To build 3 synthesizers.
The red faced unit with a green board is a Tsynth kit from ElectroTechnique. It is a "virtual analog" with the usual knobs for oscillators, amp, and filter but all the sound is generated digitally in a Teensy 4.1 module and output through a stereo DAC board. I built it about two years and it works good. I took it down from its perch in my modular mess cabinet to take the pictures and upgrade it's firmware. I noticed that two newer versions have been posted on their GitHub since I built it.
The black board comes with a black panel. It is called Progue from JSI and it a clone synth, part Moog Prodigy, part Moog Rogue. It took me several months to populate about 500 mostly SMD parts on the board. I started this build during the great semiconductor shortage and it has never worked. I got some of the chips from Ali Express and at least one of the LDO regulators is bad or counterfeit since the DC voltages are wrong. Since then I have acquired some genuine TI chips so I will simply swap them all out and hope for the best.
The shiny silver "rats nest" is the back side of the MFOS Ultimate panel. I installed the parts that I have yesterday and started soldering wires to them. More parts will be arriving in the next few days. The "jack field" at the top left must be populated one row at a time then wired up since it's too crowded for my shaky hands to solder the jacks without melting them. This will take a while to finish, then there is the Expander panel.
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You dont have an Xray machine, like at work? ;') Look inside, see a couple of smd's soldered onto the pins wireframe, that they encapsulated over.
We had an X-ray machine, as well as the ability to decap and analyze just about any chip made. At one time we had a fancy electron microscope that had the ability to "see" approximate voltage levels in the top few metal layers on a powered up die. The fancy equipment actually belonged to the semiconductor group, but needed to be installed in a place where there were no issues with vibration, earth tremors and anything that could interfere with putting an electron beam on an IC die with nanometer precision. The million dollar scope was first installed at a Motorola facility somewhere out west but got moved to South Florida in the early 1980's for reasons I never knew.
Sometime in 1983 or 1984 I got to fix that scope. Some big shots and some engineers from the Semiconductor Division out in Arizona or Texas (don't remember which) had come to Florida in search of answers to an unknown process issue with low Beta in some transistors that they had been reliably making for several years. When they fired it up it refused to finish the power up sequence. They came into the Calibration Lab looking for help but nobody there would rip into a million dollar scope and the closest service tech from the manufacturer was in Boston at least two days away. The lab boss told all the suits that "the evening shift lab tech can fix anything, and he gets here around 3:45 PM." I worked the evening shift in the Cal Lab for a reason, it was so I could be out in the Atlantic Ocean on my Hobie Cat all morning long, then slide into work by 4 PM. So, I showed up in my usual shorts, flip-flops and a T-shirt or tank top expecting my usual night of fixing factory stuff and playing with all the idle toys in the factory. Instead, I was met by half a dozen "suits" who had a justifiable concern with letting the "surfer dude" play with some seriously expensive stuff. They gave me the 45 minute lecture about high vacuum equipment and the ease of damaging a diffusion pump, but the night shift crew worked a little differently than the structured day time environment. There were several different "factories" each with their own maintenance teams, but we all knew each other and often learned what others did. We had high vacuum stuff in three different "factories" since we made quartz crystals and thin film microelectronics. I convinced the suits that I wouldn't destroy their equipment and went on to make my rounds through the two way radio factory. I had to do that before anything else.
Once I got the covers off the back of the scope's rack there was an obvious blown electrolytic cap. I dug up a suitable cap, swapped it in and proceeded to go through the power up sequence. I got a friend from the microelectronics group to go through the hi-vac stuff. Within about an hour I had the "suit's" transistor die up on the CRT screen so I paged them (it was the 80's, no cell phones yet). They arrived in a few minutes since the Mirage Disco Lounge was right across the street from the plant (not a coincidence). They were totally shocked when they walked into the room and saw the CRT screen. I got free silicon for all of my home projects for several years after that, even stuff that wasn't out yet (MC68HC11 chips).
The "bad transistors" were traced to a guy who had been dipping metal belt buckles into one of the gold plating solutions somewhere along the process flow for those parts. He did this every week or so with a new buckle which he was then selling at a local flea market. Exactly what happened to him is unknown, but it cost Motorola a lot of $$$$.
Little by little all of that fancy stuff went away. By the time I left my 41 year career in 2014 all of the neat playthings were gone. The X-ray machine was one of the last things to go and I think it was just scrapped. It went when they took out the full in house PC board shop we had that could do multi layer and HDI boards. The last time I visited the plant was before Covid, 2019 or 2020 maybe. The SMD assembly line was the only "toy shop" left in the building and I think it's gone now too.
I soldered three of the suspect transistors into the PC board and I am about 1/3 of the way through the "wiring it up" process. This has taught me just how NOT to design an electronics kit, especially one this complex. I would use a PC board behind the panel, and plug the actual synth board into it, or put the synth on the back side of the front panel board.
Sometime in 1983 or 1984 I got to fix that scope. Some big shots and some engineers from the Semiconductor Division out in Arizona or Texas (don't remember which) had come to Florida in search of answers to an unknown process issue with low Beta in some transistors that they had been reliably making for several years. When they fired it up it refused to finish the power up sequence. They came into the Calibration Lab looking for help but nobody there would rip into a million dollar scope and the closest service tech from the manufacturer was in Boston at least two days away. The lab boss told all the suits that "the evening shift lab tech can fix anything, and he gets here around 3:45 PM." I worked the evening shift in the Cal Lab for a reason, it was so I could be out in the Atlantic Ocean on my Hobie Cat all morning long, then slide into work by 4 PM. So, I showed up in my usual shorts, flip-flops and a T-shirt or tank top expecting my usual night of fixing factory stuff and playing with all the idle toys in the factory. Instead, I was met by half a dozen "suits" who had a justifiable concern with letting the "surfer dude" play with some seriously expensive stuff. They gave me the 45 minute lecture about high vacuum equipment and the ease of damaging a diffusion pump, but the night shift crew worked a little differently than the structured day time environment. There were several different "factories" each with their own maintenance teams, but we all knew each other and often learned what others did. We had high vacuum stuff in three different "factories" since we made quartz crystals and thin film microelectronics. I convinced the suits that I wouldn't destroy their equipment and went on to make my rounds through the two way radio factory. I had to do that before anything else.
Once I got the covers off the back of the scope's rack there was an obvious blown electrolytic cap. I dug up a suitable cap, swapped it in and proceeded to go through the power up sequence. I got a friend from the microelectronics group to go through the hi-vac stuff. Within about an hour I had the "suit's" transistor die up on the CRT screen so I paged them (it was the 80's, no cell phones yet). They arrived in a few minutes since the Mirage Disco Lounge was right across the street from the plant (not a coincidence). They were totally shocked when they walked into the room and saw the CRT screen. I got free silicon for all of my home projects for several years after that, even stuff that wasn't out yet (MC68HC11 chips).
The "bad transistors" were traced to a guy who had been dipping metal belt buckles into one of the gold plating solutions somewhere along the process flow for those parts. He did this every week or so with a new buckle which he was then selling at a local flea market. Exactly what happened to him is unknown, but it cost Motorola a lot of $$$$.
Little by little all of that fancy stuff went away. By the time I left my 41 year career in 2014 all of the neat playthings were gone. The X-ray machine was one of the last things to go and I think it was just scrapped. It went when they took out the full in house PC board shop we had that could do multi layer and HDI boards. The last time I visited the plant was before Covid, 2019 or 2020 maybe. The SMD assembly line was the only "toy shop" left in the building and I think it's gone now too.
I soldered three of the suspect transistors into the PC board and I am about 1/3 of the way through the "wiring it up" process. This has taught me just how NOT to design an electronics kit, especially one this complex. I would use a PC board behind the panel, and plug the actual synth board into it, or put the synth on the back side of the front panel board.
Great story! Good luck with the remainder of your wiring up process.
I heard a similar one from a component engineer, I think working at Raytheon at the time of the story. More than the usual # of dies failing off a wafer. Exam turned up an oil based contaminant. "How the H*** could oil be getting onto these wafers?" Turned out a worker, noticing the hot, dry environment the wafer containers had inside, was keeping their french fries left over from lunch in there along with, so they could be enjoyed still hot and crispy later in the afternoon.
Not quite as nefarious as the belt buckle guy, but makes me glad I was never a people manager.
Well after fighting the flu and slinging solder for over a week the MFOS Ultimate got fed power for the first time about an hour ago. Nothing blew up or smoked. All of the front panel controls seem to work, all three VCO's work, but there is no audio output. There is likely something miswired, but I haven't got the patience to start digging into it right now.
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I got an email from Perfect Circuit, a seller of everything synth related from component parts to complete synths, with an emphasis on Eurorack. Their "newsletter" is just an advert for stuff they sell, but most of it is unique stuff that I haven't seen yet. It seems that Serge Tcherepnin is back in the game:
"Serge Modular is more visible than ever thanks to the work of Random*Source. Not only due to their work in producing authentic Serge panels in the classic 4U format with refined circuits for improved performance but also from adapting the designs to the Eurorack modular synthesizer format. And through their partnership with Serge Tcherepnin himself, Random*Source has become the source for official Serge modules and synthesizers straight from the man who started it all."
Now, the all-new GTO kicks off the latest generation of Serge Modular designs, drawing its functionality from the famous Smooth & Stepped Generator, or SSG for short."
I read the whole article just to see where the name came from. My guess was correct:
"Even the name of the module, which is an homage to Pontiac's iconic GTO, further drives (pun intended) the point home that it is truly a revved-up version of the original SSG."
In my last post, I had completed the MFOS Ultimate synth but could not get it to work. The next morning I busted out the scope and followed the signal to the VCA where it went in but did not come out. It helps to apply some "V" to one of the Control inputs, so the Amplification can happen. DUMM BLONDE at the controls, the synth works good, but I haven't taken the time to go through the calibration procedure yet.
Could this be the elusive vacuum tube based Voltage Controlled Ampli-filter? Would those 4 identical tubes be wired as some sort of ladder? Could a project that was first seen in posts #20 and 25 have crawled out of the "box full broken dreams:" and been resurrected from the dead? Might the 5th tube be a modified version of the VCA seen in posts 39 and 56?
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Very cool! Might want to post over at the DIY forum on ModWiggler. That's a huge community of solder slingers over there with some mad projects. Somebody actually cloned the Moog Memory Moog! They don't shy away from big projects. They'd love to see this.
https://www.modwiggler.com/forum/viewforum.php?f=17
https://www.modwiggler.com/forum/viewforum.php?f=17
That poor piece of perf board has been occupied with several iterations of attempts at a working 4 p[ole ladder filter. A couple months ago I rescued it from the "box of dead projects" where non functioning, boards, experiments, and electronic disasters go to be harvested for parts as needed. When I pulled it out of the box it was a failed attempt at a vacuum diode ladder filter. 6JU8 tubes are simply a pair of 6AL5 dual diodes in a 9 pin envelope. The ladder worked but failed to deliver more than two octaves of frequency range without feeding the board well over 400 volts. Most of the original circuitry was ripped off leaving only the tube sockets and the mosfet buffer. I created a new ladder from 9AJ based triodes with an IXYS 10M45S CCS chip at the base of the ladder for the CV controlled current source. There are 17 different tubes with the 9AJ / 9LP / 9EP basing that are pinout compatible with the socket wiring on that test board. Those 4 sockets are currently filled with 6DJ8 / 6922 tubes since they are known to work well at low voltages. I have over a dozen possible candidates to try. The VCA is currently populated with a 6ES8 tube. The board does show signs of life, but lots of testing needs to be done. At this time, I don't even have a schematic of what's on the board as I kinda made it up as I went along. I was surprised to see that it didn't self destruct on power up, but even more surprised when I found the filter and amp both exhibiting some functionality.
Been busy with my modular this Spring, but I never got far to get the whole che-bang together but:
- Made me a bigger cabinet and painted it baby-blue.
- Ordered simple "power rails" and a +/-12V PSU. The rails are screwed to my cabinet, but the PSU is difficult to fit in a good way.
- Ordered a bunch of power connectors and have started to solder them to the PCBs.
- Brought a number of PCBs back from my trip to Chicago this winter and have assembled them.
- Have started a few more projects and have some new PCBs for a LPG, an odd LFO and a dual-AR.
- Watched Barton's site and looked at his cool 8-step sequencer and have stolen most of the design to build a sequencer with 4 VC outputs that are two clock cykles apart.
- Have to get the last pieces together in my Ultimate ("in-door" transformer, not the wall-wart), and adjust/trim VCOs, VCF and VCA.
- Laid my hands on some nice heavy aluminium sheets and can make a panel to the T2000.
- Finally stuff the boards back in the Polivoks and make things work.
- Repair my MG-1
I have spent far too much time trying to reinvent the guitar amp and frying some parts in the process. The only thing that I have actually completed is the 1 X 12 inch speaker cabinet sitting under the amp head cabinet that I made several years ago. Meanwhile there is a new Behringer Kobol Expander sitting in its box because there is no room left in my modular cabinet without some serious rearrangement. The MFOS Ultimate synth still has no cabinet and there are two Eurorack module kits waiting to be built.
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Mine's hit a rut too. I got some clickedy ALPs pots to install, as the other stereo pots I've been using track so horribly. Looking for the motivation to do so. Been spending that on learning to play the guitar / sing, where it seems I'm beneath a glass ceiling much of the time.
My synth will be sitting idle for a while longer. I have three different guitar amp ideas in process concurrently and also need to work my short, fat, and mostly non functional fingers daily so I can play the guitar for more than a few minutes at a time. I bought a cheap full length Jazz Bass clone a few years ago before I realized that I can't span 3 frets on the long end of the neck. I have several guitars that I can play, but for only a short period of time before my fingers refuse to listen to my brain. This is improving with effort though. Singing, never did happen, never going to happen. Singing into the DAW and playing with Melodyne or Ableton pitch correction is an exercise in futility. I have come up with some neat, weird sounds to play from the keyboard this way, but the best samples came from the cat!
Well over 10 years ago there was a challenge called the Hundred Buck Amp Challenge, now a sticky at the top of this forum. I have 3 guitar amps and some non-functional boards from my efforts in that contest. The last working amp has developed an intermittent condition and only works when there is a pair of Vise Grips hanging off of the volume knob. Thinking it was just a bad pot, I ripped it apart to find that the DIY home etched PC board is coming apart. That is also the case with one of my other HBAC amps. Some of those boards that I made in a hurry were pretty ugly when they were fresh. The shortest path to a working amp would be to just send the old Gerbers to a board house and get some good boards for a rebuild. Unfortunately, being an engineer, I just have to make it better which will likely result in some screw-ups. At least one out of the three should work, right? Can I squeeze 50+ watts out of a board that used to make 20?
Well over 10 years ago there was a challenge called the Hundred Buck Amp Challenge, now a sticky at the top of this forum. I have 3 guitar amps and some non-functional boards from my efforts in that contest. The last working amp has developed an intermittent condition and only works when there is a pair of Vise Grips hanging off of the volume knob. Thinking it was just a bad pot, I ripped it apart to find that the DIY home etched PC board is coming apart. That is also the case with one of my other HBAC amps. Some of those boards that I made in a hurry were pretty ugly when they were fresh. The shortest path to a working amp would be to just send the old Gerbers to a board house and get some good boards for a rebuild. Unfortunately, being an engineer, I just have to make it better which will likely result in some screw-ups. At least one out of the three should work, right? Can I squeeze 50+ watts out of a board that used to make 20?
Yeah. I seem to have better days with that than others. Got a nice click in my left index, to the pint where I dread the part coming up where you have to move from an open chord shape to a barre - usually to a Bm, Bb, F, F#, C#m - click - ouch.
I also need a significant warm up time to avoid failure on some chord like that. Guy at the 'mike a few years older says "you gotta come on hard with that first chord" - Hell, I can barely play when I first get up there; first song's a warm up and needs to be chosen as such. It's summer, so I can go out in the parking lot to do that, with an eye on the sign up sheet and who's playing. When I'm next in line, I'm usually sitting with my guitar fretting chords on muted strings to get my fingers moving.
I'm very, very, very fortunate that I can sing and hit a pitch on key better than a few others. Helps to make up for my crappy playing I suppose. Its something I could stand to be more grateful for and approach the whole thing more from that perspective. Many times my ADHD brain actually gets bored with the whole package and I drop out of what I'm doing off into something else. Not on stage where there's at least enough pressure to actually hold my attention for 3.5 minutes,,.
Up tonight is (hopefully) "Dead Flowers", "Blue Moon" and John Gorka's "Bottom Line". Blue Moon comes from a Saturday morning singing group at some Universalist church my wife has decided she likes to attend regularly, the guy that runs it is a hoot. Bottom line is a song another guy does, that the "hard chord start" guy showed me, to where I could pick up the rest on my own - with the help of the internet of course. Dead flowers is from a conversation with him wherein I didnt know who Townes Van Zandt was. So I looked him up on Ultimate Guitar and thought "He wrote that?". Turns out it's a Stones original with 3 chords. I can do that.
Anyway, attitude of gratitude needs as much work as rehearsing, that I'm still alive and can even do something at all these days. In front of friends anyway; I wouldnt dare post a performance on YT or Reddit.
I've been getting together some hand-drawn plans to build an analog modular synthesizer with the design based on the Moog System 55, but using modern, easy to source ICs and other parts, I bought a book called Make Analog Synthesizers by Ray Wilson, who used to run an online website called Music From Outer Space, there are some great circuits in the book, particularly the Sawtooth VCO, which I'm going to be modifying to be able to put out more waveforms apart from a Sawtooth, one other module I want to include is the MFOS 16-Step analog sequencer with vari-clock, but also include a way to tempo-synch the sequencer to a Daw master tempo via midi, I was planning on using some Yamaha ICs from a broken Yamaha CS15D Synthesizer in my modular synth, but found out that the Yamaha VCO ICs are not easily V/Oct scaleable, they are actually Hz/Volt VCOs, I'm planning on including 44 modules in my modular synthesizer design, including 8 VCOs, an LCD Oscilloscope, and a Midi to CV converter module.
Sounds like a big project. I will say that I think the only reason to do it nowadays is for the love of DIY or if you want a different form factor (bananas, frac rack, etc.). Behringer has made a credible system 55 clone at an incredible price. You can get the entire system complete with case and power supply for $1700. That’s a 7 oscillator, 38 module system! Their individual modules are also insanely cheap. I’m not a fan of eurorack but that is a solid deal! I have been tempted to get it just to imbibe in a historical system. Luckily I don’t have the extra space lol. Still better than the original format i guess lol.
Speaking of historical systems, I had an original white face Odyssey with the Little Brother Expander and a pair of Univox branded Mini-Korg 700's before Korg became the brand name. I was stupid enough to sell it all in the digital 90's at the low point in their worth. I do still have my Roland JV-880 and JV-1000. The Korg DW-8000 died long ago and was parted out.
Now while my "Eurorack system" holds 4 complete Behringer synths plus a few modules, Behringer just dangled another piece of bait in front of me which makes it too easy to add a whole bunch more functionality for a reasonable price. I don't know if I can resist a 2600 clone for $419. I got to play with a newly released ARP 2600 at the University of Miami in 1972 for a few days before I would leave my job at an Olson Electronics store next to the U of M for a career 40 miles to the north. I never saw the U of M or the 2600 again. Could I have $420 worth of fun with a clone? You bet!
Behringer also dropped the price of their system 15 to $739 and the System 35 to $939. All are at Sweetwater Sound.
Now while my "Eurorack system" holds 4 complete Behringer synths plus a few modules, Behringer just dangled another piece of bait in front of me which makes it too easy to add a whole bunch more functionality for a reasonable price. I don't know if I can resist a 2600 clone for $419. I got to play with a newly released ARP 2600 at the University of Miami in 1972 for a few days before I would leave my job at an Olson Electronics store next to the U of M for a career 40 miles to the north. I never saw the U of M or the 2600 again. Could I have $420 worth of fun with a clone? You bet!
Behringer also dropped the price of their system 15 to $739 and the System 35 to $939. All are at Sweetwater Sound.