Pulling my hair out over volume control, Please Help!!

Hello theremin lovelies,
I am new to the world of theremin construction although this is not my first electronic kit assembly project.
so, I'm a newb in the theremin world but not completely unaware of circuitry and such.
Now that I have prefaced this, I am having a problem with the
Theremax Kit:

Problem:
tuning, I can tune with the clip lead in place, I can hear the pitch and adjust just fine but as soon as I remove the lead, I have no sound. I have L4 and L1 adjusted 1 turn in from full out and as I adjust L3, I get no volume, no sound at all.
I do, however hear a drop spike and drop (similar to the sound that the tuning produces) but higher pitch and quieter than the tuning sound.
There is no audio, but there is a hum. When I touch the volume antennae, the hum stops.
All of these things seem to be correct according to the instructions I'm following
except that I have no actual volue without the clip lead in place.
I have ordered some new parts (as I suspect the choke coil was damaged, and possibly the oscillator coil for L3)
but wondered if it is a User error more than a hardware issue.

If you can possibly help, I would appreciate it!!!!
thanks so much!
-Karin

Karin,

Don't pull your hair out! Just relax. Took me four evenings to troubleshoot my Theremax when first building it, and I am an experienced kit builder.

This procedure worked for me:

After tuning the pitch oscillators, before you remove the jumper, go ahead and turn the adjustment on L4 and you may find a place where L4 interacts with the pitch oscillator. Adjust L4 to a position where the pitch is stable as you move your hand to and from the volume antenna. Then, remove the jumper and tune L3 to achieve your desired volume response.


~~ explanation ~~

If the pitch and volume coils are tuned at or near the same frequency, then the variable frequency oscillator for volume will interact with the pitch circuitry. Try experimenting with different settings for L4 -- one turn may not necessarily work.


Good luck and keep us posted.

-- Kevin

Hi Kevin and All,
Thanks so much for your advice. I did a few things and have some level of volume control now. The suggestion to move L4 was very helpful. I also gave my board another good glance and discovered that L3 was not solidly attached. I double checked all of my solder points, now all 4 lugs are responsive.

I still have a problem with volume though. There is an audible squeal over the volume peaks and valleys. I don't think this is normal is it? I would really appreciate any advice on how to troubleshoot this problem.
I am also getting radio interference over the volume control. Got any suggestions as to why?
I got a new choke coil that I plan to install (as the choke coil was definitely damage during installation of the new antenna) and I'm wondering if a bad connection there could be a part of the radio and volume problems.
Thanks again for your help and support in my theremin endeavors!
-Karin

Hi,
I had the same problem. Further tuning is required.
I found that if I 'just' turned the L4 in/down a bit, (a dash?, a smidgen? I cannotbtellyou exactly, sorry), and retuned L3 the whine went away. Also, you should let the Theremax 'season, or 'age' alot longer than PAIA suggests, before you can expect a reliable tune--- especially on the pitch side of the oscillator.
Naguma

Hello,
I thought of something else that can make a big difference in trying to get a reliable tune on your Theremax. A wood case made of thick wood, 3/8" or greater can actually change the null-point of the pitch and volume oscillators. I have found through experience, that what makes for a great tune/ null-point reference, can really change once you "put the lid on it", so to speak.
Good Luck!
Naguma

Hi again,
Does the amplifier you are using to hear the Theremax have an Earth ground? Battery powered amps will let the Theremax whine until it receives an Earth ground!
If you insist using, or only have a battery powered amplifier, find or buy a 1/4" phono plug to 1/8" phono plug cable and insert the 1/4" end into the CV pitch output of the Theremax and the 1/8" end into the ground hole of a A.C. wall outlet or the same ground hole on a multi-tap A.C. strip. ONLY DO THIS AT YOUR OWN RISK! DO THIS ONLY IF YOU UNDERSTAND WHAT I HAVE JUST BEEN TALKING ABOUT! IF YOU LIVE I EUROPE I CANNOT HELP YOU!
If you do this with success, you will find that the pitch and volume antennes will track better.
I also tune my Theremax in reference to Earth ground.
The Theremax wants an Earth ground reference to operate at maximum playability.
teslatheremin AKA Naguma

What do you know ...another Ohioan!
Hey kids...why don't you think about adding yourselves to the Theremin World Frappr map? Here'a the link.

http://www.frappr.com/thereminworld

Good luck with your Theremax!

Oh... the thought of putting a metal object near an a/c outlet is frightening...

You can get a wrist strip from Radio Shack... and simply use yourself as a ground.

Give that a try!

I feel so welcome in theremin world! Yay!
So, I am using an old Marshall Guitar amp for now, not battery powered. I believe it is properly grounded.
The case is Acrylite, 3/8", though I made a mahogany case for it (also around 3/8") and I might re-install the theremin in it per your suggestion.
I've been tweeking the L4 and L3 lugs quite a bit and have actually found a pretty significant range of sound and volume qualities that are pleasant enough, or nearly right but find that I loose them rapidly.
Perhaps that is the "seasoning" that you mentioned.
I'll keep tweeking and fiddling with the little bugger until I find a sound that fits.
I am able to get a good sound with distinct notes with no radio interference but only at pretty low volume. I'll keep trying. :)
Anyway, this is all very useful information.
I can't thank you enough for your support and answers to my questions!!!
Yay! Team Theremin!
-karin

kkissinger,
I bow to your wisdom on this matter. :)