Inspired by this (thanks to Cortexturizer)
Quote from: Cortexturizer on September 18, 2013, 09:43:39 AM
Something like this
Some classic circuits tweaked to perfection. The pedal is insanely pricey, but I get it. There's a lot going on in there. If I had enough time maybe just maaaybe I would attempt a build like this but I doubt I could pull it off. Not saying this is the most complicated build out there, but it would be an ultimate pedal for me, hells one could start a band around this pedal alone hahah.
I remembered the fun you can have with ringmodulators on synthesizers.
I also have a far memory of John Scofield using one on several occasions (probably from a Line 6 MM4 Modulation Modeler).
So that made me look for an easy solution to analogue multiplication (without using transformers and rectifiers like the old).
Here are some schematics: http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/
Older designs seem to rely on the (obsolete?) 1496 ic. But there's also the AD633 (http://www.analog.com/static/imported-files/data_sheets/ad633.pdf):
(http://i00.i.aliimg.com/photo/v0/353755578/AD633.jpg)
That chip does all the hard work and you just need to add an oscillator to have a carrier:
(http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/AD633%20Ring%20Mod%20with%20LFO.jpg)
(based on http://www.sowa.synth.net/modular/rm.html)
Has anyone here already tried this or a similar design?
Edit: I wonder why the op amps (at pins 1 and 3) are biased with a trimmer. Shouldn't ground be fine?
Edit 2: Of course, there should also be the option to use the input signal also on the second input (instead of the carrier wave) to get a nice octave up effect.
Sounds cool. Aren't the trimmers for fine adjustment so that you can knock out everything but the output signal (remove all traces of the carrier and the input).
Ouch the AD633 is costy at Mouser. The LM13700 spec sheet has an example circuit for doing four-quadrant multiplication too. I haven't tried it, but you could probably get a both the multiplier and the carrier generation out of a single LM13700. It might be worth looking into. I wonder if it's been done in the synth world.
Edit: Didn't find anything on using the LM13700 as a multiplier yet, but here is a synth project using the AD633 and the LM13700 to get a sine carrier signal.
Quote from: RobA on September 21, 2013, 04:14:56 PM
Aren't the trimmers for fine adjustment so that you can knock out everything but the output signal (remove all traces of the carrier and the input).
Yeah, that's quite possible. Thanks for this hint.
Quote
Ouch the AD633 is costy at Mouser.
I will try my luck with ebay, that is, China.
BTW There's one US seller (http://www.ebay.de/itm/5pc-lot-PN-AD633JR-IC-/190854387482?pt=LH_DefaultDomain_0&hash=item2c6fced71a) selling a 5 piece lot of the SMD version for $10, but what he asks for shipping to Europe is ridiculous...
Quote
The LM13700 spec sheet has an example circuit for doing four-quadrant multiplication too. I haven't tried it, but you could probably get a both the multiplier and the carrier generation out of a single LM13700. It might be worth looking into. I wonder if it's been done in the synth world.
Right, I need to look into that!
Forgot the link in my edit. Here it is anyway,
http://www.musicfromouterspace.com/analogsynth_new/RINGMODULATOROCT2007/RINGMODULATOROCT2007.html (http://www.musicfromouterspace.com/analogsynth_new/RINGMODULATOROCT2007/RINGMODULATOROCT2007.html)
Edit: That one is also using the AD633.
Here are a couple of other projects that do use the LM13700
http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/LM13700%20ring%20mod.pdf (http://experimentalistsanonymous.com/diy/Schematics/Ring%20Modulators%20and%20Frequency%20Shifters/LM13700%20ring%20mod.pdf)
http://lushprojects.com/lushone/contour/build/ (http://lushprojects.com/lushone/contour/build/)
They might be good starting spots for using the LM13700 as a multiplier.
Yes, using an OTA looks quite straight forward. But I can't find data up to what frequency this would work.
I've used the LM13700 in a tremolo circuit and run it up to around 400Hz and it works fine. In the Lush project he's running the ring modulator from an audio oscillator as the carrier, so I think it would be OK in that regard.
Yes, reading up on these links, this OTA idea should really work.
Can you really get a suitable oscillator from half an LM13700 alone? [Edit: you could get a triangle wave, right?]
Or would it be more fun to have two ring modulators going using both OTAs?
I've seen schematics where the LM13700 is used to waveshape an input waveform to get an a good sine wave. I doubt if you could do it with the OTA alone. This link shows an example of shaping a triangle to a sine. http://www.musicfromouterspace.com/analogsynth_new/OLDIESBUTGOODIES/LFO/lfo-3.html (http://www.musicfromouterspace.com/analogsynth_new/OLDIESBUTGOODIES/LFO/lfo-3.html)
I'm sure you could come up with something else to do with the other half. A simple alternative for getting a sine wave would be to use an XR2206. I played with using these as function generators and they work well. But, I think they are hard to find now too.
Edit: Thinking about it some more, it would be cool to do a two voice version. You could us an ATTiny84 to generate two carrier waves to drive it too.
Quote from: RobA on September 21, 2013, 05:43:39 PM
Edit: Thinking about it some more, it would be cool to do a two voice version.
That's what I wanted to hear ;)
Quote
You could us an ATTiny84 to generate two carrier waves to drive it too.
Using a microcontroller would also allow for many different waveforms.
:D. Yeah you can get some pretty good flexibility in waveform output using the microcontroller. You do have to be a bit careful though because the easy ways to get output oscillators require some pretty aggressive post filtering. Still, you can do quite a bit that way.
One other thing about filtering, on my AU ring modulator, I found it really helpful to run the guitar input signal through an LP filter first and then do the ring modulation. If you use a good musical LP, a Moog type say, the results can be very cool. The main point though is to pull down the upper harmonics so that there are fewer cross terms out of the ring modulator.
Anyone verified this schematic? I'm waiting on my mood ring, though this could work too.
Quote from: RobA on September 21, 2013, 07:31:54 PM
You do have to be a bit careful though because the easy ways to get output oscillators require some pretty aggressive post filtering. Still, you can do quite a bit that way.
Sure, you need to be careful with aliasing and bit noise.
Quote
One other thing about filtering, on my AU ring modulator, I found it really helpful to run the guitar input signal through an LP filter first and then do the ring modulation. If you use a good musical LP, a Moog type say, the results can be very cool. The main point though is to pull down the upper harmonics so that there are fewer cross terms out of the ring modulator.
Interesting idea! It woudn't need to have resonance and maybe the corner frequency could be fixed too? So would two Sallen-Key in a row do?
Quote from: kothoma on September 21, 2013, 04:22:50 PM
Quote from: RobA on September 21, 2013, 04:14:56 PM
Aren't the trimmers for fine adjustment so that you can knock out everything but the output signal (remove all traces of the carrier and the input).
Yeah, that's quite possible. Thanks for this hint.
Quote
Ouch the AD633 is costy at Mouser.
I will try my luck with ebay, that is, China.
BTW There's one US seller (http://www.ebay.de/itm/5pc-lot-PN-AD633JR-IC-/190854387482?pt=LH_DefaultDomain_0&hash=item2c6fced71a) selling a 5 piece lot of the SMD version for $10, but what he asks for shipping to Europe is ridiculous...
Quote
The LM13700 spec sheet has an example circuit for doing four-quadrant multiplication too. I haven't tried it, but you could probably get a both the multiplier and the carrier generation out of a single LM13700. It might be worth looking into. I wonder if it's been done in the synth world.
Right, I need to look into that!
Edit: N/M
Quote from: kothoma on September 22, 2013, 05:37:07 AM
...
Interesting idea! It woudn't need to have resonance and maybe the corner frequency could be fixed too? So would two Sallen-Key in a row do?
Yeah, I'd think so. I've used various different filters to do it. In the AU version, I use a driven multi-stage ladder-like filter with a non-linearity between the stages, but it isn't needed for just reducing the harmonics. It had the frequency as a parameter, but it was fixed to a value -- it didn't move with the input note. A couple of Sallen-Key filters with the right frequencies would get you a pretty big range of useful input frequency.
Edit: I should explain that the reason I went with that filter was that if you back off the drive, you cut the upper harmonics and does what I was talking about above. On the other hand, adding a lot of drive is like putting a fuzz box followed by the filter in the circuit. So, it kinda causes it to act more like a filtered square wave going in to the ringmod. In an analog circuit, you could do better using a real fuzz as an option in the signal path.
Quote from: RobA on September 21, 2013, 05:43:39 PM
A simple alternative for getting a sine wave would be to use an XR2206. I played with using these as function generators and they work well. But, I think they are hard to find now too.
Tayda to the rescue!
http://www.taydaelectronics.com/xr-2206-xr2206cp-xr2206-monolithic-function-generator-ic.html
Quote from: culturejam on September 22, 2013, 04:37:28 PM
Quote from: RobA on September 21, 2013, 05:43:39 PM
A simple alternative for getting a sine wave would be to use an XR2206. I played with using these as function generators and they work well. But, I think they are hard to find now too.
Tayda to the rescue!
http://www.taydaelectronics.com/xr-2206-xr2206cp-xr2206-monolithic-function-generator-ic.html
Ah cool! It's definitely worth looking at. I see that Tayda has the spec sheet linked for it there too. I'll have to pull out the one I have to try it out as a carrier wave.
Quote from: culturejam on September 22, 2013, 04:37:28 PM
Quote from: RobA on September 21, 2013, 05:43:39 PM
A simple alternative for getting a sine wave would be to use an XR2206. I played with using these as function generators and they work well. But, I think they are hard to find now too.
Tayda to the rescue!
http://www.taydaelectronics.com/xr-2206-xr2206cp-xr2206-monolithic-function-generator-ic.html
Hey, it is great news that it still is available!
Ha! Dudes I am so glad to see The Carrier under the magnifying glass (sorta) it's crazy how much can a ring modulator add to the music yet a small portion of people use one,and a DIY version always looked extremly hard to do to me. I mean listen to Tortoise, or Wayne Krantz, you'll hear how this type of effect can sound incredibly classy.
As to The Carrier,it's a beast,the guys from Hexe really tuned it perfectly. But dude,it's like...700 dollars...no thanks, i'd rather buy another guitar hehe
I think I figured out something to do with the extra half of the LM13700 (in a one voice setting). I'll report back if it works.
Quote from: RobA on September 24, 2013, 03:40:02 AM
I think I figured out something to do with the extra half of the LM13700 (in a one voice setting). I'll report back if it works.
Eager for news. Meanwhile I've ordered some AD633 and XR2206. Still interested in using an LM13700 though.
Quote from: Cortexturizer on September 22, 2013, 09:15:34 PM
[...] it's crazy how much can a ring modulator add to the music yet a small portion of people use one [...]
Perhaps because it is easy to get random sounds but it's a bit tricky to reproduce settings and results?
I like the random sounds, though.
Exactly. Ring mods are worse than envelope filters, as far as having to stop and fiddle with it until you get what you want.
(For annoying whole rooms/halls/buildings full of people, though, there are NO OTHER pedals that come close to an angry ring mod in full shriek...)
But they do have other uses -- or so it seems. We had a ton of hits on our website once for our software ringmod. I discovered that someone had posted instructions on a forum about how to set it up for processing voice recordings to sound like a Dalek. It completely cracked me up and kinda blew my mind at the same time. It was totally fun though.
A ring mod has always been something that I've wanted to build but on researching I usually end up hiding under my bed for a week.
Eagerly watching this thread :D
Quote from: chromesphere on September 25, 2013, 07:53:54 AM
A ring mod has always been something that I've wanted to build but on researching I usually end up hiding under my bed for a week.
Eagerly watching this thread :D
Doesn't look so scary after all?
I'm really curious where this could lead to.
Just brainstorming a few additions to the basic lowpass/carrier/multiplier/mix setup discussed so far:
- LFO to modulate the carrier pitch (see Moogerfooger MF-102 and Hexe The Carrier)
- envelope follower to control the carrier pitch (now, you saw that coming...)
- lowpass after the multiplier (as in The Carrier)
An alternative to the XR2206 could be a ICL8038 (http://www.intersil.com/content/dam/Intersil/documents/fn28/fn2864.pdf) as used in the EH Frequency Analyzer. Oh, it's marked "OBSOLETE PRODUCT - NO RECOMMENDED REPLACEMENT". Damn.
Frequency sweeping the carrier was where I was headed with the second half of the LM13700. There are a couple of ways to go with this based either on using the OTA as a variable resistor feed by an LFO or by using it to do the LFO itself and applying the resulting CV as in figure 10 of the XR2206 doc. There are some hangups that I'm having using the LM13700 for the LFO itself involving the wave shapes that I'd want to use. I still need to experiment a bit and see which way is better, using figure 10 or the OTA path as a variable resistor.
I played around with the LM13700 and the XR2206 today and I did get a working ring modulator. But, it is a pain in the butt. It's already got 5 trimmers in it and I've only done about half of what I wanted to do with it. The XR2206 does work to produce a pretty nice sine wave, using three trimmers to get the wave shape just right. It also pretty much takes a spectrum analyzer to dial the sine in. I'd say that it is doable, but I think I'm going to hold off on the ring mod idea for a bit.
I'm still interested in how the experiments with the AD633 turn out though.
I'd say pinch one of the analog synth world's voltage controlled oscillators that have a sine out -- quite a few just have one sine adjustment trimmer (the sine part gets fed from the triangle output.)
Do you have any links to one or even just a name? All of the sine shapers I know of are just about the same as what's in the XR-2206 plus you have to build an audio frequency VCO as well. This example is pretty much the level of what I've come across in the synth world,
(http://www.musicfromouterspace.com/analogsynth_new/VCO20120618REV0/images/vco20120615wsoic_page_2.gif)
The site has been dead for a long, long, long time but Electronics 4 Musicians had a few really good, really simple designs. Here's one --
Hm, this sine wave is only a crude approximation through distorting (wave shaping) the triangle wave.
Don't know if this is good enough.
One could get a better sine out of an oscillating bandpass filter.
On the other hand, some ringmodulators only provide triangle and square wave anyway.
Not sure there is a good solution that is simple with little to no trimmers. Probably come down to which is least offensive to the ears.
Thanks for the schematic. I'll check it out and see how well it does. The XR-2206 is using an internal wave shaper on a triangle wave, so the concept itself is OK. I don't know about this implementation though. I could fix the values of two of the trimmers on the XR-2206 and get a reasonable approximation. But, for what I was trying to get from the ring mod, it's fairly important to get a clean sine. Every frequency component in the carrier wave creates its own side bands, and since the guitar signal is already pretty rich in harmonic content, it gets pretty noisy.
The other thing I wanted to be able to do was to sequence the carrier frequencies. It looks like the voltage control here would make that possible.
Found this, rather accidentally: http://moosapotamus.net/files/stompboxology-ring-modulators.pdf
Have you checked out CircuitSalad's surprisingly flexible and (potentially musical) ring mod?
http://circuitsalad.com/2013/06/23/ring-modulator-pcb-info-and-misc-notes/
It comes as a complete project with an ExpressPCB layout.
Unfortunately, Express PCB's postage costs to the UK are prohibitive and my attempts a while back to drum up interest for a US-based order failed miserably...
Quote from: jaidee on October 05, 2013, 10:55:11 PM
Have you checked out CircuitSalad's surprisingly flexible and (potentially musical) ring mod?
http://circuitsalad.com/2013/06/23/ring-modulator-pcb-info-and-misc-notes/
Hey, thanks for this link. That's an interesting design using an H11M1 optocoupler as multiplier.
Instead of the modulated lowpass (quite expensive MAX7410, and a bit hard to source in non-SMD) on the wet signal I'd prefer to have modulation/control on the carrier frequency. And a sine wave carrier option.
But there are many fine ideas in this design.