Moog Melodia

Senior Falcon,

Thanks for the tone setting tips.

I advertised for help on Craigslist and found a retired electronics expert here in Pittsburgh who remembered building a theremin in his younger years and found the Melodia a welcome project.  He had it working with about an hour of work by replacing the main capacitor and 3 of the four plug in transistors  or oscillators above and next to the tuning coils (forgive my ignorance of electronic components).  

The battery terminals were not reversed.  The 16 page booklet was unfortunately missing from the fragile original box that the theremin kit was shipped in.

There is no written rule about what the Melodia can play....Rob Schwimmer is living proof of that.  If you ever get the opportunity to see him play live you won't be disappointed!  

Today I got the Melodia out of storage and it was unplayable because the tuning coils were loose and out of alignment.  Hopefully I will be able to work on it tomorrow.  Who knows I may get up enough ambition to make another video.  Any requests?

Brian ;^)

Since Rob did Scene d'Amour and you did Plaisir d'Amour how about one of these:

Chanson d'amour; Melodie d'Amour; Ivre d'Amour; Salut d'Amour..... just kidding.

When you have the melodia open take a look at the transistors to see what kind they are.  There should be a number on them like 2N414, 2N168A, 2N1086.  Or you could just verify that negative on the battery goes to ground and positive to the switch.  Setting the coils is kind of a pain. It is pretty easy with the lid open, but when you close it the tuning changes, so it is a bit of an iterative process.  Once you have them where you want be sure to lock them in place by gently tightening the nuts. (I never used to do this but have finally learned my lesson.)

The original plug in transistors are 2n414.  The one that was replaced has 2n1381 on it.  
The positive wire from the battery box is connected to the positive connection on the original battery holder.

Now if I can just get it tuned.  I fiddled with it for a couple hours tonight and can't get any linearity out of it a all. I don't know how I did it the first time....guess I was just lucky.   I am following the instructions written by Bob Moog.

Have you seen this demonstration? 

This time around I tried tuning the Melodia a little lower than described in the manual.  I screwed in one of the slugs on the right about 1/3 of the way in, (not the 1/2 way specified in the manual), and then fiddled with the other one until I could get sound.  This loses the higher notes (which are too shrill for me anyway), but the payoff is that the lower notes get much more playable.  There are about 4 octaves that can be played, and they are reasonably linear.  The neat thing is that the note spacing is pretty much identical to the 6 octaves on my Etherwave with the ESPE board, but everything is pushed a little closer to the pitch rod. 

I work at Cornell University,  just a short walk away from the Moog archives, so I'm hoping to get over there soon to see if there is anything interesting about the Melodia.

Senior,

I can't get more than 1 1/2 octaves no matter what I do.  Also why do the instructions say to ground R11 and C12? When I do this I can get no sound whatsoever! 

Brian

I don't know if this will help or not, but here is how much the threaded rod extends on the four coils.  Looking at the melodia with the top open on the right I will call them the rear right and the front right.  On the left they will be rear left and the front left. With the nuts tightened, both right coils have about 3/8" of threaded rod exposed. The back left has 7/16" exposed and the front left is between 7/16 and 3/8". 

Once I knew the melodia worked, I set both variable capacitors so they were half meshed. (When you look at them you'll see what I mean.)  I started with the back right coil set at 3/8" which is less than halfway in.  I started with the front right coil all the way out and then turned it in until I started getting sound. There are two places where you get sound; one is harsh and nasty and the other is much sweeter sounding. As I recall, with the nasty sound the notes are reversed so that they get lower as you approach the pitch rod. Adjust the front right coil until you get normal pitch response.  I get about 4 octaves with these settings. Since the oscillators are essentially identical, there should be about the same amount of threaded rod showing. 

When adjusting the volume circuit I did not follow directions. I just started adjusting the coils until the volume responded the way it does on my etherwave.  Maybe someday I will try setting them according to the manual.

These settings should get you in the ballpark.  Of course up to now the lid has been open.  When you close it the settings will have to be changed a bit to compensate.  If you can only get <2 octaves then something is not right - about all I could suggest is to try reseating the transistors in their sockets in case there is dirt or oxidation. (I'm assuming you started with new batteries.)

Thanks I finally got several playable octaves from your tuning advice.   However, the sound I am getting out of it now has a very smooth string-like tone similar to the Burns B3 Pro which I think sounds like the speaker is under a blanket not lending to the clear timbre like sound I originally had in the video.  It's a mystery but maybe I will solve it if I keep fiddling around.

If I can't do better I will not be playing the Melodia as it is not close to the tone of the one Kip Rosser or Rob Schrimmer plays. Perhaps a different amp is necessary or maybe there are some aging components that just aren't up to par anymore.  Maybe I will get a sound byte to post.

One more thing.   I have noticed that my amp volume has to be turned up twice as far as my EWS or EW Pro for the Melodia..... Have you found that to be the case with yours?  I did use fresh batteries.

Odd that the timbre would change so much. If you are getting less than 4 octaves try turning in the coils on the right, maybe a turn at a time.  I understand from the instructions that this will make it reach higher notes. I haven't noticed much difference in the outputs of the two instruments, but then I wasn't paying much attention to it.  The volume trimmer knob on the left has a large effect - maybe that needs to be tweaked.  www.westfloridacomponents.com/ has 2N414 transisters at $2.50 each. You might try getting some of these to try in place of the replacement transisters that were used when it was first repaired for you.  The replacements are a bit different, but it did work with them so maybe they're OK.  

You have two really first rate instruments, and maybe the melodia will never be able to measure up.  I will say that I am quite pleased with how mine is working after a 5 year rest.  Bob Moog designed this when he was a 25 year old grad student, and we're still talking about it.  That is pretty remarkable to me!

I was wondering if anyone scanned the Melodia Manual yet. I am particularly interested in the pictorials as they show test points referred to in the setup procedure.

Thanks a lot,

Doug

I will scan the pictorials tonight.