Tubelab Said:
In 1970 I saw ELP and became infatuated with the Moog Synthesizer. All synthesizers in 1970 were analog, voltage controlled. I got an idea for a completely digital synthesizer and in 1971 I started building it. It took about a year to make sound, after all I was using free IC's obtained from the dumpster behind the Coulter Diagnostics (blood counters) factory. They were all RTL. This was before CMOS was invented! Yes, there are about 400 chips on those boards, all hand soldered PTP style. Yes, I still have them after 40+ years. I have started work on a new synthesizer, and several other music generation related devices. No tubes in these projects with the exception of a vacuum tube VCA / Envelope Follower and compressor. This is not just another copy of one of the $$$$ classics. There are plenty of these out there already.
And I said:
George, I was very in to building electronic instruments. I built a big modular. In contrast to Tubelab, when I got in to synths was the late 80's and everything was digital, so I built an analog modular. I've been thinking about getting back to it..
I've been reading up on tube analog synths, and am thinking about building one... But they're difficult to control (if you want standard tuning and keyboard control).
And Tubelab said:
I have been investigating that as well. A true 1V/OCT scale is hard to do with an all tube design, and keep the tracking and drift issues to a minimum. I decided that the VCA would be the easiest circuit to tackle first since errors only affect amplitude, not pitch. It is also a path I need to conquer in order to design a new vacuum tube audio compressor. A compressor is a VCA, a controller, and an envelope follower. There were several "reference standard" tube compressors used in the broadcast industry that have become cult classics commanding stupid price tags today. ALL of these used the 6386 tube which has become rather hard to get....Even Sovtek knockoffs cost over $100 each!!!!! I have about a dozen from the 1950's and started characterizing their control characteristics about 2 years ago. You get about 50 db of gain control from a CV that goes from -50 volts to zero. I am still looking for a cheap TV tube that can do the same gain range on a 5 volt CV swing.
Reality probably dictates that there will be some silicon, and maybe even some digital assistance in whatever "tube" synthesizer modules I design. You can find high voltage opamps that can scale a 1V/OCT CV into whatever needed to control a tube VCO, but tracking is still a problem, not to mention thermal drift.
I have been experimenting with a PIC microcontroller and a 16 bit D/A converter. Use the A/D inside the PIC to read the CV, then a lookup table applies the needed correction and sends the data to the D/A. The lookup table can be different for each VCO, and one PIC chip can handle a dozen SPI or I2C D/A's, each with their own VCO, AND feed a hand full of DDS chips.
In 1970 I saw ELP and became infatuated with the Moog Synthesizer. All synthesizers in 1970 were analog, voltage controlled. I got an idea for a completely digital synthesizer and in 1971 I started building it. It took about a year to make sound, after all I was using free IC's obtained from the dumpster behind the Coulter Diagnostics (blood counters) factory. They were all RTL. This was before CMOS was invented! Yes, there are about 400 chips on those boards, all hand soldered PTP style. Yes, I still have them after 40+ years. I have started work on a new synthesizer, and several other music generation related devices. No tubes in these projects with the exception of a vacuum tube VCA / Envelope Follower and compressor. This is not just another copy of one of the $$$$ classics. There are plenty of these out there already.
And I said:
George, I was very in to building electronic instruments. I built a big modular. In contrast to Tubelab, when I got in to synths was the late 80's and everything was digital, so I built an analog modular. I've been thinking about getting back to it..
I've been reading up on tube analog synths, and am thinking about building one... But they're difficult to control (if you want standard tuning and keyboard control).
And Tubelab said:
I have been investigating that as well. A true 1V/OCT scale is hard to do with an all tube design, and keep the tracking and drift issues to a minimum. I decided that the VCA would be the easiest circuit to tackle first since errors only affect amplitude, not pitch. It is also a path I need to conquer in order to design a new vacuum tube audio compressor. A compressor is a VCA, a controller, and an envelope follower. There were several "reference standard" tube compressors used in the broadcast industry that have become cult classics commanding stupid price tags today. ALL of these used the 6386 tube which has become rather hard to get....Even Sovtek knockoffs cost over $100 each!!!!! I have about a dozen from the 1950's and started characterizing their control characteristics about 2 years ago. You get about 50 db of gain control from a CV that goes from -50 volts to zero. I am still looking for a cheap TV tube that can do the same gain range on a 5 volt CV swing.
Reality probably dictates that there will be some silicon, and maybe even some digital assistance in whatever "tube" synthesizer modules I design. You can find high voltage opamps that can scale a 1V/OCT CV into whatever needed to control a tube VCO, but tracking is still a problem, not to mention thermal drift.
I have been experimenting with a PIC microcontroller and a 16 bit D/A converter. Use the A/D inside the PIC to read the CV, then a lookup table applies the needed correction and sends the data to the D/A. The lookup table can be different for each VCO, and one PIC chip can handle a dozen SPI or I2C D/A's, each with their own VCO, AND feed a hand full of DDS chips.
George, keep us updated. I'd love to work on a tube based synth (would be modular in my case).
Personally, I only care if the voicing is tube. VCO, VCA, VCF. Interfacing w/ standard CV is definitely a goal. Using silicon to do so, is probably the best option. Then your VCA tube doesn't need to give a certain range based on 5v.. Amplify or shift that 5v cv w/ some opamps, and feed the tube whatever it needs to give the range of gain control you want.
And for control, 1v/oct, I was also looking to a microcontroller. (Unfortunately, I have almost no experience w/ programming microcontrollers, so would definitely need assistance at this point in the project)
There's not a lot of info on tube synths out there, so you've probably found this already.. If not, here are some designs to take ideas from:
Audio Synthesis via Vacuum Tubes
Synth schematics--::--Vacuum Tube VCO
I haven't read those pages in about 10 years, since before I got in to tubes... I can probably make some good progress now.
Personally, I only care if the voicing is tube. VCO, VCA, VCF. Interfacing w/ standard CV is definitely a goal. Using silicon to do so, is probably the best option. Then your VCA tube doesn't need to give a certain range based on 5v.. Amplify or shift that 5v cv w/ some opamps, and feed the tube whatever it needs to give the range of gain control you want.
And for control, 1v/oct, I was also looking to a microcontroller. (Unfortunately, I have almost no experience w/ programming microcontrollers, so would definitely need assistance at this point in the project)
There's not a lot of info on tube synths out there, so you've probably found this already.. If not, here are some designs to take ideas from:
Audio Synthesis via Vacuum Tubes
Synth schematics--::--Vacuum Tube VCO
I haven't read those pages in about 10 years, since before I got in to tubes... I can probably make some good progress now.
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Why make a tubed analog synthesizer?
The earlier experimenters on the 40s and 50s would have *murdered* to get some 741 Op Amps , go figure.
Their only option was some:
Each cost like a small car and any 741 would **destroy** it , spec wise.
Why build pyramids this way:
when now you can build them this way:
The earlier experimenters on the 40s and 50s would have *murdered* to get some 741 Op Amps , go figure.
Their only option was some:
Each cost like a small car and any 741 would **destroy** it , spec wise.
Why build pyramids this way:
An externally hosted image should be here but it was not working when we last tested it.
when now you can build them this way:
Because in subtractive synthesis distorted signal sound a lot more interesting than clean ones. A sine wave is completely useless as a signal, you must get the harmonics somehow so the filter can get its teeth into something and distortion is just as viable as choice of different waveforms. The option of both would be ideal.
I suppose the OP knows about this lot:
Home
I suppose the OP knows about this lot:
Home
I have known about Metasonix ever since Eric announced his vacuum tube synthesizer at the NAMM show several years ago. Eric Barbour was the applications engineer for the original Svetlana corporation, before that operation shut down and Mike Matthews bought up the name.
Eric has done several vacuum tube devices including some guitar amps with rather interesting names and graphics on their covers......get small children out of viewing range before checking out his web site....unless it has changed since I last looked.
Vacuum tube synthesizers.....this is the original. A Hammond Synthesizer from 1939!
Novachord Restoration Project
Eric has done several vacuum tube devices including some guitar amps with rather interesting names and graphics on their covers......get small children out of viewing range before checking out his web site....unless it has changed since I last looked.
Vacuum tube synthesizers.....this is the original. A Hammond Synthesizer from 1939!
Novachord Restoration Project
I started one of these when I was a first year apprentice in 1973.
ETI 4600 Website
It has now been 99% complete for 40 years. Happy Birthday to my ETI4600 project.
Cheers,
Ian
ETI 4600 Website
It has now been 99% complete for 40 years. Happy Birthday to my ETI4600 project.
Cheers,
Ian
It's been so long ago that I nearly forgot, and it seems that the web has already forgotten....
Surplus electronic shops used to be very common. They were more common in cities that had a large tech base. We had good ones in the Melbourne Florida during the 60's and 70's "space race".
There were a lot of good surplus shops in the Boston area during the dawn of the computer age. Sometimes the surplus shops even created electronics kits from their surplus to augment sales.
There was a Boston area surplus shop that designed and sold a music synthesizer kit. The company name was BNF, which is still listed as a Peabody, Mass. corporation. They made a synthesizer kit in the late 70's or early 80's. I bought one at a hamfest, had it for a few years and sold it at another hamfest.
It was an impressive looking modular with a separate keyboard, but this particular one never worked. The guy I got it from was an electronic tech, but not the original owner. He gave up. I got sound out of it, but it was temperamental, and very unstable. I was convinced that there were severe power supply problems, but never made it work right, and eventually sold it.
I can not find any info on the web. Does anyone else remember it....did anyone ever make one work?
Surplus electronic shops used to be very common. They were more common in cities that had a large tech base. We had good ones in the Melbourne Florida during the 60's and 70's "space race".
There were a lot of good surplus shops in the Boston area during the dawn of the computer age. Sometimes the surplus shops even created electronics kits from their surplus to augment sales.
There was a Boston area surplus shop that designed and sold a music synthesizer kit. The company name was BNF, which is still listed as a Peabody, Mass. corporation. They made a synthesizer kit in the late 70's or early 80's. I bought one at a hamfest, had it for a few years and sold it at another hamfest.
It was an impressive looking modular with a separate keyboard, but this particular one never worked. The guy I got it from was an electronic tech, but not the original owner. He gave up. I got sound out of it, but it was temperamental, and very unstable. I was convinced that there were severe power supply problems, but never made it work right, and eventually sold it.
I can not find any info on the web. Does anyone else remember it....did anyone ever make one work?
Don't remember BNF, but a friend built up a modular system from another 70's Boston area modular kit vendor, Aries, which eventually worked pretty well after a bit of massaging on my part.
One of my first real electronics gigs was at ARP, ca. '77, and doing an all-tube build was definitely discussed from time to time on the tech line. Most of us were more interested in figuring out how to implement digital technology to greater effect at that time though.
One of my first real electronics gigs was at ARP, ca. '77, and doing an all-tube build was definitely discussed from time to time on the tech line. Most of us were more interested in figuring out how to implement digital technology to greater effect at that time though.
Don't know what became of BNF, but they had a pretty close tie in with MIT and sold kits for a variety of things designed by people in the engineering school and labs. I was there once in the 1980s with a friend who purchased a speaker kit designed by someone at MIT, not Dr. Bose.. lol
Eli Hefron was another surplus outfit located in Cambridge IIRC.. Abbott Electronics in Woburn had a lot of HH Scott surplus - bought quite a lot of it when I realized what it was for repairing Scott amps.
Eli Hefron was another surplus outfit located in Cambridge IIRC.. Abbott Electronics in Woburn had a lot of HH Scott surplus - bought quite a lot of it when I realized what it was for repairing Scott amps.
I found pictures of the Aries on the web, and that was indeed the unit I had. Trying to think that far back isn't always possible but I believe that there was a connection between those two companies, or Aries may have evolved from BNF's surplus operation. I had a scan of the manual somewhere, but I don't know where right now since I am in the process of moving.
Google finds a 1977 Aries catalog. The AR-300 is the machine I had. I see no obvious BNF connection, so maybe it's all inside my head?????
https://archive.org/stream/synthmanual-aries-catalog-1977/ariescatalog1977#page/n7/mode/2up
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At the time of my last post in this thread I had recently lost my job of 41 years, and had to pack up all of the stuff I could and get out of my house (37 years there) with three weeks notice. I moved 1200 miles north into a temporary location, then moved again a little over a year later. Needless to say, a lot of stuff got sold, given away, or just trashed, and what got moved is now stored in random boxes scattered across 4 different locations. I can't find squat! Some of my tube amps and a spectrum analyzer are still missing.
During the time in the temporary house I had no work bench other than a card table, so I played with an appropriately sized project, a little synth kit from MFOS connected to a pair of headphones. It has grown a bit.....
I finally moved into a new house where I plan to live for a long while and it has a big empty basement. All of the workbenches, wiring, lighting, etc in the Florida house was left behind, since it was all built in place, and had been there for about 35 years. I am slowly building a new, bigger, better lab. In the mean time I have been tinkering with music synthesis, and my path has taken on a rather strange new direction......
A co-worker in Florida had built a rather large and amazing modular synth, which I watch evolve from a single box on a table to a whole wall of modules over several years. He decided to make his 3 oscillator ARP clone do 4 note polyphony by expanding it to 12 VCO's and 4 separate CV's generated by a PIC chip based MIDI to CV converter. It sounded cool, but you need to leave it on for several hours, tune all 12 VCO's, play it for a few minutes over a limited range (2 or 3 octaves) then retune......not much fun, or live event friendly.
I decided to reinvent the VCO, by adding some digital assistance to the analog sawtooth ramp / reset based 1V/oct VCO. I built a few prototypes using a PIC chip and it's 32 bit timer wired into the reset circuit of the typical analog VCO. After all, the ramp can easily be generated by a semiconductor, neon lamp, or a vacuum tube.
Before I got the analog / digital VCO perfected I stumbled across a fully digital, and easy solution. There is an Arduino compatible board called the Teensy, and there is a 44/16 audio board shield for it. There is also an audio library for it that offers a GUI based code writing tool with blocks like oscillator, filter, mixer, and others. I have "made" several 1V/oct digital synthesizers with this little board that sound pretty cool.
OK, digital VCO's that track 1V/oct perfectly with some adjustable "slop" are now pretty easy, and a sawtooth sounds like a sawtooth, regardless of what makes it.
However, only a Moog ladder filter sounds like a Moog ladder filter.....I plan on integrating some of this new digital stuff along with the "old school" analog, and maybe toss in a tube based VCA.
Yeah, the tube stuff is a stretch, but I recently heard this, an all tube synth with 25 tubes. Play the last tune first. It sounds too good. It is called the Knifonium, and there are some Youtube videos, but most are rather lame.
https://soundcloud.com/jonte-knif
During the time in the temporary house I had no work bench other than a card table, so I played with an appropriately sized project, a little synth kit from MFOS connected to a pair of headphones. It has grown a bit.....
I finally moved into a new house where I plan to live for a long while and it has a big empty basement. All of the workbenches, wiring, lighting, etc in the Florida house was left behind, since it was all built in place, and had been there for about 35 years. I am slowly building a new, bigger, better lab. In the mean time I have been tinkering with music synthesis, and my path has taken on a rather strange new direction......
A co-worker in Florida had built a rather large and amazing modular synth, which I watch evolve from a single box on a table to a whole wall of modules over several years. He decided to make his 3 oscillator ARP clone do 4 note polyphony by expanding it to 12 VCO's and 4 separate CV's generated by a PIC chip based MIDI to CV converter. It sounded cool, but you need to leave it on for several hours, tune all 12 VCO's, play it for a few minutes over a limited range (2 or 3 octaves) then retune......not much fun, or live event friendly.
I decided to reinvent the VCO, by adding some digital assistance to the analog sawtooth ramp / reset based 1V/oct VCO. I built a few prototypes using a PIC chip and it's 32 bit timer wired into the reset circuit of the typical analog VCO. After all, the ramp can easily be generated by a semiconductor, neon lamp, or a vacuum tube.
Before I got the analog / digital VCO perfected I stumbled across a fully digital, and easy solution. There is an Arduino compatible board called the Teensy, and there is a 44/16 audio board shield for it. There is also an audio library for it that offers a GUI based code writing tool with blocks like oscillator, filter, mixer, and others. I have "made" several 1V/oct digital synthesizers with this little board that sound pretty cool.
OK, digital VCO's that track 1V/oct perfectly with some adjustable "slop" are now pretty easy, and a sawtooth sounds like a sawtooth, regardless of what makes it.
However, only a Moog ladder filter sounds like a Moog ladder filter.....I plan on integrating some of this new digital stuff along with the "old school" analog, and maybe toss in a tube based VCA.
Yeah, the tube stuff is a stretch, but I recently heard this, an all tube synth with 25 tubes. Play the last tune first. It sounds too good. It is called the Knifonium, and there are some Youtube videos, but most are rather lame.
https://soundcloud.com/jonte-knif
I'm sure you've seen this, its truly fascinating:
I Dream of Wires
I Dream of Wires (2014) - IMDb
At the time I watched it, i was suffering with horrible microphonics/ringning in my pre-amp. And I thought that someone might want to make a module that uses a relay's actuator to tap the tube. The result could be a sound itself or a signal to shape other signals.
I Dream of Wires
I Dream of Wires (2014) - IMDb
At the time I watched it, i was suffering with horrible microphonics/ringning in my pre-amp. And I thought that someone might want to make a module that uses a relay's actuator to tap the tube. The result could be a sound itself or a signal to shape other signals.
George, if you make some progress, could you post a rough schematic about what you've done w/ the digital/analog vco?
Or if you have the time/motivation, you should make a complete set (vco, filter, vca, maybe a digital modulation source like LFO's.. (Well, if you do that, lets talk! I think having your modulation sources syncable to MIDI is super important for any new design) and you could sell PCB's...
I haven't made any progress on mine in years, but might as well take the opportunity to post a pic of my old modular again.. (I'm still proud of her) Evolved from a "PAIA" kit, to copying other designs, to finally designing a few modules before I got busy w/ other things..
Or if you have the time/motivation, you should make a complete set (vco, filter, vca, maybe a digital modulation source like LFO's.. (Well, if you do that, lets talk! I think having your modulation sources syncable to MIDI is super important for any new design) and you could sell PCB's...
I haven't made any progress on mine in years, but might as well take the opportunity to post a pic of my old modular again.. (I'm still proud of her) Evolved from a "PAIA" kit, to copying other designs, to finally designing a few modules before I got busy w/ other things..
Attachments
I got started with the first PAIA kit, the 2700 I believe. It used little shirt buttons for the keys. I think I ordered it in 1971 shortly after seeing ELP, but I didn't get it for what seemed like a year. They came out with a real keyboard about a year later, but it required a new case, so the synth met the jig saw.
It was a drifty temperamental beast, and I eventually got an Odyssey, and expanded it with a Little Brother, and some home made stuff. By the mid 70's I had the Odyssey, an ARP / Solina String Ensemble, and two Univox Mini - Korgs (before Korg became the brand name).
Career, wife, kids, life happens......all the synth stuff got sold
With the exception of the JV1000 that my daughter left behind when she moved out, all my synths now live on my hard drive, the Arturia V collection.
The first PIC based hybrid VCO consists of a few parts sky wired on top of a "Microstick for 5V PIC24 K-Series" EVB board. I never made a real schematic since there isn't much hardware other than the PIC chip. The PIC24FV16KM202 chip has the A/D comparators and op amps built in. I added a few resistors, jumper wires and the timing cap to make a VCO. No progress has been made since I discovered the Teensy.
The Teensy synth is much simpler.....there is virtually zero hardware other than knobs switches, the Teensy module, and the Teensy Audio Adapter. Enclosed is a picture of my pile of partially completed synth boards that will eventually be used to build a modular synth.
Partially shown on the left is the Orgone Accumulator board. I purchased this board at the recommendation of my friend in Florida with the wall of synth. He said that it is the coolest sounding single module that he has ever built, so I got one. It's waiting for me to make the panel with pots and switches. It uses the Teensy board as the sound source. There are two partially assembled MFOS boards, also waiting for pots and switches. There is a Raspberry PI on an inverted touch screen. I downloaded some free synth programs, but I am not impressed with any so far.
In the center is the Teensy synth breadboard. It consists of a Teensy module with the audio adapter stacked on top of it. There are 12 pots, 3 push buttons, and 3 rotary encoders and a few bypass caps. There are two 1/4 inch jacks hanging from the red / black wires for CV and gate input from my keyboard (an AKAI MAX49). All of the magic is done in code. Most of the code is drawn in a graphical interface. Included is a screenshot of a 4 osc, two filter synth I made.
Attachments
I was one of the very few people sticking silicon in tube HiFi amps about 12 years ago. It was frowned upon big time back then. A few people even suggested changing my name to Transistorlab. My amps sounded good, and those designs from 10 years ago are still popular today. Mosfet followers and CCS chips have become quite popular in tube HiFi amps today.
I have also owned a few digital synths and they definitely sound different, more clinical......and well digital. I will play with both analog and digital technology, and eventually come up with a happy mix of both.
If you look at some of the popular new high $$$ stuff from Dave Smith (Prophet 6) and Modal, you can find a successful blend of both analog and digital.
A link with maybe some useful info - no tubes but mostly analog.
ETI 4600 Website
I bought a kit for an ETI4600 (Australian Version) when I was a 2nd year apprentice in early 1974.
40+ years later it is sitting on top of a cabinet in my workshop 98% complete, it has been 98% complete for at least 35 years.
Any Aussies want one cheap?
Cheers,
Ian
ETI 4600 Website
I bought a kit for an ETI4600 (Australian Version) when I was a 2nd year apprentice in early 1974.
40+ years later it is sitting on top of a cabinet in my workshop 98% complete, it has been 98% complete for at least 35 years.
Any Aussies want one cheap?
Cheers,
Ian
I had found the documentation for the Maplin (UK) version somewhere on the web several years ago. It's definitely not the common ARP / Moog clone that was popular in the 70's. It's interesting that both groups claimed to be the designers of a very similar synth. I just downloaded the Australian manual. It will be interesting to see what the differences are.
Too bad it's on the other side of the planet.
Too bad it's on the other side of the planet.
20 posts in 2 and a half years, and nobody has built anything? Somebody build something, anything.
OK, OK, I twisted my own arm into building the first of several ideas on vacuum tube ladder VCF's. Well it looks good. Doesn't work though. It was a flawed idea and it didn't take me too long to realize that this path was a dead end. It did have a whole bunch of gain (10 mV in gave 100 V out) but the range was barely one octave at 20 volt on the CV input.
I will try out some new ideas as time permits.
I decided to start with the filter, since that's what defines the sound. I have a nice little 1V/oct synth operational now, but it's mostly digital.......A fat MOOG style ladder filter is just what's needed.
https://www.youtube.com/watch?v=gWf8Ohfw9EU&t=60s
OK, OK, I twisted my own arm into building the first of several ideas on vacuum tube ladder VCF's. Well it looks good. Doesn't work though. It was a flawed idea and it didn't take me too long to realize that this path was a dead end. It did have a whole bunch of gain (10 mV in gave 100 V out) but the range was barely one octave at 20 volt on the CV input.
I will try out some new ideas as time permits.
I decided to start with the filter, since that's what defines the sound. I have a nice little 1V/oct synth operational now, but it's mostly digital.......A fat MOOG style ladder filter is just what's needed.
https://www.youtube.com/watch?v=gWf8Ohfw9EU&t=60s
