Moog Memorymoog Plus analog polyphonic synthesizer

Last Update 10-11-2017

The Memorymoog is both a landmark and a low point in the history of Moog synthesizer instruments. While its position in the list of top ten fattest analog synthesizers is deserving, so is its reputation of unreliability. Age has not been kind to Memorymoogs, largely due to oxidation on the internal PC board connectors. The Memorymoog is chock full of them and they are the achilles heel of the beast in that they are the primary source of tuning foibles. Other causes of malfunctions are dirty keyboard contacts and faulty solder joints on the voiceboard trimpots. Owning a Memorymoog is like owning a Triumph automobile - the price of admission is the high maintenance.

I purchased my unit direct from the factory in 1985 when all synthesizer production had ceased thanks to the Yamaha DX-7. I owned a Polymoog then and when I found out that the factory was a mere one hour drive from my college, I called and arranged a visit. I got a nice tour of the place and I learned they were clearing out inventory, so I bought a brand new Memorymoog for $1000 - a bargain back then and a bargain today. Mine is actually an early Memorymoog with the sequencer added along with the reliability upgrades, and it has a new serial number on it. I know this because the serial # on the LH control board is lower and they added the sequencer overlay over the original.

Moog had pioneered the polyphonic market with the release of the Polymoog in 1975. Then the assignable voice polyphonics that followed - Oberheim FVS Four Voice SEM in 1975, Yamaha CS-80/60/50 in 1976, Prophet-5 in 1977, Oberheim OB-X in 1979 - showed the world the superior implementation of polyphonic synthesis. The major difference is that the Polymoog is a top octave divider system while the assignable voice system was capable of far more sounds. The reason for the limited palette of the Polymoog's top octave divider system (TOS) is because it cannot implement voice modulation - if you wanted to modulate the VCF or the PW using the oscillator of an independent voice, you could not do it. Want to modulate the pitch of an oscillator in a TOS? Can't be done.

Moog had their share of teething problems with the Polymoog and it became an orphan with the competing synths. It also gained a reputation of unreliability (it is the rare Polymoog that is 100% functional today and few repair shops will touch them). Moog finally gave in and released the Memorymoog in 1982 - a pretty late entry in an already crowded market! Alas, before the Memorymoog could establish a foothold, the Yamaha DX-7 effectively killed the analog synthesizer market in one sweep.

The Polymoog was my first endeavor in polyphonic synthesizers but it didn't take long to learn of its limitations. The Memorymoog was a worthy successor to the Polymoog in that it was a proper polyphonic. The major difference is that the Polymoog is a top octave divider system while the Memorymoog is a assignable voice system which is the superior design. There are a lot of tricks in the Memorymoog that is not possible in the Polymoog, chief among them voice modulation. That is why the Memorymoog has a broader palette of sounds over the Polymoog. top

Sounds

The palette of sounds from the Memorymoog are impressive. Its filter and modulation options can conjure up strings, brasses, and pads that most users are familiar with. By using filter FM tricks via voice modulation some good clavinet sounds can be dialed up. Flutes and percussive sounds are also a specialty.

On the synthesizer palette the Memorymoog delivers a-plenty. Check out this filter sweep. My particular model has the upgrade for the noise source to eliminate the periodic "heartbeat". Effects - no problem. The Memorymoog is one of the few polysynths that is effective for lead sounds because you can specify how many voices in a unison monophonic patch, often one voice is effective for lead sounds. If you like all six voices in unison they can breathe some massive bass sounds, one of which demonstrates filter EG routed to pitch for a great intro heard on the Scorpions live record from the late 1980s.

Polyphonic glide isn't something you find on many polysynths, and it's even better combined with the HOLD button with chords you can play with one finger. Some of the arpeggiator samples here demonstrate both features in powerful ways that can keep your kids entertained for hours (but this is no Trix cereal so it's not for kids you silly rabbit).

One of my favorite tricks I learned on the Memorymoog is VCO3 configured as an LFO with its frequency tracking the keyboard as heard here. It is especially effective for choir patches.

All of the previous sound samples are dry with no effects whatsoever, on a freshly calibrated unit. This one is processed however, as it shows off the massive pipe organ sound that I heard years ago when I saw Petra in concert: Pipe Organ: JS Bach - Come Sweet Death

All mp3s encoded with RazorLame. top

Versions

The original Memorymoog was introduced before MIDI. Last known factory firmware revision for the non-plus Memorymoog was v2.4. In 1984 they offered a MIDI retrofit that included a polyphonic and monophonic sequencer, and the model became known as the Memorymoog Plus. Last known factory firmware revision for Memorymoog Plus was v4.1 (press C-0 for the "light show" - if the program LEDs display "85" then this is firmware v4.1). Earlier firmware versions of Memorymoog Plus can be quickly identified by pressing the arpeggiator button then any of the numeric keys - if you do not see a descriptive display such as "UP L" (up latched) then the firmware is earlier.

The factory MIDI implementation is extremely basic - note on/off and program change. That's it! No mod wheel, pitch wheel, volume, filter cutoff, MIDI clock sync - nothing! Not only that, it operated in Omni mode which meant it responded to note commands on ANY MIDI channel - useless in a MIDI rig!!! There was also a latency "delay" between key presses and the voice being triggered. Since production ceased in 1985, so did firmware upgrades. Also the MIDI output on a stock Memorymoog had a bug that rendered it useless as a MIDI controller - any key on the local keyboard generated a MIDI Note On message for ONLY note #64!

The ultimate MIDI upgrade is Rudi Linhard of Lintronics in Germany where he performs a comprehensive retrofit that improves the tuning reliability and implements a modern world implementation of MIDI, including patch dump over sysex and transmission of panel manipulations over MIDI. This became known as the Memorymoog LAMM (Lintronics Advanced MemoryMoog) and they are very valuable on the used market today, if you can find one. Although the LAMM upgrade removes the sequencer, the loss is not that great as the sequencer is pretty rudimentary by todays' standards.

There used to be a "poor mans' LAMM upgrade" called the dBm upgrade which is no longer commercially available. This upgrade worked in a Memorymoog Plus only and with a replacement set of ROMs and some wiring changes you got better MIDI features like Volume Controller, Mod Wheel, Pitch Wheel, Foot Controller (for controlling filter cutoff, VCO2, among others), and got rid of the damn Omni mode. It also decreased the latency "delay" between pressing a key and the voice triggered. While this was a big improvement over the factory implementation, the dBm upgrade still retained the bug of MIDI output (almost nobody uses a Memorymoog as a MIDI controller anyhow).

I have provided ROM images and upgrade documents for the dBm upgrade below - you will need (4) TI TMS2532A 350ns (or faster) EPROMs and an EPROM burner that can program them. Note that 2532 EPROM pinouts vary between manufacturers and may not work in Memorymoogs. You are on your own with this upgrade and I do not have these parts or tools so please do not email me.

Install documentation page 1	Page 1	EPROM binary image U2 (right-click and "Save Link Target As...")	U2 ROM
Install documentation page 2	Page 2	EPROM binary image U3	U3 ROM
Install documentation page 3	Page 3	EPROM binary image U4	U4 ROM
Install documentation page 4	Page 4	EPROM binary image U5 (sequencer board)	U5 ROM
Install documentation page 5	Page 5
Install documentation page 6	Page 6
Install documentation page 7	Page 7
Install documentation page 8	Page 8

How do you tell the difference? On the original Memorymoog, the buttons in the LFO section are all grey, the Memorymoog Plus are white. The telltale of a Memorymoog LAMM is the rear panel. On a dBm unit the display will read "DBM TECH" when powered up.

There is also the "mysterious" Moog Sanctuary... this is a re-badged Memorymoog Plus with a factory sound library tailored to churches. Dave Van Koevering, a maverick moog salesman from the early days, arranged for a set to sell through his business. Reportedly there were 100 of these made. top

Features

The Memorymoog voice is heavily based on the CEM chipset. The VCO is built from the CEM3340, VCA is CA3080, and EGs are CEM3310. The lowpass filter is the classic Moog transistor ladder filter. The Memorymoog is not multitimbral. Each of the six voices consists of three VCOs, the Moog 24dB ladder filter, VCA, and independent ADSR EGs for the VCF and VCA.

Be aware that the Memorymoog uses about forty CEM chips which are now getting very rare and are running $50 and up apiece.

Each VCO has triangle, ramp, and variable pulse waveshapes which can be combined (the only Moog synthesizer other than the modulars that had this feature). VCO2 can be hard synced to VCO1 for nasty biting sync sweep sounds. VCO3's keyboard control can be turned off and can be dropped to LFO mode like the Minimoog - this is a powerful feature in voice modulation. The frequency control is an interesting (and USEFUL) dual control with a fine and coarse control implemented with concentric knobs, the smaller knob controlling fine adjustment. Only the Oberheim SEM voice had this kind of control and it is very effective at dialing in fine tuning offsets, and the resolution is much higher for this control so you don't hear "stepping" like the Prophet-5 or Oberheim OB-X/Xa/8. A proper mixer controls the levels of the VCOs and the white noise source, and an interesting feature of the mixer is you can clip (or mildly overdrive) the level as you raise it past "5". This not only gives you distortion effects, but you can transform a triangle into a sine wave.

The 24dB/oct filter is the classic Moog transistor ladder filter and it sounds excellent. My only complaint is instead of continuously variable keyboard tracking with a knob, Moog used the 1/3 and 2/3 octave switches like the Minimoog.

A multi-waveform LFO (triangle, rising ramp, falling ramp, square, S&H) can be assigned to any/all of VCO pitches, PW, and VCF. The modulation amount can be preprogrammed with a separate knob or varied with the mod wheel. The LFO frequency can't be modulated (but this can be done using VCO3 as an LFO) and its range goes from 0.1hz to 100hz.

The EGs are full ADSRs, one for VCF and one for VCA. A Keyboard Follow button enables keyboard tracking of the transient times, IE the higher you play up the keyboard the faster the attack/decay/release times. This is not variable unfortunately but it was heady stuff for 1982. A Release button turns off the release stage for instantaneous release. Unconditional Contour forces the EGs to complete the full ADSR stages regardless whether a key is held down or not. Return To Zero forces the EGs to reset to full off in the middle of an envelope if that EG is re-triggered. When using the Memorymoog as a monophonic synth the EGs can be single or multiple trigger, a nice feature for emulating monophonic patches.

There are two input jacks on the rear panel for CV controllers such as control pedals, #2 is normalled to #1 so you can use a single controller for both. You can use foot pedal #1 for controlling volume, pitch, and/or filter, then foot pedal #2 for mod amount and/or VCO2 pitch (think sync sweeps).

The Memorymoog doubles as a monophonic synth by pressing MONO, and you can vary the number of voices from 1 to 6. All six voices in monophonic mode gives you one of the hugest sounds in analog land, you get the sound of eighteen VCOs and six Moog filters all at once yielding a massive unison sound with few rivals. The voice allocation choices are flexible - cyclic, memory cyclic, reset, memory reset. Cyclic cycles through all six voices when you play the keyboard, Memory Cyclic "remembers" the same voice if you repeatedly press the same key, Reset always resets to voice one when all keys are released, and Memory Reset is a combination of Reset and Memory Cyclic and is most effective when using polyphonic glide.

Then we get to the REAL power of the Memorymoog... Voice Modulation. The VCF EG and/or VCO3 can be used to modulate VCO1/2 pitch, PW, or the VCF. The modulation amounts are variable and can be inverted. What's the big deal? VCO3 can be put in LFO mode and when you route VCO3 to the PW of the other two VCOs, you get independent LFO modulations of the PW for a rich fat sound. If you use the standard LFO, the PWM of all the voices will all be in sync; if you use VCO3 as an LFO, the PWM will be independent. The sound is much thicker and much more animated. For more fun, turn on keyboard tracking for VCO3 while it is in LFO mode. Voice modulation is quite effective using the filter EG to modulate PW on a per voice basis.

A couple of interesting buttons in the voice modulation are Invert and Contoured OSC3 Amount. Invert is used to reverse VCF EG to negative envelopes or to transform OSC3 falling ramp to rising ramp - remember that VCO waveshapes can be combined so the invert function has some interesting modulation options. Contoured OSC3 Amount routes filter EG to OSC3 level so you can modulation OSC3 modulation level with an EG - good for introducing transients or creating weird ring modulation effects.

This is territory that the Polymoog was not capable of. The Prophet-5's claim to fame was its Polymod feature, and the Memorymoog takes it even further.

An arpeggiator provides a lot of musical fun in the Memorymoog. What is way cool is combining the HOLD button and the arpeggiator - when you press a single key that comprises a chord under the HOLD button, the arpeggiator cycles through each note in the chord. The options are combinations of latched/unlatched of up, down, up & down patterns, autotrigger, as well as first to last or last to first.

The sequencer (Memorymoog Plus only) is fairly rudimentary and I haven't used it in years. You can store six polyphonic sequences and six monophonic sequences in memory, and the monophonic sequences can be routed to the external interface jacks so you can sequence an external monosynth (complete with scaling and range trimpots) from the Memorymoog. The sequences can be in step or in realtime, you just press record, start playing, and press stop. You can specify the maximum number of voices so that you can have some left over for playing along with the sequence. Pretty basic by todays' standards but it was powerful for 1984 when it was released.

You can store 100 of your own patches. There is a program sequencer which you can define program patch numbers in a sequence which can be advanced or backstepped with a single button or footswitch. This was pretty handy when I gigged with this beast.

The Prophet-5, Oberheim, or CS-80/60/50 synths never featured an arpeggiator or sequencer so this was a step up from older machines.

The five-octave keyboard has no aftertouch or velocity sensing. A headphone jack has its dedicated volume control for monitoring, and a programmable volume knob balances volumes between patches. Patch dump is done with cassette tape interfaces, unless you're lucky enough to own a LAMM. top

Cleaning Keyboard Contacts

If random notes do not play on the Memorymoog keyboard, you have the common dirty keyboard contact problem. This unit as well as the Korg PolySix, Mono/Poly, SCI Prophet 600, and Oberheim OB-8 uses the Panasonic keyboard assembly whose achilles heel is the rubber dome keyboard contacts which get dirty with age and render a key inoperative.

This cleaning procedure is shameslessly lifted from my tech friend Scott Rider and is duplicated here with changes relevant to the Memorymoog. This procedure assumes you are competent with electronics and with disassembly of this machine. The author is not responsible for damage to your equipment or for any health incidents incurred as a result of this procedure. If you question your skills at all, then you should seek the services of a qualified service technician.

Step 1: Removing the Keyboard from the Machine

1-1: Make sure the unit is unplugged from the AC power line!

1-2: Open the machine and locate the keyboard's connector on the left side of the keyboard assembly. Unplug this cable from the assembly.

Step 2: Removing the Keyboard's Circuit Board

2-1: Place the keyboard upside-down on the work surface, oriented as shown in the following picture.

2-2: Using a Phillips screwdriver, remove the sixteen retaining screws as shown above.

2-3: Lift the circuit board up at the back and carefully remove it from the retaining clips. This board is long enough that it becomes flexible, so be careful not to break it.

Step 3: Removing the Rubber Contact Strips

3-1: Holding the circuit board as shown, grasp the end of one of the rubber contact strips (there are ten such strips on this keyboard; nine 6-cap strips and one 7-cap strip) and gently pull it up. It helps to push against the rubber "pins" underneath the board to get them to come out. These rubber strips are more resilient that it might appear--after all they have to stand up to millions of key presses--but even so take care not to tear them. A strip comes out easily once it is started.

NOTE: I do not remove them all at once. I usually pull up one strip, clean the contacts as described below, and replace the strip before pulling up the next one. This keeps things relatively neat.

Step 4: Cleaning the Rubber Strip Contacts and Board Contacts

4-1: For each contact face, there are a few ways to do the cleaning:

Method 1) use a pencil eraser and gently rub the black contact face 2 or 3 times as shown. This is the easiest solution if only a few contact pads are causing problems.

Method 2) use denatured alcohol and a Q-tip swab to clean the contact face. These 'elastomeric' contact pads tend to dry out over time, which causes a thim film to cover them. The idea is to rub the film away. Don't overdo it, however.

Method 3) for cases where the majority of contacts are failing, it is best to purchase a rubber keypad contact repair kit, such as the part# CW-2605 available from Hosfelt Electronics. Also get a part# CW-7400 'Gold Guard' cleaning pen from them as well, which can be used to clean the gold-plated contacts described in the next step.

4-2: Now, similarly, for each gold-plated, interleaved contact area on the circuit board, it is recommended to use a gold-contact cleaning pen such as the 'Gold Guard' model offered by CircuitWorks and sold by Hosfelt Electronics as noted above. Alternatively, use a different eraser than was used for the rubber contact pads and rub each area 2-3 times as shown, or use denatured alcohol and a Q-tip swab. Don't rub the gold plating off!

4-3: Make sure no eraser crumbs are still present, then press-fit the rubber contact strip back onto the board. A properly-seated strip will not be 'pulled' or 'buckled' in appearance.

4-4: Repeat steps 3 and 4 until all the contact areas have been cleaned.

Step 5: Keyboard Reassembly

5-1: Align the board with the keyboard frame. The end with the cable connected to it goes on the right if the keyboard is oriented as shown in the above images. Hook the front edge of the board under the retaining clips. Be sure that all the clips are in place and holding the board. (The clips can slide out if you pick the keyboard up without the board installed, so be careful).

5-2: Pay attention here, this can be tricky. Align the rubber caps with the holes in the keyboard frame, checking to make sure every cap fits in its respective hole properly as shown. These caps tend to hook the edge of a hole and scrunch up underneath the keyboard frame. Use a blunt tool (I use a plastic TV IF transformer adusting tool) to coax finicky keycaps into place if necessary. Do not use anything with a sharp point like a pencil which could tear the keycap.

5-3: Once the keycap fit for each key is verified the board can be refastened with the sixteen screws.

At this point the keyboard can be placed back in the machine and its cable reattached to the circuit board. Do not bolt the keyboard back down just yet. Restore the keyboard connector to the assembly and apply power on the machine. Select a decent patch and play every note on the keyboard to verify that it sounds. if a key seems 'sticky' or otherwise unresponsive, note which key(s) this happens on and go through the cleaning procedure again for those specific key contacts. It will take a minimum of deduction to remove the correct rubber strip and clean the correct contacts. Eventually, all the keys will be working fine again.

After all the keys are working satisfactorily, power off and unplug the machine, and reassemble the Memorymoog. top

Comprehensive Tuning Upgrade

Standard disclaimer: this is not a job for the novice. This procedure assumes you are competent with electronics and with disassembly of this machine. The author is not responsible for damage to your equipment or for any health incidents incurred as a result of this procedure. You should have excellent soldering/desoldering skills and experience with double-sided PC boards. The Memorymoog has many cable bundles that are vulnerable to damage. If you question your skills at all, then you should seek the services of a qualified service technician. For an online primer see http://www.synthtech.com/tutor/tutor1.html

This upgrade involves removing DIP sockets and header pins - tedious work which can damage the PC board if you are not careful. A good soldering iron is definitely recommended. You'll need desoldering tools (wick or solder-sucker) to remove the parts. In most cases you'll have to physically destroy the DIP sockets to get them out. The trick is doing it without damaging the PC board pads and traces. If you've never removed parts like these before, start with the voice cards since they are single-sided boards.

Before you install the new parts, apply flux to the pads so that you get a clean solder joint, and clean up the excess flux with flux cleaner. I use a brush to apply flux cleaner and a wadded paper towel to soak up the residue, using a towel fresh surface each time. Good lighting makes a difference here. If you don't clean it up, leftover flux will cause problems down the road like low-impedance shorts across PC board traces.

Wear a ground strap or do your work on a static-safe mat. You're going to be working with irreplaceable static sensitive components. The CMOS and CEM chips are safer in their sockets on the boards.

I used a Panavise with a PC Board clamp so that I can work with both hands free, which helped a lot. Some of the MM's boards are too big to fit this clamp.

I suggest that you work with one board at a time and confirm 100% functionality after rework before you move to the next board.

I also suggest that you label plugs with a permanent marker as you remove them, IE S11E or P16E for voice card "E". There are too many places to plug the wrong connector and too many connectors to get mixed up.

Remember that when you install a new part that you have to have proper solder fillets on the pads of *both* sides of the double-sided PC board. If you're good enough with the iron and apply the solder to the pin and not the tip of the iron, the solder will flow well enough to make a fillet on the other side by itself. Note that only the voice cards are single-sided.

Some connectors have a "key" so that you don't orient the plug the wrong way. The mating header simply has a pin (and PC board thru-hole) omitted where the "key" is. In your new part you can pull out a pin by heating it and pulling it out of the header strip as the plastic softens.

Do not handle any of the gold plated parts with tools. The plating on the pins is extremely thin (10 or 30 microns) and can be destroyed if you scrape it with metal tools.

----------------------------------

The Memorymoog has a history of problems with tuning. If your unit has to be calibrated more than once a year, or the calibration values get noticeably worse each year, or the tuning changes from day to day, or the monophonic mode is out of tune with the polyphonic mode, or the tuning changes with any movement or impact (just hold a note and hit the case with your fist), that is the result of multiple causes:

Oxidation on the connectors inside the Memorymoog. There are almost 100 connectors inside these beasts, which aid in servicing but are a frustrating source of malfunction.
failing range/scale trimpots on the voice cards cause tuning problems. On the resistive elements of the trimpots, the precise area where the wiper contacts corrodes over time and will no longer work reliably.
untinned leads on the tuning trimpots. Believe it or not, I removed trimpots from the voiceboards - by hand!!! Moog didn't pre-tin the leads on the trimpots, so they never made a proper connection to the solder fillets. You have to tin the leads, remove the old solder fillets, and re-install the trimpots.

Replacing Connectors and IC Sockets

The connector contacts in the MM are tin-plated. Over time, oxidation forms on the contact surfaces in the form of an impedance, which 1) varies with humidity and temperature, and 2) is non-uniform over the contact surface, where simple movement changes the impedance. The consequence is that you lose voltage across these oxidized contacts.

The polyphonic control voltages that drives the voices cards travels through three boards (six connectors), while the monophonic control voltage goes through four (eight connectors). If ONE OR MORE of these connector contacts has oxidation, the control voltages are degraded. Note the emphasis; at worst there will be six points where the polyphonic CVs are losing voltages across the connectors. This is the primary cause of the MM's tuning problems. To add to the problem, these critical voltages are carried over ribbon cables via DIP16 plugs, and the mating sockets in the stock MM are poor quality for analog signals. You can verify this with a DMM; probe the signal at the DUMX board and at the voice card where it terminates, if you measure any voltage drop then you're seeing contact loss.

Power busses are equally vulnerable, if the voltages aren't stable no amount of calibration will help. TTL logic signals (d*g*t*l) with their built-in interim zone between high & low are insensitive to these losses and generally don't have a problem.

As a temporary fix, the contacts can be cleaned by periodically removing/re-inserting the plugs as to "scrub" the oxidation off, or they can be shined up using an eraser.

Ultimately the contact surfaces will corrode beyond cleaning. I am the original owner of my MM, and it took less than ten years for this to occur. I was now faced with having to replace connectors.

During that time, I had acquired an ARP Pro-Soloist which predates the MM by ten years. It had laid dormant, yet was perfectly in tune and 100% functional when I powered it up. This is an instrument that is over twenty years old yet at half its age was in far better health than my MM. My interest piqued. Closer inspection revealed that the connectors used in the ARP were a combination of tin plating and gold plating, IE the pins were gold plated while the contact inserts in the mating plug were tin plated.

Before starting ARP, Alan Pearlman designed and built amplifier assemblies for the space program and the military. I also have many years of experience in military electronics. The military demands reliable equipment, and the standards mandate that all connectors contacts have gold-plating; tin plating is not acceptable. Al's experience with military electronics carried over to his synthesizers and is a big reason why his instruments were more reliable.

Connectors with tin-plated contacts are rated for ten years, while gold-plated contacts are rated for TENS of years. Gold also does not oxidize. In my experience, I've found that the most reliable equipment either have the fewest connectors or the connectors are high quality.

My first impulse to fix my ailing MM was to replace every tin-plated connector contact and pin with gold-plated equivalents, but there was a problem. The gold-plated contacts for the AMP MTA plugs used in the MM couldn't be found in any catalog and were available only from AMP in lots of 10K, and AMP only produced a stock when the demand justified the expense. You also need a special insertion tool for the MTA plugs.

However the ARP demonstrated that you can get years of reliability at reasonable cost by combining gold/tin platings on connector systems. So I decided to focus my efforts on replacing only the connector pins and DIP sockets on the PC boards and leave the plugs as is. This was more cost-effective in parts and in labor, and the parts are easier to locate. I also minimized my work by targeting only those connectors which carried any analog signals, since logic signals weren't a concern. You can find this info in the master connector chart on the MM's schematics, which you'll need for this work. If you need schematics you can get them from the world famous Mark Glinsky Manual Manor.

----------------------------------

For the MM, you'll need to find a source for header strips with gold-plated pins on 0.100 centers and 16-pin DIP sockets with gold-plated contacts. These are not hard to find in catalogs or online. I got lucky and sourced gold-plated parts at a surplus shop. I recommend Augat DIP machined sockets if you can get them. You can buy header strips with 40 or so pins which can be cut into the quantity you need. Side cutters work well, although occasionally you'll lose part of a pin. Buy more than you need. All together, you'll need 42 DIP16 sockets, more than enough header strips for 305 pins, and header strips with right angle pins for 32 pins (you might get away with the straight pins but I don't know how it will clear when put back together).

If you can find them (and let us know where 'cause I would really really like them for mine), you'll want new headers for the power supply board. These are the larger pins and are 0.156 centers. You'll need a 15-pin strip and three 3-pin strips. I have yet to find a catalog (Mouser, Digikey, etc) that carries these.

The complete list of connectors to replace is:

Voice Cards A-F (x6): S11, S12, P13, P14, P15, P16, P17, sockets for CEM3340s (x3)
Common Analog: S21, S22, S23, P25, P26, P27, P29
Contour/Glide: S32, S33, P31, P34, P35, P36A-F (x6)
Digital: P40, P48a, P48b
DMUX (big one!): S53, S54, S55, S56, S57, S58, S59, P511, P512, P514, P515A-F (x6), P516, P517, P518, P519, P520
RSC: P63, P64
LSC: P76, P77, P78
Power Supply: P131, P132, P133, P134
Keyboard: 16 pin right angle

Note that the LAMM update from Lintronics does not include this work.

If you have an older MM, you may need the reliability updates that Moog Music has issued, the complete list of service bulletins are online at http://www.memorymoog.com/.

Altogether this can take over 40 hours of work, but the reliability improvement is worth it. In the years since I have done this to my MM, *none* of the tuning problems have surfaced. I recently checked the calibration, and the oscillator range is slightly off but the scaling is *rock solid*.

Failing Trimpots

Here's another MM foible: failing range/scale trimpots on the voice cards cause tuning problems. On the resistive elements of the trimpots, the precise area where the wiper contacts corrodes over time and will no longer work reliably.

You can unsolder each trimpot, rotate them 180 degrees on the PC board, and resolder them. By rotating them you will have to set the resistance to its previous value, but it will be no longer around the corrosive area. You will have to perform major oscillator re-calibration when you do this, because they will be WAY out (hint: don't use the C-7 routine. Calibrate the oscillators by ear with a reference).

Of course you can only do this once. After that it's time to spring for 36 new trimpots. top

----------------------------------

This beast has been my number one axe for years and it is the standard against which every polysynth is measured in my book. I've tried to find a smaller lighter polysynths that could replace the Memorymoog but they all come up way short. Not the Oberheim OBMx, not the Matrix, any VA, etc. Only the Alesis Andromeda comes close to it, and I've successfully duplicated many Memorymoog patches in the Andromeda. Even though the Andromeda now replaces at least four keyboards on stage, I am still hanging on to the old stuff. I'm just too attached to it. It's my favorite synth and I'm forever learning how to get new sounds on the thing.

Of any of the Moog synths ever made, the Memorymoog does the best Minimoog impersonation. It's got that big bad Moog sound. It's a lot of machine just for basses and leads, but it's fantastic for FX, pads, rezzes, strings, brass, etc I can get a LOT of sounds from this. The key is the voice modulation feature. "Brawny" is the best way to describe the Memorymoog because it sounds so big and strong. This thing will get ANY analog synth sound from the 70s and 80s, it is THAT versatile. I've been using the Memorymoog to cover songs by ELP, Styx, Rush, and many many others. It's been my workhorse for YEARS. I've even used some string and tympani sounds with a community orchestra band and it sounded fine. I wish it had some aftertouch in the keyboard though.

But... the Memorymoog is one fragile creature. I gigged with mine with a flight case for years yet the tuning and reliability went to hell. There are two problems: the trimpots fail and the connectors oxidize. The Memorymoog is FULL of connectors and Moog Music used really crappy ones. When mine wouldn't hold its tuning or calibration anymore, I ripped out selected connectors and replaced them with gold-plated ones for a phenominal reliability improvement.

Moog issued quite a few factory service bulletins to correct problems, which you can find here (warning large PDF file).

The Memorymoog is THE classic polysynth to own but you'd better be prepared for the cost of maintenance. You'll need to range and scale all eighteen VCOs once a year, and if it gets worse than that then I suggest the connector remedy described above. If you keep it tuned up like a fine import motorcar, the Memorymoog will reap many rewards. It's pretty heavy too, weighs about 80 pounds. You'll want a sturdy stand for it.

contact info

Looking for Patches?

Home