It has been a long and twisty road to get to this point — it was a journey that began almost 40 years ago when a nerdy young teenager read an advertisement in Radio Electronics
magazine talking about the über cool (and surprisingly affordable) modular synthesizer gear made by this upstart company called PAiA Electronics
. I sent away for the catalogue (which I still have in a box of keepsakes in the basement as I have grown up to be a nerdy old man). I drooled over the stuff in that booklet for years, but could neither afford to buy nor justify purchasing anything from them.
Years came and went, and during the 80s, analogue synthesizers and related equipment fell out of favour to most (not to me, but I was otherwise occupied at the time). Through the 90s, the limitations of digital technologies were slowly being charted out, and there was a revival of analogue electronics for certain tasks. In particular, it was the nearly unlimited flexibility of digital synthesizers that presented the problem: the capabilities exceeded the abilities of anyone to master. Another problem with digital synthesizers was, ironically, limitations with their interface and of control. With an analogue system, you could (had to, really) "tune" the experience in microscopic increments; but with a digital system, by necessity, there were only certain discrete values that you could set a control to, and that limited the possibilities for subtleties in the sound. The advantage of digital systems was (and remains) that once you had a setting you liked, you could call it back (presuming you were smart enough to have saved it...) at whim and it would be exactly like the last time you used it — exactly like the last time, and the next time. And that was another limitation of digital: life is change and a digital patch was static and unchaging... it mimicked life, but was not alive. Analogue synthesizers and equipment are never the same way twice and will generally even drift a bit during a single performance (like a guitar going out of tune as the humidity or temperature changes)... it really has a life of its own and that's where it is an instrument that can be part of a performance instead of being a computer that just cranks out a sound at command. I have a lot of digital equipment, and I love the heck out of it, but there is something to be said for having organic components (in the metaphorical as well as literal sense) in a performance.
In late August of 2014, I was finally able to "justify" the purchase of a piece of equipment I have wanted for a long time by the simple virtue that I had (barely) enough money to do so, and had decided unilaterally that I had displayed sufficiently notable restraint thus far — thirty-six years is a long time to wait, and enough was enough! I ordered a PAiA model 6710 Vocoder kit
(with the optional front panel cutout, but no power supply... a detail that will become important later in the story). Last year was pretty much absolute hell for me and was a non-linear slide into full burnout by the end of it. I did a lot of really cool stuff related to physics and my academics, but my actual academics definitely suffered as a result and I ended up getting extremely ill in April and through much of May (picked up some nasty flu virus or something and it laid me flat for six weeks... might even have been viral pneumonia, but the doctors I saw never really figured out what was going on with me [but that was one wild-ass guess they made]... gave me antibiotics that did nothing, thus my supposition that it was viral whatever it was). I actually failed a critical class and I now don't know whether it's going to take me one year or two to finish my degree(s)... not a great feeling, but I'll make the best of it either way, just like I always do. All that to say that it should come as no surprise that I didn't finish assembling the kit until my break from school in December 2014. It was a pretty gnarly assembly job (there were so many wires
!) but I only made one assembly mistake (a polarized capacitor put in backwards), and I caught it with a close visual inspection as part of the assembly process. Overall, it was good to be soldering stuff again, I truly enjoy doing that sort of thing with my hands!
Now remember that power supply thing I was mentioning earlier? Yeah... that. I have spent much of my life around electronics and power supplies and whatnot, so I didn't bother ordering PAiA's power supply kit
. To be honest, I just don't like the looks of it with its wall barnacle and open board (and $50US price tag). I figured I would just go out and buy a nice little +/–15VDC power linear supply locally, or just pick up the parts and do it myself. Let me rephrase that, I mistakenly
figured I would just buy one or the parts. A lot has changed since I last made a +/–15VDC power supply... like everything has changed and it's literally impossible to get the parts locally anymore to do that sort of thing. There are companies like Digikey that will ship components to Canada, and they are quite reasonably priced, so there was always that to fall back on (the shipping will kill you though... I remain convinced the package delivery service in Canada is run by the mob, or at least some sort of monopolistic, price fixing, conspiracy... when it's cheaper to ship something from Bangalore, India to here than from Toronto (Canada), you know there's a problem... but that's another story I guess). I went to one of the few remaining "electronics" stores in the city (Active Electronics) and discovered that they didn't really sell electronics anymore, or at least not any of the components I needed. What they did
do was sell Arduino and Raspberry Pi boards and their ilk and related kits and shields (which they do very
well, for what it's worth). I did manage to pick up a little hobby box from them though and decided that I would just recycle an old +/–15VDC power supply that I had designed and built many decades ago (if it still worked).
job took me forever to get to and even after I found it in my boxes and boxes of boxes of boxes in my basement, I just didn't have the energy or willpower to actually sit down and test it until sometime in May 2015. Long story short, it did work just fine still, and would fit nicely in the box I bought. Short story long? Anything by Dickens. The problems of moving forward and actually putting the power supply properly into the box were legion though, and involved many dozens of hours sorting through things in my basement to find the tools and parts I needed to complete the job. This is something I'm working on anyway, so the work is all part of a longer project, but it does mean that I was not ready to actually start the assembly of the power supply until about mid-June. Sigh. The good news is that most of my tools and bits of hardware are now in known locations to me instead of being spread around in dozens of hidey-holes and boxes and chests and cabinets and rooms. It still probably took me 40 hours of effort to actually machine the enclosure, wire and assemble the electronics into it, and finally test it... which is too long for a job like that, imho. Did you know that the LM7815's case is ground
, but the LM7915's case is input
so if you don't have thermally conductive but electrically insulative pads and hardware with which to mount them to the chassis for heat dissipation you short the output of the transformer to the electrical ground and fry everything? Uh, huh... I was wondering why I had used those pads on the original design... good thing I double checked and repeated the procedure, and triple checked with an ohm-meter before turning anything on (I'm pretty good, and very careful, at this stuff and most of what I build works the first time). I finally got it all together two days ago and solved one little stability issue with the negative supply output yesterday (all it needed was a 10µF tantalum capacitor on the output) and it was the most beautiful and quiet (from an electrical perspective) linear power supply you'll ever set eyes or oscilloscope on (very low electrical noise is critical for analogue electronics because any power supply noise will usually appear as a signal on its output... which is why I could not [or at least would not] just pick up a switching +/–15VDC power supply... they're just too noisy electrically).
Once the power supply was assembled and tested, I finally added power wires to the assembled vocoder and installed the integrated circuits into their sockets on it (I had kept them safe in a bag until I was ready to do the testing). It's funny how little techniques learned decades ago and not practiced in many, many years come back to mind. Here, in specific, I'm referring to the technique of pressing the sides of the integrated circuits onto a flat surface to bend the pins from the angle they are shipped with to the straight up and down position that is needed to insert them into sockets. I guess it's like falling off a bicycle: you never forget how. I powered on the vocoder and no smoke poured out of anything, so far so good! Since there are no indicators or anything on the unit, the only way to test it was to actually hook it up and give it a whirl. To get a good effect, you need a raspy/grumbly sound as the "instrument" and I hooked up the little Yamaha digital synthesizer I have (it has many, many preset sounds that would serve perfectly). I also got out one of my crappy microphones and hooked that in as the control signal (the power envelope of the control modulates the sound of the instrument being used, and that's how you get the "vocoder" effect). The output went into a little guitar amp I have and with a little tweaking of the knobs... it worked! I finally have my very own vocoder and I am very, very happy (and now I sound really cool too)!
Here's the assembled vocoder kit itself (ugly as sin inside with all those wires):
Here's the guts of the power supply I designed, built, redesigned, and rebuilt:
And here's a photo of my test setup for the vocoder, it works like a charm!
I will be playing with it a little more today (and into the evening), but then it and all the related equipment, tools, parts, and such will be moved into the basement to wait for when I am ready to set it up in the recording studio space I'm setting up in the basement (that's part of that longer-term project I mentioned above). I am so
looking forward to getting my dining room table back, and I know Beep and Happy can't wait to see my shit gone from there as well! Going forward, I will eventually have room in the basement to do this kind of work and won't need to repeat the "middle of the main living area workspace" experience again (or at least not as often or as drawn out timewise... but sometimes working on stuff in a social environment is better than putting away in a cave). Anyway, I'm off to make more cool noises and learn some of the techniques needed to get optimal and interesting sounds out of the thing (the one page operations description that came with the kit suggested a week or so of farting around with it should provide a sufficient basis to use it competently as a real instrument... the secret, apparently, is the sounds you feed it (both as instrument and control... using synth drums as control instead of voice was one thing suggested that sounds really, really cool), and learning how to play with the various levels to get the effect that's right for what you want). It also has an effects send/receive loop that I can use to add other effects on the control (e.g. my voice) to the mix, so I will be playing with that as well eventually.
Now, back to working on my differential equations homework (I have a test on Wednesday) and studying vocabulary words and grammar (last Thursday, I started my class on the Anishinaabewin [Eastern Ojibwe] language for beginners I'm taking as well this summer).