A quick note about solid ground connections and clean potentiometers

It's amazing how much better things work when you actually provide solid grounding for all of your jacks, and you use either nice new potentiometers or cleaned up old ones.

I re-potted my VCA and re-wired the "output" module to be a generic attenuator, with the input normalled to my VCA's output. (It's actually normalled to the VCA's normalled output, so if I insert a cable in the VCA's output OR the attenuator's input, it breaks the connection. Maybe overkill, but what the heck.) The attenuator is currently linear taper pot, which doesn't work well for audio, so I may wind up replacing with an audio taper if I can score one. It still works fine for audio output as it is, and linear will be better for its other potential uses.

I also changed 1/2 of my A/R EG's pots from 5MOhm to 1MOhm. This means the total envelope time is much shorter, but I can actually dial in reasonable short times. So now I can either do the long, slow sweeps in the 5-10 seconds range, or a more manageable <2sec sweep. I found that the Microbrute's trigger isn't strong enough to run both A/Rs at the same time. Bummer, but I don't feel like buffering the trigger inputs at the moment.

The only module I have left with the old pots in it is my LFO, and it's still a little dodgy. I'll swap out those when my fingers are less tired. :)

But Wally's renovations are just about complete now, and I can start worrying about new stuff. The last truly wonky module is my "interface" module, and I can probably just gut that and re-solder it to be a multiples panel.

... in which Wally gets a new outfit

Over the weekend, I did one of those "Ikea Hacks" to convert their unfinished pine end table into a studio rack mount unit. I wound up getting two of them and inverting one to get a 6-4-6 space unit.

Because I suck at blogging, I didn't take pictures along the way, but here's how everything turned out:

Here's my new Microbrute and my monitor speaker on top of the case. I used two cases, turned upside down and glued together, and then outiftted with Raxxess brand Rack mounting rails. I got the rails from Guitar Center because they (oddly) had the best price, though I did have to order the sizes I wanted.

The 4-space area in the center was about 1/8" too short though, and I had to sandwich a thin piece of wood between the two parts. I happened to have some suitable basswood around (don't ask), so a few minutes with a straight-edge, x-acto knife, and some wood glue fixed things right up.

I have everything connected to a "juice goose" in the bottom part so that  I can turn the entire rig on/off from one switch.

I think things turned out pretty well. It's HEAVY, but sturdy, and easier to deal with.

Here is a better view that shows how things are from the "working end". Sorry about the glare. The top 6 spaces has my VCO, VCF, A/R EG, a Ring Modulator and a blank panel. The middle 4 spaces has the "interface panel" and my FracRack. The bottom 6 spaces has the juice goose, a patchbay and my two analog Tama drums (analog drum voice modules.) The patch bay is currently there to expose the Tama rear-mounted jacks to the front so I can get to them. I had been planning to sell the Tamas, but I figured what the heck, they're the other pure-analog gear I have, so why not put them in Wally?

I need to find a decent solution for holding cables. I'm thinking about maybe putting either a container or some hooks on one side of the cabinet.

In the near-ish future, I'm moving into a bigger place, so I'll be able to set up a proper workspace where Wally doesn't have to sit on the ground. I may wind up re-allocating what goes where when that day comes.

But for now, I've been able to drive Wally from the Microbrute, and use both machines to cross-modulate each other. I even discovered that the MB's gate out CAN drive my A/R EG, just not both halves at the same time. So that's been pretty cool. I definitely need to do something about not having enough multis, but I can probably find a way to cross-wire that patch panel to act as a multi, if I can find enough patch cables to dedicate to the problem. If only this stuff were free....

I also tried hooking up my old PAiA Fingerdrum to the MB's gate in, which works as expected. I can manually advance the sequencer by banging on a key pad. Of course, I can also drive the Tamas with it, which was why I dug it out. I'm absolutely pants as a drummer though, so I'm seriously considering trying to make some sort of drum sequencing box, It would be relatively easy to make something like that with an Arduino, though I'd probably over-design it.

Once I get my "studio" into some shape, I'll find a way of recording some Wally sounds and post them.

I guess it's not DIY if you buy it, but....

I got almost no work done on Wally over my holiday break.

But I did get my new Microbrute SE (the blue one - pictures to follow). The Fates have conspired to keep me from spending too much time playing it, but I have managed a few necessary experiments. Here are my results:

1. The ARF VCO tracks the MB's v/oct almost exactly. That is, the ARF VCO stays in tune with the MB's VCO, at least over the ranges I tested. This is great news, as it means I can use the ARF VCO easily as a secondary oscillator. It also means I can consider retiring the PAiA MIDI2CV8, or reconfigure it solely as a trigger source. That would open up some spaces on the FracRack to be sure. I'll need to meditate on that some.
2. Wally's VCA works great with the MB's Envelope out. Which means I can use the MB's CV and ENV outputs to drive Wally directly. It was quite a kick playing Wally with a better EG than my admittedly ghetto AR generator. He sounds almost like a real synthesizer now. :) I guess if nothing else, that should convince me that Wally needs his own full-featured EG.
3. Unfortunately, the MB's gate signal does not seem to be able to punch my AR generator hard enough to make it go. This means I must use the MB's envelope output if I'm trying to play Wally. I suspect I can figure out what the problem is though, since my PAiA MIDI2CV's gate will drive the AR generator. I'll need to bust out some scopes and stuff for this though.
4. Wally's LFO doesn't seem to like driving anything on the MB. It's entirely possible that I'm just "doin' it wrong" somehow, so more experimentation is needed.
5. The MB is happy being played through my guitar amp, but of course guitar amps are EQ'ed for guitar sounds, so it doesn't sound as good as it does though my monitor speaker. But my amp's built in delay line (limited though it is) is fun, so I definitely need to look into picking up an MXR Carbon Copy or similar delay pedal.

What I haven't tried yet is patching my ARF VCO into the audio input of the MB, and just using it as a second oscillator. I have little doubt that it will work, but I suspect the signal will be much hotter than the MB is expecting. Hopefully the MB's input attenuator will be able to tame it enough.

I also need to try going out from the MB into my ARF VCF. I'm assuming the VCF will handle the MB's relatively weak signal without trouble. (MB outputs line level, but Wally internally uses +/- 5v signals, which are about 5x larger...)

I've also ordered some Raxxess rails to do an Ikea Hack like this one. I'm still waiting on parts, but I'll put up construction pictures and of course final installation pictures once I get Wally's panels moved over. I'm building it as a "double" with three sections 6|4|6. The plan is to put Wally in the top, the FracRack and JuiceGoose in the middle, and my non-modular stuff in the bottom.

Wally gets a little brother for Christmas

Looks like I'm getting an Arturia Microbrute for Christmas!

I know it seems like it's not much of a surprise, but I like to think of it as a surprise I know about early! My wife is getting it for me with some support from other relatives.

The thing I like about the Microbrute so much is that it has a patch bay and "speaks" the same voltage languages that Wally does. So this means that I'll be able to use Wally's modules to supplement the MB's features. Which is handy, since the MB only has one oscillator. Wally's VCO will mix in nicely, though I imagine I'll have to spend some time with the o-scope and tuner re-scaling the VCO to match the MB's range. (And tuning the MB's keyboard too - it should be pretty well in tune from the factory, but like with guitar action, I've heard that many MB's need a little adjustment to be perfect. No biggie, that's one thing I do know how to do.)

This does make some of Wally's new modules less urgent, thought I really need to get his scratchy pots cleaned up.

Fortunately, I have a few weeks of vacation coming up soon, and at least half of my time isn't already committed to being places other than where my toys are. Expect some pictures and maybe sounds in the next few weeks.

Ther perils of "almost there"

I've found that now that Wally is 90% usable, I find I'm more interested in playing ON it than WITH it. I've been experimenting with different wave shapes, feeding the VCO's sine wave back into the FM modulation jack, etc.

My current favorite setting is a PWM square wave with the pulse width lightly modulated by a random noise source. I've set the filter to very slowly come down over time so that if I play legato or sustain for a quarter note or two (assume 120-140bpm or so for my noodling around) the sounds mutes some. The random PWM makes the sound seem noisy, but not out of tune like it does if I feed that same signal into the Frequency Modulation. Hardly a revelation, but there you have it.

I still need to get that DeOxIt though, since a number of my pots are still pretty scratchy.

Also, I'm becoming increasingly interested in getting that step sequencer project (or the similar touch keyboard project) going. I'm going to have a little time off next week, so hopefully I'll have pictures of some new projects to post.

I haven't forgotten about you...

I just didn't have the chance to work on Wally last weekend.

Through a little experimentation, I've discovered that I DO need to ground the sleeves of all those new 3.5mm jacks I added. So that, and the new power cables are the next things on my list.

I'll keep you posted.

Frak, Jack and Roll

I promise I'll try to make better titles in the future.

Bolstered by my success with the ARF VCO and Fry's actually having some parts I want for a change, I decided to "finish the job" of re-jacking all the banana plug connections.

This is a view of the half and half stage, with the Noise module completed, but the LFO still rockin' the banana plugs. I started off with the noise module because it's the one I could most afford to mess up. As a side note, it, like most of my modules, is based off of the simple reverse biased transistor noise source, amplified and filtered to get "pink" noise and a random wobble. The "Volts" knob is just a 0v-5v constant source, which is sometimes useful for biasing a CV parameter or testing something out.

That reminds me - I did some tests with my oscilloscope to make sure I had a good understanding of what voltage levels Wally uses internally. My tests show that I do recall correctly - Most of my signals are in the +/- 5v range, with the envelope generator at maximum output swinging from +/- 10v.

Just so you can get an idea what my late-90's DIY work looked like on the inside, here's a shot of the rear of the LFO module. The orange caps are power supply bypass caps, and as you can see, this is a picture from before the banana plugectomy.

Finally, here is a close-up of the finished DIY part of the FracRack, now completely 3.5mm connected. The "Output" panel is not really a separate module. It's connected to the VCA's output jack. With the Vol knob at 12 o'clock, Wally's signals come out about line level, so he won't blow away my mixer's input bus.

I had a brief scare with the VCA. It stopped working during the middle of some testing. It seems that one of the ICs had a faulty solder joint. Hopefully, I won't have any more trouble with it.

Here's a kind of blurry (sorry) picture of Wally, sporting his new chrome-colored connectors. I still have the "1/4 to banana" adaptor panel (right above the ARF VCO) because I found that with cross-patching the banana plugs, I can use it as a 3-way multiple, and feed pitch CV into both VCO and VCF. I'll have to make a real multi at some point, but for now, this hack will work.

So right now, Wally has 7 rack spaces of usable modules, and a total of 9 individual functional units, if you count the dual A/R generator as two functions. Power distribution takes up 3 spaces, and there's a double blank in the FracRack and a single space blank right above the PSU.

With his current configuration, he can make some musically useful sounds, some cool wind effects, and some cat-destroyingly horrible screeches. When I get some time, I'll try putting together a video or something.

My next project will be to rework my power distribution scheme. Fry's had the molex connectors I need for the project, but I have some thinking to do before embarking on that project. Largely because the FracRack also has a PSU in it, and the MIDI->CV converter runs from a separate wall wart. Ideally, everything should run from the same "on" switch.

One other consideration - Ikea makes a nightstand that is exactly the right size to use for an 6 rack-space high enclosure. It can go to 8 spaces if you mount the bottom shelf lower. That would be a lot nicer than the open frame metal thing I'm using now, and for about $30 total, I can add some protection to Wally, as well as hopefully a place to mount the PSU that doesn't take up front panel space.

ARF VCO - No Bananas

Last night, I went ahead and performed the "bananaectomy/phonejackoplasty" operation on my ARF VCO. Sorry for the quality of the pictures. I'm not sure how to insert proper links to the larger images. Blogger seems to just want to use the thumbnail version.

The original panel was hand-drilled, hand-labeled, and fitted with banana jacks. Since this is a "free rack" module (that is, a 19" rack unit, not a FracRack or other sub-rackspace format), it's destined to get 1/4" jacks.

The conversion was both harder and easier than I was expecting - the banana plug mounting nuts were a bear to get loose until I remembered I had an appropriately sized nut driver in the garage. The wires however, were pretty easy to get loose. I wound up labeling them with masking tape so I wouldn't get confused about which wire went where.

I also performed the conversion one column at a time. Here's the view after the first column was replaced.

Grounding is always a problem with 1/4" jacks. Though they were mounted to a metal face plate, and that provides a common solid grounding point, I also decided to go ahead and wire each ground lug together. I "snaked" the ground through all the lugs, and attached a fly wire from the last one back to the PCB's ground area, approximating a star grounding configuration. I suspect this step was unnecessary, and my multimeter's continuity tester showed that the panel was already electrically connected to the module's ground line, but since my other ARF module wired all the ground lugs together, it seemed appropriate.

Here's the final back panel. After hooking everything back together, I returned the module to its home, and everything is working fine! I really do like the feel of phone jacks over bananas. It's so easy to repatch things that nothing gets in the way of sonic exploration.

The whole project took around two hours, including time for trying to find hookup wire and nut drivers. Not too bad, though now I'm out of 1/4" jacks, and future work will require actually spending some money. Alas, can't be a cheapskate forever. ;)

Here's the VCO patched up for a simple "play me a square wave mixed with a triangle wave, with vibrato added from an LFO" voice.

The one down side to this scheme is that I lose the color coding for the SYNC plugs, which are not V/Oct control voltages.

Stop Jackin' Around and Give Me Some Power

So my conundrum about how to reconcile the fact that Wally uses pretty much every different connection standard ever gained another twist.

I asked my wife (who is way more practical-minded about, well, everything than I am) for some advice. I'd been trolling the PAiA and Blacet websites, ogling FracRac format modules I can't afford (don't judge), when it occurred to me that most of my modules are actually 3.5mm jacks, and so are the jacks on some of the other gear that I've been lusting after (Arturia MicroBrute, Korg Volca series). Well, that's not strictly true, most of my jacks are Banana Jacks, but I'm almost positive that I want to move away from those.

"So," says my wife, "why not just use 3.5mm jacks for everything that's Frac format, and 1/4" jacks for everything else?"

Why not, indeed?

So that means I can convert the LFO, VCA and Noise modules in-place by swapping out their jacks. The ARF VCO will still get 1/4" jacks to match the ARF VCF and A/D Generator.

I'll need to get more 3.5mm -> 1/4" cables. I already have 3, and they work fine. I'll also need a fist full of 3.5mm patch cables. Blacet makes a cable kit I could use to get both, but I should shop around some. I also just discovered Stackcables, which makes banana jacks even less desirable. Though at over $8 a pop, I won't be getting a ton of these. :)

This leaves the question of power distribution. At the moment, the FracRack itself has a simple but effective +/-15v supply in it. Power from that is distributed by basically the same sorts of connections we used to use to power disk drives in computers. It turns out that that's a TERRIBLE way to distribute power to analog equipment. But what can I say, I was young and needed the milliamps.

My "big boy" power supply uses three screw terminal blocks (+V, Gnd, -V), and expects each module to have a 3 wire connection that can clamp down. Electrically, it's sound enough, but it's relatively hard to attach and remove things.

My old MOTM stuff had this great block sort of like this one, and lucky me, I found the extra one I had! So, clearly, it's time to retrofit my system to use the more stable and convenient connectors. Blacet sells a kit of headers and wire which I can use. I might be able to get equivalent parts from Mouser or Jameco, so I'll be doing some shopping.

So there you have it - 3.5mm jacks for my FracRack stuff, 1/4" jacks for my "free range" modules, and MOTM-style power blocks for everyone!

Time to start saving my pennies.

Touch Keyboards and Step Sequencers

Aside from module renovations, I'm also planning on creating some "modular synth" style controllers. I do have a MIDI interface which works well enough, but I've always been intrigued by step sequencers and "Serge Touch Keyboard" type controllers.

I'm still very much in the brainstorming phase, but essentially, I have two projects planned - a simple 8 stage step sequencer and a capacitive touch keyboard controller (TKB). I'll have a lot more to say about these in the near future, but for now, consider this a sort of "statement of intent".

I've also started a YouTube channel to put up some video reference for these projects. So far, it's just me running my finger over the pins of a touch sensor chip and a few linked videos of devices like I'm considering. I plan to shoot a similar 10 second video of the 4-stage prototype sequencer I breadboarded over the weekend. It's also just some flashing lights at this point, with a rate controlled by a knob, but it's progress.

My sequencer is based off of a 4017 decade counter and a 555 timer. Hardly a creative and unique design, but I need something simple for my first time. I'm planning to base it off of the version in Barry Klein's book, which in addition contains some logic to support external and manual stepping controls. I'm going for a single CV output, portability and the ability to run off of a 9v supply.

The TKB is similar - this first version is 8 stages with touch-capacitive plates to activate each stage. The stages will be individually tuneable, so the keys won't correspond to piano keys, unless you tune them that way of course. So it's a very small keyboard at the moment, but I'd like to save the expense of a larger keyboard for after I've discovered what's horrible about my design.

The TKB is going to be controlled by an Arduino, since I'm better with software than hardware. The sensor I'm using is an AdaFruit CAP1189. I'd like to build some sequencing features in as well, so you can either play it like a keyboard, set it running, or both. The Korg Volcabeats is an inspiration, as is of course the Serge TKB.

A side note about the CAP1189 - it seems from the datasheet that I could use the built in LED driver hardware to trigger the key stages, as the chip can be set up to output whatever values you want from those ports instead of echoing the touch plate sensors. I had originally planned to use 74HC595 shift registers, driven by the Arduino using data pulled from the CAP1189. But if I can use the CAP1189 for both duties, then I can save some board real estate and part counts.

Sounds like a good next step for the software part of that project.

A quick note about schematics

I'm not much of an analog circuit designer, though I did spend a few years in Electrical Engineering before giving up hardware for software. So mostly I adapt existing circuits. I do generally understand the principles behind what I'm building though, and I've made a few modifications here and there to basic designs.

Aside from the commercial kits, I got most of my schematics from the web and books like Terrence Thomas' "Sound Synthesis: Analog and Digital Techniques" and Barry Klein's "Electronic Music Circuits", which was heavily influenced by the classic newsletter, Electronotes. If I were going to suggest a single book to someone looking to do modular synth DIY, it would be Barry Klein's book. I've noticed there's a PDF of it that Google finds easily. I'm not sure if it's a legitimate copy though.

My dual Attack/Release module is almost exactly Barry's version, except that I put a Serge Modular inspired inverter/scaling control on the output. (It's a knob that takes the AR's output and lets you vary it from, say, a +5v signal all the way down to a -5v signal. So the AR's can subtract or add to whatever you send them to. Pretty neat.)

My LFO is a straight up copy of Barry's LFO With Variable Triangle Offset and Symmetry, with a two color LED mounted in it so you can see it swing positive and negative.

And my Noise circuit, which is really nothing special, is also clearly derived from the Electronotes simple noise source, which also appears in Barry's book.

I used Thomas' design for the octavizer/pulse divider module, with an added comparator to condition the input. It's still in the "half constructed phase", though a breadboarded prototype worked pretty well.

First Steps

This post is a more rambling discussion of the basic steps I need to get what I have working better. I naturally have tons of ideas for new projects related to Wally, but I'll do my best to stick to maintenance and renovation of Wally's existing modules. This is nuts-and-bolts stuff, but it needs to be said before I can get to more interesting topics.

Clean and Repair

Since Wally was in boxes for over a decade, and those boxes were stored in my garage, some parts of him aren't working at 100%. Pretty much all of his potentiometers are scratchy, and a number of wires had come loose.

The VCA and LFO are in the most serious need, with the other modules being only intermittently scratchy. Some DeOxIt should fix things up.

The Noise and Dark Star modules actually had some broken wires in them. I've already re-soldered them, so they're working well enough.

Side note: actually, the Dark Star wasn't working at all. In fact, I'd never gotten it to work, since it was one of my earlier projects. With a little help from the good people at Blacet Research (who made the Dark Star) and some diligent circuit tracing, I think it's mostly working now. It's a strange enough module that I'm not entirely sure. But it responds more predictably to its controls now, and I've managed to CV all the parameters successfully, so I'm going to say it's working now.

Tuneups

The MIDI->CV converter and my VCO both have a lot of trimmers in them. It seems like almost all of them need to be trimmed.

The MIDI->CV box has a trimmer that tunes 1v/oct sensitivity. If you know anything about guitars, it's almost the exact same thing as setting intonation - the pitch of each octave relative to the other. The goal is to get exactly one octave for exactly one volt. The control is VERY touchy though. I got it pretty close the other day, but it might still be off. It would be much easier if this trimmer was a multi-turn trimmer, but it's not, and the PCB isn't designed to make it easy to swap one out.

The VCO has trimmers of its own for mostly the same purpose. That's right, both the MIDI->CV and Oscillator can go out of intonation, and they both need to agree with each other. In addition, this VCO has a radial octave dial that lets you pitch it up or down an octave relative to the input control. At least one of these is out of tune with the others. That will be "entertaining" to adjust as well. Fortunately, Ric built these all as multi-turn trimmers, so I should be able to get very precise trim.

I suspect the VCF has a similar v/oct adjustment, but given my current inability to put pitch CV through to both VCO and VCF, it hasn't come up yet. :)

Circuit Upgrades

The Attack/Release module, based off of a modified circuit in the Barry Klein book, is pretty good, but the timing control pots are linear 5M ohm pots. While they have VERY long decay times, their precision for short times is touchy. They need to either be replaced with Audio taper pots or converted with that "add a parallel resistor" trick. Since the pots in that circuit are just "rheostat" type variable resistors, and I don't mind having my resistance cut in half, I think I can get away with it. Or maybe I'll just buy 4 5Meg Audio taper pots and be done with it.

Another upgrade is to replace the second AR's gate input jack with one of those "switch normal" jacks, and permanently hook the "normal" connection to the first AR's gate. That way, I can run them both with one signal, and only break the second one free if I plug in a second signal. I've hacked this with an alligator clip, and it's very useful. I need the different jack/switch part to make this a permanent change though.

I plan to do more with this sort of "normaling" in other places.

Much Ado About Jacks

I need to deal with the heterogeneous jacks issue. I can't really upgrade the 1/8" jack modules to 1/4", but I can replace the banana jacks in my VCO. The panel was already drilled for the larger jacks, so it's really just a monster soldering effort. There are 15 jacks to upgrade. Fortunately, I have 20 good quality jacks left over from the Old Days, so I can do the upgrade for nothing but time. I'll admit that the job scares me a little, since I've never been good at panel hookup.

The FracRack banana modules are a bigger problem. There just isn't the room to upgrade them in-place. I might be able to 1/8" jack them, but I think I might want to re-panel them.

FracRack Modules

These modules, specifically the Noise, LFO, VCA and Output modules, present a problem. For one thing, since they were the first things I had ever built, they're cobbled together on perfboard and not well mounted to their panels. They also have banana jacks, and can't possibly fit in their same sizes with the larger jacks. The FracRack is pretty tight for space as it is.

Consequently, most of this work seems like it's going beyond First Steps and into Next Steps. I'll need to keep these modules around, since really all of them are essential to Wally's utility as a musical instrument.

State of Wally, October 14th, 2014

At the moment, Wally consists of these units, from top to bottom:

• PAiA FracRack containting
• PAiA MIDI->CV8
• Blacet Research Dark Star Chaos
• Blank panel
• Noise (White, Pink, Brown, and a knob/jack that puts out a solid voltage)
• VCA (CA3080 based)
• Output (just a volume knob, decoupling cap and an output jack)
• 15v bipolar power supply.
• Juice Goose power strip (master control for Frac, MIDI->CV8 and other power supply)
• 1/4" to Banana Jack interface. Also has a simple CV pedal and foot switch interface.
• A.R.F. VCO - CEM based oscillator with a unique "wave slicer" that allow you to combine top and bottom halves of different waves. (Note, ARF is gone from the web, but here is a link to a guy with a lot of Ric's stuff.
• A.R.F. VCF - CEM based 4 pole low pass filter
• Dual Attack/Release generator with "+/- output" (knob that varies output level from positive to negative) Custom design from Barry Klein's book.
• Blank Panel
• 15v Bipolar Power Supply (much beefier than the little one in the FracRack, originally used to power the MOTM stack.)

I also have a Ring Modulator that is finished and an Octave Divider PCB that's finished and mostly just needs to be wired to its panel. The RingMod was made back when I had plenty of space - spending a whole rack space on three jacks and two knobs seems extravagant now.

With that stack, I can (and have) wire up a simple mono-synth configuration to play around with. I'll try to get some short video together sometime.

The frame I'm using is a 12 unit high "rack mount" frame, which is very cramped. Ideally, I'd have a box with front/back mounts, and move the power supply stuff to the rear.

Internally, my modules mostly follow the "Electronotes" standard - 15v bipoloar power, control voltages in the +/- 10 volt range, and audio in the +/- 5v range, though as audio, it will often have much lower range. I don't have a decent power distribution scheme yet - I just run 3 wire bundles to a trio of terminal blocks. The MOTM scheme was great, but unless I find a cheap alternative, it's too expensive to re-adopt.

One concern is that at the moment, the system is about half and half banana jacks and 1/4" jacks, with a few 1/8" jacks thrown in for good measure. This makes it very trying to connect things together. I'm disenchanted with banana jacks these days, and I like the feel of 1/4", so even though they take up a ton of panel space, I'm considering standardizing on them.

Why so many jacks? Historical reasons. Originally, I was planning to do everything with banana jacks, since they're cheap, reliable, and can "stack". But MOTM was all 1/4", and when I went to that system, I converted a few of my favorite modules (VCF, A/R). The VCO is a prodigious amount of soldering though, so I hadn't gotten around to that one before the Dark Ages struck. Likewise, the PAiA and Blacet stuff was 1/8" only, since it was designed to fit in smaller spaces. The FracRack was mostly put aside when MOTM moved in, though ironically it's back to being very important in the new system.

Introduction - Hello Wally

The purpose of this blog is to help me chronicle my efforts to create my own modular synthesizer - "Wally", short for "Wall of Knobs".

To be more precise, I began working on electronic musical synthesizers back in the late 1990's, and managed to DIY a few modules as well as built a number of Synthesis Technology's "MOTM" modules. By 2000, I had lost the drive, and a few years later I sold my MOTM modules and packed away the rest of "Wally".

Recently, I've experienced somewhat of a Renaissance in my interests, and I re-assembled what parts of Wally I still had around, just to see what I could do with him. The results were encouraging, and I've decided to resume work.

Here is what Wally looks like right now, spread all over my parlor:

Wally, a Theremin and some old TAMA drums, posing in front of the piano.
Excuse the mess.

Not much of a "wall" anymore, that's for sure. Maybe a nightstand of knobs. He was a lot more impressive when he was 3x that tall in a large rack enclosure with two rows of MOTM modules. The link above has a picture that's closer to the mark - the tall skinny one second from the right.

The "ARF" modules were built for me by a fellow named Ric Miller, and they're the majority of the working parts of this synth - the VCO and VCF. The PAiA MIDI->CV8 converter I built from a kit, and the rest is my design, done on a variety of perfboards and copper-clad boards.

In future blog entries, I'll discuss my plans, dreams, and progress. I hope you'll join me for the ride.

(And equally, I hope the ride actually gets out of the driveway.)