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Oberheim Xpander Module

free standing synth

Get yourself expanded! Far from being an advert for an educational establishment or even for some dubious marital aid, this seems to be the latest slogan of the musical instrument industry. And it makes sense, particularly in these days of MIDI control and computer interfacing. Keyboards aren't always necessary or even desirable any more, and in the near future a good proportion of the new synths released will also be available in expander form. Examples at the moment include SIEL's expander, Roland's piano and touch-sensitive JX-3P modules, and now the Oberheim Xpander.

Unlike some of the other products on the market, the Oberheim isn't simply an existing synth design with the keyboard left off in favour of a MIDI input. In fact it's a completely new design with several innovative features – so many, in fact, that it's pretty difficult to get the hang of it in its present form.

The Xpander fits in nicely with the existing Oberheim system of OB8 synth (with MIDI retrofit), DMX drum machine and DSX sequencer, but since it's MIDI-equipped it will work quite happily with equipment from other manufacturers. Interestingly enough, this will include Yamaha, because although the Oberheim synth won't give velocity-based information, the Xpander is quite capable of dealing with it.

Just the basic spec of the Xpander is pretty frightening, and things don't get much better. The advertising claims 'six voices, each with two oscillators, 15 VCRs, five LFOs, five EGs, four ramp generators, three tracking generators, lag processor, 15-mode filter and FM'. It takes a while to get into the sort of versatility this spec can offer, but it can be worth it. In addition, the layout of the Xpander (which includes three large LED displays) is as helpful and informative as could be hoped.

As we hinted, the Xpander is a six-voice instrument, and like the Sequential Circuits Six Trak, it's multi-timbral – the voices can produce different sounds simultaneously, under the control of different MIDI channel inputs (1-16) or of individual CV inputs on the back panel.

There are three main displays, one in the programmer section and two in the page modifier section, and each has several sets or 'pages' of functions. There are six large, infinitely rotatable knobs below the page modifier displays, and these do most of the donkey work if you make any changes to the factory preset sounds.

The programmer display has eight buttons beneath it – two of them select single or multi patch (conventional polyphonic playing where all the voices are the same; or multi-timbral playing) and the remaining six decide which voice you're altering at any given time. The display also gives a name and number to every patch, and there's a good selection ranging from conventional 'strings' and 'brass' to the more exotic 'air rezz', 'flangey' and 'squarcmp' ('squarcmp'?!?). Beneath these controls is the 0-9 keypad, with + and - controls to step through the presets and for various other functions.

The heart of the system is the large patch display on the right hand side which shows how the various sections of each voice are connected up. Hit the button in the VCF section and the page modifier displays all the VCF parameters – mode, level, modulation and so on. As mentioned earlier, the VCF has 15 modes, from conventional low pass to high pass, band pass, notch, three-pole phase shifter and one-pole low pass and other such exotica.

The six incrementor dials alter the required parameter and you can then enter the new sound if desired. The same procedure applies to the VCA, lag processors (for delay modulation effects), LFOs and so on, and you can fairly quickly get the hang of calling up and changing parameters.

What isn't so simple is coming to terms with the full potential of the system, because the possibilities of FIVE envelopes or LFOs (for instance) in a single sound are frightening. There's a huge bank of 14 modulation source switches across the top of the Xpander, and it's possible to have vibrato, filter, pulse width, volume and depth of modulation itself all modulating at different speeds with different delays in a single sound, which can get pretty heavy.

In addition there are some very unusual functions, such as the zoning facility which appears to split the keyboard up into several sections for selective modulation, and the FM facility which makes VCO 2 in each voice an operator and VCO 1 a carrier (Yamaha DX owners sit up and pay attention at this point). In fact the Xpander's FM is very limited, and much more similar to the Prophet's PolyMod than to Yamaha's buzzword system. Still, it's capable of some very twangy sounds – what the handbook describes as "some of the rudest sounds you've ever heard", which is fair enough.

There are a good few hidden functions, such as a tune page which allows you to check up on the status not only of the oscillators but also of the filters, pulse width and VCR performance. There's also an impressive series of engineering test routines, such as one which flashes all the LEDs on the machine together and one after another, and then flashes every segment of all the displays individually and collectively – great for the promo video.

The basic sound repertoire is 100 single patches, and 100 multi patches formed from combinations of single patches with control source (CV or MIDI channel) for each voice, keyboard split point, volume of each voice and stereo pan position. Multi patches can be chained together for quick access and all information can be dumped to tape.

Back panel connections include six CVs, six gates, MIDI, stereo and mono audio out and inputs for pedal and footswitch control (with exact functions definable within a patch). Overall there's virtually nothing the Oberheim can't interface with and no combination of control inputs it can't handle.

The sound quality is something else, as the Americans say. Very brassy and bold like the OB8, but a little cleaner and much more versatile, encroaching on FM synth and large modular system territory quite convincingly. Some of the sounds, such as Freefall and Sweeper, have an extraordinary amount of internal movement, but even so, given the modulation and patching facilities, it must be possible to do much more.

So the Xpander is difficult to get the hang of, but infinitely versatile and sonically powerful. The problem is of course the price, which fits right in with Oberheim's avowed intent to stick with the professional market and not compete in the cut-throat world of budget polysynths. A shame though, because they're going to be undercut something horrible by the SIEL, Roland and forthcoming Korg expanders we've already mentioned. Now none of these can offer 80 VCAs, 25 LFOs, 25 envelope generators and so on, but on the other hand you could have five SIEL expanders for the price of the Oberheim. That's 30 standard voices as opposed to six very complex ones, and if you're into MIDI multitrack composing the choice will be quite clear. It should be possible to get some of the very complex effects from the Oberheim by using banks of conventional voices stacked up too – but then, you can't stick your MC4 straight into the back of the SIEL or Roland as you can with Oberheim.

Overall then, smart, stylish, powerful, imaginative, expensive. Four out of five ain't bad.

OBERHEIM Xpander module: £3,500

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One Two Testing - Copyright: IPC Magazines Ltd, Northern & Shell Ltd.


One Two Testing - Aug 1984

Gear in this article:

Synthesizer Module > Oberheim > Xpander

Gear Tags:

Analog Synth

Review by nk

Previous article in this issue:

> Ibanez Digital Delays

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> Shredder

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