Moog Music Forum

Hi everyone,

I've been lurking on this list for a while now, but someone outed me on the Theremin forum, so I decided to come clean here as well.

I play shakuhachi (my main instrument) and theremin, with several MFs as well as other toys. Amongst the MFs is a 107, and it surprises me that in all the discussion of this bix no-one has mentioned what seems to me to be one of its more esoteric but most sonically beautiful uses.

Far from being a complex or glorified distortion box, the 107 can be viewed as an analogue implementation of 2-operator FM, as pioneered digitally by John Chowning and implemented with varying degrees of complexity in the Yamaha DX synthesizers, culminating in the FS1R synthesizer. (FM of course appears in lots of software, and is easy to build-your-own in MAX/MSP for instance).

What we basically have is a VCO with cv in for frequency control, with variable waveshape, and the ability to offset its frequency. The important thing, though, is the ability to use an audio signal to modulate the frequency of the VCO, as well as enveloping the output signal via an envelope follower, to make the output follow the input signal level.

What htis means is that if you provide a monophonic input audio signal and simultaneously a cv that tracks that signal's pitch, you can modulate the VCo with a constant interval between input and VCO. If the audio signal modulates the frequency of the VCO, the result is analogue 2-operator FM synthesis, and the exact sound produced is determined by the FM level, and the complexity of the waveshapes of the input and the VCO. With complex waves, the harmonics go wild, giving the impression of highly.coloured distortion. If you keep the waveshapes simple - triangle, sine - you have a chance of producing delicate timbres, which run the spectrum of FM metallic etc, depending on what interval is set between input and VCO. The tracking of the VCO is not perfect, but still pretty usable, in my experience.

Now to do this, you need something that can produce a simple audio signal and a cv that tracks its pitch. A VCO module driven by a keyboard can do this (think Voyager with breakouts for signals and cvs). But Moog (meaning Bob and everyone else who's been involved) came up with a perfect way of doing this for expressive playing. Firstly the Etherwave Pro theremin, which can put out a pretty pure signal, and a cv. Audio signal to audio in of 107, pitch cv to VCO cv in. Voila - a theremin that produces FM metallic sounds, with accurate tracking, all analogue. (A few years ago, the lore was that this was impossible in analogue...) Secondly and more recently, the Etherwave Plus. While I don't own an EW+, I assume that the same setup works with it as well. Even with the purest waveforms, the output signal can get pretty rich in harmonics, so I find it useful to put it through an MF101 - which of course can be controlled by the volume cv out of the theremin. This becomes an extremely expressive instrument with a huge range of timbres.

So, if you own a 107 and haven't tried it in this way - you might want to experiment...

Cheers,

Jim F

Wow. Lots there and I'm afraid I do not completely understand it (maybe after some sleep and a good meal) but agree that the freq is an incredibly device.

I've used the ENV follower to drive the filter within my OldSchool via bass guitar [and love it] but have actually been disappointed that I could not simultaneously play the OSC via freq input and OSC out but I think what you are saying is that you use the in conjunction with tweaking of the FM knob to create a
unique and tame synth tone which is somehow a relative of the synthesis employed by the DX-7?

Clearly lots more to experiment with and I thank you for that posting.

-Mike W. from NJ

Welcome to the forum.

Ive always loved the sound of the shakuhachi, and ill bet that playis some of the traditional songs on it is very difficult. Never thought about running something like that through the freqbox.

I have tried with my theremin's attenuated CV output to get both the Voyager AND the Freqbox to track at an interval. I haven't experimented very much, nor have I had much success.

I have noticed that as you approach the volume antenna, you can definately hear the sum and difference clearly associated with Ring Modulation.

I really think the 107 is a great addition to my setup. I don't use it much, because at this point Im trying to program sounds from scratch on the Voyager but I love to use it as a second voice. For example running an instrument through it, like the theremin, with an expression pedal on the mix, and a c251 throwing random voltages at it. Then at a point in ht theremin or other instrument's phrase, I will bring up the mix amount to allow for that second modulated voice come through.

Eric

Great post .

Like most who have a couple I've really been on the fence about
what 'fooger to add, next.

The Freq Box has been very near the top of the list and this post has
pushed it up a bit further..

This is exactly the thing I needed to hear about the freqbox. Thank you jeff. Do you have any demos, im all about the demos

I tried playing around with that today, and it works great! I have several foogers daisy chained through the insert jack on my Voyager, so I sent the EW's audio out to the external audio in on the Voyager. I then sent the pitch CV from the EW to the Freq box, and the volume CV from the EW to the volume CV on the Voyager. Much fun!

Your method also works with the Voyager by routing the pitch CV from the Voyager to the freq CV on the Freq box. Good for also adding a fourth oscillator, except that the oscillator on the Freq box isn't as stable as the Voyager's. Still lots of fun, though.

Nice discovery, thanks! And welcome to the forum!

So let me see if I understand you.

You say that
1 What we basically have is a VCO with cv in for frequency control (this is the knob or CV input and/or Freq knob)
2. with variable waveshape (this is the wave knob or CV input)
3 and the ability to offset its frequency (this is the Env Knob or CV input)

And

4. The important thing, though, is the ability to use an audio signal to modulate the frequency of the VCO, (are you talking about synced mode hear or using an audio source into the Freq CV?)
5 enveloping the output signal via an envelope follower, to make the output follow the input signal level. (I don't understand this part)

I'm hoping to get a Freqbox sometime soon (2nd thing on my wishlist after a CP 251) and its def a disappointment to me that there seem to be no Youtube demos that apply both FM and the envelope follower together >__>

Heres the thing with Freqbox Demos that are on youtube. They aren't done in a way that people can actually see what the Freqbox is capable of. They usually show the ultimate extremes of it, and people end up thinking that its a 1 trick pony.

My youtube demos tried to emphisize the more subtle aspects of the Foogers, so that people aren't so quick to reject it.

All of the whacky sounds that it makes is with the FM and envelope up.

if you haven't seen my demos, please give them a chance.

youtube.com/rhythmicons
"Freqbox with Rhodes and Bass guitar" and
Freqbox Bassballs Hybrid Synth

Eric

I love my freq box, and I find it to be a very versatile unit. Lately, I've been slaving it to my Voyager RME for a 4th oscillator.

I think it's a very underestimated piece of equipment. You can do a LOT with them if you're creative...

peterkadar wrote:I think it's a very underestimated piece of equipment. You can do a LOT with them if you're creative...

Isn't that the whole point? >__<

Hi everyone,

Been offline for a while...

A couple of answers to previous comments.

Basically, the FreqBox, when used as I suggested in my first post, becomes a relative of the synthesis method used in the DX7s etc. The Yamaha implementation is more complex, with 6 (or 8 in the FS1R) oscillators per voice, connected in a range of patterns which Yamaha terms "algorithms". In Yamaha-speak, the oscillators are called "operators".

Using the FreqBox in this way, we have 2 operators (oscillators), connected in the simplest of possible algorithms - one oscillator (in my setup, the EWPro theremin) modulating the frequency of the the other (the FreqBox VCO). So, it's highly simplified compared to the Yamaha digital implementation. BUT - it's analogue, and it's directly controllable via cvs in real time, which makes it hugely more complex and flexible than the Yamaha implementation, which has as its basis a MIDI/keyboard paradigm - press the key (or send the MIDI message) and you get what you programmed. (In the Yamaha implementation, even real-time control of various parameters via MIDI controller messages is quantized - 128 steps - thus fundamentally flawed in comparison to the infinite controllability of the FreqBox via cvs.)

A fundamental point here is the FreqBox's envelope follower. This has an important role - the envelope (ie moment-to-moment amplitude) of the input signal (in my rig, from the theremin) is internally patched to control the amplitude of the internal VCO, presumably via an internal VCA. This means that the volume of the output signal follows the loudness of the input signal. Additionally, the input signal is modulating the frequency of the VCO, so the amount of modulation (and thus the timbre produced) is dependent on the momentary level of the input signal. It's this which gives the FreqBox it's real-time flexibility in this FM mode.

I hope this helps a bit...

Cheers,

Jim F.

BTW - I don't mean to put down the Yamaha FM synthesizers. I think they're great, classic instruments. I've owned a lot of various Yamaha models over the years, and still love my DX7, TX7s and FS1R

A Theremin's best friend is an Envelope follower.
If you have a Theremin without CV's, then you can generate CV's easily with the volume antenna. I did that for the longest time until I got mine Modded.

I posted an article about this in the theremin section of KnobTweak.

Eric

Remember, a key part of Yamaha's operators were the fantastic EGs they each had. The envelopes added so much to modulation, since at A, D, S, and R you could program both level and rates

Thanks for this thread . . . it has caused me to dig deeper into my MF-107.