[sdiy] Good choice of capacitor type for Moog 904A VCLPF 4 stages...

[Oren Leavitt]

Capacitors: If you don't want to spend a lot of money on caps, use the 
common polyester "greenies". These work well with the ladder filter.

I've had large ceramic disc capacitors at the inputs of audio amplifiers 
act microphonic.

Best of luck!

On 5/7/2014 8:15 PM, Jean-Pierre Desrochers wrote:
> Thanks Dave,
> Do you have any cap type suggestions ?
> It seams that film caps would be a good choice
> But again there are LOTS of film types around..
> Capacitor value vs temp  drifting is not a big issue
> But microphonics are not welcomed at all.
> JP
>
> -----Message d'origine-----
> De : Dave Manley [mailto:dlmanley at sonic.net]
> Envoyé : 7 mai 2014 21:05
> À : Jean-Pierre Desrochers; synth-diy at dropmix.xs4all.nl
> Objet : Re: [sdiy] Good choice of capacitor type for Moog 904A VCLPF 4 stages...
>
> Put pads for different size caps, that way your PCB is compatible with a range of parts, and you can see what you like best.
>
> Dave
>
> P.S. usually polystyrene is reserved for low leakage uses like in a sample/hold.
>
> On May 7, 2014 5:52:30 PM PDT, Jean-Pierre Desrochers <jpdesroc at oricom.ca> wrote:
>> I posted that question some days ago with no replies left..
>> Here it is again:
>> I'm not an engineer and try to figure out what type of capacitor would
>> be the best to be used for the 4 low pass stages of a Moog 904A low
>> pass filter ?
>> I read that some type tends to be 'microphonic' and other have easily
>> DC leakage... And I know that polystyrene are greatly appreciated for
>> their 'stable' caracteristics.. (but $$$).
>> I found Panasonic has the ECQ series that could be a choice but.. and
>> what about film polypropylene ?
>> I'm in the process of PCB design and need to choose the good cap
>> footprints for the 3 capacitors I'll use which are: 1.2uf  0.33uf  and
>> 0.075uf like in the original Moog drawing.
>>
>> Your good advises are WELCOME !!!
>> JP
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