once could use almost any step size, so I am looking
>> > for the smallest sensible size to use.
>> 
>> Well, the minimum possible difference for 24bit is between -2^23+1 and
>> -2^23, and that would be about 0.000001dB.
>
> He said sensible not possible.

If you are using ramp gains, then you don't want to use courser steps
than available because you are buying additional noise in that
manner.  If you wanted that noise, you'd not be using 24bit.  So there
is an application where this kind of step is "sensible".

Since he does not tell what application he has in mind, one can't
choose what would be sensible for that.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum