External In-line box to convert line level to guitar level?

Posted: 12/4/2010 11:55:08 AM

From: Florida

Joined: 11/15/2010


I just started playing theremin, and I would like to be able to play through my Digitech GSP-2101 guitar effects processor.

I'm not really very handy with a soldering iron, so I'm hesitant to modify the theremin to reduce its output level (as described in the hot-rodding manual). I would probably end up damaging the board or something.

Would it be possible to build an external circuit into a small project box with 1/4" jacks on it, and just put that inline between the theremin and my guitar rack?

Is there a schematic somewhere for something like what I'm talking about?

I'm not all that experienced with electronics, but I could probably put together something simple. I've built a couple of projects from Radio Shack project books. Anything more complex than that would be over my head.

Does this sound workable? Thanks.
Posted: 12/4/2010 2:35:49 PM

From: Florida

Joined: 11/15/2010

I don't know why I didn't think of this before, but my 2101 has an effects loop on it. I should be able to plug the theremin into the effects return, since that should be at line level. That would bypass the guitar preamp but let me use all of the digital effects.

But if anyone has any ideas about my original question, I would still be interested in hearing them. If I could step my theremin down to guitar level, then I could use the tube preamp section of my processor also. That might sound kind of cool.
Posted: 12/4/2010 5:57:31 PM

From: Colmar, France

Joined: 12/31/2007

You may buy a simple volume pedal and insert it between the theremin and the guitar effect processor.
(Recommendation buy Gordon Charlton aka BeatFrequency)

Or you learn first playing the theremin so well that you don't need electronic effects... ;-)
(Recommendation in the spirit of Clara Rockmore)
Posted: 12/4/2010 7:44:13 PM
Jeff S

From: N.E. Ohio

Joined: 2/14/2005

Here are some more options...

RS Attenuating Cable (http://www.radioshack.com/product/index.jsp?productId=2103841)

-40 dB attenuating cable schematic (http://www.sounddevices.com/notes/general/xl40-schematic/)

-15 dB attenuating cable schematic (http://www.sounddevices.com/products/xl15master.htm)

The schematics might not be worth much since they are for a balanced output but interesting to know anyway.

If I were you, I'd find someone familiar with a soldering iron and modify it with both resistors and a SPDT switch to give you the choice of high and low output like many vintage keyboards.
Posted: 12/6/2010 9:19:23 PM

From: Florida

Joined: 11/15/2010

Thanks for the feedback. It sounds like there are multiple good options.

I think that the best one sounds like actually modifying the theremin itself (with the switch). I've done enough soldering that I could probably pull it off, but I don't want to chance it.

I'll probably either find someone who can modify it for me or maybe just go with the volume pedal.

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