[sdiy] THAT2180A

[Tom Wiltshire]

Do you mean this one? “VCAs in a Pan potentiometer Application”:

	http://www.thatcorp.com/datashts/dn120.pdf

Personally, I never liked the hacky make-it-nonlinear approach. In practice it works more than well enough. If it was me, I’d use a lookup table and a DAC. Whatever floats your boat, I guess…;)

Separate question: Is there any analog way that *does* give a constant power panning curve? I remember seeing the “expo crossfade” example from the SSM2024 datasheet which uses a differential pair to split a linear control current between two linear VCAs (e.g. not applicable to the expo VCAs we’re discussing here) . If I remember correctly, when I tried it, it gives subtle “hole in the middle” effect as a panner, as the volume apparently drops as the signal reaches the centre. This experiment was a long while ago though, and I might be mis-remembering.

What others have said about the VCAs is all true - you pick the cost/quality ratio you’re after and then the parts choice will make itself!

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================



> On 27 Nov 2020, at 16:27, Ben Gebhardt via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> I second what Eric said and would note that THAT has a good app note for a pan pot application which I used for a mastering grade cross fader. Worth a look.
> 
>> On Nov 27, 2020, at 10:50 AM, Eric Schlappi <eric.schlappi at gmail.com> wrote:
>> 
>> 
>> if you are going off of the THAT Corp app note for equal power panning, it is totally possible to adapt that to the ssi2164. Just change the scaling and you need to invert and offset one side.
>> 
>> On Fri, Nov 27, 2020 at 7:27 AM drheqx <drheqx at gmail.com <mailto:drheqx at gmail.com>> wrote:
>> I'm looking at the THAT2180A for a voltage controlled pan pot application. They're not cheap. Any ideas for a less expensive vc pan pot?
>> 
>> Mike
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