My Oberheim OB-X story and restoration

The Oberheim OB-X synthesizer stands as a hallmark of analog synthesizer excellence, emerging during the vibrant era of electronic music in the late 1970s. Designed by Tom Oberheim, this iconic instrument epitomizes the lush, rich sounds that analog synthesis is renowned for. With its distinctive sound architecture featuring multiple oscillators, versatile filters, and robust modulation capabilities, the OB-X quickly became a favorite among musicians seeking to craft expansive pads, searing leads, and intricate soundscapes.

One of the OB-X’s defining characteristics is its polyphonic capability, allowing for the simultaneous generation of multiple notes, a feature that was groundbreaking at the time of its release in 1979. This polyphonic prowess, combined with its warm, organic sound, made the OB-X a staple in both studio productions and live performances, gracing countless hit records across various genres.

Beyond its sonic prowess, the OB-X’s sleek design and intuitive interface contributed to its enduring popularity among musicians and synthesizer enthusiasts. Despite the evolution of technology, the Oberheim OB-X remains a cherished instrument, celebrated for its timeless sound and its significant influence on the landscape of electronic music.

It was an early March of 2008 after about a year of desperate searching, I’ve finally found it – an Oberheim OB-X. One of the two synths that inspired me the most as a kid (the other synth was a Pro One). The OB-X record in question was Jean Michel Jarre: Magnetic Fields which was his main synth for the whole album and which I really liked to listen. Many many years later to find out which synth was behind all those fantastic lush and fat sounding pads. If you want to know what I’m talking about, load Magnetic Fields Part 1 to your player and listen to the intro.

The unit itself originates from the famous Audio Playground keyboard museum on Florida. The price was all right, but the cosmetic condition was horrid. To be honest, the only thing that interested me was the fact that it was an 8 voice version and that all 8 voices have recently been checked at their service. I wasn’t much worried with the rest aside the fact the unit will be shipped from Florida to Chicago and something might go wrong during transport.

Arrival and inspection
Well, as expected the unit was in terrible cosmetic condition (part of the reason why Audio Playground decided to get rid of it). Keys were in bad condition as well, dirty as hell with broken / damaged bushings that would make them wobble and give that nasty “clack” sound when pressed. I was very nervous, TBH.

The first thing I did was replace the bushings on the keyboard. I also washed all the keys, and aligned key backs (check the photo to see what I mean by non aligned keys!). Each key is held by a screw and it takes a while to take them all down. Then to remove the holders as well, and a spring from each of them, clean everything and then approach the bushings, remove the old ones and install new ones. Cleaning of the keyboard contacts is assumed, for each key several times. Though summarized in just 4 pics, that was a lot of work actually!

Next thing was replacing old capacitors in the PSU and cleaning all the switch contacts and potentiometers. I also replaced all the electrolyte and tantalum caps while the boards were out. While open, I did small pimpn’ by installing a green led for the Tape check. Some of the original red LEDs were dead, so replaced them as well. There was one dead CMOS chip that would regulate turning LEDs on and off, and that was the only chip I had to replace (it cost me $3 or less).

Paint work
There was no much to think. If you look at the condition of the metal surface all the scratches and marks, only one thing to do, repaint the whole thing. I secured the parts which should be protected and hit the rest with standard matte black spray. Applied total of three layers to ensure proper results.

Custom side panels
A friend (Chris) made a pair of nice side panels for OB-X based on those of OB-8 which I gave him. Material was cherry wood but we decided to modify it to mahogany (using stain and lacquer) which worked like a charm. I also restored the rusty screws, cleaned them fully and painted in black for some more pimpin’.

Calibration and tuning
The rest of the work was to calibrate all the voltages to original factory specs and tune the machine. Tuning was pain given a lot of response changes once once you put down the upper motherboard. So you have to do it again. And again. But in the end somehow I’ve managed it.

Final results and impression
In my book, Oberheim OB-X is one of the best sounding polyphonic synthesizers ever. I was lucky get one right on time before the “analogue bubble”. It is hard, and perhaps unfair to compare a discrete based design to a chip based one, but there is definitely a difference in sound. For example, while OB-8 will cut through most dense mix, its oscillators do not have this softness and width of an OB-X. This is perhaps where this synth’s beauty lies, in its discrete VCOs. Luckily, the design incorporates a 12dB filter slope (which is IMO a crucial thing for polyphonic synths) and in combination with it, some magnificent and wonderful sounds can be created on this machine.

When I removed the keyboard this is what I found. A lot of mess and a bunch of dead / broken bushings.

As noted before, the unit was pretty beaten up.

And here as well.

Pretty nasty, isn’t it?

Actually horrid.

Look at the dirt of the keyboard and the “alignment” of individual keys.

After removing all the keys, time to reach the bushings and also to do some aligning of those little hooks.

Dead bushings in many cases were easily removed. You can see why.

After removing the springs i prepared the bag of new bushings. Big thanks to Syntaur.

And installed them.

Keys sent to where they belong to.

In the meantime I prepared for the paint job.

First layer on. Looks better.

After three layers looks much better.

Switches cleaned with contact cleaning spray.

To ensure proper voltages, the PSU has been recapped. I also removed the notorious tantalum caps.

Chris K provided me with those. I did the drilling and some finishing to the wood (spot the sandpaper).

When restoring something, don’t forget the small things like screws. It does make a difference once you clean them and paint for some sexy look.

So. Before…

And now, one month later. Over 40 working hours went into this.

OB-X in action:




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