Let's Design and Build a (mostly) Digital Theremin!

Patriotic Minion

Vincent's (Mr_Dham's) minion preset voice is really fun to play with, reminds me somewhat of Tomita's random jabbering vowels: https://d-lev.com/audio/2023-10-08_patriotic_minion.mp3

New SW & Librarian

New D-Lev SW & Librarian available: https://d-lev.com/support.html

I didn't want to belabor those who have little interest, but spam filters are flagging the D-Lev web site as a source of malicious unsigned malware (!) so I'm not sure my bulk emails to the kit owners are getting through.  No good deed goes unpunished...

Trigger Happy

I've been working on a "Tibet" series of singing bowl presets.  I spent a day making a spreadsheet to automate the process, and thankfully it's been taking a lot of the drudgery and guesswork out of this sort of preset creation.

But one thing that's constantly eluded me is the reliable triggering of percussive voices which use high filter Q as the decay envelope - things like bells, triangles, bowls, glasses, etc.  For these types of presets I've often used a subsonic sawtooth waveform for periodic sharp attack, sometimes mixed with gated noise to provide some variability.  But many times I just want a single "bong" with a rapid volume hand movement, and the way I've been doing this is with mixed subsonic sine waves, in hopes that the AC amplitude at the point of hand "triggering" via velocity and a sharp volume knee will be sufficient.  This actually works pretty well, but the technique understandably sometimes produces a somewhat weaker attack than desired, so it can't be trusted 100% in a performance situation, where hope isn't a particularly good plan.

The solution clearly is to have some source of DC for the steep knee attack.  Looking over the synth architecture, the pitch preview module is currently used as a 4th oscillator in modes 0, 4, and 8.  Specifically, in these modes its output is mixed in at the input of the triple oscillator multi-mode filter.  There are 12 modes, 0 thru 11, and by simply expanding this by one to make the max 12, we can in this new mode set the preview oscillator to +1/2 full scale DC, this before the volume hand envelope modulation.  The preview output has its own tone control, which is a combined second order bass an treble in a single knob.  Turning up the bass in this DC situation leads too easily to overload and filter limit cycle oscillation, so we bypass the bass filter in mode 12, leaving the treble to conveniently handle overall brightness of the attack.  

Rather like the very recent addition of ring modulation, this modification took literally less than 10 lines of assembly code to implement, and it provides a very welcomed reliable trigger source for these "invisible bell" types of voices (of which there are probably too many already, but what the heck).

[EDIT] A sampling of 10 Tibetan singing bowl D-Lev presets: https://d-lev.com/audio/2023-10-29_tibet.mp3

Hornucopia

Been working on various horn presets including fog, train, and car.  

Train: https://d-lev.com/audio/2023-10-20_train2.mp3
Cars: https://d-lev.com/audio/2023-10-20_traffic_jam.mp3

D-Lev Halloween Submission

Quite possibly the most unspeakably evil sound known to humankind (leaf blowers): https://d-lev.com/audio/2023-10-26_tis_the_season.mp3

Antennas Source

I haven't seen these in person, but in pictures they look quite nice and professional (see the email link at the bottom of the page):

http://www.giorgionecordi.it/theremin/antenne-per-theremin/

Antennas SourceI haven't seen these in person, but in pictures they look quite nice and professional (see the email link at the bottom of the page):http://www.giorgionecordi.it/theremin/antenne-per-theremin/

Thank you! Very nice antennas. I've written email to Augusto, asking if I can order a few sets...

Carolina!

Carolina Eyck masterfully demonstrates various voices in the D-Lev kit:

https://www.youtube.com/watch?v=BnWEo-7r3tM

"Thank you! Very nice antennas. I've written email to Augusto, asking if I can order a few sets..."  - Buggins

You're welcome!  One of the kit builders used them and they look quite spiffy in the pix.

Chipping Away At Optimal Volume Response Mysteries

Today went from this:

  Drop => High Pass Filter & Velocity => Knee

To this:

  High Pass Filter (store HPF) => Drop => (recall HPF) Velocity => Knee

Which is a major improvement because the velocity sense is positioned before Drop, so Drop's low volume gain-down doesn't result in high velocities.  This, coupled with velocity sensing starting at -48dB, has eliminated the large false velocities and triggering associated with transitions out of the low volume region.

As with most things, pretty obvious in retrospect.

Am also auditioning a bi-modal high pass filter for velocity, 20Hz for attack and 80Hz for retreat, with the rationale that the faster retreat "re-arms" the attack faster.  On the minus side it also lowers the influence of that retreat by a factor of 4, though at these rates things are rather subtle, so I'm not sure how important it is.  It started out as an attempt to reduce wind-up, but I rather doubt that it has a significant influence over that.

The volume field response is really complicated!  My goal has been to make it as effortless and intuitive to play as possible.  Beyond pitch field linearity, volume field response is super important to get right - whatever that is, but purely linear it definitely ain't.