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.