Oberheim OBXa

My Favourite Analog Polysynth

The purpose of my blogs is to put things into perspective and reflect on the zeitgeist these instruments were introduced in.

There is tons of info out there, which are much more specific on the technical side of things, but not many people reflect back on the era. Why were these instruments designed the way they were, what other alternatives were there, how was it received, what was their historical significants, etc... I like to shine a light on these things and at the same time covering the general features of the instrument. I might have left details out or am perhaps completely wrong. Again, the emphasis is more on the role the instrument played and its relevance in today's synth landscape.



This was the era of the heavyweights and the OBXa, together with the Roland Jupiter-8 and the Sequential Circuits Prophet-5, shaped the classic analog poly synth as we know them today.

The sound shaping architecture was still mainly based on that of the Minimoog, but beside these synths being polyphonic versions of the Minimoog, they featured something that was first introduced on the Prophet-5 in 1978, the Microcomputer.

This allowed for all the parameters to be stored into a microchip.

When we look at the analog poly synths on the current market, then they pretty much share the same features.  

The JP8 and OBXa both introduced a cool new feature. 

Dual & Split mode.

In dual mode two sounds could be stacked and in split mode the two sounds could be played on the lower and upper half of the keyboard.

Another thing that made Oberheim synths unique, was that the OBX and  OBXa could be purchased as a 4, 6 or 8-voice version.

Because of its clever design, voice boards could be added, so if you were tight on cash, you could purchase the 4-voice first and then purchase the voice boards at a later stage.

When opening an OBXa, you can't help but marvel at the beautiful design and layout of all the electronics, with all the voice-boards situated to the right, stacked on top of each other with spacer-studs in between them.

This design is probably the reason for the instrument being bulky.

The controls on the front panel are all liberally spaced, unlike those on the Prophet-5, which is a much smaller sized instrument.



We now take character traits such as pitch drifting as desirable, as we have become familiar with the static sounds of digital synths and software plugins (most plugins even have builtin drifting), but there was a time when pitch-drifting was the least desirable feature.

That now seems hard to imagine, but if you were a gigging keyboardist in the early 80's, or you were a session keyboarder trying to get a live take right as studios were charging escort type rates, the last thing you would anticipate for was your synth to go out of tune.

Even though all of them featured an Auto-Tune button, that put all oscillators back in tune, a sudden change in temperature would throw things back out again, especially if you were playing in the open air, or inside a club where doors were constantly opening and creating a draught.

Somehow the American models were more sensitive to pitch fluctuations than their Japanese counterparts.

With lots of new music styles added over the decades, one needs to remember that in the early 80's most music made still relied on harmonic stability and musical guidelines.

In the different styles of techno music today it's okay if something is dissonant, but back then you had to be musically credible, so it was important that your instrument was reliable, which the Japanese managed to do to a tee.


Nederland Muziek

This was the name of the store and Oberheim distributor in The Netherlands, which was close to where we were living at time and frequently visited.

As they also distributed countless other brands, such as Gibson, Bayer Dynamics, Senheisser and Dynacord, they had their own Tech Workshop for products that were sent back for repairs.

We were often let into that workshop and we would often hear of Oberheim synths breaking down the most.

This had consequently left a bad impression on us, so for many years to come we always perceived Oberheim synths as unreliable.

With anything in life that seems unattractive, unattainable and exotic, there comes a point when the fascination for it grows and it starts pulling you like a magnet.

The OBXa was that one polysynth that had created that strong pull.

Of course there were the countless records that I knew featured Oberheims and for some reason that made it even more exotic.

Combined with hardly ever seeing one popping up on the second hand market, I never thought I would find one. 



Purchased it October 2013.

The guy had just listed it 5-minutes before I checked the internet.

He had left his phone number in the ad, so I rang him straight away.

On the photos the instrument also looked in absolute mint condition.

It was a 6-voice version, which I didn't mind.

He said he was selling it for a friend.

Luckily I had just sold my MKS-80, without the programmer for around the same price.

The guy was living in an old apartment and had the Oberheim sitting on the floor, connected to a cassette tapedeck with headphones.

The instrument looked breathtakingly beautiful, without any blemishes.

When I played it though nothing really worked as I expected.

Voices were jumping left and right, the modulation section didn’t do anything, all the knobs were not very responsive and some functions weren’t accessible.

My dad was nervously watching the parking metre outside through the apartment window.

He said, let’s go son, don’t bother with this thing!

The guy seemed very desperate to sell it, as he was a vintage microphone collector and needed the money to purchase a rare ribbon mic, which he had to decide on that same day.

I told him that he couldn’t sell the instrument in that condition.

He then rang a synth repair guy who was only familiar with ARP synths.

When he passed the phone over to me, I explained to the technician what was wrong with it.

The guy said that by the sound of it it definitely needed attention.

When we were about to walk out, the guy suggested a pretty significant price drop, so I could have it fixed myself.

My dad still said not to do it, but I already had my money out.

There was no way that a repair would exceed that price drop.

My dad looked at me with worried eyes.

I told him that if I didn’t take it, I would forever be kicking myself.

With the OBXa on the backseat and me ranting on about how good this purchase was, my dad kept quiet.

When I got home I put the Oberheim on a stand and switched it on.

The first thing I did was download the user manual.

As I was reading along, a lot of things suddenly became clear.

This synth was very strange indeed. 

  • The voices were panned using pan pot metres inside the synth. When I connected it to the Mono output, all voices came out fine. Because the guy had connected it in stereo to his tapedeck, the voices were panned hard left and right. Each key trigger activates another voice-board.
  • Then I read that all the pot metres on the front panel were set relative to the preset selected. To get them to work full range, each knob had to be opened and closed.
  • The oscillator settings only work in certain situations; the 4-pole switch only works when oscillator-2 is set to Full. 
  • Storing a sound requires the Write button to be held for at least 3-seconds. This was also not working when I tested it.
  • The modulation settings next to the keyboard have knobs that pull out to set the range.

On this rare occasion, not having a clue how the synth was working, things were in my favour.

Ignorance turned to bliss.


Small Fixes

One switch cap was missing, but luckily a guy in Amsterdam, who used to own a shop called Sensomania, had them in stock.

I replaced the entire switch, which meant I had to take the board out and re-solder the switch back in.

Upon opening the front panel, I also noticed that the Cassette Interface indicator was bent and didn’t pop out through the little hole.

I was wondering before what the hole was for.



I don't think there are any two other synths that have identical looks and similar features but are named differently.

The OB-8 was released 1-year after the OBXa and can be considered as an upgraded version, with which many would like to disagree, but that's always hindsight talking.

In 1982 the OB-8 was definitely seen as an upgrade to the OBXa, because it's essentially the same with some added features, such as an Arpeggiator.

There are even two different version of the OB-8, the pre MIDI model and the one that standard featured MIDI.

In terms of sound the OB-8 and OBXa sound most similar, with perhaps slightly faster Envelopes on the OBXa and a higher drift factor.

Having played with an OB-8 after owning the OBXa for a few years, I can confidently say that the OB-8 would be a better purchase, as it has far more to offer.

The Arpeggiator, most of them featuring MIDI, the standard 8-voices and 128-memory locations, make it much more attractive.



So, why is this synth so special?

All Oberheim synths have this undefinable sound, something that is impossible to describe.

Compared to the other polysynths of the time, the OBXa was a lavish design, but suffered stiff competition from mainly the Roland Jupiter-8 and Prophet-5.

The Japanese synths were surely more reliable, but because of that also lacked character.

Professional players, which was possibly the majority of users back then, needed an instrument that delivered stability every time they did a gig or studio session.

The Japanese provided that stability 100% of the time.

Oberheims, Moogs, ARPs did not.

This was the harsh reality in 1981.

However, the American synths were still used heavily on big hit records.

One of the most loyal users of the OBXa was Prince.

Other notable users were The Simple Minds and The Thompson Twins. 

Personally I always considered the Envelope Generators to be the most important component of a synthesizer.

They have to be fast and accurate, creating that snap and punch.

Very few synths have this quality, especially synths after 1982.

This is because manufacturers needed to cut down on cost, in order to sell more units.

The OB-8 is the last Oberheim synth that included fast envelopes.



So what if you are lusting after that sound and you lost hope in finding an original OBXa, or simply don't have the dosh, what else can substitute it?

In terms of hardware there is only one contestant and that's the Dave Smith and Tom Oberheim OB-6.

This synth has already reached cult status, as it sounds awfully close and adds so much more, like built-in effects, a step-sequencer and arpeggiator, but mostly unparalleled stability.

Yet, for a spoiled OBXa user like me, that has that sound engraved in the brain, the OB-6 lacks those snappy envelopes and the oscillator phasing.

To me the OB-6 reminds me more of the Matrix-6.

Another big company are working on cloning the OBXa, but there hasn't been much news about this lately.

A very bright 18-year old lad in the US by the name of Jacob Brashears, designed an Oberheim clone called the Relic-6, but very little about this has surfaced since that other big company announced their attempt to clone the Oberheim.

In terms of software there is a myriad of emulations, with a lot of them emulating the OBX.

The most impressive is the free OBXd VST, which sounds awfully close to the real one.


Final words

So, what about that sound, how to describe it, as this is what sets it apart from everything else.

When I got my OBXa, I was working on my Fusion album, which you can find here.

I was almost done with the album, but still had trouble controlling some of the analog sounds that I had made on the my Rolands.

For some reason they sounded too stale and flat.

I then started replacing them using the Oberheim and instantly noticed how well it sat in the mix, without having to do any processing.

It just poked nicely through the mix, with much more definition and animation.

Especially when double-tracking it added another dimension.

I then started replacing more parts and ended up replacing the majority.

Somehow the harmonics in the Oberheim sound is so well balanced, that no matter where you place them they are not obtrusive.

The harmonics seem to fill up all the little gaps and combined with the ever moving changes in the behaviour of the oscillators and envelopes, it keeps claiming its spot in the mix, without being too dominant.

Moogs and Sequential Circuits synths have a lot of cream, which can saturate the mix, but the Oberheim tends to have just enough cream to leave enough flavour for the other ingredients.

Even when I create a track with only the Oberheim, I hardly have to EQ anything.

This to me is the standout quality of the Oberheim sound.

Perhaps it was a stroke of luck by Tom Oberheim, perhaps he purposely wanted his synths to sound significantly different to the rest?

What he did to it may forever be a secret.

Even though it has that 12dB filter, when using the 24dB filter that magic is there.


If I had to keep just one vintage Polysynth, the OBXa is definitely it.

I can program a particular sound on all other poly synths and always end up finding the Oberheim producing the best results.

I instantly recognise the sounds from my favourite records, like New Gold Dream by the Simple Minds, The SOS Band, Prince, Thompson Twins, Nik Kershaw's early work and countless Fusion records from the early 80's.

Another album that features the OBXa a lot is by a Dutch/British act called "The Limit" and their self titled album from 1985. I'm convinced they used the Oberheim.


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