I’ve been considering getting a theremin for some time now.
I’m particularly interested in being able to get a pure sine output, in addition to any coloration with harmonics. I’ve been playing a lot with signal generators to create dense tone clusters with complex beating patterns during deep listening excerises. I would like to be able to layer a more dynamic line on top of the tone clusters without being limited to the interface of a piece of test gear; a theremin seemed perfect in every regard.
I had always assumed that a theremin would naturally be able to output a pure sine tone, but reading the manual etc. on the Etherwave left me uncertain – is it possible to use the brightness/waveform etc. controls to get a completely unmodulated sine output?
A truly pure sine waveform is important for the specific things I’m doing these days – I know it’s not necessarily what most people would want most of the time.
So my question is, is this possible with a stock Etherwave?
If not, any pointers or suggestions would be very much appreciated!
My experience is mostly in modular synths. The one thing I know is, while it’s not astronomically expensive, it does cost extra money to output sine waves and generally even more money to produce ones free of audible harmonics. If you look at “affordable” analog synths you will find a few but not that many with sine waves. The main factor is cost versus how many people have to have them.
As an aside, the waveshapes on analog synths are more often than not far from mathmatically perfect in shape, but as I’m sure you know, imperfections in sine waves really stand out. I can hear harmonics on a lot of sine wave outputs out there. So I’m just bringing up that depending how critical you are you might be offered sine waves that have audible harmonics (a good example is the basic Doepfer VCO is obvious harmonics, the expensive VCO is better though). Not surprisingly Serge offers a waveshaper that shapes saw waves into sines. The amount is voltage controlled and of course it’s expensive.
It might not help you, but a trick to get some very pure analog sine waves is to use a self oscillating VCF as a sound source.
If anyone cares to know, there is a reason you don’t see many sine waves on analog oscillators.
Its not really difficult to create a sine wave oscillator, if fact, its very simple. Its easy to do tri/square OR sine, but it gets a bit more complicated when you want to do all three. Most triangle/square wave oscillators are contained in the same circuit (very simple example HERE). That is why you usually see triangles and squares paired up on gear. The sine wave is achieved by a waveshaping circuit that takes the triangle and makes it into a sine (regardless of frequency).
You don’t see sines on a lot of synths because you can easily get a sine by filtering the triangle or using resonance as an oscillator. Filtering the triangle will not give you a true sine, though, because the frequency of the tri wave is changing as you play different notes. Close enough for most audio purposes, though. By using having a tri instead of a sine, you are allowing the user more possibilities.
I think there is another reason for a lack of audio sine waves…they’re harmonically boring. Dull. Yuck. They bore the ear. The more complex the waveform, the more interesting it is. While it is true that a few rare additive synths used sine dozens of sine waves to create interesting waves, the sine wave by itself is like lisenting to a radio or TV alert signal.
Where sine waves are valuable is for subaudible controls. There, they have a much different effect than a triangle, ramp, etc. Some cheap old analogs used triangle waves to control EGs, Filters, etc., and although they had their own charm, they weren’t the same as a sine wave.
Comment on how ‘interesting’ sines are to listen to…
I generally agree that in isolation a pure sine is not particularly interesting to listen to (though compositionally they have their uses)…
…that said my interest in them (and in particular in trying to find out if I can get one out of an Etherwave or any other commonly available theremin) is that a cluster of densely organized sine tones can (YMMV) be deeply hypnotic.
You can produce very interesting (not really conventionally musical, but, er, aurally fascinating and not necessarily disagreeable) relationships with five or six pure sine tones – where it really seems to get interesting is when you use clusters of three slightly detuned frequencies to produce complex beats centered on one tone – AND then layer stacks of these “triplets” to create “triads” (diatonic or not) etc.. using five, six, nine tones…
The beating frequencies between the main tones themselves can be harmonized in contrast to or on top of the primary harmonies, which can create some very subtle relationships and really enlighten the ear about, say, just intonation.
Beyond that though I’ve been playing with very slowly moving a single tone on top of such densities – because as it picks out “islands” of visceral harmony it illuminates all sorts of potential relationships between all the other frequencies. For me this is the most interesting and revealing ear training excercise I’ve had in a long time.
But, it really does work best with pure tones, where the additional complexity (one would normally say “interest”) of the harmonics doesn’t obscure the primary relationships I’m trying to hear and learn about…!
There are a few type of synthesis that rely only on sine waves.
You should look into FM synthesis. The Yamaha DX7 was based on the idea of modulating sine waves with other sine waves. Yes, it can sounds incredibly cheesy, but you can get some really unique tones out of it.
Additive synthesis is based on the idea of adding up waves (usually sine). The Hammond organ was based on this idea.
Or maybe you should look into getting a simple analog modular synth with a bunch of sine wave oscillators. That would be pretty neat.
I remember the the software synth Reaktor had a bunch of cool additive and FM synthesis tools. If you really want to get into hardcore sound design, check out the demo.
Thanks for the pointers, but I’m actually set with the exception of a theremin that can put out pure sine tones.
I have a collection of test signal generators; you can pick up vintage ones cheap on eBay with patience (including tube gear) ~ they usually put out sine/square waves in a better than audible range. I also have modern versions – Rolls makes a great compact analog test generator that I love!
The only thing I’m looking for is a theremin or similar instrument that would allow much more gestural free input for a single line; something more expressive and instant than a knob/wheel/ribbon input.
I could break down and use a laptop with a touchpad etc etc. of course but when the rest of the gear is pure analog signal chain that’s pretty unappealing on several fronts.
The etherwave pro has a CV output so you could drive something else with a pitch CV input, though if what’s being driven doesn’t have a CV level input you would need a VCA.
Also Doepfer makes theremin-like CV controller module for pretty cheap though it would need a housing and power. I have two, you are not talking about a high end theremin but they are incredibly useful to create control voltages and configuring say 1 or 3+ of them is no problem.
here’s a moogcentric and somewhat expensive solution:
get two mf101 lowpass filters. tune the etherwave so that it makes an audible pitch whenever you are within its range. now run the output of the etherwave into one of the mf101 filters, and patch the ‘env. out’ on the back of this 101 into the ‘cutoff in’ jack on the second 101. plug the output of the second 101 into your amp. boost the second 101’s resonance up to self-oscillation. your etherwave’s volume antenna now controls the frequency of a pure sine wave…if you want to control volume of this sine wave, run one of those cheepo plastic moog expression pedals into ‘res. in’ or ‘mix in’ on the second 101.
[two 101s and an expression pedal aren’t cheap, but i betcha there are a couple of people in your neck of the woods who would briefly loan you a 101 for an experiment or performance. ]
if you apply full keyboard tracking to the filter (so that it responds chromatically) the freq of the filter will change along with the freq of the sine, if you have the cutoff freq really low then you should get a pure sine
also you could get an etherwave pro, 2 CP-251s and 3 MF-101s
plug as follows
theremin pitch CV out to 4-way multi of first cp 251
three outputs of 4-way multi into cutoff ins of each MF-101
theremin volume CV out to 4-way multi of second cp 251
three outputs of 4-way multi into mix ins of each MF-101
crank the resonance, detune the filters and you’ve got yourself something crazy, also you plug the theremin outs into the cp mixer before the multi, so you can add all the other goodies like S/H or noise modulation
or you could use the input mixer after the mulit so that only one filter channel gets mangled
this setup would cost a lot but it would be very cool! and you could use it for countless other things in different configurations!
