A-Z of Analogue: RhodesBy Peter Forrest  <email@example.com>
The following information is being reprinted from The A-Z of Analogue Synthesisers, Part Two, N-Z (Revised), with kind permission from the author. See the Bibliography for more information.
Chroma: 16-VCO 16-voice* 64-note (E-G) wooden weighted keyboard synthesizer. 1982-1983
Original price: £3850. typical price: £750 - £1400 (Up to £2000 for the first 50, which were hand-produced by Philip Dodds' ARP team.) *Although it strictly had 16 voices, nearly all patches double up the oscillators for 8-voice operation, unless you're specifically looking for a thinner sound. Thanks for this & other advice to Chris Ryan - his Chroma website is a goldmine.
Users include: Jeff Bova [21030407++], Duncan Bridgeman, Vic Emerson, The Enid, Norman Fay, Ken Freeman, Global Communication, Jerry Goldsmith (Psycho II & Twilight Zone film scores. "I don't really like the sound of it. It has a sweet sicky sound to me. I think the idea of it was wonderful, but I don't like the one-knob programming bit." Keyboard Feb 85), Joel Goldsmith, Ralph Grierson (later with Expander), Herbie Hancock ('Future Shock,' and apparently still using his with great pleasure in 1995), Garth Hudson (later MIDI'd to a DX7 and two MkS80s), Mike Kapitan / Thomas Dolby, Jaron Lanier, Lyle Mays, Oscar Peterson (with Expander; 'Africa' album "..a heavy instrument to program. You have control over so many parameters. ..I want to alter [the Chroma pedals] for the Synclavier. I think they're great; they're like piano pedals." Keyboard October 83), Scott Plunkett / Don Henley band, Andy Richards, Joe Sample, John Shykun, Martin Straw, Tangerine Dream, Peter Vettese (spelt Vetesse throughout the E&MM Sep 83 interview in which he talks about the Chroma at great length), Jimmy Waldo ("an unbelievable amount of bottom, but I've found that a lot of that low end isn't really usable when you're playing in a 10000 seater or on a record." Keyboard Nov 84), Joe Zawinul.
ARP previewed the Chroma at NAMM 1980. The biggest obvious external difference between the prototype and the main production run of Rhodes Chromas was in the casing, which went from tolex to partial wood. I had thought that the Rhodes version toned down the colour-scheme from the ARP, but this may not be true. According to Keyboard Oct 80's report on the NAMM show, "ARP's marketing team raised a few eyebrows by talking about a list price of only $2200." The report also said that the keyboard was the same as on the 16-voice piano.
Another eventual difference from the original design was the implementation of pressure sensitivity - aftertouch. Although the electronics were designed in right from the start, the aftertouch sensing mechanism doesn't seem to have been available at first. It was introduced in early 83 as an optional retro-fit, and then (possibly) became a standard feature - though Chris Ryan's Chroma, bought in late 83, didn't have it. The amazing thing is that this was actually polyphonic aftertouch - the rare preserve of the CS80, T8, the best Synclaviers, and, later, not so nice Ensoniqs.
Martin Straw (Sound On Sound Nov 95 letter, p8) says that the latest machines, with software revision of 13 or above, responded to polyphonic aftertouch via a suitably-endowed MIDI interface as well - and, of course, if they had the sensor installed, output as well.
Interviewed on the Chroma site [see Philip Dodds/Tony Williams Interview], Philip Dodds says that the first (ARP) design was actually scrapped, and a fresh start made (albeit with the basic structure and philosophy intact) in CBS' less stressful financial circumstances.
The Chroma signalled a radical change in design policy for polyphonic synths, by dispensing with all the knobs and most sliders, and using serial parameter access instead. The Moog Source was the first monosynth to do this, and I believe the Chroma was the first poly. The DX7, for example, didn't come out until 1983. Unfortunately, the slider (with a curious mechanical solenoid 'thumper' telling you each time you hit another step) was not as good a device even as the Source's wheel. (The thumper could be disabled if you didn't like it.)
Where it didn't go all the way down this pretty miserable road, though, was in the amount of flexibility it still allowed you in routing the signal. That didn't necessarily make it a lot more popular at the time, because along with flexibility comes complication: but it does make it an instrument that's well worth looking out for today, when synths that have that extra something are not easy to find. You can go for a patch-lead modular to get a sound no-one else has used - or you can go for a hardware virtual modular like the Xpander, Andromeda, or, not quite as powerful but still interesting, the Chroma.
It also beat the DX7 to another dubiously friendly innovation: algorithms. That might be a questionable virtue, but it more than makes up for it with its sound. It's said that having a separate signal path for each of its eight voice pairs means no possibility of phase-locking. Each of the VCOs is running free, and sounding richer because of it. I don't honestly understand this, but the Chroma certainly does sound rich.
Thanks to its good keyboard (specially designed for it), it's a pleasure to play, once you've sorted out your sounds. If CBS had been persuaded to go ahead with Philip Dodds' suggested 88-note version, it would have been even better.
Patch and parameter selection is by touch membrane switches, reminiscent of those seen on the ARP Quadra. Fifty are available, doubling as program numbers 1-50, and parameter selectors :-
- Five for basic CONTROL, including 8/16 voice selection, sync and ring mod, filter mode (parallel or series), keyboard note priority, arpeggios, de-tuning, etc.
- Two for GLIDE - portamento / glissando.
- Five for SWEEP (LFO control, including all of 16 waveforms and 16 modulation sources;
- Six and seven for the two ENVELOPES respectively - ENV2 has an extra 'delay' control.
- Seven for PITCH, including three independent modulation sources and amounts.
- Four for WAVE SHAPE - basically pulse-width controls.
- Nine for CUT-OFF (filter controls including three independent modulations,and notch and band pass filter selection).
- Five for VOLUME - with loads of choices for modulating the VCA.
Resolution of the different parameters varies from eight steps to 128. Not all parameters (for instance filter resonance, with only eight steps) have as much resolution as you'd ideally want, but nearly all of them are sensibly chosen, and produce a musically useful result. For instance, VCA mod depth is 32-step, but VCF is 128, which makes sense to me.
As well as the large two-digit LED program display, there's a small 8-digit DATA READOUT display.
Another radical feature of the Chroma was the computer interface - originally to the Apple II, and then, theoretically, to the PC (which amazingly enough came out after the Chroma). It's quite likely that the PC interface never went into production, though. The Apple version was very powerful for the time, including probably the first computer sequencer ever, with 64 tracks, real-time playing, punch-in and -out, and detailed event editing. Remember that this was pre-MIDI (MIDI became available as a retrofit for the Chroma a year later - using the machine's computer socket). The Chroma was the first synth to be able to transmit velocity information - a major step forward.
Other features included the ability to assign patches to different outputs (or use the outputs to insert effects); program the function and polarity of performance sliders / levers for each patch; and use a pedal to advance to the next patch (in a programmable sequence) during a performance.
Philip Dodds, in the Keyboard article re-printed in Vintage Synthesizers [see The Synth That Survived ARP's Fall], goes into great detail about the fact that the Chroma used the Intel 80186, which he describes as the heart of the Chroma. In which case it was probably one of the first pieces of equipment in any field to use the Intel  chip - not surprising, if it pre-dated the PC. But it seems likely that he was getting confused with the Polaris, which did use the . According to Tony Williams, the main processing chips were actually an Intel 8039 and a Motorola 68B09.
Keyboard split was programmable - again a radical departure for the time.
The back panel has the 25-pin parallel computer socket (potentially so much better than MIDI's serial socket, but there we go..), twin XLR outs, high and low level mono jack outs, sockets for two footswitches and two pedals, cassette in/out via DIN socket, and four jack 'AUDIO INPUTS / OUTPUTS'. It also has the memory protect switch for programs.
After the first fifty, there were big problems of reliability until CBS finally sorted out some production goofs at the Gulbransen factory - the main one being a nice new revolutionary board-bath which resulted in a tendency for oscillators to go haywire in high humidity.
There are two performance levers to the left of the keyboard, more like Oberheim or Yamaha levers than Moog wheels, and probably not as nice to use as any of them.
CBS are believed to have marketed a 60-minute video featuring Peter Vettese using the Chroma - but no-one I know has ever confessed to seeing it.
The Chroma is a bit like a Citroen DS. Ahead of its time, full of quirks, slightly over-sized, but very loveable. The 34cm-long weighted wooden keys give it a real couch of class, its cherry end-cheeks add to the charm, and its modulation possibilities, while not in the Xpander class, are still impressive.
On the Chroma site there's a fascinating machine with wood casing but autumnal colours for the graphics - red, orange, and yellow. This is described as the Halloween model by Dodds. This is not simply a different choice of ink colours, either - one or two of the legends are differently positioned as well, and the 'switches' are grouped slightly differently. Strangely, the serial number  would make it a later machine, not an early one.
Typical serial number/s: 21010022 (the 22nd made - originally Ken Freeman's, and then owned by Global Communications), 21010247, 21030417, 21030620 (the Halloween model mentioned above), 21030725. The serial number list on the Chroma site (with, in May 02, around 20 from  to 21010299, one 21020003, 40-odd between 21030085 and 21030930, and one 21040012, might back up the following guesstimate of numbers made: around 300-350 of the first series (2101); 3-50 of the second series (2102); 1000-1200 of the third series (2103); and 1-50 of the fourth (2104). It looks likely that about 1500 were made.
There have been more Chromas added to the Registry since Peter wrote this article: there are now two 2104s, and the highest-numbered 2103 is now 21030936. [June 2004] See also How many Chromas were manufactured? in the FAQ.
By 2002, David Clarke had designed the ChromaKnob, - a programmer with a huge number of knobs, similar in concept to the Jellinghaus DX Programmer. See the Chroma site.
To help this synth communicate with anything other than an Apple II or a Polaris (or other Chroma / Chroma Expander) you need a MIDI interface. Usually this is external, and probably the best of the bunch is the Chromacult MIDI interface, dating originally from 1985, but updated recently, and still available in 2002.
The other most well-known rival was the J L Cooper ChromaFace, but that appears not to be highly thought-of nowadays.
A Chroma Expander was also available - see below. In fact the Chroma doesn't quite look complete without one sitting on top of its nice flat top panel. But Martin Newcomb of the Museum of Synth Technology warns that although the Expander was obviously designed to sit on the Chroma, it can be a bad idea if either of the machines is at all delicate. heat build-up, and damage to tightly-packed components can easily result. Some Chromas are liable to overheat and break down (the power supply seems to be the biggest problem area), and so the argument is that it's best not to have anything near it at all....
Several owners seem to have added fans to try to keep things under control Others, I must say, have encountered no problems whatsoever with this! See the Chroma website for the best info.
Further Reading: Vintage Synthesizers (1993); Vintage Synthesizers (2000); The Whole Synthesizer Catalogue; Synthesizer von Gestern Volume 1; The Museum of Synthesizer Technology; Keyboard April 1982, Keyboard August 1982 review; Keyfax 2, 3 [see excerpt from Keyfax Omnibus Edition]; International Musician Jan 83; 1-2 Testing Aug 83, Electronics & Music Maker Oct 82; Sound On Sound Oct 95, Nov 95 [letter]; Music Maker (Netherlands) Dec 82 p41 review. Chris Ryan's Chroma website at [www.rhodeschroma.com].
Ratings (total score: 58):
UK Price History:
Triangles indicate years of production; diamonds are highest price you were or are likely to pay; squares are lowest price you can reasonably expect to pay (without getting lucky). [For more explanation and information, I highly recommend the book! See Peter's contact information at the top of this page.]
Chroma Expander: 16-voice 16-VCO expander module
Original price: c.£2000. Typical price: £850 - 1400.
Users include: Herbie Hancock, Joe Zawinul.
Precisely a Chroma without the keyboard facilities, designed to sit on a Chroma and make it 32-voice (or sixteen layered-voice). But see the warning above - despite appearances, it's not necessarily a good idea to sit the Expander on the Chroma.
Expanders are far rarer than Chroma keyboards. Ten were listed [1631, 1633] on the Chroma site in Mar 03, with numbers ranging from 16330008 to 16330135 - so a guesstimate of 150 made seems reasonable.