Monotron mods

[sonic]

Santa brought me a Monotron for Xmas. It's friggin' brilliant!

I want to mod for gate/cv, cutoff etc but I really want to keep it as cosmetically unaltered as possible. The best method I've seen so far is a mini-usb jack in the back. Super discrete and provides 5 pins. I've also seen a (slightly jutting out) 4-pin mini-DIN installed on the right side of the case. Any additional circuitry I'll put in a little breakout box.

I'd be really interested in any suggestions for attaching a small multi-pin connector on a small enclosure, and how to install cleanly and securely. I love my little Monotron and the idea of cutting/drilling into the case gives me the heebie-jeebies! Perhaps I should get some different types of connectors and experiment on scrap plastic? I have no previous circuit-bending / modding experience.

[umschmitt]

Lucky you. On the other hand, you may find handy to take away the (cosmetically unaltered !) enclosure and put the synth + mods & things in one bigger box ! I"ve also seen a wallwart mod and a one shot LFO mod, both super easy and googleable.

[MadScientist]

I'm planning on 'modularizing' my Monotron, which should allow me to use it as separate modules (VCO, LFO, VCF, headphone amp). This will require external components for buffering etc., and a few reversible modifications to the PCB. I only intend to use the PCB itself, while the rest of the gizmo will be put into storage. Maybe not quite what you had in mind?

- Frank.

[sonic]

Thanks chaps. Yes that's actually very useful. In my over-enthusiasm I overlooked that rehousing the pcb would actually be the more reversible approach. Perhaps it could even be done in a way that made the pcb quickly swappable back to the original enclosure. I have an enclosure on the shelf which looks to be an ideal size. Hmmmm...

[Cynosure]

Sonic - I am moving up to a bigger case. That tiny case won't allow me to add much.

I already have it running on a wallwart, and I added these mods:

- Square wave with PWM and phase shifting (so the peak of the square can be anywhere from the top of the monotron's saw to just before the next saw's peak).

- Comparator clocking a 4040 to give 3 sub octaves that can be mixed in.

- Feedback loop through a diode that provide a unique sounding overdrive/feedback.

Soon I will test adding an envelope.

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[blackdiscoball]

I added a small mini dsub connector on the side of mine. There is just enough room and it gives you 9 pins to work with. I then had a box that connected that gave me cv and gate in. Cut off in, audio in and out, and a switch to turn tracking on and off. I could plug this box in and use all that or I could unplug it and most people didn't even know it was modified. I just recently added an LFO in which I can now control the LFO speed with an external lfo. The wire I used was a little big but it all fit. Its tight though. I plan on buying another monotron and just rack mounting that one with all the mods I did on my first plus some new ones. I mounted the Dsub on the far right (next to the pitch ribbon) by drilling a couple small holes and then filing the shape out with some needle files.

[Lorenzo]

[sonic]

I just noticed your post @blackdiscoball. Many thanks. That's just the kind of thing I'm interested in. I don't suppose you could post a couple of photos?

[blackdiscoball]

Yeah, I could try to do that.

[sonic]

Merci!

[v-un-v]

I must say that Korg's marketing team are a bit out of touch with the modern world. They would make a killing if they sold Monotrons through Toys r us, but all you can get there is the Stylophone- which is shit (compared to.....)

Monotron POWER!

Which Mono did you get, Sonic?

[blackdiscoball]

I wish I could have taken a picture of the inside but its an absolute mess and Its a pain to get closed up. I made the mistake of using wire that was a little to thick. There is definitely room to work in there (if you are tidy) but I highly recommend the SMALLEST wire you can find. The stuff I had on hand was a little to big so I kind of handy capped myself. My initial mods made it so that if you didn't have the box attached it worked 100% normal, most people didn't even realize I had added the extra dsub on the side. I recently added control over the lfo and now if you don't want the box attached, you need to plug in a small dsub that I have two pins wired together, if not the lfo doesn't work. This has kind of been my test monotron. If I did it again I would just do cv and gate in and no other extras. I might do that at some point but the next thing I would like to do is rack one up with all these mods for the modular synth Im working on.

[v-un-v]

Nice!

It's just a shame the breakout box isn't as pretty.

[sonic]

Wow, you must have done quite a job to fit it all in @blackdiscoball. Would you use the same type of connector again if you made another modified case?

@v-un-v I got the original Monotron. The mrs claims she got it for $25 + shipping, although this offer seems no longer to be available. I would probably have bought a couple more at that price. I hear crazy deals on these appear every so often. I'll probably pick up the whole set eventually. I'm envisioning a mini battery-operated analog performance setup made up of a collection of little boxes. Something instant and fun. A percussion box, synth(s), mini sequencer, mixer etc.

This video really got me thinking. I love the mini trimpot baby-8.

http://www.youtube.com/watch?v=5SbXBVfZMSc

[blackdiscoball]

I would definitly use the same connectors. Its a tight fit but it gives you a lot of options and I like the option of having it work as normal with little extra attached.

[v-un-v]

I'd be well impressed if the breakout box was as beautiful. But what has already been done is excellent.

[Lorenzo]

[Cynosure]

[Lorenzo]

[Cynosure]

Here is a video clip showing the waveforms. I have no idea how it does it, but it sounds cool

[Paradigm X]

there was an amazingly compact modded monotron posted at muffs recently, http://muffwiggler.com/forum/topic-53496.html

i think you need to be logged in to see the pics. amazing tho. Im such a klutz.

the tiny midicv thing looks a good idea too

http://www.midi-hardware.com/forums.html?section=prod_info&product=MINICV

been meaning to mod mine for a while but not got round to it.

[Cynosure]

That one is very cool considering how much he managed to cram into the original case.

I have finished up most the soldering on mine and I am working on the case now.

I added a simple active lowpass filter to the squarewave and sub oscillators, as well as an envelope that controls the filter cutoff.

[sonic]

Wow. Thanks for posting this Paradigm X. Really useful to see this. Current plan is still a DB9 connector with a breakout box, but I think I'm avoiding the job as I'm afraid to hurt my poor little Monotron! I picked up a Dremel type thing last week for this kind of job, as my power drill is perhaps a bit brutal. Especially if I forget to switch off the hammer drill setting!

#edit:

p.s. I should say thanks blackdiscoball for the DB9 connector idea!

[v-un-v]

Does anyone know what to do to modify the volume pot so the travel is far less? So say, rotate by half, then you get full volume from nothing.

[richardc64]