Possible EW Modification board - *continuation part 2*

Sorry Eitherspiel.. I have a lot of shit on my mind at the moment, I should not have been so gruff!

[i]"What if you could somehow replace the transistors in the EW with tubes (a voltage nightmare, I am sure). Would the sound be much more like the RCA?"[/i]

The things which mainly affect to waveshape from the EW oscillators is the oscillator synchronisation.. IOf the valve oscillators synced to the same degree (which they need to because of the way low end linearity is achieved from the pitch antenna) then I dont think valve oscillators on the EW would make much difference.

Replace the VCA / Distortion stage with a valve circuit, and that would be a different matter - and an entirely different instrument.. even if the original transistor oscillators remain unchanged.

BUT -

To get a true 30's 'complete' Theremin sound, you would need to get rid of a LOT more harmonics at the top end than the EW does with its present design, and you would need to make the sound actually heard from the Theremin A LOT more sinuosoidal than the present EW design..

Regarding your edit about speakers from the Thirties, I agree fully. I've been chasing better tone through single 8" or 12" speakers lately. I put a little info about what I've been doing on the General Blasphemy (http://www.thereminworld.com/forum.asp?cmd=p&T=4138&F=3) post.

I didn't fully think about it before you mentioned it but could really detailed, full range speakers be part of the problem some people have with the E-wave tone? I know I hate tweeters with my Etherwave but I still like some buzz. It just seems that tweeters are either really shrill or just allow way too much buzz through.

Could a combination of box with sine wave mixing and a speaker with an adjustable high end allow a wider range of tones or would that be redundent, achieving the same end through two different means?

oops.. got the threads muddled..
Due to site being down some postings seem to have got lost - this should be on the 'blasphemy' thread..

This is a reply to postings here (http://www.thereminworld.com/forum.asp?cmd=p&T=4138&F=3) and the above:

[i]"Regarding your edit about speakers from the Thirties, I agree fully. I've been chasing better tone through single 8" or 12" speakers lately...

Could a combination of box with sine wave mixing and a speaker with an adjustable high end allow a wider range of tones or would that be redundent, achieving the same end through two different means? ..

I find if I run my Etherwave through my full range speakers with tweeters it sounds horrible. Way too much buzz in the high end. But run through a good single 8" or 12", mostly full range speaker, the sound is much better. So far I've only tried a few Eminence and a few Jensens. The Jensens are MUCH better... " - Dae23 [/i]

The first thing I want to say is this.. From the many emails I have had since my recent comments, a clear fact has emerged - There are those who love the EW tone as it is, played through modern equipment, and Hi-Fi speakers..

There are those who strongly dislike the EW tone played through modern equipment, and Hi-Fi speakers.. Even with the waveform set to its most mellow..

The majority neither particularly like or dislike the tone - They rightly proclaim that without The EW there would probably be no viable low cost Theremins available today - That without having brought this Theremin onto the market, other manafacturers would probably never have thought about producing Theremins, and Theremins would never have become so popular and available at reasonable cost.. These people declare that "Without the Moog EW Standard I would never have played a Theremin" - And I think they are right!

Anything I have said, and anything I say, must be with the above kept clearly in mind - The EW is THE Theremin "of the people" - It is the first instrument which TRULY brought Lev's dream of an affordable instrument, into reality.. Without Bob Moog's efforts in this field, I highly doubt that we would be chatting on TW.

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I believe that, even if one was to emulate a RCA output waveform perfectly with another design, it will NOT sound the same as an RCA did in the 30's.. and that to get the same "RCA" sound through modern amplifiers / speakers, one would need to design an instrument with output harmonics which are MUCH lower than the harmonics seen on the output waveform of an RCA.

To do the job as precisely as possible, one would need to get a complete original RCA setup (amp, speakers etc) and analyse the sound coming from this, and then produce an instrument to match this sound when played through a modern system.

The above is NOT what I am trying to do with this 'box' idea.. The 'box' is simply a way to achieve mellower (more sinelike) tones from a slightly modified (one connector added) EW Standard, for those who prefer a mellower tone - The original EW tone in this latest version of the idea would remain unaffected.

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[i]"Could a combination of box with sine wave mixing and a speaker with an adjustable high end allow a wider range of tones or would that be redundent, achieving the same end through two different means? .." - dae32 [/i]

The basic idea of the box is the attenuation of high(er) frequency harmonics - And there are many ways of doing this.. including modification of speakers etc..

None of this is simple.. Design of speakers / cabinets and the effect of resonant ports, posiotion of the speaker from the wall, size of room, nature of furniture etc all affect the eventual shape of the 'sonic spectrum' - So yes, changing the speakers and amplifier responses WILL change what you hear..

The main effects will be heard at the high frequency end - (and if the speaker cannot handle bass, at the low freq

If, for any reason, TW goes down for an extended period - or people are not able to communicate on this project..

I have a (presently empty) page on my website where the project can continue while TW is down.. and also (more important) where links can be placed and schematics etc pasted..

The 'home page' for this project is here (http://www.therasynth.com/html/ewtone.html)..

this is:
[b]http://www.therasynth.com
/html/ewtone.html[/b] .. Please note this for reference

If you wish to communicate technical ideas / questions, and are not able to do so here, please email me fred[at]fundes[dot]co[dot[uk] with EWTONE in the subject line.

Any EWTONE email could be pasted on the above website.

I DO NOT want to steal any trafic - this is just a provision so that IF anything prevents continuation here, there is an emergency temporary route - particularly if people are actually building things and need support..

I want this project to remain a TW project, and for what ever 'box' comes out of it to be a TW box!

Or you could get yourself a facebook account. There's a few name's you'd recognise there. But not for the next three weeks. OK? Far too distracting.

Not facebook.. I have enough trouble getting my head 'round Myspace.. It would take me 3 weeks just to work out how to do facebook..

God - 3 weeks... Looks swine flu has struck one of the teens - but it is quite mild.. Hopefully its really just a cold..

Anyway - I dont expect we will have got to actually building this box until September - more about getting ideas at this stage.

Which brings me back to topic..

Anyone have expierience with designing compandors? I am looking at the SA571 and SA572 parts at the moment, as they are cheap (<£5) and available in DIL.. The alternatives I have found are all SMD..

Alternatively, (the way I have done it before), using opamp for rectification / integration and having a seperate good VCA (a THATS or similar) which is more complex and costly.. I think doing it this way I would only need one VCA - But the SA571 and SA572 have 2 compandors, so one could be used as a VCA..

I would be interested in input from anyone with any expierience of signal compression and expansion in high quality audio.

to be continued here -> (Part 3) (http://www.thereminworld.com/forum.asp?F=3&T=4139&cmd=p&p=1)