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Practical 
EtherWave Standard
Non-Hacking Adjustments & Enhancements


Purchase a finished EtherWave Standard board for $96, add my $50 modification and you will have a theremin better in design & sound than Clara Rockmore - That's Priceless

- Have the full range of classic theremin sound from beautiful flute to Clara to violin -

Hot Rodding the EtherWave Standard Info & Schematic 
Other tuning instructions found here

This webpage below is about things the everyday EWS owner should become comfortable with... as your local TV repair shop is not going to be of any service to you and will take your money anyway. They replace boards which you could do!

Never use black paint your EWS wood enclosure, the carbon can have terrible effects on performance!

If your EtherWave Standard has been in storage for several years you should buy a quality potentiometer cleaner like DeoxIT Fader Lube and spray each Pot to clean up the contact surfaces. This is the first area to go bad in an EWS due to environment and time, do not adjust any coils until you clean the Pots. Do Not Use WD40 on your Pots as this will gum them up and leave a film that traps dust over time.

Notice the wire loop around the base of the antenna: This 8" (20cm) wire trick looped around the antenna base is temporary and used when tuning with the wood cover is off. Remove the wire loop when the cover is placed back on, this avoids the need to drill holes for retuning.

The wire can also be a temporary fix when the Null Point is too close to the antenna, a tight pitch field. The wire pushes the Null point away from the antenna, so twist and snip a little shorter to move Null towards the antenna, a little longer to push Null away from the antenna.

Ignore my Agua Bella clamps next to the antenna, that's another webpage. The EWS can be much more, I am exploring how to get a natural new voice .mp3 using acoustics.  This could use some polish but it is still very interesting, what do you think? I say enough of that Jimmy Page puny whistle stuff. LOL

Visit My Using Acoustics with an EWS
.


Hot - EtherWave Audio Signal?  Use this inline Attenuator   $6
Drive any amplifier,  keyboard or guitar, effects, etc. You will need adaptors for the RCA ends.


.This $5 Bass Mod can be done without hacking the board!

This $5 trick at the left smoothes the EWS sound into something rich and beautiful. These clips are a bit to large but a good way to test different capacitor values. My choice is a 82pf capacitor solder tacked across the D4 diode.

For myself the authentic theremin sound is like this sample below. No puny whistle or phony digital synth sound buried in reverb, you are better off getting that from a keyboard.
.

Finding Clara's Voice mp3
$150 or 100 euro's to build, plans coming soon
Altermen 100% Mouser

 

The photo above left shows temporary clips holding either a 47pf or 100pf in place. Solder the cap you select from the top side of the board on each side of the diode. The 100pf gives the smoothest low end, maybe too smooth. I prefer a 82pf capacitor. This added cap also tames a Hot EWS Output.

Now about the 3M switch  You might use Radio Shack switch on-off-on and have three sound possibilities using two 100 pf capacitors.  Original, Mellooow and somewhere in the middle.

Radio Shack  < $5  Here is the budget EWS sound bella-pitch-mod.mp3  750k 100pf

Here is a nice photo by Dana (Sewerpipe) mounting his switch.

Nothing in this is critical other than physical stress on the diode, keep the added wire length short, less than 7" (175 mm). The switch could mount downward behind the Waveform control out the bottom of the wood box. Thread it through a snug drilled out hole. The Mod has no specific direction so connect it either way.


Have the EWS mounted on a Mic Stand or sitting on top of a cardboard box before making any adjustments. The sensitive volume loop and pitch antenna must be clear of surfaces and at least 5-feet from large metal objects. Set all front panel knobs to half way.

Tuning Your EtherWave Standard is something every Thereminist should become familiar. 

Avoid adjusting L5 if you do not have a frequency counter. This needs to remain tuned (~286khz) to match the antenna circuit.

A well tuned EtherWave can have excellent linearity and a good sound, not Clara Rockmore, that's another webpage.

Adjusting the Null Point Location: Have the Pitch knob set half way. To compensate when the wood cover is off of the EWS place the 8" white wire loop (see above photo) around the base of the antenna. Adjust L6 in the middle of the pc board (Not L5 on the right) to set the proper distance of the Null Point. 

L6  adjusts the Null Point distance to the Pitch Antenna by matching L5 (286khz) in frequency exactly. 

Remove the 8" white wire loop from the antenna after the wood cover is placed back on.


L11 is adjusted after all else is done for the proper Volume Control response. Remove C28 jumper, somewhere in the middle of the tuning range, you should hear the sound start to be audible, reach a maximum loudness, and then die off again. Turn the lug back to the point where the sound is loudest. Your hand approaching the volume loop should quiet the sound now.

To Bypass the Volume Loop control temporarily, place a jump wire (alligator clip lead) across (short) C28 for continuous sound.


Touching the test probe to tuned circuit sections directly might load down that circuit giving a false reading.

Have the folded over 8" white wire seen in the above photo on the antenna in place while the cover is off. 

Here are some general frequency test points, connect the black test lead to ground.
All measurements are with the EWS Control Panel facing you.

With the plastic part of the meter red probe held next to the pitch Antenna you should get about 286 kHz.
L5  Oscillator if working you will get about  286 kHz off the top side of  L12 with direct probe contact.
      
The meter indicated is sensitive enough to pick up the RF signal with the red probe two feet away from the pitch antenna.
L6  Oscillator if working you want around 286 kHz off the left side L13 with direct probe contact..
L11 Drape the red probe cord over the Volume Loop, no direct contact. You should measure about ~498 kHz.
       
Do not mistake a 286 kHz reading from the Pitch Field as the Volume ~496 kHz reading, hold the pitch antenna to disable it.

Using a frequency counter is best and Amazon has many. This $15 bargain Multimeter with 10 MHz counter works great. It arrived from China in 7 days by regular snail mail with free shipping to my home in California. It uses a single 9v battery not included.

It is at ~ 286 kHz that the factory tuned EWS develops the most linear pitch field on the later designs. The adjustable hex head on the L5, L6 & L11 is 5/64" (2mm) on latest models. 

Earlier EWS models use around 260 kHz for the pitch oscillator.

This meter can also work as a Pitch Tuner if you install your own Pitch Preview jack. Reach for 440 hz or any musical note frequency for an instant reading.


Most EWS owners don't have a counter? Using an AM Radio can work for minimal frequency verifying but not recommended.

An analog AM Radio placed next to the pitch antenna can be a useful tool to determine if the RF oscillators are working.

If you tune an Analog AM Radio to 858 kHz which is triple the 286 kHz fundamental freq you will hear a whistle or blank spot over the AM Radio. Lightly tapping your finger on the top Q1 the antenna side or Q3 the fixed pitch oscillator will shift the freq slightly which makes it easier to find as you tune the AM Radio to the right spot.

This is a quick test to see if the main oscillators are working when no sound is heard at the audio output jack. This is listening before the audio Op amp and the volume control section.

If you found the analog theremin whistle response over the analog radio you can verify with even better accuracy the theremin operating frequency by switching to a Digital AM Radio set to 860 kHz and see if you find the theremin response. 

Before adjusting anything you must determine if the Fixed and Antenna Pitch oscillators are at already at ~ 286 kHz. If it is do not touch L5 which is the coil closest to the antenna, this is tuned to the frequency of the antenna circuit.

Only adjust L6 in the center of the board, to set the proper Null distance with the pitch knob set halfway. 

Turning L6 CCW  raises the RF frequency along with the audio frequency, only do 1/4 turn adjustments without every getting out of the range so you always hear heterodyning tone over the radio.

The digital radio will not demonstrate any noticeable theremin signal or audio sound unless heterodyning is occurring, this is the down side to using a digital radio but it will give a more accurate frequency reading than an analog AM Radio. Heterodyning is heard when L5 & L6 are approximately the same frequency.

The digital radio window is 10 kHz wide, if you don't have a frequency counter you want to tune L6 to move the operating freq to the bottom edge of the detected signal at 860 kHz on the digital radio display.

The ideal frequency for the EWS is to adjust L5 & L6 to about 286 kHz which can be listened to at 858 frequency harmonic on the digital AM Radio display.

L11 is adjusted to get the proper volume response "after" L5 & L6 are properly set to your liking. Somewhere in the middle of L11 you should hear the sound start to be audible, reach a maximum loudness, and then die off again. Turn the lug back to the point where the sound is loudest. Your hand approaching the volume loop should now quiet the sound.

If the pitch oscillator stalls out, (stops working) have the Pitch Tuning Pot set to 1/2 way, then turn L5, which is closer to the antenna slightly (1/4 turn) clockwise and see if the oscillator runs reliably, then readjust L6 to return the Null Point setting. L11 may then need another tweak

Finish the fine tuning of the antenna circuit by bending the connecting wire more or less, away from the grounded foil. This changes the static capacitance ever so slightly.  Bending it towards the foil normally spreads the inner field out a bit in the higher octaves. Experiment with bending it slightly, you may not notice any change. 0-:


One source of the EWS tuning tool is the "Trituner" and it can be ordered directly on Coilcraft's website  Thierry

http://www.coilcraft.com/ tools.cfm

This tuning tool is a 5/64" (2mm) hex head and a must have if you lost the one that came with your instrument.  

Visit:    Visit Using Acoustics with an EWS 

Did you know Lev Sergeyevich Termen was a Professor of Physics at Moscow State University (Department of Acoustics) developing his inventions and supervising graduate students.