The Guyatone MC2 Micro Chorus

[Krinor]

I just got a nice little vintage box in the mail today. It's a Guyatone MC2 Micro Chorus. Upon opening it up I noticed that it has a rather low parts count and I realized that it might be turned into a relatively simple DIY project. So to see if there is any interest I'm posting some photo's.

The chorus is very nice! It does what a chorus is supposed to do without being able to go to the extremeties that for instance a Small Clone can do. It gives you a nice "widening" of the sound at lower depth and if you crank it up on both depth and rate it gives you a nice, fast warble which is passable as a simple leslie effect. It has a little bit of noise which I suspect might have something to do with some of the capacitors.

From what I have taken note so far the circuit has an MN3102 (49) and an MN3207 (4B), two NJM4558L ic's and I have also taken note of three transistor values: Two C1815's (GR4L) and one K81 44 C.

If anyone find this interesting I can take more photo's and (if time alows) upload some sound clips.



Size comparison





Main PCB rear



Revealing 2nd PCB



2nd PCB (switching and pots)



IC's

[petemoore]

  I have a salvage board that's sitting on the table, it has almost the exact same chip complement.
  MN3207 and MN3102, 4558's and etc.
  I'm thinking I can sucessfully remove the chips and...build...something with them.
  It came out of a 4 effect 'Diplomat' [chorus not bad, wah, distortion and...uh the last one escapes me.
  @@rate the switches on the unit junked out real early, I got it and made it into a more reliable unit, a volume pedal. Don't know if it survived, haven't seen it lately [hmmm.
 

[mnordbye]

Looks like a very interesting chorus! If you are planning on reverse engineering it, i'm sure i would try out the project.

Magnus Nordbye

[Krinor]

Well Magnus, I guess if I reverse engeneer it you and I will be fighting for norwegian customers over this circuit ha ha  Just kidding. Yeah I guess I'll give it a try and see how far I get... Time is limited these days... I'm building synths on order like a madman...
We'll see how many people find this little chorus interesting.