[sdiy] AC coupling caps on MS20 clone

[cheater cheater]

On Fri, Jul 30, 2010 at 09:38, Oren Leavitt <obl64 at ix.netcom.com> wrote:
>
>
> David G. Dixon wrote:
>>
>> Hey Team,
>>
>> When are AC coupling caps necessary on filters?  Should they be on the
>> input
>> and the output?  Should they be on all outputs of multimode filters?
>>  Should
>> they be switchable?  What's the best value and type?
>>
>> I haven't used them on my lowpass filters, but I'm unsure how to handle
>> this
>> aspect of my 2164-based MS20 VCF clone design.  Any suggestions would be
>> most appreciated!
>>
>
> Hi David,
> Cumulative DC offset in the signal path would be a reason for me to want
> optional AC coupling in an input.

But then, signal asymmetry when it is fed into nonlinearities can be
very very desirable.

> Value/type?
> Combined with input impedance, the coupling cap forms a high-pass filter.
> The value depends on the lowest frequency you want to pass.
> For example, a 0.1 uF cap coupled to a typical 100K input impedance will
> cut-off frequencies at 16Hz and lower.
> Most any non-polar type ought to work.
>
> - Oren
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