Dear Abby...

[goodrevdoc]

Just picked up an MN3208 cheap. Was wondering what to do with it. Would like to possibly do a chorus of some kind, but don't really know how to go about designing one. Worst case, i think i could just make a little slap echo deal, but would to use some imagination/creativity for a change. Any thoughts?
-Lonely BBD in Boston

[RaceDriver205]

Get ideas from existing chorus circuits. See the Boss Chorus and the Small Stone Chorus at tonepad.com.
The principle of chorusing is the same no matter what pedal. Mix a time delayed signal with the original signal, and vary the time delay.

[Mark Hammer]

Dear LBIB,

Your chip is certainly amenable to a high-quality chorus that is also capable of ADT effects (see that thread somewhere on the first screen of threads).  The difficulty, or challenge, posed is that there are no PCB layouts for such a device.  Consequently, you will either have to fashion one yourself, or use one of the "improv" techniques, like perfboard or veroboard.  It is important to realize, however, that circuits using HF clocks (which all BBD-based circuits do) need to be well laid out or else they invite objectionable noise.  Pushing a 2048-stage BBD to generate chorus-range delays will mean a fairly high HF clock so the noise risk is not AS great as it would be with an MN3207-based chorus (with half the clock frequency needed to generate the same delay time), but it is still there.

What might be more useful to you, more problem free, and equally satisfying, would be to spring for a second chip over at Small Bear and whip up Scott Swartz AD3208 project, for which there is already a board layout, confirmed builds, and smiles all around.  Note that the BL3208 from Small Bear is the current production pin-for-pin replacement for the MN3208.  There are no confirmed reports of diferences in sonic quality so do not be deterred.  As well, note that the BL3208 comes in a 14-pin and 8-pin package.  Scott's layout assumes a 14-pin package so make sure you order the right one.

[goodrevdoc]

Hey thanks for all the info guys. I've been checking all over and reading up as much as i can on the subject of choruses. Not a lot out there relative to your standard TS, FF, Booster info which is easily obtainable by the truckload. Not really into making another delay, although Scott's project at GGG does look nice and I've read great things about it. I would rather design a cool chorus from the ground up. I do have some idea of what this entails, I would just like to know more about the "effect" of the effect per se, kind of like a "technology of the..." but for chorus. I've been reading the afformentioned article on flangers and phasers, as i understand flangers and choruses are somewhat similar. I guess i just need more reading. If anybody's got some good info, please let me know. Thanks...
-justin