Equal value caps in SSM2044 projects

Peake

Even in the SSM datasheet, three of the cells use equal value capacitors and one uses a very different value. I don't know if this harkens to the TB303 filter, which through hearsay I've heard described as a 24dB filter but that the last pole is higher in frequency than the three matched poles.

The SSM is great, but sounds lacks a tad of that rubbery thrum I love in some other designs. I've just dropped a cap in to match the other poles and note several probably unsurprising items:

-Resonance will only reach self-oscillation at the highest audible frequencies even with the trimpot wide open
-The overall response is much darker, I don't know about "warmer" or not
-Must adjust some values to allow for higher Fc ranges

I'm just throwing this out there to see if those of greater knowledge might have some insight or maybe, just on the off chance, find something interesting from this change. Especially considering the amount of these chips floating around.

Thanks again Matthias/Fonik!

Peake · Posted: Mon May 12, 2008 6:09 pm Post subject:

Moderators: I can change a cap but not the forum I'm posting to. If you'd be so kind as to either delete or move this one?

blue hell · Posted: Fri May 16, 2008 1:05 pm Post subject:

Ah, right, I forgot, move it here?

Mooger5

Peake · Posted: Fri May 16, 2008 5:23 pm Post subject:

Yeah; someone pointed out to me in another forum that the SSM designs in production synths all use the 3/1 cap design as well. Unless someone just comes up with something beneficial about this, I'm just going to return mine to the spec.

Nice filter, especially at the price point.

Edit: Thanks Blue Hell.