Passive ring modulator - what booster to use?

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Hi. I am building this simple passive transformer/diode ring ring modulator:
http://www.asciipr0n.com/4096/ringmod/index.html

I have ordered the mouser TM018 transformers (42TM018-RC), here is some info on them:
Primary & secondary impedance 10KΩ, Primary resistance: 500Ω, secondary resistance 550Ω, turns 1:1
(data sheet = http://www.mouser.com/catalog/specsheets/XC-600134.pdf )

I am guessing that I will need to boost the signal either before or after the ring mod if I want to use it with a guitar or other high impedance input. I have built a bunch of stuff, but usually as more complete designs, and I think there are aspects of input impedance that I don't understand yet.

Could I use the simple booster "first build" project given here to achieve this? If not, can anyone else suggest a different circuit to use? Preferably a simple circuit using a single transistor.

Also, would it be enough to just boost the signal after the ring mod, or would it also be necessary to boost each input as well?

Thanks for any help

[wavley]

You know, I ran across this project before, meant to build it, forgot to order transformers, forgot the project.  I just ordered three transformers and used them for other stuff, Dangit!!

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Ok let me try this again... I am guessing that this really isn't too complicated... but maybe I am wrong...

Any idea how much of I boost I would need to apply to get the signal to roughly the same as it came in? And where the boost should be applied (before, after, both?). Just some ballpark idea, so I can look at what circuits are appropriate to add on to it.

Schem:

[Meanderthal]

 I guess it would depend on the voltage drop of the diodes you use, as well as the signal strength of whatever you're going to use in input Y.  I know that's not the answer you're looking for, but I suppose a simple LPB(or the beginner project) circuit both before and after would be fine. I would try one before first to make sure ya get enough umph to get the ring mod going, then add one after if it doesn't at least achieve unity gain.

What do you plan on using for input Y?

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Thanks, that is at least a start... I was planning on experimenting with the diodes, but seemed to find info that germanium ones would work best. I didn't know if I would need something more powerful to drive it like an LM386 or something. I am just getting into more customized designs so I don't know about the options really.

As for the inputs, I plan on keeping them both open to be able to mix different signals, but the idea now is to mix the signal with itself in some variation ie: guitar into one input, same guitar with some other effect into other input, but I want to have it flexible though so I can use it for modulating different kinds of signals against eachother in recordings, etc.

My plan right now is to put in a patchable box with a PWM and a Gargletron and maybe a spring reverb for a sort of small odd/synth sounds processor box.

[brett]

Hi
a really good booster for this is the LM386.  (Yes, I know it's mainly used as a power amp, but it is single supply, is easy to set up, and drives low impedance transformers easily).  Boost before the passive ring mod.  As much as you can without clipping.  THis reduces the gating due to the diodes (use Ge diodes for less gating, too).  Gain of about 20 times is about right (so that a 0.2Vp-p signal becomes 4V p-p).  With a 386, you can use a pot as a gain control, like in the Ruby amp.
Have fun.

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Thanks for that input. Then I suppose I would want one of these boosters on both inputs.

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I just wanted to follow up on this with my results. I ended up going with the beginner booster circuit to drive the passive ring mod - I built one for each input on the ring modulator and it works great. It is possible to get above unity output using those boosters on the inputs.

I used 1N4002 diodes (not matched, as far as I know) and the ring modulator actually works really well. I just got some germanium diodes delivered finally, but don't really see the point of putting them in as it works great with these.

With the boosters tweaked correctly, it is possible to eliminate bleed-through on the carrier pretty much to nothing while still getting a great ring modulated sound. It is such a simple circuit and it sounds great - classic ring modulator sound. I actually can't understand why so many designs for complicated IC-based ring modulators are around when this simple circuit works so well (I built the EPFM one a while back, which did not sound as good as this and always had some carrier bleed).

I have been using a sine tone from my casio SK-1 as the carrier for testing purposes, but I like that you can put anything on the carrier input. Splitting the guitar to each input sounds great too.

[Taylor]

IC-based ring mods tend to sound cleaner, especially when playing multiple notes simutaneously. Also, yours is still IC-based, it's just that your ICs are in the SK-1.  I know that sounds jokey, but it's important to note that a big part of a ring modulator for guitar is in the oscillator. Getting a good sine wave from discrete technology can sometimes be more complex than a nice little function generator IC.

[dr.benway]

Hope someone will see this. I am struck by ring mod fever! love this effect and the sounds possible.
I've got the passive ring mod circuit with an onboard sine wave generator that can be switched on the carrier input, a boost on the other input...and a dpdt to bypass the whole ensemble.

two questions :
some beautiful soundsl but there is a volume drop compared to the bypassed signal. Is this why the second boost is needed on the output?
also I'm considering adding a simple blend (http://www.seanm.ca/stomp/images/fet-minblend1.png) --- in that case would the send wire go from the input boost "out" to the ring mod "in" and the return from the ring mod "out" to the output boost "in"  ?

Thanks for any help anyone can provide.

[alex frias]

Very interesting, I will try it out with the guitar modulated by a pitch shifted version of its own sound, I think it can be fun...

[dr.benway]

brett, you mention a 386 booster but I can't find a layout for this. keep getting amps, ruby and whatnot.

would this do ?

http://www.beavisaudio.com/techpages/BlocksFragments/images/Smokey_LM386_Guitar_Practice_Amp.gif



otherwise since i've got a utility boost on the input should i use the same on the output ?

[Top Top]

IC-based ring mods tend to sound cleaner, especially when playing multiple notes simutaneously. Also, yours is still IC-based, it's just that your ICs are in the SK-1.  I know that sounds jokey, but it's important to note that a big part of a ring modulator for guitar is in the oscillator. Getting a good sine wave from discrete technology can sometimes be more complex than a nice little function generator IC.

I realize this post is old, but just saw the reply. I meant that the ring modulator part of IC-based ring modulators seems really complicated, not the oscillator part. The transformer/diode arrangement sounds great and is dead simple.

Dr. Benway, you can probably look at the 386 datasheet and see some basic schematics. You can use the 386 as a booster pretty much in the same way it is used in an amp. Just limit the gain to the level you need with a resistor or pot across the gain pins (1&8 I think).

You could also look at how the 386 is used in other non-amp circuits like the pwm or other tim escobedo circuits. A lot of them use a lot of gain though, maybe more than you actually need.

[dr.benway]

thanks for the advice top top thanks for answering - old post as you say and the ring mod lovers seem relatively few
...sounds simple enough for the 386 which I know from  escobedo's uglyface and the mid-fi clarinot...will give it a go.

[dr.benway]

Top Top I have one more question for you : did you place a boost after the ring mod as well ?