Want to build a filter pedal with an envelope output (kraken? sharkfin?)

[neandrewthal]

I'm thinking of selling my moogerfooger filter pedal (I got it a long time ago to turn my Japanese synths into a Moog, It didn't work) because it's huge, clunky, requires a backwards power adapter and I don't need an envelope filter for guitar and bass all that often. I would rather have a smaller, simpler pedal for when I need to do that.

However, I am starting to build a line of more modular guitar effects that have CV inputs (starting with the Twin Peaks Tremelo) and I really appreciate the envelope output on the moog pedal and anything I replace it with would have to have it too. It is also a bonus that the Kraken and Sharkfin have attack and decay controls for the envelope while the moog just has a sensitivity switch.

I don't really understand how the envelopes work well enough (except that that they both seem to built around rectifiers, but curiously in opposite directions) to know what kind of output to expect form it, but I understand how the linear voltage control section works on this:

http://www.musicfromouterspace.com/analogsynth_new/DUALVCA/DLLVCA001.html

and I see that the shark fin and the kraken both feed the OTA in the same way and I conclude that the output of the envelope on those is at least some positive voltage that may or may not need to buffered or scaled to achieve what I want: a 0-5v output. The shark fin has the bonus of a sample hold I can tap and a negative power rail in case I need an op-amp buffer that doesn't clip close to 0v.

Has anyone done anything like this before or have any insight on whether I'm on the right track?

[neandrewthal]

Well, crazily enough now I'm kind of gasing for a meatball even though I said I want something smaller and simpler. If it's more complex I will obviously use it more, right?

It actually still can be smaller than a moogerfooger if it is this relatively compact layout:

http://stompage.juansolo.co.uk/images/meatball-i.jpg

I think I saw I thread from a couple years back on here where someone bought one of those from musicpcb.com but now they seem to have a larger layout. Does anyone know where to get one of the ones in the pic I posted?

[zombie_rock123]

It's a forum members layout - Alan's - so you'd have to order three https://oshpark.com/shared_projects/iObFkEAm

[alanp]

I don't know exactly what the envelope CV of the Meatball is, but it shouldn't be too hard to bodge in a bit of vero with an opamp -- stock, the envelope cv drives a couple of LEDs, so you might need to ramp it up a bit.

[neandrewthal]

I've been grazing through some schematics and the Meatball envelope is very similar to the Kraken which is very similar to the Mutron III evnelope.

I really only need one Rissole board but after spending only a couple of weeks on this forum I'm sure some greedy fellows would snatch up the extra two like hotcakes if I were to sell them on here.

Hmm, $51.15 for three boards. That is quite reasonable.

[neandrewthal]

Now I've got nothing but Rissole's on my mind. Just trying to sell my Juno-106 so I have money to buy parts.


For future reference, are one or both of these the correct switch for the Rissole board?

http://smallbear-electronics.mybigcommerce.com/26mm-enclosed-3p2-4t/
http://www.taydaelectronics.com/electromechanical/switches-key-pad/rotary-switch/rotary-switch-4-pole-3-position-alpha-sr2612f.html

[alanp]

The Smallbear one is correct, 3 poles, the Tayda one is not (4 poles)

[neandrewthal]

Ok, Thanks. I posted the wrong tayda one by mistake. I think the equivalent 4 pole tayda one is the same as the small bear.

I've got a trick or two up my sleeve to try out and I hope to make possibly the smallest DIY meatball clone (with all the fixings) yet, plus my envelope output of course.