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DIY Stompboxes => Building your own stompbox => Topic started by: jacobyjd on November 28, 2009, 09:23:54 PM

Title: Simple Ring Mod?
Post by: jacobyjd on November 28, 2009, 09:23:54 PM
I've done some reading tonight on ring mods, and so far, they look rather complicated--not unbuildable, but definitely not mega-simple.

Anyway, I'm trying to gauge the buy/build decision at the moment. Essentially, I'm just looking to add a little clang to my sound (i.e. 90% dry signal w/ 10% carrier...ish), and if it's going to be an extensive build, then I'll just save up to buy one :)

Any suggestions for a relatively simple, subtle ring mod?

Title: Re: Simple Ring Mod?
Post by: rousejeremy on November 28, 2009, 09:43:19 PM
I bought an EHX Frequency Analyzer for $100 on craigslist. It has a blend knob as well.
The Maestro Ring mod on GGG looks like an intermediate build http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=114&Itemid=26
But no blend control. From reading your posts Jacob, you're probably already all over that though. 8)

Buy vs. build is a strange argument. I myself seem to have more respect for pieces I buy than pieces I build. i think this has an effect on the DIY'er.
Title: Re: Simple Ring Mod?
Post by: earthtonesaudio on November 28, 2009, 09:47:05 PM
http://en.wikipedia.org/wiki/File:Ring_Modulator.PNG

Plus:

Simple phase shift oscillator (see EA tremolo)
A couple buffers/makeup gain stages.

...Equals full featured ring mod.  The extra complexity in other designs I imagine has a lot to do with taming the unwanted noise and carrier frequency bleedthrough.


Unfortunately, I think "subtle" and "simple" are conflicting goals in ring mod design... though as rousejeremy suggests, a simple output mixer with a "blend" control would go a long way.
Title: Re: Simple Ring Mod?
Post by: jacobyjd on November 28, 2009, 10:01:44 PM
The EHX FA is what I'd go with if I were to buy.

I suppose the only real controls I need are carrier and blend. I think I'd prefer some sort of filter control as well--that might have to be a switch...

Anyway, the Maestro one doesn't seem to be the one for me...

I found this one when digging through the ExAnon archive: http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/AD633%20Ring%20Mod%20with%20LFO.jpg (http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/AD633%20Ring%20Mod%20with%20LFO.jpg)

This looks totally doable, but I have no clue if it's more radical than what I'm looking for or not. I suppose I should check on that chip's availability before I get too wild and crazy...
Title: Re: Simple Ring Mod?
Post by: jacobyjd on November 28, 2009, 10:09:25 PM
Unfortunately, I think "subtle" and "simple" are conflicting goals in ring mod design... though as rousejeremy suggests, a simple output mixer with a "blend" control would go a long way.

Haha, I know what you mean. I think that's definitely where the blend control comes in--I'm not a huge fan of RMs in general--total dissonance is something I don't really want, but some of the more subtle settings of the Freq Analyzer are definitely what I'm looking for.

Thanks for the additional ideas...I'll have to do some more reading--the more theory I can wrap my head around on this, the better.
Title: Re: Simple Ring Mod?
Post by: Top Top on November 28, 2009, 10:55:01 PM
I have found the basic 4 diode 2 transformer design to sound really good. I built one and I like it a lot - use it as an octave up as well (feed both inputs the same source)... though of course if you want something you can take with you, you need a carrier source (osc) and a simple mixer if you want a blend control. Those two things are pretty easy to whip up though.

I just use a toy keyboard in drone mode (tape on the key) for the carrier if I want the full on klang. I also built two boosters to use on the inputs. I don't know if I just got lucky, but with proper gain settings on each input I get really good carrier rejection - much better than with my old EPFM ring mod.

Honestly, I can't understand why there are so many complicated ring mod designs out there when that simple one works so well.
Title: Re: Simple Ring Mod?
Post by: jacobyjd on November 28, 2009, 11:10:55 PM
I have found the basic 4 diode 2 transformer design to sound really good. I built one and I like it a lot - use it as an octave up as well (feed both inputs the same source)... though of course if you want something you can take with you, you need a carrier source (osc) and a simple mixer if you want a blend control. Those two things are pretty easy to whip up though.

I just use a toy keyboard in drone mode (tape on the key) for the carrier if I want the full on klang. I also built two boosters to use on the inputs. I don't know if I just got lucky, but with proper gain settings on each input I get really good carrier rejection - much better than with my old EPFM ring mod.

Honestly, I can't understand why there are so many complicated ring mod designs out there when that simple one works so well.

Interesting. Do you still hear the carrier signal droning when you're not playing? If so, I reckon killing the carrier when not playing is an added layer of complexity.
Title: Re: Simple Ring Mod?
Post by: Top Top on November 29, 2009, 01:45:19 PM

Interesting. Do you still hear the carrier signal droning when you're not playing? If so, I reckon killing the carrier when not playing is an added layer of complexity.

If I set the gain controls on each input booster just right, I hear very little or no carrier when not playing.

I have no idea if this is typical for this effect, as this is the only one I've built. I know other people have talked about needing matched diodes to get good rejection. I used silicon diodes that I had around (4001 or 4002), even though people have said you MUST use GE ones.
Title: Re: Simple Ring Mod?
Post by: Mark Hammer on November 29, 2009, 03:50:19 PM
If all you want is a taste of RM, just goose the frequency range of the LFO in any modulation pedal you might have (optically-based ones are not applicable) so that it can attain audio-frequency modulation rates.  You'll be okay if you can change a couple of caps here and there to get modulation speeds up to 500hz.  It's not a "true" RM, but sounds pretty darn close to it.
Title: Re: Simple Ring Mod?
Post by: madstringbean on November 29, 2009, 05:13:29 PM
Has anyone here built their own simple ring modulator with a built-in carrier?  I'm working on one right now.  If so what LFO circuit do you recommend? 
Title: Re: Simple Ring Mod?
Post by: DougH on November 29, 2009, 05:53:19 PM
I've been wondering similar things, Josh.

I found this a week or so ago: http://www.moosapotamus.net/IDEAS/stompboxology/RingMods.htm (http://www.moosapotamus.net/IDEAS/stompboxology/RingMods.htm)

Looks interesting but more intense of a build than I want to get into for the amount I would use this thing. OTOH I don't really want to spend $150 on an EH Freq Analyzer either. (I'd rather save that $$ and get a reverb.)

I like Mark's idea of modding a modulation pedal so the LFO will sweep in the audio range. I have an old Boss BF2 Flanger I may sacrifice in the name of science. I played with this and it sounds promising although right now it only goes to 10Hz (100ms). I found a schematic for it and I may try modding the LFO to modify the rate. (Just have to figure out which caps to change.)

BTW- Here's the BF2 schematic: http://www.hobby-hour.com/electronics/s/boss-bf2-flanger.php (http://www.hobby-hour.com/electronics/s/boss-bf2-flanger.php)
Title: Re: Simple Ring Mod?
Post by: liquids on November 29, 2009, 08:25:50 PM
Have you tried this yet?  http://folkurban.com/Site/ThingModulator-709.html (http://folkurban.com/Site/ThingModulator-709.html)  I remember liking it when I bread boarded it...

Just combined it with a buff and blend...not sure if you'd need phase inversion or not.

Likewise, this is borderline for 'simple,' but it could be great: http://www.hollis.co.uk/john/circuits.html (http://www.hollis.co.uk/john/circuits.html) Scroll for "The Frobnicator."  Simplified version of the EH, if you will, and another, cheaper OTA (like 13600 or 13700 from small bear, though larger in size) could be easily subbed for the OTA and following buffer, I'd imagine...

And now for something completely different: http://bearison.com/worthekik/hysteresisbuild.html (http://bearison.com/worthekik/hysteresisbuild.html)

And sorry if any or all of this is old news stuff you've already tried...    :icon_redface:
Title: Re: Simple Ring Mod?
Post by: liquids on November 29, 2009, 08:32:42 PM
Honestly, I can't understand why there are so many complicated ring mod designs out there when that simple one works so well.

I'm no EE, but from what I read, on principle alone EEs avoid inductors and transformers at nearly any cost...and often for good reason.   Cost is another reason.  But, enter the beauty of DIY...     :)

What transformers are you using anyhow? More so, what are the specs, especially if it's not a txf that can be had via small bear and or mouser.   ;)
Title: Re: Simple Ring Mod?
Post by: mantella on November 29, 2009, 09:06:10 PM
I'm sure you've looked at this one already, but I thought I'd throw it into the mix -
http://www.geofex.com/PCB_layouts/Layouts/frobn.pdf

the ring frobnicator. It's a good one. It doesn't get too crazy, soundwise, but it is a pretty straightforward build.
Title: Re: Simple Ring Mod?
Post by: DougH on November 29, 2009, 09:46:57 PM
Have you tried this yet?  http://folkurban.com/Site/ThingModulator-709.html (http://folkurban.com/Site/ThingModulator-709.html)  I remember liking it when I bread boarded it...

Just combined it with a buff and blend...not sure if you'd need phase inversion or not.

Likewise, this is borderline for 'simple,' but it could be great: http://www.hollis.co.uk/john/circuits.html (http://www.hollis.co.uk/john/circuits.html) Scroll for "The Frobnicator."  Simplified version of the EH, if you will, and another, cheaper OTA (like 13600 or 13700 from small bear, though larger in size) could be easily subbed for the OTA and following buffer, I'd imagine...

And now for something completely different: http://bearison.com/worthekik/hysteresisbuild.html (http://bearison.com/worthekik/hysteresisbuild.html)

And sorry if any or all of this is old news stuff you've already tried...    :icon_redface:


Thanks! I forgot about Tim E.'s and John Hollis's stuff. The Frobnicator looks very doable and fairly simple.

FWIW, I started experimenting with my BF2. Subbed C27 and C28 with 4.7u's and it is starting to get the pseudo ring sound. I'm going to lower them further to experiment with a higher "carrier" frequency and see how that sounds. One nice thing is the BF2 is extremely easy to work on. No PCB mount components and the PCB isn't even mounted.
Title: Re: Simple Ring Mod?
Post by: Boogdish on November 29, 2009, 10:44:44 PM
Have you looked at Ray Wilson's stuff?

http://www.musicfromouterspace.com/analogsynth/RINGMODULATOROCT2007/RINGMODULATOROCT2007.html
http://www.musicfromouterspace.com/analogsynth/RingModulator/RingModulator.html

It's designed for synth but might be a good jumping off point for a guitar ring mod.
Title: Re: Simple Ring Mod?
Post by: Top Top on November 29, 2009, 11:55:08 PM
Honestly, I can't understand why there are so many complicated ring mod designs out there when that simple one works so well.

I'm no EE, but from what I read, on principle alone EEs avoid inductors and transformers at nearly any cost...and often for good reason.   Cost is another reason.  But, enter the beauty of DIY...     :)

What transformers are you using anyhow? More so, what are the specs, especially if it's not a txf that can be had via small bear and or mouser.   ;)

What is the reason they avoid transformers?

I built the one on these sites:
http://www.cgs.synth.net/modules/cgsrr.html
http://www.asciipr0n.com/4096/ringmod/index.html

I used  mouser audio transformers TM018 I think. They are around $3 each if I remember right.

Title: Re: Simple Ring Mod?
Post by: DougH on November 30, 2009, 07:56:09 AM
Quote
What is the reason they avoid transformers?

Inductors and transformers can take up a lot of space and are relatively heavy.
Title: Re: Simple Ring Mod?
Post by: liquids on November 30, 2009, 07:56:37 AM
What is the reason they avoid transformers?

Well, again, I am no EE, so take this with a grain of salt, I'm just going on what I   I've gathered from reading here and elsewhere...  :)

MY understanding is that transformers suffer similar complications as inductors, to avoid them.  Of course, guitar effects don't always follow that....

But for one, size.   They're a big part comparatively, even when small.   Likewise, transformers can suffer the same issues that inductors do, since we're still talking coils of wire...  Its my understanding that transformers (like inductors) are prone to pick up noise, so you have to design around that.  

 Likewise, I read something on R.G.s site where it says "the resistance of a wire is increased by its being in a magnetic field."  So you suffer similar effects to a pickup, I take it.  You need to drive it with a buffer, probably follow it with one too, optimally. Not that any of this can't be worked around, but on a large scale, I'd imagine that's...well, there is a lot to work around for a production unit if you have the option to do another design with common cheap and consistent parts.  

Maybe a transformer version of something 'sounds better,' but now we're talking boutique market concerned mostly with tone and sounding like hendrix and owning an authentic repro is priority (subjective), vs reliability, failure rates, customer dissatisfaction ("this thing hums when I get it next to my guitar / amp / computer" or something) when there is no 'mojo' or 'hype' involved...of course, we're talking pedal effects, and in todays market, distortions, fidelity, and noise are only so much of an issue...so you see them, sure.  And of course, certain applications like DIs and isolated output splitters or whatever, you see them.

Well, those are my guesses (http://guesses) at least.  :)    Hopefully someone educated in this can better answer your question, correct any false statements I made, or...well, ideally both.  :D
Title: Re: Simple Ring Mod?
Post by: DougH on November 30, 2009, 09:00:37 AM
Well, I just hedged my bets in case the BF2 doesn't work out and ordered a couple 3080A's from Ebay. Will be fun to see how this all ends up.
Title: Re: Simple Ring Mod?
Post by: earthtonesaudio on November 30, 2009, 10:27:57 AM
See figure 88: "Low Frequency Mixer" in this appnote (http://www.national.com/an/AN/AN-72.pdf).

You don't necessarily need the Norton amp for this; just take a look at the schematic and you'll see the internal construction is fairly simple.  Just make two common emitter stages, tie the collector of one to the base of the other.  Call the collector-base junction the (-) input and call the base only connection the (+) input.  Add a collector resistor to the free collector.  That's a very basic discrete approximation of the LM3900. 
Then add the external components as shown in figure 88.  Finally, add signal and LFO like you would an ordinary ring modulator.

Just an thought.  I haven't tried any of this.