[sdiy] Equal power law

[Tom Wiltshire]

Rutger,

There's a circuit on page 5 of the SSM2045 datasheet you might find interesting too. It uses a a differential pair to make a pair of VCAs into a panner/crossfader, but the graph seems to show a -6dB centre point, so perhaps it's not directly what you need.

HTH,
Tom


On 12 Feb 2016, at 09:41, Rutger Vlek <rutgervlek at gmail.com> wrote:

> Thanks! I'll have a look at it!
> 
> Rutger
> 
> On 11 feb 2016, at 21:13, Matthias Herrmann wrote:
> 
>> it is the one we used as basis for a stereo mixer module
>> http://www.thatcorp.com/datashts/dn120.pdf
>> 
>> cheers,
>> matthias
>> 
>> 
>>> -----Ursprüngliche Nachricht-----
>>> Von: Synth-diy [mailto:synth-diy-bounces at dropmix.xs4all.nl] Im Auftrag von
>>> Neil Johnson
>>> Gesendet: Donnerstag, 11. Februar 2016 20:15
>>> An: Rutger Vlek
>>> Cc: Synth DIY
>>> Betreff: Re: [sdiy] Equal power law
>>> 
>>> Hi Rutger,
>>> 
>>>> Inspired by the lin/exp/log thread, I've been wondering about
>>> implementation of other curves, most specifically those used for equal
>>> power law and BBC panning law (center at -3dB or center at -4.5dB).
>>>> 
>>>> Are there simple ways to approximate these curves in analog domain (e.g.
>>> without using a VCA). I've been playing in Spice with an approximation of
>>> the curve using a simple opamp circuit with back-to-back zeners. The zeners
>>> already have a rather 'soft knee', but I'd like to know if there are ways
>>> to get the shape even closer to what's needed for an equal power law curve.
>>> 
>>> There's a THAT app note where they use diode function generators to
>>> approximate the sin/cos curves for panning VCAs.
>>> Don't remember the number at the moment but there aren't that many
>>> THAT app notes.
>>> 
>>> Neil
>>> --
>>> http://www.njohnson.co.uk
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at dropmix.xs4all.nl
>>> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>> 
> 
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