interested in theremin but not sure how easy it will be for my guitar amp

Posted: 5/18/2006 11:37:44 PM

Joined: 5/18/2006

Hi everybody.

I'm about to buy a theremin, specifically the moog etherwave standard. i was checking their "hot rodding" manual and it said something about needing to remove and replace a transistor (R33, 4.7k resistor, replace it with a 47k resistor).

OK, I get this, but I've never fiddled with "resistors" before. Most of the hot-rodding stuff is completely over my head. I've built computer boxes before, but I've never fiddled with chips, so this would be a new experience. It sounds like a minor adjustment, but

1) How hard is it to remove and install a resistor chip? (like do you need to do soldering?)


2) Where would I purchase a 47k resistor that could do the job? Is this a Radio Shack-type item, and fairly universal, or something really hard to find?

Yes, I could buy a theremin amp, but I'm strapped for cash, and I already have this guitar amp and a couple pedals, so it seemed like that would be the cheapest route.

I've also thought of using an old stereo receiver that is in disrepair.

Thanks for any advice !
Posted: 5/19/2006 12:02:34 AM

From: Kansas City, Mo.

Joined: 8/23/2005


The resistor is a standard radio shack part -- it is not a semi-conductor (chip) though, just a simple passive component.

If you are uncomfortable with modding your equipment, you can purchase an attenuating patch cord from radio shack -- it has the resistor built into it... you would hook the patch cord from your Theremin to your guitar amp.

I would be inclined to use the attenuating patch cord... that way if you wish to use your Theremin on another amp or mixing board that accepts line-level inputs, you can just use a regular patch cord and all will work. If you permanently install the resistor into your Theremin, then you will have too weak a signal to drive line-level inputs without excessive noise.
Posted: 5/19/2006 12:49:27 AM

Joined: 5/18/2006

Ah, I didn't know such a thing existed. Thanks!

That makes sense. No use modding the actual device if I eventually want to play it with a keyboard amp or something.
Posted: 5/19/2006 7:55:10 AM
Charlie D

From: England

Joined: 2/28/2005

You probably wont need to do the mod at all - most guitar amplifiers work excellently with the Etherwave without the need to pull apart the instrument. I still use a Crate amplifier with my theremin, and plan to upgrade to a 'nicer' amplifier pretty soon.
Posted: 5/22/2006 7:19:44 PM

Joined: 5/18/2006

I got my theremin! And an attenuating audio cord from Radio Shack. However, when I use the audio cord (with 1/4 adapters), I get no signal into the amp. However, if I plug my headphones directly into the theremin, I can get a sound, so I know it's working. And when I use a guitar patch cord between the theremin and guitar amp, I get a clear signal (and LOUD--TOO LOUD for all practical considerations. Even turning it down doesn't seem to get it to the level I need it). So are we talking a defective attenuating audio cord, or something else? Is there any way I can test the attenuating cord? I would look for another one but I only saw one brand available, and it was the one I got at Radio Shack (last one in stock).
Posted: 6/6/2006 3:52:54 AM

From: CT USA

Joined: 1/15/2006

This may be a stupid question on my part, but have you tried plugging in a regular cord to check how everything sounds? I would try that first...


Posted: 6/6/2006 3:55:07 AM

From: CT USA

Joined: 1/15/2006

Oops. Never mind...
Posted: 6/6/2006 8:54:10 AM

From: Jax, FL

Joined: 2/14/2005

godvomit, what kind of amp and pedals are you using?
Posted: 6/8/2006 11:16:03 AM

From: Kingston, NY

Joined: 2/13/2005

"godvomit" great name.
Did you find a resolution?
I'm still even lower tech. Run the theremin through a digiverb pedal and then to a decent powered speaker pair normally used for computers or PMDs. The signal seems low but servicable until my real amp comes.
Posted: 6/8/2006 2:47:25 PM

From: new haven ct.

Joined: 7/8/2005

I used all kinds of amps on all three of my theremins, each a different one, and never had an trouble with any off them. I'm currently using a small self contains PA system, and have the speakers on a stand.

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