GForce ImpOSCar 2

Software Synthesizer

Published in SOS April 2012
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Reviews : Synthesizer

GForce's acclaimed OSCar emulator gets a major update — and a deluxe control surface, in the shape of the Touch Digital IMP2C.

Gordon Reid

GForce ImpOSCar 2

Released in 1983, the OSCar was, in many ways, a remarkable monosynth, with digital oscillators, additive synthesis capabilities, an unusual dual filter configuration, an arpeggiator and even a primitive sequencer lurking within its rubberised body. Consequently, it was almost inevitable that at least one OSCar soft-synth would appear, and eight years ago I reviewed the first of these; the ImpOSCar. (See Sound On Sound, May 2004.) Since then, soft synths have continued to improve, both in terms of the quality of their emulations and the range of extra facilities that build upon the capabilities of their inspirations. At the same time, the perceived desirability of the original synths has also rocketed. You would have been able to pick up an OSCar for around £600 when I was writing the ImpOSCar review, but one sold for nearly £2000 on eBay in August 2011. This seems incredible, given the OSCar's arcane operating system, its fragile physical design, and the fact that (as I once discovered to my annoyance) mice like chewing on the rubber used in its construction. But perhaps there's one thing that excuses this price, and simultaneously justifies the existence of the original ImpOSCar, the new ImpOSCar 2 and the Touch Digital IMP2C controller reviewed today: the sound. The OSCar not only sounded different, it often sounded better.

The Software

Here you can see ImpOSCar 2's Effects window, which appears at the top right of the GUI. Here you can see ImpOSCar 2's Effects window, which appears at the top right of the GUI.

Having registered the ImpOSCar 2 and loaded it as both a stand-alone application and as a VST plug-in within Plogue Bidule and Digital Performer 7.24, it was immediately apparent to me that it has been extended dramatically when compared with its predecessor. There's an additional LFO, an auxiliary modulation routing section, a unison section, a ring modulator, a chord play feature, and more. Less obvious at a glance are additions such as an external audio input and significant enhancements to the arpeggiator, the keyboard controller section, and the chorus.

Let's start with the initial sound generation. Gone is the single pulse-width knob that determined the duty cycle for both oscillators; each now boasts its own PW knob, and the widths can be destinations in the Aux Mod section, allowing you to create much richer initial timbres than before. Similarly, while the fixed-rate PWM waveforms are retained, the Aux Mod section can also apply additional modulations to these.

Another big change lies in the addition of the external signal inputs that become operative when you load the dedicated Effects version within a suitable host environment. Despite what the host might tell you, there is but a single external signal input, but you can apply this at any combination of three points in the signal chain — replacing the waveform generated by Osc1 and/or Osc2, and replacing the noise generator. Once you've inserted the signal, you can, of course, mix it with internally generated sounds (or not) and process it using the ImpOSCar 2's filters, modulators, contours and effects.

I'm also pleased to see the addition of a Ring Modulator in the Mix section, which allows you to balance the outputs of Osc1 and Osc2 as before, or Osc1 and the result of ring modulating Osc1 with Osc2. There are even two RM modes: a Full mode that does pretty much what you would expect, and a Half mode that sounds more like an amplitude modulator. Elsewhere, the editing facilities for the 24-harmonic additive waveform generators have also been enhanced, and you can now draw harmonic profiles rather than having to adjust each one individually.

GForce ImpOSCar 2Moving on to the filter, a sonic comparison reveals that the underlying sound is not quite the same; the drive level has been backed off a tad to create headroom for patches that take advantage of unison. More interestingly, the filter in my very early version of the ImpOSCar self-oscillates at a low amplitude if the separation is at or near zero and the Q is at or near its maximum. This is consistent with my OSCar, but on the ImpOSCar 2 you have to kick the filter into oscillation using a signal from elsewhere and, once this signal is removed, the oscillation quickly disappears. No matter: adding one percent noise into the signal path does the trick without sounding 'noisy', so patches that use self oscillation can be recreated with a little sleight of hand. In terms of programming, more changes lie in the ways that you can affect the filters' cutoff frequencies and other parameters. In particular, you can now select either Envelope 1 (ADSR) or Envelope 2 (DADSR) as the filter envelope, and modify the separation and Q using the Aux Mod section, all of which is good stuff. When compared with the ImpOSCar, the filter's response to the envelopes sometimes sounds a little different on the ImpOSCar 2, but this may be a consequence of the reduced drive and, again, a little judicious tweaking restores order.

Next we come to the dual LFOs that replace the single LFO on the ImpOSCar. These offer the same set of 12 waveforms as before, but the number of sync modes has been increased from four to 11, which will be of particular interest to those using MIDI-synchronised modulation. Clicking on the LEDs above three of their associated routing knobs allows you to mix them in proportions ranging from 100 percent LFO1 to 100 percent LFO2, which means that you can create many interesting modulations that were unobtainable on the ImpOSCar.

Moving on again, we come to a whole bunch of new stuff that determines the nature of the output. The six voicing modes are retained from the ImpOSCar — mono, duo and 4-, 8-, 12- and 16-note polyphony — but these are now enhanced by unison of up to eight voices per note, with adjustable frequency detune, positional spread across the stereo soundstage, and even a spread of portamento/glissando speeds. These can make the ImpOSCar 2 sound enormous, especially if you then utilise the extensive set of panning and stereo spread options. But here be dragons. There's a temptation to make every patch sound huge, but eight detuned voices per note spread across the soundstage can leave little room for anything else. Once you've had your fun, using these facilities a bit more judiciously can lead to some great sounds that will nonetheless sit nicely in a mix.

Once you've come to grips with all the above, there's yet another enhancement in the effects section at the end of the audio chain. Whereas there was just one chorus mode in the ImpOSCar, there are now four modes of increasing complexity, the first of which is the original. Another important improvement lies in the synth's response to pitch bend, which is no longer slewed, as it was on the ImpOSCar. Flick a joystick or wheel, and the pitch goes where you tell it, as quickly as you tell it. Finally, as far as voicing and playing is concerned, there's a new Controller section to the right of the keyboard. This is a two-slot matrix that allows you to direct your choice of four sources — the Mod Wheel, Aftertouch, Expression or Velocity — to one of seven destinations, with either positive or negative polarity. Unusually, all six of the controls — including the sources and destinations — can be adjusted using MIDI CCs, allowing you to control which source creates how much effect at which destination during the course of a track. That's neat.

In Use

GForce ImpOSCar 2

The ImpOSCar 2 offers three sizes of GUI, with widths of 840, 1024 and 1600 pixels. Happily, these are not merely scaled versions of each other; some design changes make the best use of the available space. I used the largest of the three throughout the review, but the ImpOSCar 2 still didn't give up its secrets lightly; despite the huge amount of space available, the legends remain a bit sparse and some of the controls and readouts are slightly arcane, so you won't get the best from it without learning what's what.

Let me offer an example. The three buttons in the Wheels section toggle between white and red when you click on them, showing that either the mod wheel or aftertouch have been assigned as controllers. But there's a third option — yellow, for MIDI Expression — which is only accessible by Alt-clicking, even though it would be much more intuitive to cycle through the options. The same is true for the noise-source selector. Clicking on the button toggles between white and pink noise, while Alt-click inserts the external signal at this point. Again, I can't fathom why one wouldn't cycle between the options. Another example concerns the new sum and multiply functions found in the Aux Mod and pitch modulation sections. These allow you to superimpose low-frequency modulations onto an envelope (sum) or to use one of the envelope generators to act as a VCA gain for the LFO modulation (multiply), the latter of which is used to create classic sounds such as 'ripped' brass and many classy special effects. But the parameter readout reports the two options as Sum and No Sum (which is obviously wrong) and, without going into the details, the operation of the controls is not quite as described in the manual. Indeed, the manual would benefit from a revision, since it is sometimes confused about what is a controller and what is controlled, some descriptions are a bit wrong, and errors such as talking about the 'stereo spectrum' (where it means the soundstage) could be eliminated.

The IMP2C's rear panel features just a USB port, MIDI I/O sockets and an input for the external 9V power supply. The IMP2C's rear panel features just a USB port, MIDI I/O sockets and an input for the external 9V power supply. Nonetheless, once you get the hang of the ImpOSCar 2, it shines. If you're after excellent polyphonic strings, pads and other ensemble sounds, allocate multiple detuned voices to each note (which doesn't reduce the polyphony!) and spread the results across the soundstage. Alternatively, set up the separation and Q of the dual band-pass filters and add chorus to create all manner of superb formant and vocoder–type patches. Lead synths, bass sounds... they're all in there too, and if you want to recreate a range of CS80 or Prophet T8 patches, you'll be delighted to find that, in addition to velocity and channel aftertouch, the ImpOSCar 2 responds to poly-aftertouch, which I must admit that I didn't test, but am delighted to have available for when needed. Then there's its ability to create all manner of glassy, ethereal pads and harsh digital textures, courtesy of its User waves, which take it far beyond what is possible with purely subtractive synthesis. Did somebody say 'Synclavier'? No... surely not!


Like many soft synths, the ImpOSCar was not merely an homage to a vintage classic. Nonetheless, it must have been hard to decide how to update it, given that any modifications would take it still further from the capabilities of the original synth. GForce claim that, in making the choices that they did, they stuck to the spirit of the OSCar, aiming for innovation, quirkiness and excellence. In this, I think they succeeded, and avoided turning the ImpOSCar 2 into a 'me too' soft synth, eschewing obvious enhancements, such as a modulation matrix, and exploiting its eccentricities in areas like the Aux Mod section. Consequently, it's now a much more powerful synth, but still retains the character of both of its predecessors.

Regarding the IMP2C controller, one has to concede that, while desirable, it's far from cheap. In fact, it's so far from cheap that even quite expensive things look at it with a certain degree of awe. But let's consider it another way. If someone offered you a 16-voice OSCar (or, if you please, a reconstruction of the fabled OSC Advanced Synthesis Generator prototype) for around £2000, would you be tempted? Many synthesizer aficionados would jump at the opportunity without a nanosecond's hesitation. But if someone offered you a Jaspers two-tier stand with a high-quality MIDI controller keyboard on the lower tier, an IMP2C on the upper and, above that, the special attachment to support a decent laptop with ImpOSCar 2 installed, again for around £2000, would you still be tempted? It doesn't sound quite as sexy, does it? Yet the combination of the three is everything that the ASG might have been, and a huge amount more.  .

Touch Digital IMP2C

Every control on the ImpOSCar 2 has a pre-assigned MIDI CC, and there's also a Learn mode that allows you to customise the software to work — to a greater or lesser extent — with most MIDI devices. But if you want to go the extra mile, there's something a bit special from Touch Digital that might take your fancy.

The concept of a keyboard controller that echoes the layout of a vintage synth is not new, and there have also been DSP-based emulations of classic synths that mimic the control panels of the originals. But the IMP2C is neither of these: it's a keyboard-free programmer designed specifically for the ImpOSCar 2.

The people behind it are familiar to aficionados of vintage synths: Richard Lawson was renowned for the excellence of the second-hand synths his company supplied (as well as for the charges he levied for them), while Kent Spong is perhaps the UK's leading guru for all things concerning Yamaha's CS polysynths. Consequently, it should come as no surprise that the IMP2C looks and feels first-rate. Its steel chassis is reassuringly heavy, the construction is solid, and there's no play in its large, smooth, custom-built knobs. There are a few quirks (such as the rather strange choice for the effects on/off button) and I would have preferred an internal PSU but, all in all, first impressions were very positive.

I already had the ImpOSCar 2 running when I first plugged the IMP2C into a USB socket on my MacBook Pro, switched it on and... everything worked immediately without any reconfiguration or need to set preferences. Wow! I then plugged a conventional five-pin MIDI cable from a Roland Fantom into the MIDI In of the IMP2C, and played a few notes. The controller re-transmitted the note information via USB to the soft synth, again without any configuration, and for that alone, the IMP2C is worthy of applause!

I started using the IMP2C by placing it on the other side of the computer to the keyboard. This turned out to be a mistake. Despite the huge amount of panel space available, it has as few legends as the GUI, and no parameter readouts to tell you what you're doing, so I found myself switching my attention between units like a spectator at Wimbledon, which was no good at all. After a bit of thought, I ended up with the three devices arranged vertically, with the controller sitting between the keyboard and the computer, and everything then fell into place. Did it allow me to forget that I was programming and playing a soft synth? In truth, no. While the IMP2C mimics the largest of the ImpOSCar 2's GUIs, it can't perform all the functions of the software interface, so I still found myself turning to the host computer on numerous occasions. Perhaps a better question would be, did it impart the hands-on feel of analogue synthesis to the soft synth? Yes, that it did. There's something human and comforting about programming and tweaking sounds using a physical control surface, and the IMP2C is a hell of a control surface. Nevertheless, I suspect that a smaller version in keeping with a computer-based setup would be more attractive to many potential users. With its 83 knobs and 18 buttons, the IMP2C is almost as large as a Jellinghaus DX Programmer and, while I love its size, weight and quality, I must admit that I might find it hard to justify the space that it would take up in my studio, let alone on stage.

£898.80 including VAT. See web site for shipping prices.

Touch Digital +44 (0)1189 472474

£898.80 including VAT. See web site for shipping prices.

Touch Digital +44 (0)1189 472474

The .SUP File

The manual suggests that you edit something called the .sup file to personalise the way that ImpOSCar 2 works. You can change things such as the default GUI size, the knob mode, the initial edit mode, the effects panel status, the patch format and what happens to original files when you import ImpOSCar patches. While you may have a sensible aversion to messing with anything below the GUI level of any software, I doubt that you can do much harm here. Nevertheless, GForce should move all of these options into a configuration page in the GUI itself.

The Auxiliary Modulation Section

Unlike many soft synths, the ImpOSCar 2 does not feature a modulation matrix. Instead, it extends the philosophy of the original OSCar by offering an Aux Mod section that can mix either envelope (but not both simultaneously) with a mix of LFO1 and LFO2 (five options, from 100 percent LFO1 to 100 percent LFO2), either summing the two sources or multiplying them, as you choose. However, the number of destinations for the resulting modulation signal is quite limited, with just eight options: Osc2 pitch, PW1, PW2, PW1&2, Filter separation, Filter Q, Osc Mix and Noise Mix. It would be nice to see (at least) the pitch of Osc1 and the filter cut-off frequency added to this list.


The patch management in ImpOSCar 2 is a huge improvement over the original's, and a click on the Browser button now reveals a bank and patch system that allows you to assign individual patches or complete banks to MIDI program numbers. There are 16 banks of 127 slots available, which should be sufficient for any project, but there's no immediate way to move patches between banks, and nowhere could I find a way to delete a patch from the library other than by finding it on my hard disk and deleting it directly.

If you want to create snapshots of your programming while working you can do so by pressing CMD-Save, whereupon the ImpOSCar 2 will store the current sound with a date and time in place of a name. This can be very useful if you later find that you've travelled down a blind alley, sonically speaking.

For quick recall, you can also save up to eight patches under the M1 to M4 buttons. This is not quite as neat as it might be because of the key combinations that you need to remember to save and recall the sounds, but it's welcome nonetheless.

Finally, it's worth mentioning that the ImpOSCar 2 will import, convert and save original ImpOSCar patches and banks. While not identical with the originals, the resulting sounds are similar enough to tweak into shape. What's more, within its extensive patch library lie the original ImpOSCar's library as well as the OSCar patches from 1983. These are also welcome.

Crashing, But Not Burning

I encountered a few hiccups during the course of the review, including chopping the starts off notes and, on one occasion, turning one voice into a harsh rasp quite unlike the patch selected. There was also a complete lock-up on one occasion. However, I could have been causing the problems myself because, during my tests, I frequently ran the original ImpOSCar alongside the ImpOSCar 2 as a stand-alone, the ImpOSCar 2 as a VST in Plogue Bidule and in DP 7.24, and yet another soft synth, such as M-Tron Pro, as an external signal input. All of this, plus Word, Photoshop, Mail, Safari, iCal, Preview... Now that I think of it, it's amazing that the synth didn't give up, pack its bags and demand a ticket back to Reading. Nonetheless, the ImpOSCar 2 is not quite bomb-proof, so you might like to test the demo version (available from on your system, especially if you are planning to use it live.

GForce ImpOSCar 2 £140£140
It sounds excellent.
It's much more flexible than its predecessor, and its performance capabilities have been greatly enhanced.
There's now a dedicated Effects version for external signal processing.
The dedicated IMP2C controller, while expensive, takes it to a whole new level of immediacy and fun.
The GUI is not always as intuitive or informative as it should be.
The patch management system should be further improved.
The manual needs a revision.
It's not quite bullet-proof.
If you like the sound of the OSCar, or want to build upon this with everything else that ImpOSCar 2 has to offer, you should head over to the GForce web site right now to download the demo version. Whether you can justify adding an IMP2C is another matter, but if you have the money and space to do so, it will add greatly to the fun, and may even enable you to obtain results that would remain out of reach without it.

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