Problem with Theremax.

Well, i messed with the timbre knob and the ghost tone is there fully CW and CCW...

Hmmmm..., this is the point where I normally would put the Theremax on a table, the schematics left from it and my oscilloscope right from it...

I suppose that you have no oscilloscope... So there is still another way: Unsoldering temporarily some specific components in order to deactivate parts of the circuitry. This would also allow to trap the problem. But before we start with that, I would prefer that you turn L1 still a quarter turn counterclockwise (we'll retune the beast later). Normally you should now have no more pitch signal at all or only a very, very high tone. What does this have for an impact on the ghost tone? Is it higher, lower, Louder, the same or has it disappeared? Keep us updated, the story begins being interesting!

How long has your Theremax 'Aged'?
I had this same problem about 15 hours into my initial Theremax volume and pitch tuning. I got an overtone---annoying! I simply re-tuned the volume oscillator slug.
Good Luck!
teslatheremin

[i]"Well, i messed with the timbre knob and the ghost tone is there fully CW and CCW..."[/i]

Does the pitch of the "ghost tone" change as you do this?

"Does the pitch of the "ghost tone" change as you do this?"

Normally it can't since the pitch knob is like a balance knob between the filtered mixer output (near sine wave) and the same signal through a simple comparator (near square wave).

[i]"Does the pitch of the "ghost tone" change as you do this?"

Normally it can't since the pitch knob is like a balance knob between the filtered mixer output (near sine wave) and the same signal through a simple comparator (near square wave).
[/i]

Sorry - I misunderstood the knobs.. What I meant to ask was related to tuning.. If the tuning (reference oscillator frequency) knob is changed, does the pitch of the 'ghost' change?

Just fishing for clues really - The Tmax is a bit unusual in having a complete heterodyning stage (reference + variable oscillator + mixer) for both pitch and volume - rather than a variable oscillator into a bandpass filter for volume.. I am using full heterodyning on my Theremin's volume circuit, but set so that the lowest difference frequency is 40kHz.. I had ghost tone problems before I did this, due to leakage of tiny quantities of audio into the modulation path (VCA CV) beating with harmonics of the audio from the pitch mixer... This was all audio frequency, not RF signal modulation.. I was wondering if something similar might be happening in this case.

Looking at the schematic, it might be worth putting a capacitor (100nF to 1uf non polarised) across the Mute connector (this could be soldered onto a plug so that no messing with the circuit is needed) - this would attenuate any audio on the VCA CV .. 100n would give ~ 1ms latency and 1u ~10ms .. but it would be an easy test to perform and may give more clues.

Thank you all for the input! I won't have time to try anything for the next few days, but I'll try your suggestions and keep you all updated later this week!
Godspeed.

OK, I'm out of this game.

If I'm already ready to invest unpaid working time and to share my knowledge and experience, I think that I may at least expect that the one who asked for help follows the instructions systematically and gives precise feedback almost just in time (which normally should not have been a problem on a Sunday) in order to not unnecessarily protract the action and to abuse other's time.

But to say in such a case "Thank you for the hints, I'll try it out perhaps some beautiful day" is simply an impudence.

Hmm, not really sure what the problem is...I honestly won't have any time for the next couple days (trig test, b-day, etc). I'm pretty sure I followed all of your advice and gave you timely feedback with as much info that I could muster given my lack of electronics knowledge. I never said anything near, "Thank you for the hints, I'll try it out perhaps some beautiful day."

I just figured it would be more polite to tell everyone why I wouldn't be responding than to just seemingly ignore everyone until I can get around to working on it.
Thanks.

[i]"I just figured it would be more polite to tell everyone why I wouldn't be responding than to just seemingly ignore everyone until I can get around to working on it."[/i]

I agree with the above, Ethan.. It can be genuinely irritating if someone 'vanishes' mid conversation..

But this is the WWW - None of us knows what is going on in the life of the other persons we chat to - they may have died, for all we know! .. Likewise, we do not know what triggers OTT responses from others ..

I think a lot of what happens (and I am speaking about myself here) comes down to an inner conflict - A person who is passionate about a subject may find it difficult to accept that other people actually have a life outside that passion - We give up our time to help others, but are often unaware that there are many 'hidden' motivations for this 'sacrifice'... When we look at the time we spend, and what we 'achieve', it doesn't make sense - If we have a wife / partner who is not supportive, and makes a scathing remark whenever we are seen "wasting" our time on-line, things can sometimes spill over onto our postings.

I have gone OTT a few times for reasons similar to the above. Thierry spends a lot of time helping people here, and his recent contribution to the Theremin community by providing an elegant solution to the EW-Pro volume 'snappyness' has, I am sure, put him under a lot of pressure.

You have every right to set your own agenda for testing / reporting back.. Thierry has every right to leave this thread.. No one is in the "wrong" here.. But it is a shame - as with Thierry's knowledge of the Tmax some really interesting insights could have come from this thread, regardless of what the problem turns out to be, or who guesses the solution first.