Moog Music Forum

I was wondering if anyone has done any mods to their Moogs that they could share.

I know that Analogue Solutions performs and sells kits to modify Prodigys, MG-1s, and Rogues. http://www.analoguesolutions.com/
They have mods to give these synths modular capabilities like CV inputs/outputs for most synth functions as well as oscillator outputs, but you have to buy their kit.

There are free DIY mods at this site for audio inputs on the Prodigy:

http://machines.hyperreal.org/manufactu ... ut.mod.txt

and also here for CV/Gate/Audio input (with step by step pictures):

http://www.synhouse.com/prodigy2.html

Has anyone performed these or similar modifications.

I also know of a Micro/Multi VCF Mod on the Synth DIY Archives which is suppossed to improve bass responce. But I was wondering if there are any other Micro mods that people may have performed.

Dear Eric,

I bought a Prodigy when it was still a fresh product in 1981 (I think .... this really LONG ago ) and modified it quite extensively by adding:

- Osc & Filter CV inputs, Trigger In/Out (the latzer version of the Prodigy had these factory fitted
- Noise Generator with "white/pink noise" selector and level control
- switchable decoupling of the Osc-Sync from the mod wheel so as to have vibrato also for sync sounds
- hold-switch.

By far the most useful mod (for me, anyway) was a rotary 11-position switch which would let me select Osc-2-Detune:
- wide (as original)
- narrow (half-step up/down so as to quickly and precisely adjust the beating of the oscillators around unison)
- major & minor 3rd, 4th, 5th preset tuning up and down so as to quickly find these important detuning positions with the detune control still governing a small adjustment range around the preset detuning.

I have sold that Prodigy long ago (in retrospect I regret this very much but at the time the Prodigy had to go because a JP-8 could only be afforded that way) but I may in fact have the scematics for some of the mod somewhere. If there is interest I will try to find them.

Except for the noise generator, the mods were very easy DIY-type stuff (mount a few switches, cut a few connections on the circuit board, solder a few pots and leads), worked great and added a lot of functional value to the intrument - but they involved drilling holes into the Prodigy so I am not sure whether anybody would really want to do them these days when the old Moogs are collectors items which are devaluated from that point of view by such mods.

Take care,

T.

That's amazing, and exactly what I was hoping for. I'm in the process of modding my Arp Odyssey for modular capability, and after this I was thinking of doing some work on a Prodigy.

I feel like there is alot of unused potential on the Prodigy that could be tapped. I'm not an electronics expert at all, but I've worked on my Odyssey changing out capacitors and a few bad chips, etc. And now I'm installing CV and audio access jacks on the back. I'm doing it from a kit I bought. I don't know enough about electronics to know what's safe to connect and what's not yet, as far as harming the synth. So, I hope to learn more after finishing this project.

I don't really feel like these mods hurt the value of the synth much. If fact, I think they're more valuable having increased functionality, assuming the mods are performed well. Maybe if it was a MiniMoog, I'd think twise.

I was already thinking of adding a Noise source to the Prodigy with a pot on the control panel in the lower part of the Mixer section as well as a pot for ext. audio in. I was also considering adding CV access to the filter, envs out, and osc. as well as Oscillator and LFO outs.
It also occured to me that if I was going to add a Noise board, maybe I could put a env. follower board in there too that would connect to the audio in and filter CV input.
These are all just ideas at the moment. some of them I have tested sources for, some I'm hoping to figure out.
Theres also a schematic on the Moogalorium site that outlines a force sensor under the Prodigy keyboard, but much of the explination is in German, and it looks pretty complicated.
If you have any notes on the mods you did, I would sure be interested. For instance, where did you get the Noise board. Did you make it?

Thanks for responding. I guess people don't do these type of mods so much anymore. I think back in the day when there were magazines like Polyphony that published modifications it was probably easier for people to get started in it. It's all very arcane now. But it really helps you to understand how your instrument works. I kind of wish that Moog would encourage this sort of thing more, like they used to.

Recently I tried bidding on a Rogue Moog that was stripped of its outer casing & knobs, but missed out on it. If I had won it, as long as it worked properly I was planning on modifying it as much as I could. Like giving it a Synhouse MIDIjack, and disconnecting the keyboard and housing it in a box to use more as a "slaved" device to a MIDI keyboard. Or whateve it would be called. I saw some interesting mods at that site you linked to... I probably would have tried those as well...

Or I could have just designed an outer shell with the pitch & mod wheels to the side of the keyboard

Hello Eric,

I am very gratified by your positive response regarding the mods! I, too, feel that a good mod can add a lot of value to the synth (or to any instrument - but then even touching the circuit in a vintage guitar with a soldering iron appears to cut its value in half these days !).

The noise source was a kit I bought from a local shop - I am shure there are still such kits around. As you already anticipated, I mounted the associated volume control on the lower area of the mixer section. The noise generator circuit board was very small an could be easily mounted in the Prodigy. Chracterwise, the noise source was "white" but I tinklered around with a few resistors and capacitors and added a switch which let me choose a more "reddish" character - no true 3 dB/Oct dropoff but more 6 dB/Oct. It was still usable for "Thunder'n' Surf"!

I will now try to dig up what I can still find on the mods I did. When I have something, I'll let you know.

Kind regards,

T.

Yeah, I can definitely see mods hurting the value of a vintage guitar. It's pretty crazy how important it becomes that every little piece of a vintage guitar is original. Not only that, but the general inflation of vintage guitars is pretty outrageous, when even 70s guitars are in the $3000-$4000 range.

I guess that hasn't really happened with synths yet. I hope it never does. Maybe it's too soon, or maybe guitars are just different. Synths can probably, for the most part, be re-created, sometimes with the exact same parts. Whereas with a guitar maybe alot of the sought after tone is a result of their ageing, and craftmanship that can't be replicated.

On that note, one thing that's always bothered me about my synths is how shoddely they're made. The only well made synth I've ever played is a MiniMoog. Probably Buchlas or EMSs are well made too, but I've never seen one in person. But my Arp Odyssey is pretty much a peice of crap with plastic sliders. It's probably my favorite synth (I've never owned a Mini), but it's so fragile. Same goes for every other Moog, and other synths.

I've always wanted to replace those Arp plastic sliders with metal ones, and maybe replace the vinyl enclosue with a wooden one. It'd be alot of work.

The hardest thing about ANY synth with sliders is replacing them. The footprint that the slidepot fits into is hard to match, and there's no standard. That's one of the reasons I avoid vintage ARP synths, they all seem to have failing slidepots and it's near impossible to fix them or find replacements. The slidepots on vintage Moog synths seem to be hardy though.

Thankfully there is someone in Hong Kong manufacturing alot of the Moog sliders now and selling them on e-bay. I've seen alot of Arp sliders being sold too, so it could be they're still being made as well. Too bad they don't make a better, sturdier version.

I agree about the Moog sliders, I wish they used similar ones on Arps. Unfortunately, I would'nt say that about the rest of Moog construction. Particularly the Rogue/Prodigy/Opus enclosures and build tend to get pretty rickety if you play them out alot. I know the Prodigy, for one, is just literally glued together.
The Micro enclosure is pretty solid, but then all the pots are plastic and pretty flimsy, and the ribbon is really easy to tear.
It seems like most all vintage synths have one or more weak points.

Still, I would avoid Arps also, if I could find another synth I liked as much as the Odyssey. Besides the Mini, none of the little Moogs really match the features or sounds that I get on an Ody. I wouldn't think of trading it in on anything less than a MiniMoog. The MultiMoog would probably come close too, but it's too big for a monosynth IMO.

Dear Eric,

thanks to a friend I could trace some of the modifications I made to the Prodigy way back in the 80's. Unfortunately, the schematics - while really simple - are not in a state where I can just scan them. I will have to re-draw some of them, which I will do soon.

What I can already tell you now is what the mods which I could find the scematics for did:

- preset interval-switching for the oscillators (6 intervals) with still active Interval Control
- "hold" switch for keeping the VCA open
- range switching for the LFO frequency (x10, x1, x0.1)
- LED showing the rate of LFO frequency

There were other mods but those I will have to "reconstruct".

I also apparently made some funny more cosmetic mods such as LED's indicating the state of the envelopes and the gate, and now seeing the Prodigy schematics again after many years makes me think how many more easy mods would be possible!

I'll get back to you as soon as I have the schematics in a readable version!

Reagrds,

T.

Cool, I'm looking forward to them. All four would be very useful. I think there is a lot of untapped potential in the Prodigy. I would want to really plan it out and do them in a way that won't detract from the classic looks of the Prodigy's control panel. I think theres just enough space in the bottom of the Mixer and Filter section for at least one, if not two extra knobs. Then it's a matter of finding extra Prodigy knobs.
I've seen listings for reproduced MemoryMoog knobs (which look like dressed up Prodigy knobs) and it crossed my mind to replace all the knobs with these, and then the new ones would fit in.

The other thing I'm wondering about is screen printing new labels for the added pots. I've never done this before, but it would be pretty cool. If anyone has suggestions on screen printing or decals I'd love to hear about it.

Dr.T wrote: I also apparently made some funny more cosmetic mods such as LED's indicating the state of the envelopes and the gate, and now seeing the Prodigy schematics again after many years makes me think how many more easy mods would be possible!

As long as you're thinking, one thing that I always think about in terms of useful Mods, and never see examples of (for Prodigys or other synths) is an input to control LFO frequency/rate. I don't know if people don't attempt this because they think it's un-neccesary after having inputs for the filter, osc, etc... and can send an external LFO... or if it's just a difficult thing to do. Have you ever thought about or added LFO rate inputs to a synth?

By the way, just so this isn't such a one side resource for me, I have a bunch of mods for the Arp Odyssey that I can share if anyones interested. I'm sure some of them could be extrapolated/interpolated for use in Moog synths too.

I also have a few for the MS20 that makes it more useful to interact with Moogs. The MS20 already has S-trig input and outputs, but I have a volt/per octave mod that allows it to be controlled from a Moog.

The reason why there is rarely a modulation input for the LFO frequency is because only on really comprehensive modular synths the LFO frequency is actually controlled by a voltage. In the Prodigy this frequency is defined by the value of a resistor (the modulation rate pot) and the value of a capacitor. One could however add an interface which would convert a control voltage into a resistance change - this would then amount to what you desire. But let's start with more simple matters!

I trust you have already downloaded the schematics of the Prodigy so I can refer to them?

More soon,

T.

As usual, I'm getting way ahead of myself.

I have a service manual/schematics for the MK I Prodigy, and I've read through them a few times, so I'm ready to make notes for these mods, but I won't being doing anything until I finish my Odyssey. I'd rather not get two things going at once. But i'm absolutely interested in anything you have.

I modiefied my Prodigy to have Osc. 2 FM the filter.
I did this many years ago. And it just involved running a cable from the Osc. 2 volume knob to a new pot. Then using the output of this to run to an unused soldering point named "Filter FM" (or something like this).
Sonically it gives you vey powerful distorted sounding leads.