Project update

Project update:

First, some rather poor photos of my current setup.

Left Cabinet, left to right, top to bottom:

1. Voltage Processor/Mixer, Dual Sample & Hold, Peak Selector, Sequencer
2. 3 VCO Type A, 4 waveform outputs each
3. 3 sets of: VCO Type B - Saw/Square, VCF
4. Oscilloscope (www.Gabotronics.com XMega Xminilab)*, Ribbon Controller
5. MIDI controlled DuoPhonic keyboard, Trigger Converter, Resistor Ladder controlled DuoPhonic keyboard connected to ribbon controller.

Right Cabinet, left to right, top to bottom:

1.   Sequencer, Frequency Divider
2. Dual Voltage Follower (Slew), VCO Type B - Triangle/Sine, Selective Inverter, VCO Type B - Triangle/Sine, ENV VD**, VCA/Mixer, Input Amplifier
3. Voltage Processor/Mixer, VCA/Mizer, Triple EG, VC Trigger Generator, VCA/Mixer
4. Multiple, Dual Voltage Follower (Slew), VCA/Mixer, Triple EG, VC Trigger Generator, Panel Power Output
5. Noise, Phase Shifter, Ring Modulator, SynthTech Moog 904A Clone***, Dual Voltage Follower (Slew), YUSynth Moog 914 Fixed Filter Bank Clone****, Tuner/Monitor, Stereo Monitor*****

 The controller is an Arturia "Analog Experience THE LABORATORY 61" keyboard, I liked the wooden end caps and it's a great controller for my Arturia modeled analog synthesizers. As a side note, the Arturia Mini Brute Page, Mini Brute Details, about half way down has a photo of Nyle in front of a modular system you might recognize :)

Notes:

* Gabriel at Gabotronics.com has some really fun oscilloscopes and the Xminilab just begged to be put behind a panel.

** ENV VD

 The ENV VD is a Steiner design which I don't think was ever released. At least Nyle can't remember ever selling one. He explained it was a more "traditional" design to compete with the other guys. When the "DAMP" switch is in the up position, the DAMP knob controls the final decay, otherwise the DECAY knob controls the first decay to the DURATION LEVEL, and the final decay. The DEL/ATT switch changes the function of the ATTACK control to a delay to the start of the envelope and then has an immediate attack, like the ENVDT design.

*** and **** MOOG Module Clones:

The next two modules with asterisks are not Steiner designs of modifications of a Steiner design and technically, they are modern clones of the original MOOG designs.I'm including them because I know that back in the mid 70's when I started this project, I would probably have tried hard to get a MOOG filter, and maybe some other modules. My goal was to have the equivalent of a MOOG 55 system. Even though Nyle had his voltage controlled filter, I probably would have eventually tried to get my hands on a MOOG filter and the FFB because the 55 came with a FFB. It also came with a Dual Trigger Delay (see below). So, I added these two wonderfully designed modules to the system. At some point, I may actually try to do my own clone of the 904A, B, and C as well as the 914 using the original parts, but that is down the road. I may just buy them from COTK or MOS Labs and try to jam them into the Euro format I've chosen. Not too sure about that however...

I also have another Jurgen Haible Frequency Shifter which is based on the MOOG/Bode frequency shifter design if I understand it right. I might want to add that as well. We'll see.

*** MOOG 904A Clone:

I thought it appropriate to add a MOOG filter clone and Paul Schreiber's designs are wonderful. Give SynthTech a look, www.synthtech.com.

**** MOOG 914 Fixed Filter Bank (FFB) Clone:

OK, so I also wanted a fixed filter. Yves Usson's Fixed Filter clone is really excellent. I love that he split the cells. It gives a very cool left/right effect. yusynth.net/Modular/index_en.html

***** Stereo Monitor:

This last module with an asterisk is based on a Steiner design. I took the Tuner/Monitor Nyle designed, got rid of the "Tuner" and doubled the "Monitor". It makes for a great output interface to my DAW and keeps true to the Steiner designs.

OTHER PROJECTS:

Trigger Delay:

There were a couple of modules Nyle never did design and were ones I would probably have purchased or cloned back in the mid 70's when I started this whole deal. My first project one is a MOOG 911 Dual Trigger Delay which was included in the MOOG 55 system. Not too exciting, and Nyle has a delay built into the ENV DT and ENV VD, but it's a pretty straight forward design and fits nicely into a 1 unit wide module.

Pratt-Read Keybed Clone:

I'm still wanting to make a "real" Steiner keyboard. I found Gino at www.en.gino-midi.nl/index.htm. He is a DIY electronic organ builder and came up with a kit involving a silver plated rod, flexible phosphor bronze contacts, custom PCBs and (unfortunately) a custom built keybed. But, I have hope. I purchased a "contact kit" and when it comes, I'll have a good look at whether or not I can modify a modern, easy to find keybed with his parts, or something similar. Then, I can build the DuoPhonic electronics into a custom keyboard controller and fore go the MIDI conversion. I'll still keep the MIDI to Steiner module because it is just useful to interface to the modern world.

Microcon:

Chris at www.synthcube.com is going to be selling Microcon kits. He really does a nice job with them and I highly recommend you look at his site. You'll see he is also carrying the SynthTech MOTM modules and DIY parts.

I'm still selling the bare PCBs, but Chris makes it very easy with a complete kit.

Music?:

There you go. I've actually had a break from building and have been tweaking knobs, great fun. I can't call it music, but it is the icing on the cake for me. 40 years after  I first heard a squawk out of a breadboarded VCO and keyboard, I've pretty much finished it.

Stay tuned. I will post some updates from time to time and hopefully audio/video of what I'm doing. I also an trying to learn Adobe Dream Weaver so I can get the website updated and cleaned up.

Thanks for the interest.
David

Micron PCBs

OK, so I finally figured out how to get back to my blog so I can post...

I received what I hope will be the production PCBs for the Microcon. I stuffed one and gave it to Nyle to test. He should be through with it within a week or so. Then, I'll be ready to sell the PCBs, so please stay tuned. the initial tests on the last prototype were great. Nyle found some layout errors and made some suggestions which are reflected in the latest layout.

Sorry to be absent, but good things come to those who wait :)

Duophonic Module Assembled

Module before racking

Module in the rack and working

Doepfer MTC 64 MIDI to TTL voltage converter

The High Octaves reed relay PCB which sits under the Dopfer MTC 64 board

Top view of module. Top to bottom: MTC 64, HIgh Octaves relay PCB, Low Octaves PCB, Duophonic PCB

Side view of module. From left to right: MTC 64, High Octaves relay PCB, Low Octaves relay PCB, Duophonic PCB.

Side View of the module. From left to right: Duophonic PCB, Low Octaves relay PCB, High Octaves relay PCB, MTC 64

The Duophonic Keyboard PCB is fully working and it is sweet. This was the first "module" I built when I originally started this project in the mid 1970s, so it is fitting it is effectively the last module in this resurrection project. It is big and deep. Using reed relays instead of solid state relays meant I had to split the Pratt-Read keybed emulator into two PCBs instead of one. But the very low resistance and zero leakage of the reed relays made it worth the trade off.

If you have an old Pratt-Read keybed, or another switch-per-key on a common buss device, you don't need the relays or MTC 64. You can make a resistor chain on the switches, like in the original and hook it up. You can also make/configure your own custom controller to drive the keyboard electronics.

Essentially, here is what is going on. The MTC 64 takes a MIDI note on/off and turns on an individual TTL level (or turns it off, you can configure it) for each note number from 0 to 63. I take 0 through 60 (for a standard 5 octave controller with 61 keys) and connect each one to its own reed relay. This acts like the buss/key system on the old keybeds. On the other side of the relays is a resistor chain so that when a key is pressed, it taps into this chain and sends this signal to the "buss" input into the electronics. So, the Duophonic electronics sees exactly what it expects, a voltage divider resistor chain, just like the old Pratt-Read keybeds.

This particular module acts like a MIDI to Duophonic Keyboard converter, but there is no reason you can't just build the Duophonic electronics into a dedicated keyboard, or even an external module.

The Duophonic Keyboard was pushing the technology at the time when most others were still using monophonic keyboards. The Duophonic was  both a low note priority monophonic keyboard and a two note keyboard.

There are some interesting "features" of this particular keyboard. The upper voice tracks the lower voice when an upper key is not pressed; there is no sample/hold for the upper voice due to the way it's generated.

Next, you can either have a new trigger/gate on each low key press event, or only a new trigger/gate when the previous key is released before the next key is pressed. Nyle calls this legato or lift playing respectively. The upper voice does not generate a gate/trigger.

There is a pitch bend knob. I chose to make this a big knob with a finger spinner to make it easier to turn. Also, because the pot is not spring loaded, I chose one with a center detente to make is easier to feel when I was back to center. Nyle added an electrical dead spot in the Pitch Bend, too so if you miss the detente, you will still be OK.

There is a Portamento knob, and I added a jack for a normally closed foot switch so I could dial in a Portamento and then hit a foot switch to activate it.

There is also an Auxiliary Scale which can be tuned for other scales and it can be switched in and out.

There is a reverse switch reverses the keyboard, and a Range switch lets you shift the keyboard output up or down by octaves.

Now I have all the pieces to my Synthasystem, I'll try to get some additional video/audio up of all the pieces working together.

Next, since the keyboard is done, I'll start ramping up on the Microcon!

Duophonic Electronics Work!

Here's a shot of Nyle after he and I had checked out the duophonic keyboard electronics. Hmmm, looks like the scope is off. No wonder we couldn't pick up a signal...

You can see some of his original Synthasystem modules in the left corner.

The Duophonic electronics all work and I've ordered some production PCBs. Next step is to figure out packaging and finish the panel.

Update on various projects

While quiet, I have been busy.

First, I have a second run of the Duophonic keyboard PCBs in and will stuff one this weekend hopefully. I have a couple of solutions to turn a MIDI keyboard into a pseudo "buss" type keybed so it can drive the duophonic electronics. Despite all the MIDI 2 CV converters out there, none create CVs, gates, and triggers the same way the Steiner Duophonic electronics did. So here the gist of the conversion process.

1. Use a Doepfer MTC64 which basically converts a MIDI "Note On" message to a TTL voltage. There are 64 outputs so you get 64 individual 5 volt gates which can drive an external device.
2. Use the TTL level signal to turn on either a solid state relay or a reed relay which acts as the buss switch. Build a series of 61 of these relays to emulate a 61 key keybed with a voltage divider connecting the switches.

I've fiddled around with this and the reed relays seem to offer the most promise, but it's expensive at a couple of dollars per relay. The solid state relays are more compact and have a great turn on time, but there is a decay on the turn off time as well as higher effective contact resistance. So, I think the reed relays are what I will use.

Next, I have the first Microcon prototype PCBs in. I just need to build one and test it.

I would also recommend this blog:

Synthasystem DIY

He's done a great job and has some great comments and advice. Thanks!

Selling more stuff

I'm selling some more redundant modules. Since I've got the Synthasystem, I don't use some of the other stuff I own, so off it goes:

All Blacet this time:
Binary Zone
Hex Zone
I/O Module
Mini Wave with Socket Rocket EPROM
Window Comparator

They have no reserve and a Buy It Now price which is less than the kit price. Have fun.

Microcon and Duophonic keyboard update

Some small progress on the Microcon front. I ordered some prototype PCBs this week. I'm sure the layout will change some as I want to make it easier to add a couple of more panel pot options. Nothing drastic, but it will change it. But, this one will be a good test to confirm the design is working.

I'm also sending the Duophonic electronics to Nyle to test. I just will not be able to make time to do it anytime soon and I want to confirm it works so I can get a production run of PCBs ordered.