There is currently a discussion on the Csound mailing list about how to emulate a theremin waveform. I put together this chart that displays the output from the Big Briar Etherwave with various settings. As some of you already know, Big Briar is Moog.
Hi.
The waveforms above are for an older model etherwave.
The current revision has waveforms like this…
http://www.flickr.com/photo_zoom.gne?id=2199492524&size=o
It is worth noting that theremin waveforms vary with pitch and volume – these were taken with a mid-range pitch and volume.
Also, if you look at hte block diagram of the etherwave Pro (recently discontinued, but a theremin with an excellent set of timbres) you will see it generates pitch and volume CVs to control the circuitry that modifies the waveform.
http://moogmusic.com/manuals/EwavePro-web.pdf
Finally, most emulations fall down by giving the sound an unvarying vibrato. Not that theremin vibrato is generated by hand, so it is irregular and variable.
I hope this helps with your discussion. A good theremin emulator is something worth working for. I have mentioned your blog on the thereminworld forum and levnet mailing list in the hope it will attract someone with actual expertise in theremin waveforms. :-)
Posting to Theremin World mentioned in my previous comment here…
http://www.thereminworld.com/forum.asp?F=1&T=3104
@GordonCharlton
I have to admit I put this chart together kinda quickly, and did leave out some important variables. I’m going to have to do more recordings over the weekend. Thanks for the info, as every little bit helps, and you’ve provided more than just a little.
You’re welcome. The feedback I have had from a very talented thereminist (sorry, private mailing list, so no names) is that the timbre is easy compared to emulating the playing of a thereminist.
As I said, vibrato is probably the main thing – if your synth has a couple of mod wheels I’d have them control the speed and extent of the vibrato. Also consider the waveform used to modulate the pitch – a fast, squarewavey vibrato will affect the timbre via fm synthesis more than a sinewavey modulation, for instance.
Secondly – there is no perfect intonation on the theremin – good players can find a note accurate to the limit of their ability to resolve pitch, but they’ll always be a few cents off, and that’s an important feature – add a little random function for that. (Preferably the pitch should be good enough that the audience won’t hear it as overly flat or sharp, but there are a lot of weak theremin players around. See youTube for plenty of examples. :-)
Thirdly, sliding between notes – thereminists call it glissing – sometimes you want to play the gliss out loud, sometimes quietly, sometimes not at all. My thought would be to assign the relative volume of the gliss to a pedal.
If you can incorporate those you’ll already be miles ahead of any other synthesised theremin.
Once again, thanks for the insight. And I agree that emulating a thereminist is key to truly pulling it off. Implementing your suggestions
should be fairly straightforward with Csound. Though I do want to point out that instead of playing this theoretical in real-time, I plan on scripting the performance. Blasphemy, I know. :)
Based on your suggestions, I had a few more thoughts.
Is it more likely that a the pitch will sharp or flat based on these factors: register, direction from previous note, interval, the experience of the player, the supporting harmony.
How fast can a player move between different intervals? And how accurate.
How often does a player miss the note they are reaching for, and how do they correct it during the performance.
I’m not looking for a definitive answer as much as trying to define as many micro variables as possible when designing my theremin/thereminist instrument. Many of these can easily be implemented using tracking curves, simple logic and controlled randomness. Will it sound human? Won’t know until after some trial and error.
Hi again.
I think you might find this useful – http://kevinkissinger.com/videos.shtml – click on “Jumps on the Theremin” which demonstrates the aerial fingering technique used (with variations) by classical thereminists – knowing the moves will give you some idea of kind of speeds and accuracies involved.
Certainly large intervals are more tricky than small ones. The top players seldom hit a bum note, and never in a recording studio where they can do retakes. The first note of a phrase is the danger zone, as you are finding it blind – not moving from another note – finding the first note is called “pitch fishing” and is often perceptible to people with good ears. For this reason thereminists stand with their head very close to the speaker, so they can find it at volume levels not perceptible to the audience, or use a “pitch preview” – an earpiece that plays the current pitch, even if the instrument is silent.
As for speed, the best players can move fast enough to affect the timbre – fm synthesis adds harmonics, spreading the energy of the note over more frequencies and causing an apparent drop in volume during moves.
How do they correct pitch in performance? Audio feedback. As a cyclist learns to keep balance automatically, so a thereminist develops hand/ear coordination, circumnavigating conscious perception and correcting pitch faster than the speed of thought.
Certainly supporting harmonies help. Without them – playing a cappella – a player with good relative pitch perception faces the dead-reckoning problem – a series of imperceptible errors accumulating over time.
Listening to a few top players might be a good idea. I suggest Clara Rockmore – very sentimental by today’s standards, with a big vibrato, but could hit notes like no-one since, and amongst many players the sound of her theremin is the holy grail of theremin timbres. Peter Pringle, Carolina Eyck – both exemplars of precision playing, and Lydia Kavina – held by many to be the best living player, uses a theremin with a very pure sine-wave-like tone. Also, for that classic 1950s sci-fi sound, Dr Samuel Hoffman.