Moog Melodia

chris, if you are collecting infos, don't miss another dusty TW melodia thread about the transistors. : http://www.thereminworld.com/Forums/T/28684/moog-melodia

but there would still be the old fashioned coils left do roll on your own. and these materials are difficult to get, i think these days. even in the local creepy electronic shop, a lovely place to get lost, and they have real cool old things, told me with a pitying smile,that i'm about 30 years to late for proper wires and cores. and it must be a fidgeting job anyway.

xther, I will add that dusty link to a remake of the webpage. The reason I have focus on the Melodia at the moment is to sidetrack my thinking as I have come up against a wall on my method of optical tuning for my single tube theremin-like design. It can work beautifully.

I started experimenting with emitter follower setups after dewster showed us his bass mod. This is how someone blends a transistor osc with a tube/valve osc, each has their own best features.

The Melodia takes its signal off the emitters. . . now why did I not ever figure that approach out? A team is more productive than a lone wolf. I may have to post my tuning design schematic for ideas. lol

Moog Melodia    updated

What I find interesting about the Melodia is the circuit design, not so much using the ancient components.

This Melodia performance is really good, it rises above theremin design. I think that is bisem who started the thread.

Christopher

"This Melodia performance is really good, it rises above theremin design."  - RS Theremin

Wow, that Melodia has a really nice bowed string timbre!  And nice playing too!

I've put scans of 6 pages of the Melodia assembly manual in an album in the Photos section.  These pages detail how to adjust the Melodia once it is fully assembled, how to play it, what amps to use, and a schematic and parts list. (Sorry, the pages are not in order) 

This might explain the change to PNP transistors: "For technical reasons, PNP germanium transistors are easy to make whereas NPN germanium were much more difficult (and expensive) to make".  A look at Allied Electronics archived catalogs from 1960 and 1965 confirms that the PNP transistors are a bit less expensive, but not by a huge margin. The magazine article mentions a kit that can be obtained from Moog and it sure implies that it is identical to the published design.  It would be interesting to find out if the earlier melodias with the Treble clef and vacuum tube logo use PNP or NPN transistors.

There was some talk about thermal instability of the germanium transistors, but I can't see that the Melodia is any less stable than the Etherwave.  Both need pitch adjustment a couple of times during the first 10 or 15 minutes.  As the etherwave warms up the octaves tend to get longer; with the melodia they get shorter.

My young protégé did a fine job at the haunted house last night, providing guests with the usual assortment of woo-woo and whooping sounds.  At one point during the setup I was playing the melodia and went into "Santa Claus is coming to town".  I heard someone say "What the...?" and then 6 or 8 scouts started singing along, really belting it out. It was quite funny but then I got laughing so hard I couldn't keep playing.

Many thanks, senior_falcon!

"Wow, that Melodia has a really nice bowed string timbre!  And nice playing too!" - Dewster

I agree - real lovely.. Got me scratching my head a bit though! - by far the best sound I have ever heard from any diode mixer - Kind of wondering if the "crude" VCA topology is giving an asymmetrical bias to the audio (giving more ramp-like qualities to the waveform) or whether its just the low-z oscillator drives, or a combination of both..

But the thereminist may also have a lot to do with it..

If I am correct, bisem played your (Dewsters) modified EW - And it also sounded wonderful...

Fred. 

One thing puzzles me a bit on the schematics.. If the PNP transistors were germanium and the NPN's silicon, I would have expected the values of R7 and R8 to be different for the two builds.. As it stands, both have 150k / 22k, which, with a 6V supply, puts the bias voltage at ~0.76V .. Now to me, this looks a little on the high side even for silicon - but for germanium I would be surprised if the theremin ever went silent! (I dont actually see how it could...)

I am probably being silly and missing something obvious which will make me go "duh!" when I see it ! ;-)

 "If the PNP transistors were germanium and the NPN's silicon..."

Both types of transistors used in the design were germanium.  A couple of resistor values are different in the PNP melodia which may answer your question.  I can assure you that it does indeed go silent when you want it to.

oh, halloween, the season of the theremin.

while i'm the guinea-pig at the hospital once more, just found a final, real old transistor thread from 1995: https://groups.google.com/forum/m/#!topic/sci.electronics/tvuknybB09A

interesting is the handdrawn schematic link mentioned in the first post, (the link  seems not to work anymore, wich is sad but so it goes.) But i spotted:  ...edu/ ~jbbarile/wwwfiles ...etc...."our" jason? 

"Both types of transistors used in the design were germanium.  A couple of resistor values are different in the PNP melodia which may answer your question.  I can assure you that it does indeed go silent when you want it to." - falcon

Yeah, I can hear that!

and the volume control looks beautiful with a good span and the right kind of slope.. I am quite mystified.. I must be missing something damn obvious, but I would really have expected the bias to be set just below Vbe so that the volume cv brought the transistor into conduction.. I dont see how the transistor ever turns off, and therefore dont see how it ever goes silent!

Time to get one of those transistors and breadboard that bit of the circuit! - I dont like not knowing how simple circuits work!

;-)

Fred

No need to build it.. I WAS being stupid! - The base is being biased into conduction deliberately, and the volume CV actually turns it off - Thats the trouble with thinking silicon voltages when looking at germanium transistors! Duh!

But I probably will build it anyway - I have a box full of old germaniums I salvaged in the '70s.. Somewhere...

"Wow, that Melodia has a really nice bowed string timbre!  And nice playing too!" - Dewster

Goodness I forgot that video was still posted!   I find the "string timbre" a bit too heavy or even raspy for most of what I play.   IMO it has a very raw and unforgiving tone that doesn't mask the inadequacies of the player such as my inability to play on pitch at that time. When I heard Rob Schwimmer play his in person in NYC it had a much smoother string-like tone.  He must have done some modification to his.

I haven't played my Melodia since the time of that video when I accidentally dropped it on my foot removing it from the mic stand and nearly broke my toe....it's a very heavy instrument!  

The volume plate is quite dynamic compared to the EWS and feels very comfortable to play with very little or no learning curve. I can only describe it as feeling like there is an invisible sphere on the end of the case.  I wonder why it never caught on?   

Finding this thread active has inspired me to fire the beast up again and see what I can do with it now  ;^)

You can adjust the timbre quite a bit by changing the tone settings on your amp.  If I turn the treble control down to about 9 o'clock and leave the bass at 12 o'clock the tone is softened up quite a bit and it sounds really nice. Interestingly enough, some of the harmonics come back as you get into lower notes and it still sounds string like, not like it's coming from under the sofa. (I assume you've already experimented with these settings, but thought I'd mention it.)   One nice thing is that you can touch the volume plate on the melodia and it doesn't make sounds like on an etherwave.

@bisem - What did you have to do to get the melodia working? What you described had negative ground and positive going to the switch.  Did that finally work for you, or did you have to reverse the battery so ground was positive?  Also, you said the melodia came in the original box.  Was there a 16 page booklet for constructing the kit, and if so could you scan the cover and pages 1 and 2 for me?

And finally, is there some unwritten rule that says the melodia can only play songs that have "d'amour" in the title?