[sdiy] THAT2180A

[drheqx]

Thank you Tom. The DAC idea is really cool. It's true, performance will
dictate performance. I can get away with less noise performance here but
the linearity is important. Some of these pan circuits have a bump in the
middle or a dip. I'll have to work that part out. This is something where a
musician would certainly notice that bump.

Mike

On Fri, Nov 27, 2020, 3:11 PM Tom Wiltshire <tom at electricdruid.net> wrote:

> 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> 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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