New Build - Modular System

[soffa]

All...

I mainly lurk here, but I thought I'd come out of the shadows to share a few pictures of my ongoing project. It started when I built a microsynth clone about five or six years ago. I thought it was cool, but it wasn't all I hoped for so I started looking into something better. One thing led to another and after many conversations with the infamous Harry Bissell, here goes my current effort. I am waiting until the content gels a little bit to settle on a real enclosure, so for now I have aluminum panels screwed to wood blocks!

Here goes:

http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/modular_1.jpg.html
http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/modular_2.jpg.html

So far I have the following:

EHX Deluxe Octave Multiplexer Tracking Filter/Fundamental Extractor
Waveshaper Circuits / Divider for fundamental, -1/-2 octave square wave, pulse, PWM, and shaper
PAIA 2700 Envelope Follower
Harrry Bissell Envelope Follower w/ lag circuit, inverted output, and gate/trigger
Dual VCA
Dual LFO
MS-20 Filter
Harry Bissell Mono P-V Board  (the rack box under the right-hand panel. It is adapted for mono input as Harry's design uses a hex pickup and string selector circuit)
XR-VCO
Mixer

I'm still working on getting everything to totally play nice and I get some pretty weird crosstalk with my current no-shielding rats nest but it does track very well and is capable of a lot of synth sounds. It's not "there" yet but it is close enough that I though someone might like to see a picture.

I'll get some sound samples up as soon as I can!

soffa

[jonasx26]

Very cool!

[wavley]

Awesome, I've been trying to take one on like this for a while, but life just keeps getting in the way.  I'm glad to see somebody actually getting one done.

[Mark Hammer]

Can't see the pics here at work, but I look forward to seeing them tonight.

We had a gathering at my place in 2003, when Osamu Hoshuyama was in town, and Harry came up from Oak Park for a visit,bringing his gear with him.  I've said it before many times, but Harry's "Muffy" guitar processor/synth is just about the most responsive guitar-based system I've ever played.  I have one of those old EFM P-2-V boards 2/3 stuffed, but Harry disuaded me from using it, expressing dissatisfaction with the design.  I do want to try out his envelope follower, though, if only because of the responsiveness I described earlier.   I really need to take a vacation this summer and do some serious work on the many synths that are sitting in stuffed-but-uninstalled state.  Lord knows I have enough rack panels and knobs to finish the task, though of course one can never have enough pots...or Lego...or time

[Jordan A.]

Wow, wonderful project!  I've had my eye on those two Harry B. projects for a while, it's great to see someone actually put them together, I'm sure they are lots of fun.

I think building everything on temporary panels like you did is a good idea also, on a big project like this things are bound to evolve as you go, looks great so far.

A few of us are currently working on MS20 style VCFs as well, it would be nice to hear your reports, can I ask which schematic are you working from?

Whats next?

cheers,

jordan

[liquids]

Just wanted to publically comment that your photos merely provide evidence that you need a girlfriend, soffa 

You're efforts are inspiring from one synth-guitar maniac to another

[soffa]

I'm pretty sure my wife thinks that the synth IS my girlfriend, but that's another story!

The MS-20 filter I am using is a LP-only OTA version - the Rene Schmitz schematic / layout. It sounds good and does some nice self-oscillating.

I actually have a bit of a collection of Harry's synth stuff. Like I said, I started out with the microsynth and wanted more waveforms and better octaves. I messed around with that and had read about Harry's synth here and in various other places. I did some more searching and realized that there are really two pieces to Harry's rig that are easy to confuse. One is the Muffy, which is his envelope follower w/ a voltage-controlled lag circuit, a fuzz with some basic waveform mods, a VCA, and a VCF PER STRING fed by a hex pickup. That's about 80 ICs for six strings! Then there is the second part, the Mono P-V. That takes the lowest three strings of the hex pickup, uses a string selector circuit to produce a mono output with selectable last or low note priority, and creates a 1V/oct CV output and a octave-down synthesized bass output. That's another 40 ICs or so!

Whew.

So - I got quotes on making up boards. It was expensive to do one set as they are about 6" x 15", so I kind of back-burnered the idea. I found out that Harry had sold one other set of boards for the Muffy. I tracked the guy down and found out that he had stuffed the boards but never finished/debugged them. He sold the mostly-completed Muffy to me.

Harry also sold a handful of boards for the mono P-V section. I found ANOTHER guy who had one, un-stuffed. He sold it to me.

Over the next few years, I stuffed the mono P-V and with Harry's help debugged it. I also got the Muffy up and running relatively easily; however I can see how the zillions of trimpots to get the strings to respond evenly to all of the CV signals might be a little intimidating.

At this point, I had a mostly-functioning P-V converter and a working Muffy. They are both a ton of fun but they did not give me what I REALLY wanted - fat mono synth bass and lead sounds. (Well, the P-V could do it on three strings....) I was going to expand the P-V string selector to work with all six strings but I got waylaid by another idea. Both Harry and the Electronic Peasant (who adapted the Mono P-V for use with banjo!) said that they liked to use a sawtooth output generated directly from the original signal with no P-V. That gave me the idea to make a really complicated microsynth using the much-talked-about EHX Fundamental Extractor. I mentioned it to Harry and lo and behold, he was messing around with the same circuit!

That's how I started building this mess. My idea was that I didn't care about any poly capability, I wanted to avoid the hex pickup, and that I really didn't care about pitch-to-voltage. As it turns out, I just adapted the Mono P-V to take a single input and it works good - for my needs. All of the usual analog guitar synth caveats apply. You can't play two notes at once or it gets confused. It prefers the neck pickup. You can't play too sloppy or unknown unpleasant noises will come from your speaker of choice. It is pretty noisy with certain patches but I think that might just be a result of my unintentionally overdriving something along the (circuitous) way.

I'm looking forward to dragging my Traynor Bassmaster w/ Altec 15" out of the attic for some serious low-frequency work. I'm going to wait until the other inhabitants of my house are gone for that, though.

Oh - one more thing. It isn't true bypass. In fact, it is NO bypass. (Unless you count pulling the cable out of the input and jamming it into the amp...)

Soffa

[liquids]

Do you have any notes on what voltages you get when you play 1) an open low E and 2) a 12th fret high E on the high E string (that is, the voltage once the tracking filter has settled in) on the 'far' side of the 27k resistors of the EHX tracking filter?  Obviously the OTA is more interested in current and hence the 27k limit and shape that current...but voltages for those two notes (more or less, the full range!) would help me out right now.

[liquids]

C'mon soffa, post some clips.   

[Earthscum]

That thing is way cool. Imagine a roadie seeing that thing... He would probably walk down the street to get a job app from McDonalds to fill out in front of you.

[liquids]

Oh - one more thing. It isn't true bypass. In fact, it is NO bypass. (Unless you count pulling the cable out of the input and jamming it into the amp...)

Soffa

Bypass?  I wonder if you'd get even a handful of results searching the DIY section of the electro-music forum....in fact I wonder if you'd get one.     Funny, dichotomy, eh?

[soffa]

I'm traveling this week so the demo will have to wait. I thought I would be able to get it done last weekend but I started having a strange latchup problem with a module that I've been using for a while with no problems.

I got to thinking and decided I'd better check the supply current since I just added another module. running current = 191 mA.

I guess I'd better step up from the 200 mA "brick". I have a stouter supply but I need to wire it up. It has +/- 15V @ 1A as well as 5V @ 10A. Maybe I could use the 5V supply for a hot dog cooker module?

[Earthscum]

5V@10A... you could run a decent sized motor off that... slow carousel that spins you and your rig while you play the original Star Trek theme. 

Actually, I'd be using that to put a full LED matrix spectrum analyzer panel somewhere in there. Should be able to power up a 256x32 panel of 3mm LED's, and a bit left over to power some stage lights. Or step that up and make an electric fence to keep your fans at a safe distance (duck the bottles). 

[liquids]

Ignoring for a moment my tendancy to blow up regulators rather frequently, i've been using ray wilsons mfos bipolar supply schematic with TO~22O regulators and cheap ac wall transformerpower from jameco, smallbear, and/or any stash of power supplies you may or may not have been collecting since childhood....or maybe that is just me!  Anyhow, ive got 1000uf electrolytic and 10n/100n film (or ceramic) caps to ground on the input of the regulators, 100 or 220uf (10uf migbht be fine too) and 10n/100n film/ceramic caps to ground on regulator outputs.

And of course that is all on a small breadboard.  But such an arrangement should do 200ma quite comfortably.  Worth a try.  FWR center tapped transformer is even better.

Either way, figure 1.4x whatever ac voltage your txf will give you is what youll get when rectified and filtered.  I tend to get a little more ac voltage than most specify too and my wall voltage is 118 most of the time.  Most of the to220 regulators tolerate 35v dc at input and its a good thing for ripple reduction for them to drop a lot of already filtered dc voltage (i.e. dont hesitate to feed a 12v regulator 30v if its within it range and your capacitors  rating.  

I see no reason not to implement some streaming seizure-inducing light show or maybe some tesla coil type theatrics if you have that 10A 5v tap at your disposal.  Hope you breaker and the wiring in the wall on ye circuit your tapping is up for the task!  Might be able to impress the wife with a speedy potato cooker or something too......?

[soffa]

I finally got around to putting together a little demo:

http://www.aronnelson.com/DIYFiles/up/modular_demo.mp3

One disclaimer: I was just noodling around for an hour or so and then I edited it down to get snippets of some different sounds. There is no musically coherent content! 

[liquids]

 

[slacker]

Very cool.

[soffa]

One more thing - The clips sound way better (I think) on speakers that have some bottom end. Most of them are more of bass synth style patches.

I played them for someone on my laptop and I realized that the laptop speakers make it sound more like a Casio VL-Tone guitar synth than anything else!

[liquids]

Whats the bissell gate/trigger?

[soffa]

It is Harry's envelope follower circuit from EDN Design Notes with a preamp, an opamp comparator to get an adjustable gate, and a schmidt trigger to get a trigger (pulse) output.

One thing that can sound kind of cool is to send the pulse to the MS-20 VCF and make it resonate and ring down. I'm sure that modular synth guys do stuff like that all the time but it's new territory for me.