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MIDIJACK LOGO The retro/vintage craze has never been bigger with Techno and Industrial music-makers finding old curios such as the ARP 2600 or Moog Source synthesizers and making new music with them. Vintage analog synths have an unmistakable sound that more than makes up for their lack of modern conveniences such as reliability and full MIDI implementation. There are several MIDI-to-CV (that's MIDI to Control Voltage) converters available that allow MIDI data to be converted into accurate analog control voltages for interfacing these old workhorses with today's computer/MIDI systems. However, these converters are a little pricey, especially when you consider they usually only control a single synth at a time and must be "patched" into the proper places of the synth's circuitry. Patching into an ARP 2600 or a Moog is simple enough because the patch jacks are right on the front panel. However, as analog synth technology progressed, cost-cutting sacrificed many of these jacks for hardwired connections, making easy patching of external MIDI-to-CV converters impossible.


Ease of Use: 3
Value: 5
Functionality: 3

What Is It?

Enter the diminutive MIDIJACK, an universal MIDI interface with a small, $99 price tag. The MIDIJACK is permanently installed and wired inside each vintage synth you may have. You can add the unit to common analog monosynths made by ARP, Moog, Oberheim, Roland, or Sequential as well as less common analog synthesizers such as modular systems by Aries, E-mu, Serge, and rare monosynths such as the Crumar Spirit, Octave Cat and Kitten, and RSF Kobol. This universality is possible by MIDIJACK's inherent good design: most old synths (if they were calibrated and remained that way) operate on one volt DC per octave scale...kinda. Unlike most MIDI-to-CV converters, the MIDIJACK's scaling trimmer lets you adjust this voltage value anywhere from .25v/octave to control an EMS Synthi or VCS-3 Putney, or up to 1.2v/octave for an EML synth such as the Electrocomp 101. The Moog Micromoog ran at .9v/octave and nobody ever knew until they tried to connect a newer Roland MPU101 MIDI-to-CV/Gate converter and could never get it in tune. Besides not having to patch in an external MIDI-to-CV box every time you wanted go "retro", the MIDIJACK is already configured as soon as you power up because all settings are held in its non-volatile memory.

MIDIJACK Circuit Board


Here are some features: one to sixteen MIDI channel selection; a MIDI panic button for stuck MIDI notes; MIDI Off mode or local keyboard on/off and MIDIJACK defeat; a four note buffer for trills with automatic error correction; single note triggering for legato playing; multiple note triggering; MIDI transpose select mode; Analog CV calibration mode; full range MIDI Note On/Off messages (MIDI notes 0-127): and MIDI sustain pedal operation.

Install it Yourself or Not!

The MIDIJACK is a fully-assembled and tested microelectronic circuit board with eight prepared, easy color-coded wire leads for simple user-installation. Your synth will still function as always even with the MIDIJACK disabled. For convenience, any service center familiar with analog synth repair can install it for you. The average installation takes about 30 minutes and is said to simpler and faster to install than the average automobile alarm system. After mounting the MIDI In jack, the board mounts by drilling only four small holes for the screws, MIDI function button, and adjustment trimmer. All mounting hardware is included with purchase of the MIDIJACK, as well as a detailed user manual and general instructions describing the theory and general installation method which allows anyone to make their own installation in over 90% of all analog synthesizers in existence today. More detailed instructions, diagrams, and photographs for specific synthesizer models can be found at and more will be added as new information becomes available.

Installed for this Review

Synhouse's crack technician graciously installed a MIDIJACK in my ARP Avatar. This optional factory installation service is available for most synths for an extra $69 and turnaround time is less than ten days. The Avatar is a guitar synth without a keyboard because it takes its control from a hex guitar pickup you mount on your guitar. I checked with some local technicians about what they would charge to install the unit and the figure most quoted was around $65 or the one hour minimum bench time. A little nervous about ruining my pristine "classic", the factory installation was clean and fit right in with the look of the rest of the synth's jacks and switches.

Set Up

The MIDIJACK has a single push-button that uses a Function Ladder™ scheme to cycle through all the various MIDI channels and setup modes. After you reset the MIDIJACK by holding the button in for two seconds, just one momentary push puts you on MIDI channel one.

After I had the Avatar making some kind of sound, I noticed the octave was all wrong. This is easy to change by just pushing the function button and holding for about five seconds. The onboard program cycles through four different octave settings: unison, one, two or three octaves down. MIDI note 60 (that's a C3) or middle C is automatically played and we tuned the synth's oscillator #1 to 130.813Hz on the digital tuner. The MIDIJACK "echoes" the same note to indicate there is no transposition. If you don't do anything, the next pair of notes will be an exact octave apart followed by a pair of notes two octaves apart followed by two notes three octaves apart. When you hear which transposition mode you'd like, push the button once. That setting is locked in and you are returned to MIDI off ready for you to select your desired MIDI channel.

Getting Sounds

I used the three octave transposition mode for a bass sound since the ARP's oscillators were very touchy at the extreme bottom of their range. Transposing what you play on the keyboard down three octaves let me set the oscillators higher in their usable ranges. Probably the wrong way to go about this because I did notice some scaling problems. There is a scale or tuning spread trimmer included on the MIDIJACK circuit fact Synhouse even provides a screwdriver for adjusting it. Even though I didn't adjust it, it is nice to know that if you have synth with this problem, you can tweak out of it.

I found the key response to be very fast using the MIDIJACK installed in the Avatar. There is a four-note buffer that gives a monophonic analog synth (such as the Avatar) "voice latest note priority." This technology was unheard of back in the 70s when synth players had to hold their wrists high above the keyboard and quickly strike and release the keys in a very staccato style to avoid missing an attack. The Synhouse MIDIJACK also employs Accelerated MIDI™, a combination of digital sampling techniques and computerized numerical data filtering to separate critical MIDI data from unusable or redundant data such as MIDI clocks or System Exclusive data.

A great boon to owners of those old stalwarts of the 60s, 70s, and 80s, the Synhouse MIDIJACK will put any analog monosynth back in action with fast and responsive MIDI implementation. My only wish is that Pitch Bend was possible...maybe in a future version! One side note: old time synth players didn't have pitch wheels on their keyboards so not having one here predisposes you to play more like "back in the day." Coming soon is MIDIJACK II for all synthesizers that function using the Hz-per-volt Yamahas and some Korgs. The MIDIJACK II will be introduced at the same price of $99 with all the same installation details. The MIDIJACK II will not have the user transpose select mode of the original, because Korgs and Yamahas have a much shorter range.

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