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ChromaTalk Archives: October 2001

Re: Bad voice cards (how many)

Go to first message in thread (September 2001)

Dave Bradley [16330135]

I have to report in the negative. One Chroma, one Expander, 16 boards, no errors. The last bad board I had turned out to be a dead capacitor that was causing the filter to fail autotune. It cost 10 cents to fix.

Of course, my power supply just died. Hopefully it didn't take anything with it.

Bernie Bean [21030671]

I have one bad and one missing voice card. Bad card may beyond reasonable repair, causes other Chroma voices to go insane when this card is install but does not seem to be the usual power or bad cap problem. Other cards are very thermal and require lots of autotuning.

Jerry Leonard [21030100++]

That's a tough one for me to answer. I have 3 Chromas, one I've got to work with all the cards. However, I've put up to 8 other cards in there and they have all erred. I didn't get to the other eight. The other two Chromas have problems and my expertise is limited, as well as my time. It is my intention to get all three Chromas up and running someday, but for now, I've just got alot of parts, and one that "kinda" works. Long story.

By the way, I haven't registered them. I will do that soon.

Interface Manual, Sequencer Manual PDFs

Chris Ryan [21030691]

The Chroma Interface Manual [PDF, 1.7mb] (technical info on the computer interface) and Sequencer Manual [PDF removed due to very low demand; contact me if you'd like a copy] (for the Apple II, Rev 5) are now available at the site, from the Manuals page.

Thanks very much to David Gowin for his work in putting these together!

David Clarke [21030085++]

A few comments/edits/clarifications on the Interface Manual ...

In the Chroma Parameter List:

  • The "Location" for Sweep Rate Mod is shown as "3/33:0" ... it is actually "3/33:4"
  • The "Location" for Volume Mod 1 Depth is shown as "3/33:4" ... it is actually "3/33:0"
  • The "Range" for Panel Edit is shwon as "1..3" ... it is actually "1..3 || 1..50"

Panel Link is stored as 2 bits, as follows:

  • 00 = no link
  • 10 = Link Lower
  • 01 = Link Upper
  • 11 = Link Unison

Panel Edit type is stored as 2 bits, as follows:

  • 00 = (error, disallowed)
  • 01 = Edit B
  • 10 = Edit A
  • 11 = Edit Both

Main/Link Transpose are stored as 2 bits, as follows:

  • 00 = No Transpose
  • 01 = Up 1 Octave
  • 10 = Down 1 Octave
  • 11 = (error, disallowed)

In Appendix C:

Some of the locations change with firmware revision. In particular, things like the Safe buffer, Stack and Cassette buffer swapped around from Rev 12 to Rev 14.

David Clarke [21030085++]

The question on the voice cards ended up generating a lot of replies!

I tend to be of the same opinion as Don Tillman who noted "...Even if one or more components really are toast the board is pretty easy to fix..."

To that end, I'm prepared to offer to attempt to repair any sick voice boards from Canadian list members - if you want to pick up the shipping and part costs. That is to say, I'd work on the board for free - you'd just have to pay for shipping to/from me and the actual costs of any parts that were replaced. (I'm currently limiting this to members in Canada to avoid any grief shipping PWBs across the border).

If anyone is interested, you can get in touch with me directly.

Similarly, if anyone (in Canada or otherwise) simply wants to sell their sick voice boards as-is (maybe to get a few $$ to go towards buying a fully functional board) let me know.


David Clarke
Ottawa, Ontario

Fredrik Bechmann

Hi David!

I was just curious if You know of anyone in Sweden or nearby who could do the same job on "Scandinavian" voice boards?

:-) Fredrik

Expander on eBay

Chris Ryan [21030691]

There's an Expander for sale on eBay. Item #1474047280.

Dave Bradley [16330135]

Hmmm, an Expander with 64 key keyboard...

And no mention of that ugly hack mod on the front panel??? Does anybody know what that is supposed to do?

Wayne Griffin [16330111]

Did anyone else notice that this Expander features:

"• 64 weighted-keys with velocity (polyphonic aftertouch optional)"


Chroma Expander forensics...

Robert Shanks [21030301]

Hi All -

I captured the pictures from the ebay site. Put the closeup picture of the "mod?" into Photoshop, blew it up 300 prcent, adjusted levels, did an unsharp mask. (graphicdesigner/synthesist) And I didn't really find out much more than you could see on ebay - The top oval label says ON and the side labels are 1-6. Now the bottom three bits of hardware are toggle switches - the top three could be switches or pots. Maybe it has to do with the "built-in" MIDI. The mod hurts me deep down inside somewhere.

You can have my Chroma when you unwrap my cold dead hands from around it.

Here's the picture:

David Clarke [21030085++]

Re: Chroma Expander forensics... --- the answer

I captured the pictures from the ebay site. Put the closeup picture of the "mod?" i... Maybe it has to do with the "built-in" MIDI.

I contacted the eBay poster and he said:

"This is the MIDI interface (JL Cooper Chromaface)"

The JL Cooper Chromaface doesn't have any switches on the outside, but it does have a bank of 6 internal dipswitches.

This would tend to mean that the six switches in the picture are all of the "on/off" variety.

From the Chromaface manual the six switches are assigned as below:

  • SW1 - SW 4 sets the MIDI channel (SW1 = the least signficant bit)
  • SW5 (when ON) enables the multi-channel mode of operation
  • SW6 (when ON) disables receiving program changes

The mod hurts me deep down inside somewhere.

I hear ya ... this is definitely one of those cases when it would have made sense to leave the Chromaface external to the box (or at least stick the switches out the rear ...)

Welcome Jeff Bova

Chris Ryan [21030691]

A while back we had a discussion about Herbie Hancock playing his Chroma on Saturday Night Live.

Jeff Bova played with Herbie on that show. Jeff has joined the mailing list and added his Chromas (three [21030407, 21030446, 21030457], and an Expander [16330100]) to the registry.

His Chromas have been featured in recordings by Cyndi Lauper, Robert Palmer, and Michael Jackson, among others; a link to his site and discography is included.

David Clarke [21030085++]

Jeff - welcome to the list (and thanks for adding your Chromas to the registry). If in your travels you stumble across other Chroma users, it would certainly be appreciated if you could point them towards the Chroma site and the registry.

Jeff Bova [21030407++]


Thanks. I was so happy to see the spirit of the Chroma still Lives!

Best Regards,

Jeff Bova

Chroma in action. (And no Bad voice cards here...)

Joakim Uddling [21020003]

In September we finally released our new album "", recorded one year ago. It's in Swedish unfortunately, but still there are some tracks with extensive Chroma use on them. Actually, the Chroma is the only synthesizer used on this album...

I'll support you with some links of material, which could be of interest. Two pages with real player links:

[obsolete URLs removed]

I strongly recommend you to chose the "bredband"-links (that is of course broadband), since the sound quality is significantly better on these.

And the main address to this site is: [obsolete]

(I am is the guy with the piccolo suit. No I'm not gay.)

Hope you'll enjoy the Chroma features, still unmatched by contemporary synthesizers...

(I'm sorry I couldn't post some WAV's or AIFF's, but I can't afford being sewed by Universal music)

Best regards

/Joakim Uddling/Sweden

Re: Mac OS Chroma Utility

Go to first message in thread (August 2001)

Joakim Uddling [21020003]

As a dedicated Mac/Chroma user, it sounds really interesting with your plans. I still use 8.6 on my beige G3, but if you find time to do a sysex/library for OS X, I got an even stronger reason to upgrade. I think you have got a strong point in concentrating in Cocoa rather than Carbon. It would be nice to be able to use such a program even in the future, when new Mac:s probably don't even run with 9.x or older systems. OS X is the future, no doubt.

Rising Chroma prices

Joakim Uddling [21020003]

The 21st of October, a Chroma Expander was sold for the neat amount of $2,711 on eBay. There is a Chroma for sale there right now, and the current bid is $800 with 4 days left on the auction. Another guy in Germany had a first bid of DM 4,444.00 on the Chroma, which is about $2,000. It seems to me that the prices on used Chromas has rised dramatically lately.

Maybe it's time for this synth to get the appreciation it really deserves...

Rob Vandivier [21030396]

of course..
Germany news innacurate but thanks for the excellent tracks on your site where in Florida, Usa can one find your cd (not quite enuff chroma for me but, hey..)???
Rob/o town

Rob Vandivier [21030396]

Sorry ,
Germany accurate at 0 bids (1st being asking price) will he get a bid? slight misunderstanding..,

Ernst Eimer [21010299]

I don't think so, because normally Chromas go for between 2000 and 2800 DM (between 1000 and 1400 US$ approximately) here in Germany. I've never seen someone asking that much before.

David Gowin [21030611]

If this was an original ARP Chroma, fuly working condition signed by Alan R Pearlman,, yeah, I'd pay his asking price.

Go to next message in thread (November 2001)

More Halloween Chromas

Dave Bradley [16330135]

I revisited the Herbie Hancock Sat. Nite Live tape, and noticed that both his Chroma AND Expander were of the Halloween variety. It figures that he would have preproduction units, but I was surprised that they had done up the Expander that early in the process.

See the July 2001 thread Chroma buttons which continued in August in the discussion Re: Chroma buttons and sub-thread Red Chroma for a discussion and pictures of the "Halloween Chroma" (Andi Beit's 21030620 is the only one currently in the Registry). See also Fwd: "Red Chroma's" (November 2003) for thoughts from the "screen-printing guy" at ARP and Fender.