Variable state filter pedal?

[niandra3]

Hey all, long-time reader here but finally joined just now. I would like to build a state-variable LP/HP filter guitar pedal, ideally on 9v. Are there any designs already out there? I haven't had much luck. Basically am looking for a synth-style filter, with freq and resonance controls. Eventually would love to add an LFO. From my limited knowledge, the LM13700 looks like a good place to start (the datasheet has a 15v version). Any thoughts as to where I could look for inspiration?

thanks!

[smallbearelec]

I just received stock of a specialty chip designed for the synth market that might be of interest. It is expensive, but it does the job of a lot of otherwise separate components.

http://smallbear-electronics.mybigcommerce.com/cem3320-work-alike/

There is a link in the details to the maker's datasheet.

Regards
SD

[niandra3]

I just received stock of a specialty chip designed for the synth market that might be of interest. It is expensive, but it does the job of a lot of otherwise separate components.

http://smallbear-electronics.mybigcommerce.com/cem3320-work-alike/

There is a link in the details to the maker's datasheet.

Regards
SD

very cool. thanks!

[Mark Hammer]

I just received stock of a specialty chip designed for the synth market that might be of interest. It is expensive, but it does the job of a lot of otherwise separate components.

http://smallbear-electronics.mybigcommerce.com/cem3320-work-alike/

There is a link in the details to the maker's datasheet.

Regards
SD

Xvive brings back the MN3005.
The CEM3320 is revived.
The CEM3340 has also been revived.
It's the 1980's, all over again!
Mark is happy. 

[bluebunny]

It's the 1980's, all over again!
Mark is happy. 

Can't wait to see the new haircut and the shoulder-pads, Mark.   

[digi2t]

Don't forget the skinny tie.

[Mark Hammer]

I'm going to follow the President's lead and go with a Flock of Seagulls hairdo.  Lord knows I'm not hirsute enough to go all Gino Vanelli on people.

[bluebunny]

I'm going to follow the President's lead and go with a Flock of Seagulls hairdo.

LOL!  So that's what Trump was up to in the 80s...

                 (but probably not orange enough...)

[EBK]

Now we just need to autotune a clip of Trump talking about "Iran". (Or I suppose one with him talking about how he "ran" his campaign would do)

[Mark Hammer]

I should point out that the CEM3320, much like the SSM2040, can be configured as 4 allpass filter sections.  In other words, it can be a 4-stage phaser on a chip.

Joel, if you're reading this, a 3320 married to a microcontroller would be....AMAZING.

In the meantime, interested parties might want to take a look at the old CEM3320-based "Multiple Identity Filter" project that Craig Anderton published in Contemporary Keyboard magazine thirty-eight years ago. http://www.synthdiy.com/files/2002/MIF.pdf

[tubegeek]

There's a state-variable filter in the "Super Tone Control" in EPFM, also Anderton. I've built and used it, it's a useful item.