Keppinger Voice

Here is the "test bench voice" of the theremin. My undeducated, no musical
training opinion is that is sounds nice. Now, don't start critiquing the
"musical" selection. The sucker is here on my workbench, all laid out, naked
and bare to the world, wires dangling out everywhere, wrench attached to a
temporary coathanger antenna, pocketknife laying on top of the makeshift
expression loop, and lacking even a cabinet to clothe it in yet. I'm trying
my best not to knock the two big coils over that are sitting on top of the
bench.

You can hear high frequency harmonics in the background, I am pretty
positive from the volume oscillator. Its almost a 2 Mb file, so be warned
before you click on it. There may be some flutter modulation to the
thing...there is a ceiling fan going in the radio shack here to keep my
dainty self from sweating. Us spoiled deskbound engineers aren't allowed to
do that too often, or we melt.

There is obviously more work to do. Some of you may have been curious how it
sounds. I vented to Uncle Howie in a separate email off list. He told me he
was expecting it from me, as these things would try the patience of Job.

The file is located at

http://home.comcast.net/~ka4koe/keppinger5-08-22-2007.mp3

Hello,
I have been watching, and genuinely appreciating the work you have done creating that tube Theremin. But, the mp3 that you submitted seems to be corrupted or recorded badly. If you recorded your Theremin performance directly into a computer interface made for such a task, then you might be recording high frequencies that might be apparent to your ears thru a monitor speaker. And, perhaps more tuning of your tube Theremin project may be in order. Perhaps tube Theremins emit a high frequency element--- I may be ignorant. If so, I apologise.
But, now I present some of my experience .
I built a PAiA Thermin and thought all was well with the tuning because I was listening to it's tone thru a tube amp that I trusted. I recorded the same Theremin thru a computer interface and a high pitch whine tracked every pitch I created.
I retuned my ThereMax while listening thru a modern amplifier with extended frequency response , and was able to eradicate the high frequency annoyance.
You played well, but I would have enjoyed your performance much more without the attendent high freqeuncy 'Ghost'.
Good Luck!
teslatheremin

No, thats actually being produced by the volume oscillator. I am still having issues with the Hartley oscillators not being entirely stable and cutting out whenever they feel like it. The trick is to set the respective frequencies of the three oscillators so they don't interact. So what you are hearing is actually there.

Its definitely a work in progress...still troubleshooting the tone chassis. I'm waiting for my repro brass antennas to get done by a local machinist/architect who is also a work associate. It should work better when the coils are connected to something other than coat hanger wires.

Thanks for the compliment. I was just trying to record a sound sample and not a performance of any kind, though.

:)

PHILIP

Here is another sound file. The high frequency stuff is still in there,
but the volume response is a LOT better.

http://home.comcast.net/~ka4koe/keppinger-09-09-2007.mp3

Philzy

Sounds good to me--but my hearing drops off rapidly before 4000 Hz, so maybe I am hearing what it will sound like without the high frequency stuff!

Sounds quite alot better! You can really hear your Theremin's voice. I think I hear some distortion when the volume antennae is used, but that is something that will be eliminated with more tuning. I really enjoy watching and listening to your progress!

Good Luck!

teslatheremin