Moog Memorymoog sucessfully cloned

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Luismarka
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Moog Memorymoog sucessfully cloned

Post by Luismarka » Wed Jul 22, 2020 11:22 pm

Hi folks,
Over the last year or so I have been working on a reproduction of the Moog Memorymoog as the Curtis chips are available again from a number of sources, making this thing possible.

So far I have a fully working unit! The keyboard itself was donated from a dead Juno 106, and I am currently working on the mechanical aspect of it. Should receive the chassis and a few other metal parts that required cutting and bending tomorrow morning, and then it is a matter of working on the wood parts. Drawings for the buttons were sent to a 3D printing shop so I can check if the dimensions are good before placing an order for those.

Tune stability is somewhat better than the original unit I used to have - sold it nearly 20 years ago - and power consumption seems to be slightly less than the original, probably because of better specs of modern components. Also, using CMOS versions for the CPU, EPROMs and Z80 CTC helped reduce the total power dissipation.

Attached pictures represent what the prototype looks like as of today. That wooden base was assembled only so that I could figure distances between boards, cabling and other components while making measurements for the chassis manufacturer.

I tried several LED colors, and decided on diffuse white instead of red. Think it looked the best from all the ones I tested.

A number of stupid mistakes were made during the process... both translating the schematics to the actual PCBs (the DMUX board had to be redone three times; pretty expensive mistake!) Also, in the first board I was not well used to Kicad libraries and ended up using a wrong symbol for the diodes... as a result, the Digital board had all diodes mounted in reverse! No wonder the presets were not being kept in memory, the reversed diodes prevented current from the battery to reach the circuit at all. A few other small mistakes were made and corrected, such as wrong resistors, etc. Other errors were found in the original schematics as well, but nothing too bad.

All circuits were kept as close to the original as possible. The main diffrence is that now the PSU is mounted in two separated boards, one with the rectifiers and regulators, and another small board for the power transistors. I was not happy with the PSU board sandwiched between the panel and digital boards; the rectifiers generate quite a bit of heat, and cabling would be compressed with the boards in the original positions.

I think I managed to debug all major mistakes, and the prototype is working pretty smooth. It sounds very, very Memorymoog-ish! Heavy, raw, loud!

Will post more information as progress is made. Cheers!
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bphenix
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Re: Moog Memorymoog sucessfully cloned

Post by bphenix » Wed Jul 22, 2020 11:36 pm

Wow.

This has to be the most epic "Hi, I'm new here" post I've seen on Muffs in years.
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Re: Moog Memorymoog sucessfully cloned

Post by Peake » Wed Jul 22, 2020 11:40 pm

Mighty.
This is not the place I'd imagined it to be.

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Michael O.
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Re: Moog Memorymoog sucessfully cloned

Post by Michael O. » Wed Jul 22, 2020 11:45 pm

Whoa, incredible work!! That is one hell of an undertaking, and those boards look fantastic. The PSU rework seems, ostensibly at least, like a great idea, and superior to the original even. Does it have the full six voices of the original?

Very much looking forward to your progress, and particularly in hearing this monster!

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Re: Moog Memorymoog sucessfully cloned

Post by devinw1 » Wed Jul 22, 2020 11:53 pm

Absolute madness. I love it.

Welcome to the best forum on the web btw!

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Re: Moog Memorymoog sucessfully cloned

Post by Luismarka » Thu Jul 23, 2020 12:21 am

Michael O. wrote:
Wed Jul 22, 2020 11:45 pm
Whoa, incredible work!! That is one hell of an undertaking, and those boards look fantastic. The PSU rework seems, ostensibly at least, like a great idea, and superior to the original even. Does it have the full six voices of the original?

Very much looking forward to your progress, and particularly in hearing this monster!
Yes, every circuit is an exact reproduction of the original (except for resistors R13 and R14 on the DMUX board, I think their values are swapped in the schematics. No way to get the panel potentiometers position to be read using the original values). Six voices, original firmware, Curtis chips, same filter transistors/capacitors/ICs. Only component changed in the audio path was the noise generator chip, I could not find the 5837 or the 5437 as in the original so I used an Electricdruid NOISE1B instead. I cannot tell the difference, the original ICs are also digital, but it would be nice to check against an original Memorymoog.

Another modification is the 100K resistors in the CV path: I used 0.1% tolerance, 15ppm resistors everywhere I could. I think this helps keeping this monster of cables and parts pretty stable, which was honestly surprising. I was kinda expecting the machine to be unstable because, well, I am no electronics expert, just a hobbyist, and it is a VERY complex circuit. Lots of room for error!

Cabling is much simpler than in the original; it became clear that the Memorymoog was a rushed project. The cabling is a total mess in the original, and after assembling my prototype I see I could had made it even better. For example, I could had placed 3 voices in one larger board instead of 3 separated boards, sharing cabling for power and a control signals, reducing the amount of wiring. Even better, instead of 2x 16-way flat cables for the voice boards control signals, it is possible to use only one 40-way flat cable making it even simpler.

See attached close-ups of the PSU and power transitor boards, and the glorious "6 TUNED" I get every time I hit Autotune!

Cheers!

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Luismarka
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Re: Moog Memorymoog sucessfully cloned

Post by Luismarka » Thu Jul 23, 2020 12:38 am

Oh, almost forgot: in my project, all VCO trimpots are accessible thru a series of slots in the back of the cover. No need to open the instrument, so calibration can be done at actual temperature. I am also considering adding a small controller, such as an Arduino or something, that reads an internal temperature sensor and adjusts the fan RPM accordingly so the internal temperature is stabilized.
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Bjarne
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Re: Moog Memorymoog sucessfully cloned

Post by Bjarne » Thu Jul 23, 2020 7:42 am

Ha ha, you and I have very different definitions of hobbyist. Excellent work!
Cheers
Luismarka wrote:
Thu Jul 23, 2020 12:21 am
... I am no electronics expert, just a hobbyist,...

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Re: Moog Memorymoog sucessfully cloned

Post by JanneI » Thu Jul 23, 2020 7:50 am

Nice work! Post some audio when you get to it!

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Re: Moog Memorymoog sucessfully cloned

Post by 3hands » Thu Jul 23, 2020 8:05 am

Oh my.

Welcome to Muffs! This is incredible. Are you looking to make these available as kits eventually?
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Re: Moog Memorymoog sucessfully cloned

Post by jorg » Thu Jul 23, 2020 8:09 am

Holy crap. I was incredibly lucky to tour the Moog factory in Buffalo when they were manufacturing MemoryMoogs. I remember the sound as you describe: HEAVY. It was overpowering and cool.

I didn't think your post was serious at first - seems nearly impossible. But yup - looks like you've really done it. I'm curious how you got the firmware - did you copy it before you sold your beast? Then you wept and decided to resurrect it?

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Re: Moog Memorymoog sucessfully cloned

Post by bwhittington » Thu Jul 23, 2020 8:09 am

Amazing labor of love, and we would all love to hear how it sounds.

PS. And be ready for a call from Uli Behringer. :lol:

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Re: Moog Memorymoog sucessfully cloned

Post by Liddlepud » Thu Jul 23, 2020 8:21 am

bwhittington wrote:
Thu Jul 23, 2020 8:09 am
Amazing labor of love, and we would all love to hear how it sounds.

PS. And be ready for a call from Uli Behringer. :lol:
He won't call, you'll just see a teaser press release about the new Behringer synth ;)

This looks amazing, one of the only vintage synths I have any gas for. I've only played with a friends but I still have occasional pangs of jealousy.

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Re: Moog Memorymoog sucessfully cloned

Post by ricko » Thu Jul 23, 2020 8:22 am

Moog used terrible thin PCB material for Memory Moog voice cards, not only slightly conductive but brittle and degrading. I have a voice card here, and it is a shocker. Using modern PCB material would be a definite improvement.

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Re: Moog Memorymoog sucessfully cloned

Post by KSS » Thu Jul 23, 2020 9:20 am

Congratulations on an epic achievement!

And Welcome to Muffwiggler!
Luismarka wrote:
Thu Jul 23, 2020 12:21 am
Cabling is much simpler than in the original; it became clear that the Memorymoog was a rushed project. The cabling is a total mess in the original, and after assembling my prototype I see I could had made it even better. For example, I could had placed 3 voices in one larger board instead of 3 separated boards, sharing cabling for power and a control signals, reducing the amount of wiring. Even better, instead of 2x 16-way flat cables for the voice boards control signals, it is possible to use only one 40-way flat cable making it even simpler.
Be careful with this. Your example 'improvements' only improve the initial build. Don't forget about the service side of your build.

When things go wrong -and they will- do you want to have to pull three voices to fix one? Can you tell a customer to swap voice boards to locate a problem? If this ever becomes a project for others to buy or build, that question may matter more to another who does not have the familiarity and skill you have than it does for you personally. As an example, with long time synth tech experience, I would prefer -making and- plugging two 16 pin cables rather than one 40 pin cable. For several reasons. And definitely prefer single or at worst dual voice cards.

Excellent build. Don't cripple it for service by trying to make initial assembly easier. Evaluate the tradeoffs carefully. Always consider service needs as part of the design process. It's the difference that makes a difference.

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Re: Moog Memorymoog sucessfully cloned

Post by Luismarka » Thu Jul 23, 2020 9:29 am

jorg wrote:
Thu Jul 23, 2020 8:09 am
Holy crap. I was incredibly lucky to tour the Moog factory in Buffalo when they were manufacturing MemoryMoogs. I remember the sound as you describe: HEAVY. It was overpowering and cool.

I didn't think your post was serious at first - seems nearly impossible. But yup - looks like you've really done it. I'm curious how you got the firmware - did you copy it before you sold your beast? Then you wept and decided to resurrect it?
The unit I had used an older firmware version, prior to the autotune update (2.1, I think). I found the newer 2.4 firmware in a website that stores thousands of synth firmware files for download, dbwbp.com

I was pretty used to the machine because when I bought it, it was not working at all (I would keep it only if I could make it work, otherwise the seller would revert the deal). Had to get the schematics - at the time, in the late 90s, they were not available for downloading so I bought a photocopied version of the schematics from Mark Glinsky. When I got to the point where it would work, I was so used to the circuits that I could almost redraw them from memory! By the way, it was a bad AMD AM6012 IC, now replaced by the Analog Devices DAC312, and a few Curtis and CMOS ICs. Everything else was OK.

Decision was made when Alfa - alfarzpp.lv - issued a note in the SDIY list offering samples of brand new Curtis chips: the 3340, 3310, 3360 and 3320. I got a few, saw they worked perfectly, and went thru suppliers to see if there were any components that would be impossible to find. 99.5% of the components were readily availabe, even if some of the transistors had to be replaced with equivalents. What I could not find was just the OSC2 and 3 potentiometers, dual concentric with - not sure how to call that - a reduction gear mounted between the two actuators, the alphanumeric display (at first I was going to use large 14-segment LED, but could source locally a lot of HDSP 6508 displays for like 2 bucks each), and the noise IC. Everything else was just standard components. I also found a replacement for the IT122 dual transistors by a company called Linear Systems, and then I was set. I also needed an excuse to switch from Eagle to Kicad, and this was a pretty good one...

Cheers!

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Re: Moog Memorymoog sucessfully cloned

Post by Luismarka » Thu Jul 23, 2020 9:42 am

ricko wrote:
Thu Jul 23, 2020 8:22 am
Moog used terrible thin PCB material for Memory Moog voice cards, not only slightly conductive but brittle and degrading. I have a voice card here, and it is a shocker. Using modern PCB material would be a definite improvement.
Agree, voice cards are terrible. Bad layout, bad material, fragile.

My initial idea was to make exact replicas of all boards so that they would fit a stock Memorymoog. But for that I would need to have a Memorymoog at hand so that I could make measurements - both mecanical and electrical - and locate the connectors and mounting holes in the exact same positions, enabling the existing wiring to be plugged directly to the new boards. Unfortunately this was not the case, so I decided to forget the original board layouts and make it all from scratch, relying only on the schematics. Digital and front panel boards, however, are pretty close to the original.

Cheers!

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Re: Moog Memorymoog sucessfully cloned

Post by SphericalSound » Thu Jul 23, 2020 10:52 am

This is as epic as a thread can get. Kudos. Keep us informed.

Maybe you would like to contact Behringer to mass produce your baby. Or do an SMD version to automatize and sell presoldered PCBs of it.

Whatever you do with it, we´ll love to listen and see videos :sb:

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Re: Moog Memorymoog sucessfully cloned

Post by jorg » Thu Jul 23, 2020 1:49 pm

What did you do about the bizarre concentric gear-reduced pots?

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Re: Moog Memorymoog sucessfully cloned

Post by steviet » Thu Jul 23, 2020 2:48 pm

I learned how to subscribe to topics for this topic.

Very very neat stuff, just to continue to echo everyone's feelings about this: nicely done :sb:
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Re: Moog Memorymoog sucessfully cloned

Post by Monofunk » Thu Jul 23, 2020 2:57 pm

What an amazing project. It's hard to imagine how much work you put into this. Would love to hear how it sounds!

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Re: Moog Memorymoog sucessfully cloned

Post by dp4 » Thu Jul 23, 2020 3:14 pm

holy crap!! this is huge

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Re: Moog Memorymoog sucessfully cloned

Post by devinw1 » Thu Jul 23, 2020 3:46 pm

SphericalSound wrote:
Thu Jul 23, 2020 10:52 am

Maybe you would like to contact Behringer to mass produce your baby.
Please don't. Haha.

If you do, please make sure you are paid AMPLY for your R&D work.

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Re: Moog Memorymoog sucessfully cloned

Post by Luismarka » Thu Jul 23, 2020 3:54 pm

jorg wrote:
Thu Jul 23, 2020 1:49 pm
What did you do about the bizarre concentric gear-reduced pots?
Standard dual concentric 10k pots, outer shaft is Coarse and inner shaft is Fine. Still in the to-do list to play with resistors in series with the 10k potentiometers to figure values that I am comfortable with. I am thinking that if I can get the Coarse to range from 10 to 90, and the Fine at +-12 or so, should be good enough. Only problem is that the shaft diameters are far from the knobs inner diameter so I will have to machine some sort of sleeve to fit those.

Just realized I made a mistake when placing the buttons... OSC 3 Low and Keyb Contr were supposed to be under the 8' and 2' buttons. I somehow placed those under the 16' and 4' instead... damn!
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Re: Moog Memorymoog sucessfully cloned

Post by paterursus » Thu Jul 23, 2020 4:06 pm

I am going to be following this. Welcome!
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