Moog Music Theremini Reviews

Posted: 7/10/2014 12:13:28 AM
Synthguy

Joined: 7/2/2014

Gosh Fred, are you sure that's the MOST damning thing you've heard about the Theremini?

Surely there must be some other absolutely horrible feature that is lurking just beneath the surface. 

Guys, it's been fun, but this really doesn't seem like a place to share info about this sorta stuff.

Cheers.

 

Posted: 7/10/2014 1:19:42 AM
FredM

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 WaveCrafter.com . ...................................

Joined: 12/7/2007

Goodbye Synthguy..

IMPORTANT! - It seems data regarding the operation of CV, on which the following comments were founded, may be incorrect!

"Surely there must be some other absolutely horrible feature that is lurking just beneath the surface"

Who knows! - But of all the issues I have seen at this time, this one is the only one that is, and can only be, an ERROR!

However - I am not even sure it exists.. I am not sure that it could exist - its just so outrageous and impossibly stupid error that I cannot imagine even a synth novice making it ..

UPDATE -> [ Yeah, its true. CV out does NOT track the theremini pitch!  SHOCKING, BUT TRUE!]

Perhaps the person taking the measurements didnt know what they were doing... [edit]-> Sorry Synthguy - it looks like your measurements may well have been correct<-[end of edit]

After all, Moog is producing the EW+ which doesnt make this mistake - it takes the pitch, puts this into a period-voltage converter, then via an exponential converter, to produce 1V/Octave..

What use is a CV output which gives 1V/Octave if one is playing say 6 octaves, and say 2.5V/Octave if one is playing 3 octaves? ... What you gonna do? Have a bunch of opamps or attenuators with selection switches and trimmers, and re-tune your VCOs and VCFs every time you change your span? - Hell, the whole modular synth world utterly relies on consistent CVs throughout - This was the innovation which created Moog!

IF The theremini has bodged this aspect, then it is utterly BREATHTAKING! - Not just an egg-on-face situation, its an unparalleled clanger that shows that Moog without Moog is NOT Moog!

But I am inclined to think "Synthguy" doesn't know a CV from a DVD! ;-) [edit]-> Sorry Synthguy - it looks like your measurements may well have been correct<-[end of edit]..... For Moogs sake (and any theremini purchasers who want to use it with their analogue synth)  , I hope this is the case.

Fred.

Posted: 7/10/2014 1:28:27 AM
randy george

From: Los Angeles, California

Joined: 2/5/2006

If I recall correctly, the Theremini is synthguy's first theremin.  Also, he does not already own a synth with CV inputs...  not a good combination for someone who wants to be taken seriously about discrepancies in industry standard implementations such as Control Voltage.  Goodbye, Synthguy.

Posted: 7/10/2014 6:20:41 AM
GordonC

From: Croxley Green, Hertfordshire, UK

Joined: 10/5/2005

Sorry to see you go, synth guy - I have enjoyed reading your posts. 

Fred asks "What use is a CV output which gives 1V/Octave if one is playing say 6 octaves, and say 2.5V/Octave if one is playing 3 octaves? "

Well, it definitely rules out having an external VCO match the pitch of the audio out from the theremini. But I guess it would still be ok to drive a VCF. Particularly if one had some sort of little device to shift and stretch the voltage into the desired range before it reached the VCF. ;-)

Posted: 7/10/2014 8:50:38 AM
RoyP

From: Scotland

Joined: 9/27/2012

Slightly OT:

' I think the mush we are all now listening to - the MP3 compression for example - is eroding the appreciation of audio quality... Really, apart from the few who lived through a few decades of real Hi-Fi between the 60's and 90's and those who regularly listen to live acoustic performances, most people really cannot tell the difference between an acoustic grand piano and a clavinova, or a Lev theremin and a theremini!'- Fred

I have for some time maintained that people of today are being sold short by the music & audio industry in so far as they (the people) are being conned into believing that a quality sound can be generated from a little i-phone or similar pumping out a distorted audio signal from an MP3 file.

But please, don't get me started...

Posted: 7/10/2014 6:10:04 PM
dewster

From: Northern NJ, USA

Joined: 2/17/2012

Synthguy, the dynamic going on here is not at all uncommon.  A manufacturer debuts a brand new electronic instrument at winter NAMM with a mountain of hype, and as models dribble onto the street 6 months later the hype gets deflated.  It's an iron clad guarantee that wild speculation will ensue and egos will get frayed.  Try not to take it personally.  I think you are getting jumped on a bit mainly due to your uniformly positive remarks regarding the Theremini, and others are just trying to balance things out via a healthy dose of doom and gloom.  The proof of the pudding is in the eating, and few of us have had a chance to take a bite of the Theremini, so a peanut gallery forms (mea culpa).

Posted: 7/10/2014 6:57:26 PM
FredM

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 WaveCrafter.com . ...................................

Joined: 12/7/2007

IMPORTANT! - It seems data regarding the operation of CV, on which the following comments were founded, may be incorrect!

 

"Well, it definitely rules out having an external VCO match the pitch of the audio out from the theremini. But I guess it would still be ok to drive a VCF. Particularly if one had some sort of little device to shift and stretch the voltage into the desired range before it reached the VCF. ;-)" - GordonC

Yeah - one ends up with a "CV output" thats about as useless as the CV from the Theremax.. Ok, one can expect this from PAIA, but not from Moog!

- And even for a VCF, its pretty useless.. In fact, the Theremax would probably be better, because although its useless for tracking anything accurately, at least it would be consistent.

Ok, sorry if I seemed to blow my top - But I cant retract a single word I said about CV.. Moog's invention of a linear CV controlling exponential modules was one of those brilliant (and simple / obvious) ideas that changed electronic music far more (IMO) than the theremin ever did - it created the industry - its why Bob became famous - and its the reason I became an Electronics Engineer .. I can still remember the moment that I understood what Bob had done, my intake of breath as its beauty hit me... Only a few such moments have occurred in my life - moments when science and/or engineering affect me emotionally in a profound way.. It was just really clever.

And its really simple - and this is what would make any error by Moog in this area so utterly incomprehensible and unacceptable. If they screwed up the MIDI protocol, that would be bad - but far more understandable to me (and a protocol screw-up can be fixed with a simple firmware update, as I know from experience ;-)

Anyway, enough said..

I personally doubt that Moog could have screwed this up, but all it would take to test it is one (1V/Octave / Exponential)  VCO.

Fred.

UPDATE ->

" The Theremini CV out is not (currently) designed for pitch control either. It runs an output of 0-10V, but it is not necessarily following the internal pitch of the Theremini itself."  xtheremin8-  quoting email from Moog Music.

 

Scanning a number of comments from users on synth forums, it seems that:

1V / Octave scaled at either 0 to 5V or 0 to 10V is available from the theremini, and tracks the pitch.

1V/Octave is NOT available when the theremini has any pitch correction (Quantizing) applied - This is apparently something Moog is working on correcting... Synth users are (rightly IMO) not bothered much by this.

Please note that I cannot confirm the above - its from various postings by people I dont know - but some of these people claim to be driving Euro-Rack and Moog modules, and I have seen no comments other than from Synthguy here regarding the "span" affecting the CV ratio... It may well be that when in quantizing mode this does happen - in fact this is probably likely, but synth users know that they need 1V/Octave so dont bother messing with quantized CV output, so probably haven't noticed this effect.

So now I have a dillema - I dont want anyone to be put off by Synthguys "observations" or my reaction to these - I would like to go back and edit / remove posts related to this "misunderstanding" and replace them with a rebuttal of these "observations".

It really looks like  MOOG DID NOT SCREW UP ITS IMPLEMENTATION OF UN-QUANTIZED CV! - AND THAT WHEN PITCH CORRECTION IS TURNED OFF, THE THEREMINI OUTPUTS 1V/OCTAVE WHICH IS NOT "DISTORTED" BY HOW MANY OCTAVES ARE SELECTED!

IMO, "distortion" of the CV due to pitch quantization is a minor matter - Minor because its most likely a software issue.. If the theremini can output undistorted 1V/Octave CV when not quantizing, then I suspect there is no fundamental flaw, and probably just a bit of code tweaking required for the other matter.

Regarding Synthguys observations - IF they are an error caused by quantization being turned on, it would be an extremely easy error to make! - A mistake even an EE involved daily with synths could make, and a mistake which could easily have been corrected without upset.

I possibly made a big mistake by not seeking more clarification before I made the comments I did - I am not out to spread "gloom and doom" or go on a Moog-bashing spree - The irony is that I was (am) actually moving towards thinking that, for its price, the theremini could be a real advance and fairly revolutionary, particularly for synth users not requiring features thereminists demand .

IF the data on CV's had been true, THEN my comments on the matter would, I feel, have been more than fully justified... But I should have checked first that this data was the truth before I made the comments I did.

 

Fred.

[there is only one technical matter that still bothers me a tiny bit, and which causes me to have a teeny bit of doubt regarding the issue - Posts I have seen declare that 1V/Octave is supplied either from 0-5V or from 0-10V.. For anything more than 5 octaves (at 1V/Octave), the 0-5V setting could not work - I assume that above 5 octaves, the output will sit at saturation (5V) - I know that some Moog equipment behaved (behaves? - Been a long time since I played with any new Moog synth stuff) in this way - but some posts didnt make much sense on this matter, leaving me with some doubt about their reliability]

 

Posted: 7/11/2014 3:57:38 AM
bichuelo

From: Bogotá, Colombia

Joined: 7/10/2014

I have the Theremini, an Etherwave Plus, Minimooog Voyager and Slim Phatty (which accept 10V), Sub Phatty and Minitaur (which accept 5V), so I can do any test in order to know how this works, for certain. I also have the attenuators on both the CP-251 and the VX-351.

I don't have a vintage analog, and I don't have lots of experience with CV, but since Audiotecna (my business) is a Moog dealer for my country (Colombia), I do have the time to do it and I want to help.

Please guide me through the tests

(PS: first post!)

Posted: 7/11/2014 1:09:10 PM
FredM

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 WaveCrafter.com . ...................................

Joined: 12/7/2007

Hello bichuelo, Welcome to TW!

The basic test for the above issue should be really simple -

You want to output CV from the in the range that matches the instrument - I would use the Minimooog Voyager or Slim Phatty on 10V as these should have the least possibility of any confusion.

With pitch correction OFF, I would tune the VCO / VCF on the synthesiser to give the same pitch as the theremini ... Not sure how one triggers the synth or controls the volume, (will discuss that in a minute) but the important test is to see that the VCO accurately tracks the theremini CV.

When this is verified, try changing the 'span' from the theremini (number of playable octaves) and check that the VCO still tracks the theremini.

If the above all works, you could (if you want, IMO its not important) check what happens when you turn pitch correction up.

Assuming VCO frequency does track theremini pitch (when pitch correction is off) regardless of span, then this proves it is usable to control synths...

Synths require at least two signals to drive them - they need a pitch control (CV and / or MIDI) and they need a trigger to activate envelope generators and/or a CV (or MIDI CC) to control the VCA.

I am not familiar with any new Moog synths - But If I had a choice of operational modes, I would drive the pitch control path (VCO / VCF Etc) from the theremini's CV output, and drive the VCA path from MIDI CC outputting high resolution volume data..

I understand that the theremini cannot output both pitch and volume CV's simultaneously, so I would try to get pitch data from the CV output and volume data from the MIDI output - If the synth can read this volume data and convert it to CV, then you have the two signals you need to drive an analogue synth in "theremin" mode.

About CV's .. General testing:

You really dont need a synthesiser to test the CV output on something like a keyboard, but with a theremin, where its damn near impossible to keep pitch stable, the CV would probably be changing so much that its impossible to take measurements.. Which is why using A VCO makes a lot more sense, as one can hear both the theremin(i) and the VCO and our hearing is far faster and better as a measuring instrument..

However, in general terms, 1V/Octave CV means that for every increase in pitch by one otave, the output voltage (or input voltage on VCO etc) must increase by one volt, and therefore that every increase of one semitone will increase the voltage by 1/12th volt (or 83.333mV)

"Please guide me through the tests"

1.) Turn theremini pitch correction off

2.) Set theremini pitch CV to 10V

3.) Optional - check with a DMM that the CV output gives approximately 1V change for every octave change in thereminis pitch

4.) Patch this CV somehow into the CV of a VCO on a synth that takes 10V CV input.

5.) Directly monitor the output of this VCO

6.) If needed, tune this VCO so that its pitch is the same as that from the theremini

7.) Play the theremini, check that the VCO pitch and theremini pitch track each other

8.) Change the 'span' of the theremini (number of octaves one can play) and check that the VCO and theremini pitches still track.

Good luck! ;-)

Fred.

 

SOME MORE NOTES ABOUT CV:

The real beauty of 1V/Octave CV' control is that its linear - this means that, if one has a voltage producing a pitch, and you add other voltages, you can shift the output pitch however you want... For example, if you have a sequence playing, and add 83.333mV, that sequence will shift up by one semitone..

With MIDI this allows one to drive a MIDI + Analogue synth from a sequencer, and add the CV from a theremin, and the sequence will move with the pitch coming from the theremin... It also means that if you have a MIDI analogue synth which is converting incoming data to CV's, you can inject CV's to any modules (if they are fitted with summing inputs on these modules) and add to, or bypass the MIDI data by using CV from the theremin.

Where the problem arises with pre-configured analogue synthesisers is that they mostly depend on trigger / gating signals to activate envelope generators which control dynamics.. Theremins need to have control over dynamics, so they really dont need envelope generators, they need direct access to dynamics modifiers (Like the Voltage Controlled Amplifier/s and VCF's.

Posted: 7/11/2014 5:50:33 PM
hewson

From: brooklyn, NY

Joined: 2/11/2009

if you want to wrangle a volume CV out of a theremini, it's worth noting (esp. for a moog retailer that might have such a pedal lying around) that the moogerfooger freqbox contains an envelope follower.  just send the theremini's audio output through the freqbox, and take the envelope out and send it to whatever you're testing the pitch/cv response with (e.g., the voyager).  assuming you don't have any weird effects like lots of reverb or delay, this will give you a pretty good semblance of a volume CV.  at this point, you might wonder, if you are using the freqbox, "why not simply test the theremini's pitch/cv ratio with the freqbox's VCO?" you can't usually do this because the freqbox's VCO is not precisely calibrated to 1V/oct, unless you open up the bottom plate and perform the calibration yourself (and even then i think the calibration is a little temperature sensitive)...

also i see that the voyager has an envelope follower in its circuitry but i don't know if you can set it up to just slave its VCA to the output of the envelope follower.... maybe there is also a way to fudge an envelope follower by using the cp-251 - first you would have to rectify the audio signal to positive only (maybe a simple diode half-rectifier?), and then send that through the cp-251's lag processor (set rise to min, fall to..whatever makes it respond correctly!)...??  not sure if that works, but to my very primitive understanding of electronics, it seems like it might work?


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