My Mini Moog Voyager. Click to go to my web site...

Friday, April 9, 2010

First Breadboard

I got my new breadboard/power supply today. First order of business was to hook up the UJT oscillator and see if I could make it work. Turns out the NTE6409 UJTs work great (but expensive, about $10.00 a piece). But, the 2N4891s I found don't work at all. I tried every combination of pinout, but no luck. I guess they are either bad or counterfeit. I'm going to try a 2N2646, too. It's 1/10th the price of the 6409.

Next, I need to figure out a way to voltage control the frequency. I'm thinking Nyle probably didn't use the UJT oscillator in his VC trigger generator. I suspect he did it this way in the Synthacon because it was simple cheap, and did the job.

I'm going to look at other VC pulse generators with VC PW and frequency.

I'm also going to hook up the VCO saw core to see if it works with the NTE JFET and if the 2N5163s I had and the NOS I found are any good. I don't think the JFET I use will have any real effect on the sound, but if I can, I want to use the 5163s.

Wednesday, April 7, 2010

Fun Times...

The fun never stops.

I ordered a breadboard with an adjustable +/- 0 to 15 VDC supply and a fixed 5 VDC supply. This means I can breadboard some of the more simple blocks to make sure the old parts work and I am reading the schematics right, (a bit faded over the years). Even the copies Nyle gave me at the time were hard to read. He also used some unique notation regarding panel connections and connections between blocks of the circuits. So, I want to breadboard some of the circuits to make sure I have them right before I spend the time to layout and pony up the money for PCBs.

I can also ensure that the "extra" circuitry works. For example, I'm adding circuits to convert to/from the S-triggers Nyle used.

I think I'll have the trigger generator breadboarded this weekend which will let me test the conversion and the UJTs.

Steiner-Parker on the road to reality.

My mid-life crisis is coming full circle. I think I have enough information to do my clone of the Steiner-Parker synthesizer I started to build in 1975 but never finished.

I can't remember how Nyle's name came to me, but as a teenager, 16-17 years old, 1975'ish, I had become swept up in synthesizers and electronic music. The typical artists like Wendy (then Walter) Carlos, Keith Emerson, Rick Wakeman amazed me. I wanted a Mini Moog, but it was way out of reach for me and my heart was set on a huge panel of jacks and knobs and patch cords. Regardless where I got his name, it turns out Nyle was my neighbor. He lived about 1/2 mile from me. I called him and told him what my interests were and he invited me over to his home. He gave me a tour of his studio; big modular, tape decks, mixers, the whole works. He gave me a demo of his prototype breath/wind controller. Amazing. Then, he gave me schematics on my promise I would not share them. Nyle was and I'm sure still is one of the most generous, kind, and just nice person I ever met. Even as the years went by and I ran into him, he always remembered me and took time to say hi and chat.

I worked that summer in his shop soldering PCB's. It was a lot of fun (my PCBs have the good, reliable solder joints :) ). I had started my home built synth and managed to get a keyboard, and oscillator going with big plans for other modules. I built a cabinet a la Moog and had my panels anodized and drilled. I also bought a Univox keyboard to satisfy my need to make sound. Then, life got in the way. School, 2 year mission in France for the LDS church, more school and marriage.

Despite life, my interest endured and I bought a Kawai K1 keyboard (which I still have) in 82 or 83 to see what the new synthesizers were doing. It was and is a fun keyboard, but it didn't have portamento which always disappointed me.

Mid life, 50's, and I rekindled my desire for a modular. I started by buying kits from Blacet Industries, and other sources. I emailed Nyle to say hi and to share the fact I was back into electronic music, loving it, and to say thanks for his help and patience. I realized over the next several months, though I love the new modules I was building, I really wanted my own Synthasystem. The one I started so many years ago. I scoured my mother's basement for the old schematics, very little remained after 35 years. I started an intense internet search, which yielded enough to fill in some blanks and to do the job.

The goal is to keep it as original as possible. I will make some minor updates, like using a monolithic matched transistor pair, like an SSM2210, for the VCO. I don't see a reason to live with the temperature drift problems notorious in VCOs of the time. Even Moog updated their VCO when they figured out how to make a more stable VCO, so I don't feel I'm violating the authenticity. Besides, I hand matched enough transistors for Nyle that summer I worked for him.

As for the other transistors, I'll probably use sockets for the transistors, too so I can swap in the vintage ones I still have with new ones just to hear if it makes a difference. I doubt I'll be able to tell the difference. I found my old stock of JFETs 2N5138s and 2N5172s I purchased in the mid 70's, and I think they are still OK. I also found a source for some NOS JFETs (2N5163s) and for the UJTs (2N4891s) Nyle used. If the old stock has deteriorated, I also have some new NTE cross referenced parts I'll try.

It will be built into 2 or 3 Euro size racks. I'm going to try to keep the general panel layouts the same, but more compact to fit well in the space. I'm also designing custom PCBs and panels for the system. I have what I need for the handful of modules which really have a distinct effect on the sound, at least in my opinion. This includes the VCO, VCF, Envelope Generator (Nyle's EGs were really quite unique and produced very distinctive envelopes), VCA, and to some extent, the sequencer. The other modules are mostly utility and while I'd love to have the Steiner original, I think modern equivalents, or vintage stuff from early Electro-Notes or other publications will do nicely, so long as the function and controls are the same or can be made the same or very similar.

To be fair, and in the spirit of my original quest, I don't think I would have hesitated to use other designs. In fact, I had already built a panning module as I loved the effect of each note playing through a different speaker, used sparingly and Nyle didn't give me any voltage controlled panner/mixer schematics. If memory serves, I think the only ones Nyle ended up giving me were a VCO, VCF, VCA, envelope generator, and the sequencer. I know for a fact if I had Moog schematics, I would have tried to build those, too...

But now, Moog cloning has been done to death, but Steiner-Parker has escaped the trend with the exception of his diode filter. I think this is attributed to the rarity of the systems and the fact the module most often associated with the voice of a synthesizer is the filter. I would argue that some other modules, such as the VCA and Envelope generator, while not directly affecting the timber, per se, they still have a profound effect on the overall response and feel.

There are the modules I will build first. The information comes from bits and pieces of the original schematics I have at long last replaced:
3 x VCOs type A (the ones with all the waveform outputs)
2 or 3 x VCFs
1 or 2 xVCAs
1 or 2 x Triple envelope generators
1 x Trigger generator (this one specifically is taken from the Synthacon with added discrete circuitry to add voltage control)
1 x Noise
1 x Dual Sample and Hold
1 x Sequencer
1 x Keyboard control. No keys here yet. Just part of the CV control circuits like the portamento control and gate/trigger outputs, so it can be used with a standard CV keyboard like the controller. I might undertake a whole keyboard in the future, but not to start with.

I plan to add these other modules, not Nyle's designs, but as close to his in function as I can.
Peak Detector
Voltage Processor
Voltage Follower
Phaser (probably Thomas Henry's design from "A Synthesizer for the 21st Century")

Lastly, in keeping with my promise to Nyle, I won't be sharing any schematics or PCB artwork, nor will I be selling any of it. If Nyle gives me permission, I will share them, but not now.

Stay tuned for progress...

I'll post updates as I go. I expect this to take the better part of a year.