From: barrett@quincy.cs.umass.edu (Daniel Barrett) Subject: Chroma Date: 3 Jan 92 21:16:46 GMT Until the Xpander came out, the Chroma had the most powerful voice architecture of any programmable synth. It was originally designed by ARP, a company who had 40% of the synth market before they unfortunately went out of business. The Chroma had 16 VCO's (usable either as 16 individual, or 8 pairs), 2 filters (each capable of highpass/lowpass) that could be put in series or parallel, and could do FM and (I think) ring modulation. Back in those days, if you had a Chroma and a DX-7, you had one hell of a keyboard rig! The user interface is unusual and a little crude. It has 50 membrane pushbuttons and a data slider (similar to DX-7 interface), but the only readout is an LED with maybe 16 characters. When you pressed a membrane switch, the instrument made a satisfying "THUNK!" so you knew you had pushed something. (Tactile feedback, anyone?) For modulation gear, it has 2 skinny levers that you push forward and backwards. The Chroma has a bunch of LFO's and envelopes, lots of goodies to modulate, and some sophisticated pedal algorithms. For example, you could load a chord into the Chroma and then play it later by pressing a pedal. It has an arpeggiator, and a minimal monophonic sequencer which is primarily an arpeggiator that plays back the notes in the order that you played them. The Chroma has a velocity-sensitive 73-key weighted keyboard. The company (Fender) claimed that pressure-sensitivity would be added, but (I think) this never happened, or the company decided against it because it adversely affected the feel of the keyboard. Chroma was pre-MIDI, but it could be interfaced with an Apple II to provide 8-voice multitimbral operation and (I think) sequencing. Here are a few of the interesting things a Chroma could do: o It had pulse width modulation, but it could be applied also to the sawtooth wave of the oscillator, not just the square wave. o Its internal voice architecture (VCO/VCF/VCA) would be re-ordered by pressing buttons on the front panel. Effectively, this was like having 10 different kinds of synth! o The Chroma Polaris (a later instrument) pioneered an interesting form of pitch bending. Hold down some keys, press a pedal, let go of some of the keys, and push the pitch wheel. Only the keys that are still depressed will have their pitch bent. Great for steel-guitar licks. o The "chord loading" feature I described above. Then, the Xpander came out. It had more (and more powerful) modulatiors, strong MIDI implementation, multi-mode filters, lag processor, tracking generators, and a host of other things. I was all set to buy a Chroma when the Xpander suddenly came out and dashed my plans. :-) I've been able to duplicate 99% of the Chroma's functionality on my Matrix-12, including the weird features like chord loading and steel-guitar pitch bending. The only exceptions are the re-routable voice architecture and the weighted keyboard, which are obviously hardware differences that cannot be accomplished with an M12! (Though the rerouting can be mimicked quite well with the M12's multi-mode filter, FM, and oscillator sync.) As for sound... the 2 instruments are both analog, but the sound is different. I feel that the Chroma's sound was less "fat" and more "buzzy" than the M12's, but these are not negative qualities -- just differences. Dan //////////////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ | Dan Barrett -- Grad student, Department of Computer & Information Science | | University of Massachusetts, Amherst, MA 01003 -- barrett@cs.umass.edu | \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\///////////////////////////////////// From: dgp@cbnewsg.cb.att.com (dennis.pelton) Subject: Re: Chroma (was Re: waldorf uWave) Date: 4 Jan 92 00:04:08 GMT An outside software firm also created a program that would provide MIDI interface thru the Apple ][+ using the Chroma interface and a standard MIDI interface. You could run the MIDI converter or the sequencer, but not both at once. The interface also provided patch library functions. > Here are a few of the interesting things a Chroma could do: One of the keyboard algorithms was "pitch ordered" assignment. The highest note got voice 1, next highest got voice 2, etc. This allowed the use of polyphonic portamento! For example: Play a G chord in the octave below Middle C. Now play an A minor the octave above Middle C. The notes will each slide to the appropriate relative note in the next chord. Cool and a half! Can the M-12 do this? > I feel that the Chroma's sound was less "fat" and more "buzzy" > than the M12's, but these are not negative qualities -- just differences. Given that "fat" and "buzzy" are real relative here, we won't be able to really talk about differences in sound, but I now have an EX8000 and once had a DSS-1 (the Korg sampler/synth). Each comes close to the Chroma in terms of "fat" but (hangs head in shame) I've never had the chance to play with a Matrix 12 (although I saw a guy in a band playing an Xpander once). The real drawback to the Chroma, and to a lesser extent of the M-12, is the weight! If you want to play one live, you have to carry it! If I remember correctly, the weight of the Chroma is/was 55 lb. With an Anvil case it weighs over 70 pounds!!! Dennis Pelton att.com!ncsc8!dgp From: metlay+@cs.cmu.edu (Mike Metlay) Subject: Re: Chroma (was Re: waldorf uWave) Date: 4 Jan 92 07:48:28 GMT >One of the keyboard algorithms was "pitch ordered" assignment. The >highest note got voice 1, next highest got voice 2, etc. [...] > Cool and a half! Can the M-12 do this? Not directly, but you can fake it in multi mode, I'll bet. The M-12 and Xpander have six different modes for assignment. -- metlay | HEY-YEH! just another guy with an Xpander | Walking in the Valley of Decision-- | HEY-YEH! metlay@organ.music.cs.cmu.edu | Reap all the Wages of Sin! (d.dax)