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Adjusting Etherwave for Pitch Linearity

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Posted: 10/19/2012 2:16:53 AM
Jeff S
From: N.E. Ohio
Joined: 2/14/2005

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After a long respite, I've begun playing my Etherwave theremin once again.  I don't recall what is "normal", but I'm lucky to have 1-1/2 playable octaves at the most.  This is just not enough for playing many pieces.  When I hit the bottom, the notes get stretched so extremely that I have to move my hand a foot (30 cm) just to play a fourth or a fifth.

Is there any way to "fine tune" the Etherwave to improve the pitch linearity?  (Short of sending it to France, that is.)  I have a Big Briar model, serial number 3864.

Posted: 10/19/2012 7:44:46 AM
w0ttm
From: Small town Missouri on Rt 66
Joined: 2/27/2011

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The tune up procedure for the EM theremin ought to work.

That sounds like a huge degradation. There may be some parts that went south. If it was dropped or otherwise bashed about, I'd suspect inductor damage. A cracked core might let it work, just not well, or an impact event may have just misaligned it.

http://www.cs.nmsu.edu/~rth/EMTheremin.pdf

Posted: 10/19/2012 10:29:01 AM
Jeff S
From: N.E. Ohio
Joined: 2/14/2005

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Rest easy w0ttm...I can assure you it was not abused or knocked about.

I've adjusted my theremins before, but it's been a while and I thought I'd get some expert advice before trying it again.  Although, Thierry seems to have been strangely absent for quite some time now.

Posted: 10/19/2012 12:06:15 PM
Amethyste
From: In between the Pitch and Volume hand ~ New England
Joined: 12/17/2010

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Maybe he's been absent cause he has a backlog of theremins to fix and people are starting to get anxious because they have been waiting for a long time to start playing again....

 

Posted: 10/19/2012 7:32:30 PM
RS Theremin
From: 60 mi. N of San Diego CA
Joined: 2/15/2005

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Maybe he's been absent cause he does not like being bitten by the male Rottweiler that is running loose.

Posted: 10/20/2012 2:39:13 AM
Jeff S
From: N.E. Ohio
Joined: 2/14/2005

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Hmm...anyway...

Well, I tried giving my Etherwave a quick tuning and now I have at least two and a half playable octaves.  Much better!  Now, it almost sounds like I know what I'm doing!  LOL   I'll have to play around with it a little more to see if the linearity can be improved at all.

The volume response of my Etherwave is a bit "snappy" - it cut out much too fast and suddenly.  I noticed that it seemed better if I approached it from the side.  So, I loosened the loop and let the front edge drop almost towards the floor and tightened the top end.  Wow! What a difference!  Now it has a smooth and dynamic volume response I've only dreamed of!

Posted: 10/21/2012 10:25:28 PM
Thierry
From: Colmar, France
Joined: 12/31/2007

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You may smoothen the volume response by turning the volume knob counterclockwise. If that is not sufficient, you should slightly increase the frequency of the volume oscillator. This is done by adjusting L11. If it's the old model with the "normal" slug turn it 1/12 turn wise counterclockwise. If it's the newer variant with the hexagonal slug turn clockwise.

Close the cover after each tuning step, let the instrument warm up for a few minutes and turn the volume knob to its center (12 o'clock) position. You are done when you obtain maximum volume with your hand around 6"/15cm above the volume loop. Then check the operation of the volume knob without a hand near the volume loop by turning it slowly counterclockwise. The max volume should go down when you are around 9 O'clock. On the other side beyond 3 o'clock, the volume response should be snappy again. Then you are able to adjust it perfectly to the desired behavior within these positions.

Tuning the pitch side for best range and linearity has already been discussed in public here on TW. In one of the ESPE01 topics you will find a conversation between Thomas Grillo, Wilco Botermans and me, containing lots of practical hints from experienced "tuners" which give far better results than Moog's original tuning method.

@Christopher: thank you for the expression "male Rottweiler that is running loose"! Couldn't have found a better picture by myself.

Posted: 10/22/2012 2:02:42 AM
Jeff S
From: N.E. Ohio
Joined: 2/14/2005

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Thierry said, "In one of the ESPE01 topics you will find a conversation between Thomas Grillo, Wilco Botermans and me, containing lots of practical hints from experienced "tuners" which give far better results than Moog's original tuning method."

I'm afraid I'm not finding it.  The only reference to anything like that is this posting...

http://www.thereminworld.com/Forums/T/28482/espe01-installation-success

But, any detailed explanation was done in private.

Posted: 10/24/2012 2:56:43 AM
Jeff S
From: N.E. Ohio
Joined: 2/14/2005

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Well, I tweaked my Etherwave a bit more, and now I have three to three and a half very playable octaves and could play up to four if desired. Enough to suit my purpose. And, all without a frequency counter or oscilloscope.

This is a far cry from what it was just a week ago.  Never had I known the standard Etherwave could be this playable.  To be honest, I was rather disappointed with it since I bought it (used).  No longer!  Now, I can't wait to receive and install the ESPE01 module I've finally been able to purchase.  If it improves the timbre even a little bit, I'm going to be very happy.

I tried to adjust the volume response, but it did little than shift the response back and forth across the dial.  It didn't really alter the response, so I went back to tilting the loop, which I am very happy with.

Posted: 10/25/2012 7:34:01 AM
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