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ChromaTalk Archives: July 2006

The mailing list was a little flaky this month; some subscribers did not receive messages and there was silence for a couple of weeks. As of the end of the month, things seemed to have smoothed out somewhat.

CPU Plus Installation Instructions and User's Guide

Chris Ryan [21030691]

New to the site this month is additional documentation for the CPU Plus (CC+) upgrade: installation instructions and user's guide.

sound set 6

Jesper Ödemark [21010135]

Hi list!

For the first time in a while I have had both time, energy, cables and luck to load some sound sets from the cassettes I bought on Ebay [see Patch Tape on eBay: Factory Sets 4, 5, and ... 6? from April, and Chroma Sound Set 6, in the May archive].

Everything seems to work out fine and I can confirm that sound set 6 (the "magic" and "mysterious" one) does contain Chroma sounds in the same league as the rest of the factory sets, i e plain pad sounds, weird effects and attempts at copying traditional instruments etc.

I recorded the cassettes at various volumes onto audio CDR and then loaded from the headphones jack of my old discarded CD-player (discarded 'cause it only accepts discs up to circa 60 minutes in length). Some fuzz before I found the right level to use, but know it works.

I have no description of the sounds though since I never got one with my cassettes. I wonder if there is any official... and yes, I think this is an original sound set and my cassette comes from an old repair shop, so... you have to judge for yourselves.

While at it I can mention the nasty cable solution I found. I had a cable from an old PC keyboard (when they still used standard DIN-5 connectors at the computer end). I mounted two female 6,3 jacks at either end of an old 35 mm film container and wired it according to Chris' scetch it the site. One side is now marked "save" and one "load" and since it's an old keyboard cable it's spirals like a telephone cord. Looks vicious indeed.


Chris Ryan [21030691]

Jesper, could you send the bank to the list, or to me so I can do a file compare with the "Chroma Cult FS 06.syx" bank [one of the files in the Chroma Cult banks] to see if they're the same?

Jesper Ödemark [21010135]


I guess a .wav to you is the easiest since all this file converting stuff is above my head... :( I'll get back...

Tom Klepacki [21030025]

I may have said this before, but keyboard tech Mike Pinto, who used to work for 'Thoroughbred Music' in Tampa, FL in the 1980's was a factory-trained Chroma repair tech. AND, at one point, either Mike or one of the salesmen there developed a Chroma patch that was a 'spot-on' acoustic piano, at least for the lowest 1 1/2 octaves. (It turned to 'mud' above that. This was way before sampled sounds.)

Does anyone know if Mike is alive and well, and fixing our beloved 'monsters'? And, if the (Tampa) Chroma 'acoustic piano' patch data survived?

Chris Ryan [21030691]

I guess a .wav to you is the easiest since all this file converting stuff is above my head... :(

Actually a diff would probably work better with two sysex files ... can you provide this?

Chroma repair NYC?

Bill Lacey


Does anyone know who could repair a dead Chroma in NYC, or close by? My Chroma has been been sitting in DBM Repairs for two years and they can't fix it. I wanted to see if I could get it repaired. Also, my Oberheim Matrix-12 is down and needs to get fixed, too.


Chris Ryan [21030691]

You could try James Reynolds, listed on the Service Centres page.

Uro [21030401]

For a repair shop actually in NYC:

Main Drag Music - 2.2 miles E - 330 Wythe Ave, Brooklyn, 11211 - (718) 388-6365

One of the repair guys from Two Lines is there now as well as his Japanese understudy.

$60/hr, $30 for estimate if not used.

If you speak Japanese, maybe you can ask him to look at it, in your home instead. :)

Otherwise, send to Greg in Oakland (email him first).

power supply aux board

Krisnallah Sumy [21010282+]


Working on testing the auxboard for my meanwell powersupply as mentioned in How to Swap the Power Supply with a Readily Avaialble Switching Unit. I wondered about the reset circuit I got about 4.06 volt on the reset output J1-6

can anyone or the godfather himself sandro tel me if that is correct. for the reset circuit on J1-5 +5 dig from the psu goes in and after the pull/push how many voltage should J1-6 Rest line give

the meanwell was factory set at +.5.05 dig when it reached the io board it is about +4.98

Sandro Sfregola [21010294]

Hi Sumy,

the voltage measured at U201-1 (or U202-1) should be near 5 volt while the voltage on the reset line under load (connected to the Chroma circuits) should be about 4.3 - 4.4 volt as there is some drop caused by the push-pull buffer.

If your voltages are different please start checking the connections of Q201 - Q202 and the value of R203.

Please let me know.

Krisnallah Sumy [21010282]


Dear friends

my name is Sumy -

My Swap of the chroma's supply as mentioned in How to Swap the Power Supply with a Readily Avaialble Switching Unit was succesfull. I have Build the Aux board myself it was a piece of cake .But I have to advice, use the components described on the side especially the reset part with the mc 34064p using equivalent components might not work straight.

The only difference I have noticed is that when I switch on the chroma the display shows an 0 in a nana second before doing the initial flashing and my eq board tune slider is one piont up the middle position.

Krisnallah Sumy [21010282+]

power supply


my name is Sumy - -->

My Swap of the chroma's supply as mentioned in How to Swap the Power Supply with a Readily Avaialble Switching Unit was succesful. with meanwell t60b fabulous powersupply

I have Build the Aux board myself it was a piece of cake .But I have to advice, use the components described on the side especially the reset part with the mc 34064p using equivalent components might not work straight.

Al problems fixed Chroma stable and went on stage again now it is time to get my expander fixed

credits and thank to lala
Christian Kleine [21030210]
Sandro [21010294] and Chris Ryan [21030691]

Chroma on Craigslist Los Angeles

Chris Ryan [21030691]

"In great physical condition." $800.

The picture along with the item was that from the Museum of Synthesizer Technology book.

bouncing mails and a few final CC+ questions

Jesper Ödemark [21010135]

Hi List!

I received a note on bouncing mails to my address. But since I received that I guess it works now... but the list has been awfully silent lately...

I re-read all the CC+ info on the site and I'm so impressed by the work and finally in the process of mailing Sandro an order. But before that I have a few last Q's I hope someone can help a sysex idiot to understand. Please... ;)

  1. I recently bought a Doepfer Pocket Dial on Ebay which is a midi control box with 16 rotary encoders and four banks. My plan is to hook this up between my Atari (w Cubase sequencer) and the Chroma to tweak all the parameters "analogue style" having each bank controlling up to 16 parameters. Could someone (Dave or Sandro maybe?) familiar with sysex let me know if this will work with the CC+?
  2. The external midi box is more or less just a converter box between the D-sub male connector and the DIN-5 female midi connectors, right? What are the LED's for? Midi message control? Are the pin-info included so I can build my own box or do you advice on necessarily buying this with the CC+?
  3. Is there any technical advantages in having the knob box connected to the new midi input and keeping note on/off message control etc through the EES midi box I currently use?
  4. Sandro, how much is shipping from Italy to Sweden?

All help appreciated. I'm very interested in blasting my Chroma into the future with expanded midi control etc, but no need in buying if I will end up getting irritated, frustrated and disappointed...

Hoping for help and understanding,

Sandro Sfregola [21010294]

In response from Jesper's questions:

1) About the Doepfer Pocket Dial:

After a look at the user manual, I can say that this controller can be used in combination with a CC+ equipped Chroma to edit parameters in real time; you will need a PC and the free editor program (you can download it from to configure the box, assigning controller numbers to the rotary encoders as you like. Once properly configured, the box will retain the set-up in its own memory. Controls must be set in "absolute" mode: of course you will have the "parameter value jump" problem, as the controller box has no way to know the starting value for each parameter; this problem could be solved with the implementation of the MIDI Continuous Controller Increment/Decrement feature in the CC+ firmware (as described in the Pocket Dial manual at page 33 and following); I think it could be a nice addition for the next firmware update.

2) CC+ connections:

You are right: the connection box is only a convenient mode to connect standard MIDI plugs to the 15 pole D connector on the rear of the Chroma; all the wiring schematics (including the pin-outs of the CC+ internal connectors) are available from the CPU Plus Installation page. The LEDs purpose is as follow: LED1 (green) - MIDI activity indicator (same as the decimal point in the Chroma display) LED2 (red) - reserved for future use You can build your own interconnection hardware as you wish; the only advice is BE CAREFUL.

3) Using separate MIDI interfaces on the Chroma:

I think no; the Pocket Dial can merge the input data to its own generated and this task shouldn't add any significant latency; maybe some problems could emerge in the case of large sysex dumps (bank loading) to the Chroma thru the controller box (some tests are needed but in case, the box is easy to bypass). Anyway, the MIDI latency of the CC+ is always lower than that of any Chroma + external interface combination.

4) Shipping a CC+ to Sweden by mail (from Italy) is 12 Euro and delivery time is about 7 days.

Best regards from Italy to all the list members

Reviving #21030175

David Clarke [21030085++]

Go to first message in thread, June 2006

My current best guess is that some other connection unseated while I was cleaning foam crud off the exterior... in particular, to get at the crud on the bottom surface, I turned the instrument up to rest on its back panel. If anyone can suggest likely culprits for a loose connection that would result from doing so, I would be most grateful.

Brian - unfortunately there a lot of different things which could go wrong, and it is hard to rule any of them in/out when the failure manifests itself in an inability to boot (could be lack of power, bad connection, a short, a component that just happened to take this chance to die, etc.)

The first/easiest thing to do (and you've likely already done this) is to visually check to make sure that all connectors are installed and well seated, and similarly that all chips that are in sockets are well seated.

If any connectors were removed (and then reinserted) check to ensure that a pin didn't actually bend under the connector (vs. going in the holes).

The next easiest item would be to check the voltages coming out of the power supply. If you already have a meter (multimeter/voltmeter), then you're all set. If you don't, then inexpensive ones can be gotten at Radio Shack for under $20 or so. (ref: Radio Shack catalog #22-810)

The Service Manual has a nice picture which identifies the voltages which come out of the supply on the different connectors.

If the voltages look OK from the power supply's perspective, you might want to also look at the 5V level as seen on the CPU board (to make sure that it is getting there OK).

The next item might be to look at the RESET signal (also available on the connectors from the power supply) to see if the system is being told that it is OK to start up.

If everything checks out up to that point, then you'd want to have an oscilloscope to start probing around to see 'how' the board is getting stuck (and/or if there's too much ripple/noise on the power).

Good luck in your debug efforts - and if the behaviour changese, or specific things are seen - let the list know as we might be able to provide some other suggestions on the appropriate 'next steps'

Herbie Hancock/Jeff Bova ? Chroma Spotting

Jim Russo [21030433]

Some real nice Chroma footage in the 1984 Hancock video: 2 Chroma's, and a Expander. Jeff Bova, Is that you on second keys?

Chris Ryan [21030691]

These appear to be "Halloween" units: the yellow and red are clear in this screenshot.

Jeff Bova [21030407++]

Yes that's me. I'm playing the chroma with the Yamaha KX1

Here's a screen capture of Jeff from the video:

Jeff Bova [21030407++]

These were the Chromas Herbie used on the albums and live on all the tours.

On the early tours Herbie linked the Chroma and expander directly. When the "Sound System" album came out we both were using the KX1's, so in Herbies case he switched to JL cooper midifaces on both units so he could play from the KX1 as well as the Chroma keyboard. I used a single Chroma face for mine. We both switched to the Syntech, but that was after we stopped touring.

Lyle Mays Chroma photo

Jim Russo [21030433]

Chroma behind Lyle

Greetings and Chroma editor questions!

Rob Belcher [16330123]

Hi peeps,

Some of you may know me from Analogue Heaven, ive just subscribed to this list too...

I have a question- has anyone ever designed a VST editor for the Chroma?

Take for example like this (in this case for the Waldorf Pulse) [url obsolete as of 2009; try here]

It is, quote " a realtime MIDI synth editor that allows you full control of every parameter of the sound on the Waldorf Pulse and Pulse Plus synthesizers..."

You launch it from inside your sequencer and have full control of the Pulse on a screen almost like its a VSTi.

If ever there was an instrument crying out for such an editor it has to be the Chroma surely.

Looking through the archives lots of people seem to want an external box of knobs to control the Chroma (but it sure seems like that will never happen), well why not an editor instead?

Launch your sequencer open up the editor, tweak some parameters and play the Chroma over midi...

The Chroma can handle the sysex so why not!

Any of you software guys ever considered doing such an editor? :)

Id be most interested to know what you guys think!

Chris Ryan [21030691]

I'm making slow progress on some Chroma software, but it will be a native Mac OS X application. I've considered doing a plug-in, but it would be in Audio Units format.

Go to next message in thread, August 2006