Claravox Centennial- known issues, bugs and quirks

I can't hear the ghost tones at all; you are welcome to take that as an indictment of my pitch recognition aptitude. I made a video playing some tones on Claravox #21 that may be of use to others who are interested in this though:

https://drive.google.com/file/d/1Pqfi--DQOOai1ivJXAv_2BfH6EARrjpH/view?usp=sharing

Several different timbres, starting with modern mode ending in traditional mode.. This is recorded directly from the theremin through an audio interface, it's not going through anything else. Probably best to download the file rather than playing it through whatever processing Google Drive is doing. Apparently I'm not going fully to zero volume in between notes sometimes; I think my mixer (or maybe speaker) is filtering out the very low sound somehow but it's coming through here...

bendra, is that Traditional mode you're playing?

bendra, is that Traditional mode you're playing?

Both. Starts in modern mode, you can see me retune for traditional mode

"Both. Starts in modern mode, you can see me retune for traditional mode"  - bendra

Ah, around 2:00 to the end is Traditional mode then?

Looks* clean as a whistle to me, no traveling hump in the spectral view.  Is it my imagination, or does the pitch tend to go flat as you increase the volume?

I extracted the audio: [MP3]

*I used to catch hell on Piano World for saying this, some loathed my spectral analysis ("If you can't hear it it ain't important!").

My tuner thinks I'm more-or-less on key. For a better answer I'll defer to someone with a better sense of pitch

Wow, I just listened to the video w/ Greg Blanc on my iPad with studio headphones and I can hear the ghost frequency! I feel somehow redeemed, don't know why.

I can't tell if Greg is playing the prototype he got in 2020 and not a production model in this videos. If it really made in recent weeks it would suggest not, but it's one more potential variable.

Thanks Bendra for providing more samples and Dewster for doing some investigative work!

Seeing the video of the lower frequency hump moving helped a lot (initially didnt realize it was a video until I went back and read the post a bit better). Its a lot more dramatic than I had initially thought considering I cant hear it very well (though seeing the hump did help my ears catch it a bit better. Using the eq in vlc player to lower the mids and highs while boosting the bass made it way more apparent too).

I'm still not entirely convinced the Claravox is at fault because I dont trust youtube though. Digital aliasing is affected by a lot. Volume, vibrato, sample rate, etc, and youtube could be messing with the audio poorly. It could one of those things where it technically happens, but at an imperceptibly low level (dewster found Bendra's samples to be clean) and the issue is just getting amplified when the audio gets passed to youtube. Though if people are hearing it in person with a theremin hooked directly up to an amp or pa system or whatever then thats another story. However ContraDude says he can't hear it in person on his...

I wonder how the spectra graph looks if one controls the Claravox through midi instead of trying to play it...

"Seeing the video of the lower frequency hump moving helped a lot (initially didnt realize it was a video until I went back and read the post a bit better). Its a lot more dramatic than I had initially thought considering I cant hear it very well (though seeing the hump did help my ears catch it a bit better."  - Mennenth

Using your eyes to direct your ears is a powerful thing.  Though it can misdirect as well (e.g. Foley "artists" in film).

"I'm still not entirely convinced the Claravox is at fault because I dont trust youtube though. Digital aliasing is affected by a lot. Volume, vibrato, sample rate, etc, and youtube could be messing with the audio poorly."

I know what you mean.  I have a fairly popular Logitech webcam, and the Windows audio driver sets the maximum sample rate at 30kHz, so I can't use it to record anything much beyond a sine wave without it aliasing all over the place.  Had high hopes for it re. Theremin videos.  Operating system audio paths are always a hot mess.

"It could one of those things where it technically happens, but at an imperceptibly low level (dewster found Bendra's samples to be clean) and the issue is just getting amplified when the audio gets passed to youtube. Though if people are hearing it in person with a theremin hooked directly up to an amp or pa system or whatever then thats another story. However ContraDude says he can't hear it in person on his..."

With the volume modulation of frequency going on, my money would be on it actually happening in the Claravox.  But it maybe only happens when you hit on some special combination of pitch and volume and local oscillator frequencies, causing a secondary pitch heterodyne from the volume oscillator?  I dunno.  Analog Theremin designers would have better intuition here.

"I wonder how the spectra graph looks if one controls the Claravox through midi instead of trying to play it..."

I would guess MIDI in can only control the Modern mode synth?  If so, I can't imagine how there would be a traveling hump in that.  Then again, the Cvox hardware and software seem to be somewhat half-baked.

[EDIT] More Claravox humping video: [MP4]

 
bendra wrote: “Wow, I just listened to the video w/ Greg Blanc on my iPad with studio headphones and I can hear the ghost frequency! I feel somehow redeemed, don't know why.”

Me too! 😀

Got mine today.

Hooked it up to my focusrite 2i2 interface, opened up Reaper, loaded the Voxengo SPAN vst (a spectrum analyzer) and messed around a bit. I'm not seeing any ghost pitches controlled by the volume antenna bellow the fundamental.

I will continue to monitor Reaper, especially when changing settings, in case I've missed anything.