Just one more synthesizer, I promise! :)

 Just when I'm sure I have the synthesizer collection I want and need, someone releases something that "I've been wanting all my life!" For several years, there have been rumors Korg would re-issue the ARP 2600, but I never heard or saw anything solid until last January. Remember the leak? I immediately emailed my contact at Sweetwater and got on the waiting list.

A little back story. In 2018, I bought a vintage ARP 2600 because it seemed no one was going to do a real re-issue. The TTSH was around and I built one. There were clones of the filter and VCO. But never a 1:1 clone of the original. So, I watched ebay and an amazing 2600 came up. I won the auction and never looked back. I also bought a vintage 3620 keyboard ( and a spare one) and restored it. New sliders, new case, cleaned the contacts, new bushings, and adjusted the keybed.

The 2600 was and still is in excellent condition. The tolex, panel, electronics, everything was and is in great shape. That said, there had been some sketchy work done that needed to be addressed. First, the power supply had come loose during shipment. Fortunately, the wires connecting it prevented it doing any damage inside. Second, there was one clearly wrong jack installed and several others with very poor soldering suggesting they were either replaced or the wires had broken. There were some wires to the power supply which were also very poorly soldered.

RANT... Just use the right parts and take the time to do the repair right if you're going to do it at all. RANT over...

I replaced the incorrect jack and the ones with bad soldering with the correct Switchcraft 41A type, re-soldered the power supply, replaced the polarized capacitors on the power supply, adjusted the output voltages, and tested all the sliders and normalled connections. Some sliders were a little "rough" sliding, and a couple were a little noisy. Given the overall excellent condition though, I opted to use just a little DeOxit rather than risk causing more harm by disassembly and cleaning or replacing the sliders. The DeOxit fixed it at least for now. There were also several jacks in the voltage processing section which I replaced. All of the closed frame Switchcraft jacks seem to work fine, but I have a stash of those which I used in my Synthasystem re-issue so if one fails, I'm good to go. The open and closed frame jacks and tini-jax plugs are still being made so it isn't difficult to get more.

Back to my new synthesizer. If I already had an excellent example of an ARP 2600, why by a "new" one? I don't have a good answer. I suppose in part it's because I love vintage gear but I love the reliability and support that new gear offers. Right now, my studio is mostly "new" old gear. My Synthasystem, my Model D re-issue, my Model 15 re-issue with the additional Synth-Werk modules, my Odyssey re-issue, and now my 2600 re-issue. I have yet to put the old and new side by side, but just on its own, this new Korg ARP 2600 is amazing. I'll put up some photos and hopefully some video soon. I don't think one can really fairly compare the re-issue with the original be it the Model D, Model 15, Odyssey, or now the 2600. Assuming the actual circuits are the same, using the same or substantially similar components, they should be very similar. All these systems evolved during their production, though. The Model D VCOs were improved, the 2600 VCF and VCOs were changed. Tolerances in components make a difference even between two systems built right next to each other. The experience of music is very subjective and can be colored by many different psychological and physical circumstances. For me, the bottom line is this new Korg ARP 2600 FS sounds wonderful.

More Updates!

 In response to some other interest in Steiner synthesizer gear, specifically the Microcon, I've added some clarification to the Microcon page regarding the DAMP switch and wiring. Please visit http://analoguerealities.com/projects/steiner-microcon/ for the details. Nothing too dramatic but I think there has been some confusion on this switch. Nyle found an error on the schematic regarding the wiring of the DAMP switch which was built into the Rev 1.2 PCBs. The fix is just swapping a couple of the wires on one side of the switch. The Rev 1.3 PCBs corrected this error and can be built as shown in the 1.3 schematic. I hope this helps.

Updates!

I updated the Moog 914 FFB project pages. I corrected some issues on both the GIC and inductor versions, nothing major. It's a simple removal and/or replacement of a few components. I also re-designed the layout of the inductor PCBs to accommodate inductors from CineMag. These are excellent inductors and are the same ones supplied to Moog for their re-issued 914 and 907 FFBs as part of their modular system resurrection. Please go to the website, analoguerealities.com, and click through to the 914 project. Contact me if you have questions.

I also added some new photos to my studio page, enjoy!

I thought I should add some kind of update to confirm that I am still here and going strong. I really need to get some videos together because I think I have some very interesting gear that should be seen and heard and compared. A good example is delay modules. I ma fascinated by these effects. I have a Blacet Time Module, Doepfer analog delay, two Moog Mooger Fooger delays, a TipTop Audio Z-DSP, and a T-Rex Replicator tape delay and I just ordered an Oakley ADR30 analog delay kit using the venerable MN3005 BBD chip.

I have also added some gear of late including a T-Rex Replicator tape delay, DFAM, Erica Synths Graphic VCO, and other gear. I also finished my restoration of a Moog 1150 Ribbon controller and am negotiating the purchase of a restored Moog 1125 Sample & Hold.

I'm most excited about an order for some modules by Synth-Werk! Gerhard has put together some amazing Moog clone modules following the original schematics, adapted to a "Dot Com" power connector for ease and compatibility, but still able to be used in vintage and the newly reissued Moog modulars! Really brilliant. He will even add S-Trigger connectors to those modules that use triggers for complete compatibility with vintage gear. I ordered a 921ABBB module set to augment the 921A and two 921Bs in my Moog Model 15. I also added a VCA, EG, HP Filter, Dual Trigger Delay, and Envelope  Follower, with S-Trigger connectors where appropriate. I also bought an "extra" 921B which I want to put in the Model 15 so I have three 921Bs instead of just two. I'll probably put the Moog Attenuators module in the expansion cabinet to make room for the third 921B. I have a second Dot Com Q960 sequencer with Sequential Switch, Sequencer Interface, and Quantizer that I will install with the Synth-Werk modules in two expansion cabinets, again from Dot Com; an "8 Space" and a "16 Space" cabinet that will sit nicely beside the Model 15. I can't wait to get it together and fire it up.

There are also other projects and gear going on in my shop/studio that I just find fascinating and would like to highlight and share on my YouTube Channel. I have a nice collection of HP calculators with and without modifications. I have acquired some very useful test gear, I love oscilloscopes, and other things. Bottom line, I'd like to share some of this, so I hope some decent videos will be forthcoming... stay tuned.

PCBs are here

I received my large order of PCBs today. As soon as I can unpack and make sure they're right, I'll update the website www.analoguerealities.com, with the new inventory.

David

Nyle came by today, which is always a treat. The occasion was there is a documentary being made about him and his life. Part of that life crossed mine and so I got to be a small part, too. When the documentary is finished, I'll post a link if it's allowed. It was a lot of fun. Nyle played his EVI hooked into my Synthasystem. Then, Nyle (and I) played around with it having fun (mostly Nyle tweaking the knobs). The photo on top is just a sort of long shot while the crew was setting up lights. The one at the bottom is Nyle himself in front of my Synthasystem.

New Web Site and Web Log

My new site is running on about 1 of 8 cylinders, but it is useable. The old web site is officially closed down and the new one Analogue Realities is taking over the duties. It's also a Web Log, so I will be making most updates there, but posting links here so those who follow this blog will get the news.

Thanks and Happy New Year!

Audio for 914 comparison

Here is audio comparing my 914 to Yves Usson's design. I compared the inductor version. There are a couple of things to remember:

1. Yves uses two cascaded filter cells, each one having the same cutoff frequency but different "Q". Mine has two cascaded filter cells as well but also follows the Moog where the first cell's cutoff is a little lower than the second cell's cutoff. The "Q" of the second cell is essentially fixed with a resistor and the trimmer on the input to the first cell is adjusted to change the overall "Q" to get a "Q" of 3.7 (per Yves' research) which seems consistent with the component values on the Moog schematics (although there are a couple of errors on those schematics, no surprise). One glaring is a missing resistor on the second cell which sets the "Q". Somehow, Jurgen missed this. I caught it when I was unable to get a close visual match to the Moog frequency response curves so I did a detailed study of the only photographs I could find of the Moog 914 and worked through the math.
2. The Moog has a fixed high pass filter with an effective cutoff of about 60Hz (if memory serves me) between the summing node of the filter cells and the input to the output amplifier. The 907 did not have this and I don't think Yves included this on his 914, but I could be wrong. Jurgen included it on his 914. This affects the low pass cell response.
3. Yves changed the 700Hz cell to a center frequency of 750Hz.
4. I think the actual cutoff frequencies for the HP and LP cells are a bit different in my 914 as opposed to Yves.

In the audio, my 914 is in the left channel and Yves' is in the right. There is some kind of funky echo or ray gun sound at the beginning of the audio. I have no clue what artifact it is. I recorded the two using a Tascam DP-24. The output of each filter was fed directly into the DP-24 with no additional EQ, or other modification. I'm driving the filters with the same sawtooth from a Steiner Type "A" VCO whose frequency is driven by a sine wave from a Steiner Type "B" VCO. The resulting audio files were mixed down to a stereo track using the DP-24 then uploaded here.

I start with all cells and let you hear the YU 914 alone, then mine. I then take out each cell one at a time HF down. I then compare each cell one at a time. I end by adding all the cells back in and then letting each filter play on its own again, YU first then mine. Saw tooth with frequency swept by a sine wave.

The most exciting 4 minutes of synthesizer sounds you will ever hear! :)

Here is a link to the uncompressed audio. It's 40 MBytes.

AR 914 v. YUSynth 914

Synthasystem VCF

Ronny just finished a build and here are some photos and excellent modifications he made. Thanks for sharing Ronny.

Ronny wrote:
"- I added a second CV potentiometer.

"- I omitted the switch and added three separate attenuator potentiometers (25k)
  for the three inputs (LP, BP, HP). They sit before the 47k resistors. The 47k resistors
  connect directly to the former "switch outputs" now. This enables to get a kind
  of all-pass characteristic when mixing the same signal to multiple inputs or to get
  a kind of frequency-dependent interpolation with different input signals. I also like
  to add a bit of HP while primarily using the LP. I normailzed the "BP in" and "HP in"
  connectors to "LP in".

"- I used 330nF instead of 1.2uF for C10 at CV in to reduce drifting with steady CV
  and to enable faster modulation. Maybe I reduce it even further.

"- I drilled a hole into the Power PCB to easily adjust the "CV reject" trimmer without
  taking the filter apart. Luckily there was just a ground plane at this position on
  the power PCB that could be drilled without damaging something.

"- I had to omit the nice Steiner wave logo on the frontpanel, but added a little hint
  to you "DI" and me "RV" :-)

"Here are some other build notes that might be of interest for you:

"- feed it with +-12V in a Doepfer Eurorack system, but reduce -12V to -10V with
  your Power PCB, also use the filtering on the Power PCB (V+, V-)

"- used SSM2210 and 2N5172 as specified
 
"- used two 2N2907 with HFE of about 140 instead of the PN5138 (HFE measured
  with a  medium-class multi-meter)
 
"- had to use linear potentiometers for everything, because I did not get logarithmic
  ones of this size, but this still feels fine

"- used a trimmer having 200 Ohm instead of 250 Ohm, works fine

"==> self resonance starts at about 2 o'clock resonance potentiometer position, this is fine
" ==> have no problems with power noise, crosstalk or whatever"

Thanks again Ronny.

Moog 914 Fixed filter Bank progress

914 Clone and studio

914 clone, Eagle v. DipTrace...

I decided mid stream I wanted to migrate from Eagle to something new. A thread on the SDIY list got me thinking again about the offerings and some of the frustrations I have with Eagle. Eagle has been a great capture/layout system, but I've been more and more frustrated with some of its core operation and workings.

One package which came up was DipTrace. I gave it a look and like it. It's got a few oddities, but seems to be well supported, with reasonable pricing even for the full unlimited version, and full featured, more than I'll ever need for the 2 layer synthesizer circuits I do. And, very important, PCB-Pool, who I use for PCBs, accepts DipTrace format directly.

I've already found that editing/creating parts is as easy if not more so than in Eagle. Schematic capture is intuitive, PCB layout is also nice and the auto place is nice for a first go at least. A nice feature is you can hand place components which have to be in certain areas, the the auto place will put the other components around trying to minimize the signal length. Again, for the simple stuff I'm doing maybe not needed, but also works nicely and saves some time. There are some quirks I'm finding, like selecting which labels to display and placement, but I think I can make it work.

In the end, I bought a license and will be migrating my future work into DipTrace. The Steiner stuff is pretty fixed and I don't plan on any modifications. But if needed, I can export the Eagle schematic or PCB and bring it into DipTrace. Not the ideal, but a workable solution should the need arise. I'll also output all the Eagle designs into Gerber files for future proofing. This is something I tested quite a bit before I decided to buy.

That leaves the 914 clone I was doing a bit in limbo. I had already laid out one PCB and had two schematics completed. While I can import the schematic and even the PCB into DipTrace, I found that there is still some work to make the schematic useable. At this point, I think I will probably just start over in DipTrace. The schematics are really pretty simple for this clone and then I'll be able to make use of the enclosed and custom libraries I've got in DipTrace.

My time line for PCB prototypes is now a couple of months out at least. I need to learn DipTrace, double check the schematics, etc. but, I'm excited to get it done. I still intend to build two, one with inductors for everything and one with GIC simulated inductors.

Studio

My new studio is done. I just need to make time to actually re-connect all the instruments and a little organizing. I'll put up some photos after it's all hooked up and neat.

New studio and Moog 914 clone

I am moving to a newly finished attic space for my studio. I'm pretty excited about it. This photo shows it with sheetrock and baseboards. The painters finished today and I should be able to move in this weekend. I get the far end, about 12 feet wide, and 15 feet long out of about 30 feet. The rest will be for storage. the two round "lights" are actually skylights. They install a mirrored tube to a clear dome cover and it collects and reflects the light like crazy. I will put some diffusers over the openings to help soften the very bright highlights.

Next, I have a new project. I decided to roll my own Moog 914 fixed filter bank. I have two of Yves Usson's version, and PCBs for Jurgen Haible's version, so why my own? A couple of reasons. First, I want it to easily fit behind a euro rack panel. Second, I want to have PCB mounted pots to minimize flying wires. Third, I found a source for inductors and I want to make it easy to use either inductors or a GIC simulated inductor like Jurgen offered. The result will be 4 PCBs which will fit behind a 28 HP euro panel.

Carsten Toensmann at www.analog-monster.de has his own 914 clone for which he made his own inductors. He has decided to offer a service of winding custom inductor values, in particular those found in the 914. I think he is also offering PCBs. Carsten is very helpful and I encourage you to look at his work. Really amazing.

I purchased two sets of coils from him and will build at least one of these clones with real inductors. The layout I'm making will allow for the size inductor Carsten is making as well as a simulated inductor for the high pass and band pass cells. The low pass will have to use real inductors or an active low pass filter like Yves Usson designed or Jurgen Haible designed.

I decided that I will have the option of using all the original Moog circuitry. Most of the parts are still readily available and the one transistor which is out of production, 2N2926, is still to be had at Nikko Electronics http://www.dalbani.co.uk/index.php. I have always had great service from them and highly recommend them.

Besides using the original Moog circuits, by flipping a couple of DIP switches and moving a jumper or two I'm going add the options of having a more useable output stage as well as an input stage that can handle higher input levels than the Moog original. In my simulations, the circuits I borrowed (from Jurgen Haible's fixed filter bank clone) match the frequency response of the original very closely with the advantage of a higher level output and higher level inputs. I am also adding even and odd cell outputs following Yves Usson's great idea.

I'm almost read to actually start the layout process. I've got the input and output stages designed and simulated. I have the basic bandpass filter cell designed as well as the high pass and low pass sections. I just have to copy and paste all the filter cells and adjust the values. Then, layout the PCBs. I think I might realistically have PCBs in hand by the end of July to middle of August. I'll post some samples when I have it built.

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.

Selling stuff

I find I have some redundant modules which are not seeing the use they deserve. I am selling the following. They are all Frac Rack format:

CUSTOM:
Makato filter
YU SYnth Mini Moog clone
Flight of Harmony Plague Bearer filter

NOT CUSTOM;
MOTM 1490 Moog modular filter clone

BLACET MODULES (All built from kits except one EG):
Micro LFO
Filthy Filtre
Splitter
Mixer Processor
5 - Dual Linear VCAs
6 - EGs (one was purchased pre-built)

Here are the ebay links:
Filthy Filtre
YU Synth Mini Moog filter clone
FOH Plague Bearer
Mankato Filter
MOTM 1490 Moog Modular filter clone
Blacet Micro LFO
Blacet Splitter
Blacet Mixer Processor
Blacet VCA
Blacet VCA
Blacet VCA
Blacet VCA
Blacet VCA
Blacet EG
Blacet EG
Blacet EG
Blacet EG
Blacet EG
Blacet EG

New Projects...

Hi Everyone!

I have 3 new projects to announce. First, I have prototype PCBs for the Duo-Phonic keyboard. I've got an idea how to modify a Fatar keybed to use reed switches and magnets as a buss keyboard. I'll post my results.

Second, I'm working on the Microcon. It will be a module suitable for Eurorack or standalone. In standalone, you will need to add a +/- 12 volt supply. I've got the schematic mostly captured. I'm thinking I can get PCBs in about 2 months.

Third, Tom Carpenter at Analogue Solutions is selling Red Square PCBs and panels. Pretty bare bones, but I'm putting a page together to help out those who are building it. There are some unique semiconductors and the BOM lacks some part numbers, eg: pots with switch. Anyway, I also bought an assembled Red Square and will take some photos of the inside so the PCB interconnection and other details will be more clear.