Snatched an Etherwave Pro, have questions

Posted: 1/16/2021 7:23:30 PM

Joined: 1/16/2021

Hi everybody,

I have just joined and it’s my first post.

I was lucky to have purchased an Etherwave Pro today for a very reasonable price, aka a bargain.

This is my second theremin. I’ve been a proud owner of a Big Briar Etherwave for the last twenty years.

The E-Pro is gorgeous and it sounds amazing, better than I expected. There are a few issues though:

1. A tuning issue?

When I got home and turned it on for the first time the tuning was all over the place. I seemed to have fixed it by adjusting the Pitch knob but I noticed the following:

When I am all tuned up correctly with the whole scale in front of me and the lowest note on my shoulder - everything's normal. If I turn the pitch knob clockwise from this position, then the lowest note moves toward the antenna as it should but at some point another partial scale appears between me and the lowest note, with the high note on me, so the lowest note kind of sits in the middle.

Before turning it on I let it stand for a few hours (it’s -15C outside!), and when I have turned it on I let it warm up on standby for about 15 minutes before playing.

I will see how it behaves tomorrow, but does this sound like it should be retuned if the issue remains?

Also, is there a user manual available somewhere, and if not, could somebody please take a photograph of the page with the tuning instructions for me? I would really appreciate that.

2. The Timbre knob is missing.

Does anybody know of any existing knob replacement options? The person who sold me the instrument said it was similar to some of the knobs Mesa Boogie used for their amps, but I am skeptical. I will also try to contact Moog but I am not sure they still have these knobs lying around.

3. The volume antenna is kind of drooping a bit, i.e. it’s not exactly perpendicular to the body. Can this be fixed? The antenna itself looks good and straight and I’m not sure what makes it droop. Maybe it’s normal?

Thanks for your help!

Posted: 1/17/2021 11:12:15 PM

Joined: 1/16/2021

Okay, I found the screw that tightens up the volume antenna. 

Posted: 1/20/2021 12:44:17 AM

Joined: 5/25/2020

Hello and congratulations on the excellent score!

To answer your questions:
    1.  This is as expected.  When the zero beat is close to the pitch aerial, once you pass the zero beat moving away from the aerial, you will encounter a pitch field going the other way (low to high moving away).
    2.  I'm not sure what all of the Mesa knobs look like but I don't think they are identical.  Reaching out to Moog is the best option.
    3.  This one sounds fixed.

Again, congratulations!

Posted: 1/20/2021 6:02:52 PM

Joined: 1/16/2021

Thank you, Brandon! 
I have finally received the Etherwave Pro manual from Moog and it also confirms what you are saying.
Unfortunately they don't have any old stock of these knobs. I have been browsing the knob sites for hours and I can't seem to find the exact same type of knob.
I wonder if they were custom-made for Moog. This is really puzzling. I wish the previous person took better care of his theremin. Oh well...

Posted: 1/23/2021 4:07:37 AM

Joined: 10/24/2020

Making a knob is actually a fun project. There are tons of tutorials online for making radio replica knobs out of resin. The toughest bit of making an EWPro knob is the chrome finish...but even that can be done. 

The other option is to get two knobs that fit those particular pots. As a matter of fact, it might be nice to make a couple out of wood, to match the ones up top. You can probably find wooden knobs that fit, and you could sand them down to match. It could be really easy...just snub the knob onto a 1/4 shaft on a drill, and zzzzow!
Failing that, if you don't personally have a wood lathe, you might be able to find someone (try a Woodcraft store bulletin board!) who wants to make a set of knobs from scratch. 

I happen to work at a place where I have access to machine tools, so I would probably make one from brass and then have it plated. 

Good luck! If you decide to replace both knobs with something different, I might be interested in getting your lone knob off of you.

Posted: 1/23/2021 1:57:30 PM

From: Northern NJ, USA

Joined: 2/17/2012

The "Register" and "Timbre" knobs look the same, so rather than trying to find an exact duplicate, maybe just replace them both with the same thing? 

There are tons and tons of guitar knobs out there that look very close, if not the same.  Do a web image search of "chrome guitar knob".  I even see stacked dual concentric variants that look like what's on your E-Pro (other knobs).

Posted: 1/23/2021 3:47:26 PM

Joined: 1/16/2021

Thanks, guys! All fair advice and I was also considering getting two new knobs for Register and Timbre, or maybe order a replica from a workshop.

I have another question though.

Sometimes the timbre of my theremin gets a bit weird, more so in the middle register. It is like on overtone that feels a bit like a very fast bubbly tremolo, or like there are two sounds in there interfering with each other somehow, or maybe like a circular saw that just about digs into metal. I know it's a weird description but I've tried my best to express what I'm hearing.

I am not sure it's constant but sometimes it's noticeable. I've played for a couple of hours today and started noticing this again closer to the end of my playing session. Maybe it was always there, I am not sure.

I've tried using different power outlets and it didn't change anything. 

Could it just be normal and part of the instrument's character or something? Not sure but I have a feeling that the sound should be cleaner somehow.

What are your thoughts on this? Could it be some interference from something? I dunno, wi-fi? Note to self: try turning the Wi-Fi router off.

Edit: I have recorded a snippet of this sound and uploaded the audio file to SoundCloud. It's not a direct recording, I was just using my iPhone. Normally I play it through a mixing desk and studio monitors. On this recording the theremin is played through a guitar amp. I wanted to see if my mixing desk was a problem, but the trembling is still here when I play it through the guitar amp. It's most obvious in the lower register. There's also some background hum from the amp, please ignore it.

Edit2: Okay, I just found a thread at Moog Forums with someone having a similar issue with their Theremini. Moog support has responded that it was probably because of some electromagnetic interference. It's weird because my standard Etherwave does not have this issue, I checked today. They are different beasts of course. Will need to identify this culprit I guess.

Posted: 1/25/2021 12:45:11 PM

Joined: 1/16/2021

I spent a good part of the weekend trying to figure out what had been causing the interference. I turned off every electrical appliance in the room to no avail. Then I took the theremin to the kitchen and the problem disappeared. It is also fine if I use the theremin in my room but plug it in in the kitchen via an cable extender.

Funny thing: I thought that my standard Etherwave broke when I tested it to see if it had the same issue in this room. It went completely berzerk and the sounds were total Star Wars with no control whatsoever. Turns out my Pro was on at the time (on standby) and it's been causing this crazy interference. LOL

Posted: 1/25/2021 1:34:28 PM

From: Minnesota USA

Joined: 11/27/2015

You may have a problem with conducted emissions or ground noise on one phase of your house power.  If you want to investigate this go to your circuit breaker box and make a list of a few outlets in different rooms that are on each phase of the power (the left and right columns in the breaker box are different phases).  Next move around to a few of those outlets to see if there is a correlation between where the problem appears and which phase the outlets are on.

If you find that the problem outlets are pretty much limited to one phase (one column of circuit breakers) then you may have some electronic device that is introducing noise on that phase of power, and you can further isolate the problem by switching off breakers on that side of the box until the problem disappears.  I have found carrier-current devices (things like X10 modules used for remotely controlling lights and appliances) to be likely culprits.  Also consider light dimmers or LED lamps to be sources of noise that can be injected onto whichever phase of power they run on.

In some cases the breaker box may have a phase coupler installed that will couple noise from one phase onto the other, but since you have some outlets that are better for the theremin than others this would seem unlikely.

Posted: 2/23/2021 3:27:50 AM

From: Pittsburgh, Pennsylvania

Joined: 1/1/2011

Let me know if I can send pictures of any other pages. This manual is very basic and non technical.  I think I have a CD that came with it but I don't remember what's on it.

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