Maestro ring modulator, anyone built one?

[Ritchie200]

Just wondering if anyone has ever built one.  I'm not sure if original parts are available and I've seen several different versions of schematics.  Anyone know anything about these antiques?

Thanks!
Jim

[Cups]

I havn't built one but GGG has the project and PCB: http://generalguitargadgets.com/projects/21-filters-other/114-maestro-ring-modulator

[Ritchie200]

Thanks Cups!  I'm glad the board is available.  Looks like I need to do some sleuthing to find that chip!

THanks!
Jim

[Danskman]

I'm currently building one, after having repaired an original (MC1495 chip offset circuit pins not responding).
I found this chip here:
http://cgi.ebay.com/MC1495P-MC1495-Linear-Four-Quadrant-Multiplier-/150530722115?pt=LH_DefaultDomain_0&hash=item230c548943#ht_704wt_907

and bought 4 of them. Great service and well packed.
The PC is not available anymore but I will try to make it myself.
Best regards,
Danskman

[Ritchie200]

Hey, thanks much Danskman!  That project was put on the back burner, but I just ordered four also!  I think it has just moved to the front burner.  I am just going to use a perfboard anyway.  Which means it will howl and hiss uncontrollably for no apparent reason....

Thanks again and good luck!
Jim

[Danskman]

Hi Jim!
I tried to it with a perfboard, but.... Not so stable and I can't suppress a permanent high pitch oscillation. I think there's some track to track interferences. I'm on my way to buy PnP blue transfer paper to make a real printed circuit board. I tried laser-printed transfer on plain paper (toner doesn't cover the copper toot much and peel when I dissolve the paper), tried laser printed on photo paper (worst, nearly destroyed my wife's iron  ) so I stop now and will use PnP special transfer paper (very high price in Europe, about $60 for 5 sheets!!! For the same amount, I found 20 sheets by an US provider. No comment! 
I will let you informed about the progression of my work.
Best regards,
Danskman

[Danskman]

Found a web page where this wise man explains how he used thin printed paper (the kind you find every day in your mailbox) to get the circuit printed; I tried it and it works perfectly! Cheap, quick and efficient method.
Link:

http://www.riccibitti.com/pcb/pcb.htm

Now, the PCB is ready to receive components. I will do this tomorrow and hope it will be finished on sunday evening.
Regards,
Danskman

[12bz7]

found this, it may be of help
http://topopiccione.atspace.com/PJ01MaestroMR.html

[Danskman]

Yes, Topopiccione's website is my reference for the PCB and other helpful informations.
Regards,
Danskman

[Danskman]

As of today, the effect is built up, but not completely satisfactory... having repaired a genuine one from the 70's, I can say mine is not so smooth. My biggest proble is that d....d pitch stereo 150K log pot, which is no more available. Tried a 2x100K log and a 2x220K log. The 2x100K seems to work better than the 2x220K, but doesn't work as good as the original. Plus, I think that the modulation is way too loud, even with the "mod vs direct" pot turn slightly clockwise...
More today, after some hours of debugging this beast!
See you,
Danskman

[Danskman]

The pedal is almost finished, but I had to use 2x100K log pot for the oscillator control, as 150K log pot are no more available (
Works not so bad, but the oscillator signal can be hear in the amp whenever the input pot is turned from 1-1/2 to 10... Don't know why. I didn't  mount the "bypass" switch with the 100k/18k network, but I don't think it can help.
Any ideas around??
THX and BR,
Danskman

[12bz7]

The only thing I can suggest for the 150k log pot is to get a 100k that measures close to or over 100k (Alpha ect.). Take the back off the pot and using a razor blade (Stanley blade) gently scape the outer edge of the carbon track until the pot measures 150k. Only need to remove the finest amount for it to start moving up in value. Check often with your DMM. Don't need to remove much
carbon just a whisker on the outer edge. I'd like to build one day when I have the time.

[Danskman]

THX for he advice, but the pots I used in this stompbox are modern conductive plastic miniature style... There's no way to scrap the carbon surface with them... Anyway, this is not a big problem, as the range of frequencies in the circuit is rather good for our taste (my friend's and mine).
I will go to my shop now and gut the beast to try to get rid of the LFO noise...
Best regards,
Danskman

[Danskman]

Good news! I checked my build and found tow miswired pots (mix and frequency)...  
I slightly lowered the squelch threshold, too, as it was too high and let the LFO output pass the gate. As this kind of effect is better used playing single notes on piano or guitar, the effect duration is not as critical than on a rev, for example, and the overall result is now quite good.
I shortened the input and mix pots wires, too. My only regret is the lack of 150K/150K log pot these days...
Does anyone compared the Maestro with the MoogerFooger RM??
Best regards,
Danskman.

[Ritchie200]

Congrats!  I have done....nothing!  I've got a bunch of parts laying around and no time to do anything.   I have looked everywhere for dual 150K and can not even find a bite.  I've tried old surplus catalogs and sites - nothing.

I've also wondered about the Mooger Fooger and some of the other ring mods out there.

Jim

[gmoon]

I built one back in the '80's from Craig Anderton's original "Electronic Projects for Musicians" book. The thing used a 565 phase-locked loop chip (I think even Radio Shack carried those chips back then!!!).

I worked, but was a little noisy. Later I figured out that I had used two positive voltage controllers (7812 or 7809) for the PS, rather than one positive and one negative. It still sits in the basement waiting for an upgrade...

Not the Maestro circuit, of course.

[Ritchie200]

I lent that book (that I got for my birthday!) to the other guitarist in a band I was in way back in the mid 70's.  Then he claimed I never gave it to him!  Darn musicians!  I wish I still had that thing.....

Jim

[gmoon]

It's really a great book! Bought mine in the late 70's. Wasn't my first foray into electronics (had an Olsen Electronics experimenters kit as a kid, made xtal radios, etc.), but introduced a lot of new concepts like opamps.

Must be out of print--some of the ICs are pretty hard to find. Too bad he doesn't update it...

[Danskman]

My best fiend offered me this book. I found it very "vintage", bad sense of this term, but it's full of very interesting and fundamental knowledge about building guitar effects electronics the right way. If it can help, I could scan and post the chapter about the low-cost Ring Modulator... Don't know if it will be a strong copyright violation??
Let me know and BR,
Danskman