Re: NSSound taper
Re: NSSound taper
- Subject: Re: NSSound taper
- From: Glenn English <email@hidden>
- Date: Thu, 12 Jun 2008 17:26:38 -0600
- Openpgp: id=96DB4CB6
- Organization: Sugarloaf Software
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Brian Willoughby wrote:
> I Googled "Daven audio attenuator" and found a lot of hardware for
> sale. 1 dB steps, 2 dB steps, 10 dB steps, and slide attentuators as
> well as rotary. Some mention "taper off and cue" which is not
> documented.
I finally found it in the 1979 edition of the Sams' Audio Cyclopedia.
Along with how to build equalizers with 6SJ7s, with some even
'converted' to work with transistors :-)
They run 1.5 or 2 db per step for the first 75% of rotation -- down to
about 30 db -- then drop off in 3, 3.6, 6.5, 10, and 30 db steps
(numbers interpolated from a fairly small graph).
In case you care...
> Personally, I don't think it's very critical what happens
> at the bottom, but I could be wrong.
Define 'bottom'. That curve kicked in at about 20 db of fade (assuming
the pot was run with 10 db gain in hand), so I suspect there's something
to it. I'm gonna try to implement it, anyway.
> In any event, I suspect that you're rather limited with NSSound.
That's what I hear. And it seems like every time I want to do something,
I end up bewildered by the core audio documentation. But he wants it to
crossfade, he wants it yesterday, and I was trying to do a decent job. I
think I'm at about the end of what I can do with NSSound, lovely as it
is for an mp3 player :-)
(Mac programmer newbie.)
> If you
> were to build a full AUGraph, then you could insert various mixers or
> other AudioUnits which implement volume in a stepped fashion rather than
> a continuous control, or you could select log taper rather than linear.
And I'm going to be jumping into that RSN.
Thanks, Brian...
- --
Glenn English
email@hidden
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