New Solid State Keppinger Design Theremin

Posted: 12/17/2008 9:34:48 PM

From: Richmond Hill, Georgia

Joined: 9/18/2005

I will tell you that getting Keppinger No. 10 Gabriella to work AT ALL was an abject lesson in frustration, hair pulling, and if it weren't for Mark's encouragement, I would have tossed the two chassis in the bin/river.

He has this prototyped now and "mostly working", so it's passed the academic schematic stage. There was an earlier design approach, which I am not familiar with which was abandoned.
Posted: 12/17/2008 9:37:48 PM

From: Richmond Hill, Georgia

Joined: 9/18/2005

Also, the coils in the solid state version will likely be air wound types similar to the ones in the original vacuum tube model.
Posted: 12/18/2008 4:03:23 AM

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

I can confirm that they are air wound.

Also that the housing will be less than 16" wide by 12" deep.

And that it [i]may[/i] be available without a cabinet for those who want to build their own.
Posted: 12/18/2008 5:01:31 AM

From: Eastleigh, Hampshire, U.K. ................................... Fred Mundell. ................................... Electronics Engineer. (Primarily Analogue) .. CV Synths 1974-1980 .. Theremin developer 2007 to present .. soon to be Developing / Trading as . ...................................

Joined: 12/7/2007

"His design may finally work and comments should be made only when one has had the opportunity to play on it in order to approve or not its sound quality and playability."

Thierry - I do not see this as a "Mark bashing" thread at all, and what you say regarding his bravery in publishing the designs is absolutely true.. Mark has made some wonderful Theremins, and his reputation for supporting his products and his contribution to the Theremin community is impeccable..

I saw the publication of the schematics and the request for comments as an invitation to comment.. I did the same when I published what I thought was a brilliant idea (audio stroboscoping) which turned out to be a completely ill-concieved lemon! I am extremely grateful to those at the nameless place who pointed out my folly.. Yes, it is painful to have ones ideas shown to be wrong, and perhaps a bit more painful when this is done publicly (should I have emailed Mark privately? perhaps I should have..) but it is a lot less painful than spending time and money developing a lemon.

[And this design of Mark's is a lemon.]
>> EDIT by FredM 20 Dec 2008..
Mark assures me it is not a lemon! – Who knows, he may be right.. He has several years at least of designing and building Theremins.. I have been at it for 18 months and do not yet have a product on the market.

"He has this prototyped now and "mostly working", so it's passed the academic schematic stage."

When it comes to Theremins, "mostly working" is, in my expierience, the same as "under development" .. and it is not "passed the academic schematic stage." until it is FULLY working - Why? because the difference between a pile of "mostly working" circuits and a good playable instrument is as long as a piece of string.. and the modifications required to turn a "mostly working" system into a musical instrument can be a complete redesign.

If this was not the case, I would have had many "mostly working" Theremins and related products on the market months ago.

>> Following removed by FredM 20 Dec 2008..
Posted: 12/18/2008 6:43:56 AM

From: Richmond Hill, Georgia

Joined: 9/18/2005

Yes, I asked Mark about the antennas....

"...I was planning on going with the 'honking monster coils'. Don't you like
them? LOL!..."

I love big honking coils. They're pretty.

Posted: 12/18/2008 2:00:56 PM

From: Escondido, CA

Joined: 2/6/2008

Sorry if anyone thought this thread was rude or all nay-saying. I think it has been a very enlightening thread for all of us who have built, have "mostly built" or are contemplating building theremins "from scratch" (as opposed to just buying a kit from Moog, PAIA or B3).

We may have all heard it, but still have to be "hit in the head with a 2x4" to get the concept that it is the journey not the destination!
We have been sharing our discoveries along the way.

I am at the "mostly built" stage because of lack of time.

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