Very Basic Ring Modulator Questions

[neddyboy]

I spotted a cool ring modulator schematic here: http://www.cgs.synth.net/modules/cgsrr.html. It's an old-school passive ring mod circuit using two 3k transformers and 4 germanium diodes.

It's on a site called Ken Stone's Modular Synthesizer, so the design may be specifically for synths. I'd like to use it as a guitar pedal. Possible? It has an IN and OUT jack, but also a CARRIER jack. What's the carrier input for?

I'd like to use it with a DPDT footswitch for bypass and a pot to mix the effected and dry signals. The switch I can manage, but how would I wire the pot? Also, any suggestions on what value the pot should be?

Thanks in advance for any assistance,
neddy

[Harry]

From what I've been told for guitar you need input and output boosters. The carrier is what you are going to modulate with the guitar signal, this can typically be an oscillator circuit or it can be a radio or whatever else catches your fancy.

[RaceDriver205]

Ah yes, the good old ring modulator - For when you don't want people to know what notes your playing.
That circuit will perfom the modulation, but is not a complete circuit - Im afraid building one is not that simple.

A ring modulator mixes two signals and produces two new signals - which are non-musically related. This output thus sounds "robot-like" and phone-dial-tone-ish. The two inputs are the guitar signal, and a separate 'carrier' signal - which remains at a constant single tone.

Cut a long story short you need a proper ring-modulator guitar effect, which does all this for you.
How good/complicated do you want it to be? (more complex = better) Welcome to the forum 

[tcobretti]

I guess I'll be the guy to recommend that you search the archives; just a couple of weeks ago we had a big discussion about RMs.  From sifting thru the archives I learned: they are wicked complicated to build, and almost as hard to tune so they work correctly.  Also, some designs certainly work better than others, so you may spend a huge amount of time building and troubleshooting only to have it suck.  I may still build build that design you posted just to play with, but for it to do anything you have to have something that generates a sine wave to feed into one of the inputs.  As well, I read that component matching is critical with the old design, and so I'd have to do a bunch of research about finding matching diodes/transformers for the circuit.

Basically, it is probly worth it just to buy one unless you are just looking for a challenge.

[markusw]

Maybe have a look at http://homepage.ntlworld.com/paul.nelson666/StringRingerv12r.pdf and http://www.diystompboxes.com/smfforum/index.php?topic=35398.40

It uses the same 4 diode 2 xfmr circuit plus a VCO for carrier and it was confirmed to work.

Regards,

Markus

[Transmogrifox]

I highly recommend the string ringer.  It's a very well put together project, so the problems you'll experience will not be problems with the circuit design, or from things being finickey and touchy. 

It is good to understand exactly what a ring modulator is, though.  A ring modulator as a circuit is an analog multiplier.  You have 2 inputs: A and B.  We'll call the output C.
C = A*B

That's all it is in concept.  Input A is multiplied with input B.

The result of multiplying inputs that change over time (guitar signal, oscillator...) has a "messy" effect in the frequency domain.  Every frequency contained in A produces a sum and difference with every frequency contained in B.

In short, the above description (from a different post) is more simple:  It produces frequencies that aren't musically related.

Whatever you use on the "carrier" input will be multiplied with your guitar.  A CD player or a siren or an alarm clock or a single pitch oscillator...all would produce strange effects. 

[RaceDriver205]

What did you use for the transformer Trans?

[Paul Perry (Frostwave)]

People usually use those transformers designed as audio interstage transistor radio transformers (not that anyone has used one as that for 30 years!).
The kind you see advertised as 1k to 1k or similar. Mouser has them.

[jmusser]

Has anyone ever built the Craig Anderton Ring Modulator (Project #9) out of the "Electronic Projects for Musicians" book to see how it performs?

[RaceDriver205]

The Electronic projects for Musicians book disappeared from my local library one day and never returned. It disappeared from the computer database too. Wierd.
The string ringer indicated it needed 20k transformers, ones you can only get from Maplin. Have people used alternative ones successfully in this design?

[smnm]

Has anyone ever built the Craig Anderton Ring Modulator (Project #9) out of the "Electronic Projects for Musicians" book to see how it performs?

I built this from a kit, it's a balanced modulator not a 'real' ring mod, but I think it's pretty groovy - carrier bleed-through is hard to elminate without a multi-turn trimpot though (and I haven't got around to subbing one in yet). Has wet/dry mix pot and an effects loop also.
I haven't really used it though, apart from messing around.

I made the passive diode ring + transformers "real ring mod" too, (transformers from craplins, yeah) - it works pretty well with cheap keyboard output as the carrier, and a boosted gtr signal.

Simon

[Floyd Pepper]

I went past Maplin today so got the audio transformers for the String Ringer.  I perf boarded up just the ring modulator portion of the String Ringer circuit.

I recently build one of these http://www.musicfromouterspace.com/analogsynth/YOUR_FIRST_SYNTH/YOUR_FIRST_SYNTH.html which emits beepy oscillation sounds.  I figured I could use it as a carrier.

I can't get the ring modulator to work.  I copied the String Ringer circuit from the top of page 4 http://homepage.ntlworld.com/paul.nelson666/StringRingerv12r.pdf.  There's only 4 leads going in. To get the two inputs and one output I wired the black ground to each of the jacks' ground and white, violet & red to the tips.  I fed my oscillator into violet and plugged a guitar into white but nothing came out of red. 

Looking at this circuit http://www.cgs.synth.net/modules/cgsrr.html each input/output has its own ground giving a total of 6 wires.

My oscillator outputs a line level.  Can I use the String Ringer circuit with my oscillator and a straight guitar?  If I re-wire to use the alternative circuit will it work?  Am I being too simplistic?

[Jaicen_solo]

I think you'll probably need to get the guitar up to line levels before you're gonna hear anything. Have you tried wiring the oscillator to both inputs? If you do that you should get the sum and difference of the input, which you'll easily distinguish from the input signal.
I'm interested in the effect of multiplying the guitar signal with say a sawtooth wave, rather than a pure sine. I imagine the harmonics would create some really dischordant effects!

[Transmogrifox]

...I'm interested in the effect of multiplying the guitar signal with say a sawtooth wave, rather than a pure sine. I imagine the harmonics would create some really dischordant effects!

I was playing around with this a while ago.  It's a little more "lo-fi" synth type sound.  Check out this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=38429.0

[markusw]

There's only 4 leads going in. To get the two inputs and one output I wired the black ground to each of the jacks' ground and white, violet & red to the tips.  I fed my oscillator into violet and plugged a guitar into white but nothing came out of red.

Maybe try to feed the carrier into red, your guitar into violet. Then you should get the modulated signal from white (at least this is how it works in the RS).

I think you'll probably need to get the guitar up to line levels before you're gonna hear anything.

I think that this is exactly the reason why you don't hear anything. I'm pretty sure too that you will have to amplify your signal with a gain of about 5-10 to hear the modulation This is done by the gain stage IC1/1 in the String Ringer schem.

Markus

BTW: I realised that there are still some bugs in the file: while in the parts list there are Ge diodes indicated for the Ring mod (which is obviously correct) in the wiring diagram there are 1N4148.

[vortex]

My recommendation for a "simple" ring mod would be Tim Escobito's(sp?) Thing Modulator.

http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html
Scroll down about 3/4 on the webpage.

For a "simple" circuit it is surprisingly cool. It's no competition for a Maestro Ring mod but you don't need a EE degree to make it happen!

[Floyd Pepper]

BTW: I realised that there are still some bugs in the file: while in the parts list there are Ge diodes indicated for the Ring mod (which is obviously correct) in the wiring diagram there are 1N4148.

I wondered about the didoes but used 1N4148's as I had them infront of me.

I worked out why the ring modulator wasn't working - One of the audio transformers is dead.     I'll get back to Maplin, get it swapped and will try again.

[markusw]

I wondered about the didoes but used 1N4148's as I had them infront of me.

I'd use Ge diodes because you loose much less signal than with 1N4184 (Schottky diodes should work too).

[Floyd Pepper]

I got a new audio transformer and wired it in with the 1N4148s.  I plugged the white into the amp and put a guitar into each of the other two sockets.  If I I turn down the trim I can hear the guitar comming though OK but quietier than if plugged in direct to the amp.  If I play both guitars I get a bit of distortion but nothing that sounds like a ring modulator. 

Should I be able to ring mod two guitars or do I need to put a sign wave into one of the inputs? 

[John Lyons]

J musser
I've built the Craig anderton ring mod on perfboard. It's pretty wild, the chip centers around a square wave so it doesn't get the gong type ring mod sounds as the sine wave units. It has a slight bleedthough all the time which gets on my nerves...I'm building on now by the PCB layout to see how it compares to a badly laid out perf build. Mark hammer recommends using some kind of gating/downward expansion which would deal with the carrier bleedthrough when your not playing....

I'm building the Maestro RM1 right now. From what samples I've heard this thig really sounds nice! Pretty complex build though....
John