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ring modulator: mc1469
MUFF WIGGLER Forum Index -> Modular Synth General Discussion  
Author ring modulator: mc1469
oneiric.tomb
Anyone know about this circuit?

I really want a ring modulator like the one in the Macbeth Elements (preferably in euro format)
But perhaps I don't know enough about RM and why RM sounds different synth to synth.

the one in the elememts (which i used to own) was perfect.
Any idea why or know of comparable designs?
Pelsea
There are three basic circuits that produce ring modulation.

Old school is a passive design with a pair of transformers and a diode ring. This is nearly 100 years old. The key to quality sound is the choice of transformers, which can be pretty expensive.

Most modern modules use an integrated circuit designed for FM radios such as the mc1496 or ad633. This is often called a balanced modulator or four quadrant multiplier. There's a certain amount of leeway in the associated circuit design that allows designers to optimize carrier rejection, distortion and noise, which results in some variability between models. The most common alternative to the 1496 design is a discrete circuit by Serge with roughly the same architecture.

Ring modulation can also be done digitally (with essentially one line of code), so modules like Disting will give an ultra clean (but possibly boring) response.

I've never used Elements, but anything on modulargrid that is not passive or digital is probably pretty close.
nigel
If you go to the DIY forum and search for MC1496 or LM1496 (not 1469), you should find a bunch of circuits.
ersatzplanet
Check designs you find for whether they are AC or DC coupled. Many designs are AC couples (the Doepfer RM for instance) which makes a difference when using them as VCAs and some other exotic things.
Rex Coil 7
Pelsea wrote:
There are three basic circuits that produce ring modulation.

Old school is a passive design with a pair of transformers and a diode ring. This is nearly 100 years old. The key to quality sound is the choice of transformers, which can be pretty expensive.
This passive one pictured below is constructed using EDCOR transformers, rated at 20hz to 20khz and may be purchased directly from EDCOR for $15.00 each plus shipping, thus spake their webpage.

LINK =
https://www.edcorusa.com/xsm_series



I've found that a rather major difference in sound may be had by changing out the "boring" (and unimaginative) use of germanium diodes in the buck standard diode ring/transformer style ring mod design to LEDs. Even different types of LEDs will have different influences on the sound. After many many trials (and as many errors) I ended up on 3mm "blue water clear" round LEDs. The ring modulators outfitted with those diodes require less input gain to make up for the signal level loss that germanium diodes suck out of the signal. LEDs also sound quite a bit different, I guess it could be described as more full range opposed to the midrange heavy sound produced by these types of passive ring modulator core circuits which are fitted with germanium diodes.
















Pelsea wrote:
Most modern modules use an integrated circuit designed for FM radios such as the mc1496 or ad633. This is often called a balanced modulator or four quadrant multiplier. There's a certain amount of leeway in the associated circuit design that allows designers to optimize carrier rejection, distortion and noise, which results in some variability between models. The most common alternative to the 1496 design is a discrete circuit by Serge with roughly the same architecture.
Some of these types I find to be almost lifeless. The harmonics they create seem to sit above or perhaps "separated" from the foundation waveform. Almost as if another VCO was just added or mixed with the original sounds used as the modulator and carrier. I've owned a couple of Moog ring mods (the big MoogerFooger, and the Minifooger). I sold them. They simply did not serve my purposes.

Pelsea wrote:
Ring modulation can also be done digitally (with essentially one line of code), so modules like Disting will give an ultra clean (but possibly boring) response.
I cannot speak for the Disting, but I can speak for the ring modulator model that Line 6 uses in their M5, M9, and M13 FX modeller units. In fact, the Line 6 modeled ring modulator is pretty much the benchmark that I compare all other ring modulators to for a certain function I require. When coupled with analogue signals (such as my Dot Com modular) the ring modulator in my Line 6 M13 produces a very rude and very expressive sound. It's useful in the same way that guitar players that can create upper harmonics using a technique known as "pinch harmonics" make use of those rude and expressive sounds. The Line 6 ring modulator model used with analogue synths creates the screeching screaming piercing upper harmonics that when used with pitch bend and deep rolled-in vibrato (and properly timed) is highly expressive.

The Line 6 ring modulator model is also highly useful when applied to my 1962 Hammond C3. FAR more so than the Minifooger and Moogerfooger were. For the same reasons; rude, piercing, sharply harmonic enhancement of the Hammond sound. This is most well applied for rock organ sounds.

Whether with analogue synth or real tonewheel (aka "analogue") Hammond organ, the Minifooger and the Moogerfooger were failures.

One other digital ring modulator that I find very VERY useful and highly expressive is the "Ring Thing" by Electro Harmonix. I have one of those and I find it as bitchin as the Line 6 ring modulator model. In different ways, mind you. There are things that can be done with the Ring Thing that simply cannot be done with any other ring modulator on the market. ANY ring modulator on the market. It also allows you to save up to nine presets as well.

When either the Line 6 ring mod or the Ring Thing ring mod are used with my Hammond or the Dot Com modular, adding a 0.500ms to 1.0 second delay while sweeping either the carrier frequency or the modulator frequency produces a VERY dramatic and expressive effect. The cascading harmonics interact with one another and sound extremely bitchin! Super bad ass 1970s "acid rock" or "psychedelic rock" stuff going on with it.

That's my story and I'm stickin' to it.

Rockin' Banana!
cornutt
Rex, have you played with having mixed diode types in that circuit? Does it do anything unique, or does the lowest/highest diode drop dominate the circuit?
Rex Coil 7
cornutt wrote:
Rex, have you played with having mixed diode types in that circuit?
Yes, quite a lot actually. Perhaps at least 1,000 man hours devoted. Yea, at least that much.

cornutt wrote:
Does it do anything unique, or does the lowest/highest diode drop dominate the circuit?
Well now, that's a rather small question with a massively large answer. Actually it depends on your ~ear~ ... what it is your hearing can focus on. In short, no, one diode will not dominate or drop the entire signal ... it will only drop the negative or positive half of the signal (this is where the notion of "asymmetric clipping" applies as well).

Get comfortable, pour some tea or open a beer, fetch your reading glasses, and relax a bit.... I've some things to say about all of this.

The diodes in these diode ring type ring modulators affect the sound just like clipping diodes in your average buck standard clipping distortion guitar pedal. This is something I made something of a project out of and studied it for a few years.

Let's stick with the diode clipping distortion pedal paradigm for a moment. Imagine the guitar plugged in to the audio interface of your DAW. Arm a track, hit ~record~, and play a note. Observe the waveform on the screen. We've a positive "half" and a negative "half" .... let's say the positive "half" is displayed on the top of the waveform representation, the negative "half" displayed below the zero gain line of the waveform representation.

Got that all pictured in your dome? (dome = skull). Moving on ...

If "diode X" in the clipping pedal is oriented so that it is clipping the positive half of the wave, and "diode Y" is oriented so that it is clipping the negative half of the wave ... as long as both diodes are the same type/design (aka "part number") then they'll apply the same amount/type of clipping to both "halves" of the waveform. Now, let's put a silicon diode as the positive, and a germanium diode as the negative, the waveform on the screen will change pretty drastically. That should come as pretty obvious.

Here's the variable ... depending on how the guitar player plucks or picks the string, the string's orbit (as it vibrates above the pickup pole) will be different for the positive and negative halves of the waveform. Pick aggressively downward (down stroke) and the string's orbit will be very uneven and highly asymmetrical. Use your fingernails to "pluck" the strings, and you've produced an entirely different orbit, which produces an entirely different gain bias .... perhaps much more gain on the negative half of the waveform and less gain on the positive half.

We need to recognize and remember that different diodes can make the signal a LOT louder (relative to diodes that are more restrictive) than others. If you place an LED paired up with a germanium diode arranged as a "clipping pair" if the LED is flowing the positive half of the wave the positive half will be A LOT louder (that is to say, it will have higher gain) than the germanium side of the waveform. This is what I am getting at when I refer to "gain structure". LEDs used a clippers will produce at least 5db more gain on the output of the distortion pedal than germanium diodes used as clippers. At least 5db. That is a LOT. Now think about how an asymmetrical clipping setup would respond with one LED and one germanium. The "loudness scale" comes out to being LEDs are loudest/most gain, silicons come in the middle, and germaniums have the lowest amount of output gain. This is how one can adjust the gain structure of the positive and negative half of the wave with a diode clipping distortion pedal ... or ... a diode ring style ring modulator.

That having been said, it is likely that orienting the various diode types (positive vs negative .... silicon clipping the negative half, germanium clipping the positive half) ... that will have a certain affect on how the guitar's sound is made and how the gain structure that hits everything after the guitar pedal is influenced. Including the preamp circuit in the guitar amp. Flip-flop the two diodes in the clipping pedal, use the same guitar player and his same technique (plucking? ... picking? ... down stroker? ... up stroker?) and the gain structure will change .... just by flip-flopping the diode pair.

The gain structure changes because with one clipping diode configuration the negative half is louder than the positive half. Flip-flop the diodes and now the positive half is louder than the negative half. That is to say, if you set up an LED as positive and a germanium as negative, that will sound a certain way with a given guitar player. Now, change only the way the two diodes are oriented ... place the LED as negative this time, and the germanium as positive this time (same guitar player, same technique as the first example) the sound will be much different. This is due to the orbit bias on the string and how the heavier "swing" of the string (aka higher gain) is processed by each type of diode. So how the diode pairs are oriented is EVERY BIT as crucial as the diode type itself. Few people understand this, and even fewer guitar pedal builders understand this. It also applies to passive ring modulators as well.

Everything I just said is what motivated me to design and build this ....









This device plugs into a clipping distortion pedal of my own design, instead of using a pair of diodes that run from the "hot" signal inside of the pedal and shorted to ground, I ran the wires that would normally connect the diode pair to the hot and ground out to a 1/4" jack. You simply patch this diode array into the "clipping jack" of the pedal and you're provided with a completely remote set of diode pairs. The toggle switches permitted you to choose which diodes were on the negative side of the wave, and which diodes were on the positive side of the wave. You could select one diode for each half, or (let's say) four diodes on the positive half and one diode on the negative half. The diodes could be any type, in any configuration ... arranged in any polarity you wanted.

Using a standard Tip/Sleeve 1/4" guitar/instrument cable to connect the two permits remote mounting of the clipper array. It could even be mounted on the mic stand, easily within the guitar players reach so it could be reconfigured mid-song without having to stoop down and fiddle with the toggle switches.

It's weird, but it works. Very well!





This device permitted guitar players that were very (VERY!) tuned in to their own playing styles, and how their playing styles influenced the gain structure and overall sound of what was coming out of the speakers. But even better than just the sound ... it allowed the guitar player to configure the clipper array to make the guitar respond in exactly the way the player wanted his guitar to respond to his technique. How did it sustain? How did each note's gain envelope respond to his technique? How did the fading brightness respond to his technique? ... (think of how a VCF responds to different EG settings).

All of this makes the upper-echelon player be able to really adjust precisely how the deeply experienced player's guitar (and the entire rig .... from strings to speakers) will respond to his touch. Thereby making his instrument all that more expressive.

This may sound like a bunch of hooey .... but it's real. Really excellent players want that finely nuanced control over how the guitar and the rig responds to their every touch. And this system of mine provides them with just that. I built and sold MANY of these systems over the course of about ten years. Most of which were delivered to recording and/or touring professionals. I designed my pricing structure to dissuade your average hobbyist guitar players which allowed me to focus on serving the professional community.

BACK TO SYNTHS AND RING MODS:

Ok, so the ring modulator (the passive diode ring + transformer style) works precisely the same way in that nuanced changes happen when you begin fiddling with which diodes are oriented one way or the other, and which types of diodes are introduced into that formulae.

Will you be able to hear a tangible difference if you put (let's say) silicon diodes on the positive and germanium diodes on the negative?

Yes.

Especially so in patches that are sensitive to audio signal polarity. Just like the guitar rig, we're dealing with various types of phase cancellation, waveform bias, and how various filters will react/respond to positive and/or negative signal bias. And with the diode ring ring mod you have some control over what happens, where, and how, and why, and so on. Some of the changes and experiments may be very nuanced and barely perceivable (going back to "it depends on your ear").

So:

If you are interested in experimenting with these sorts of mad scientist notions and nonsense ... I'd suggest building a test bed ring mod. I built a CGS "Real Ring Modulator" by installing a set of component sockets in place of permanently soldering diodes into the through holes (see picture below). This permitted me to very easily install any types of diodes in any polarity configuration of my choosing, as well as being able to reconfigure the setup in any way I saw fit.

See the other pictures of how I made up the CGS Real Ring Modulator outfitted with component sockets for doing empirical testing with various diodes in various configurations in some of my other posts seen further up in this very thread.

As crude as a hammer, and every bit as useful!










How well does it all work .... all of this diode moving around business in a passive ring modulator?

That, goodfolk, is 100% entirely up to you!


(Jan 07, 2019 - I'm no longer monitoring this thread, please feel free to send me a private message if you wish to correspond, I'll be happy to hear from you)

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