Coron DS-7

What's the world's smallest (and probably smartest) fm -synth? Indeed, it's the Coron DS-7 `Drum Synce' (I wonder just who came up with that name? And: DS-7? That a joke?)! Coron, usually known for bootlegging MXR- stompbox efx, also released (to my knowledge, so far) two drum- synths (see my Coron Drum Synthe RDS review on this site) of which this is the smaller and probably more interesting one. It's of the mere size of a MXR phase 90, has only seven knobs and three jacks. Its great strength lies in its maximum twiddlability, `cause few knobs allow you drastic changes in timbre. Finding sweet spots with FM has never been easier.
(And -hey!- it runs on 9V batteries!)

In the bottom row of knobs you find a volume control, a decay knob and one for the vco pitch. The upper row features a control for the LFO/ modulator speed and modulation amount (labeled "mode")as well as a vco sweep amount knob. It controls the amount of decay- env modulation that gets applied to the vco; sadly only downward sweeps are possible. Well, there's a seventh knob on the upper bout, labeled `intensity' that allows trigger- sensitivity control.
Furthermore there's an OUT -jack and two jacks labeled `FT / SW',foot switch, that is. If a foot switch pedal is applied you can mute the unit. Two of them, right? So how do you trigger it?
Well, you hit the unit with a drum stick (or your knuckles). Yep, that's right. The unit was originally aimed at drummers as an electronic add on to their drum kits. There even is a little vice whith which you can attach it to the rim of a drum.
Now thats a little stupid, which is why i re-arranged things a bit with mine. Its easy and all you need is a switchable jack and soldering gear.
Open up the back and turn the unit so that the two jacks are on the right and the one FT / SW jack and the "intensity" knob are on top. Now you should be able to detect a little piezo disc in the middle of the unit. There's a lead going from there to the "intensity" knob (blue in mine). Another lead goes from the upper FT / SW jack to the one on the right (purple). Do the following: carefully disconnect the purple lead as close to the right-hand side jack as possible without affecting other parts by means of applying scissors. Pull off the "intensity" knob and remove the nuts of both the potentiometer and the upper FT / SW jack. Desolder the purple and the black lead from the jack (the black one is the common), as well as the blue one from the pot. Get your switchable jack ready (actually if you want to lose the possibility of hand triggering you wouldn't need a switchable one, but just think of how you could hammer away a solo center stage!;)). Connect the black/common lead to the ring, the purple lead to the tip and the blue one to the switch. If no trigger signal is applied, the DS-7 works just like before, but if you connect it to -say- the HH- out of a 707 (or something similar) you'll just be ready to really explore FM!
One thing: it's a VCO, right. If you take a stereo jack instead and connect the sleeve to the VCO -pot (you'd have to remove all the jacks and knobs and carefully get all the innerts out of the housing. The actual spot to connect the cv-lead to would be the middle contact of the pot) you could even change the pitch with the help of some other device (e.g. a KORG SQ-10 step sequencer or a cv-pedal).
DISCLAIMER: I've done all the above mentioned with my DS-7 and everything is milk and honey. However if you are going to mod yours it's of course totally on your own risk and nobody else (including me and the providers of this web-page) can be made responsible.

All this thing features are one sine oscillator that gets fed out and another one to modulate the first one. The "LFO" indeed goes way up into audio frequencies, its lowest setting is about medium speed with ordinary LFO's. With the turn of just one knob (either LFO speed or V.C.O.) the timbre changes a damn lot. And it sounds fat and in the face, kids! The VCO pitch ranges from almost sub- audio to piercing nearby super-sonic. If you turn the decay to max you get a constant tone (at least if you keep on triggering it), but in the area between six and nine o'clock there'd be typical closed/open HiHat sounds. If you put accent on some of your trigger signals and set the sensitivity right, it's even velocity sensitive.
Don't forget the sweep function. If set right, the FM-sound changes over time due to a varying ratio between carrier and modulator.
But of course you can also produce those silly diso-toms, simple sweeps ore scifi sounds (e.g. with a lower LFO).
I say! That's a damn lot for a battery- driven seven knob midget synth.
Plus if you have an envelope follower pedal around, you'd have a complete little mono-synth set up together.

Pretty sturdy metal box. Don't have it long enough to judge , though.

Coron's gone for quite a while.

It's small, inexpensive, pretty exclusive, really easy to use and sounds great.
I think I'll sell my MS-20 ;)!
Honestly: if you love creating analog drum sounds, this is it! At least for the clangorous variety. But it ain't limited to that. I think it's great for more experimental stuff, too.
I simply loved it right away, the "Coron Drum Synce".