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ChromaTalk Archives: June 2003

Any interest in seeing voice card build details on site?

David Clarke [21030085++]

As pictured in Chroma Voice Board Revisions: The Changing Face of Chroma Dual Channel Voice Boards and Voice Board Revisions: Clarke I had to make a set of Chroma voice-cards from scratch a while ago.

As part of that effort I ended up out the circuit board and purchasing all the parts from scratch and:

  • generating a complete parts list, identifying all components on the board (including values of otherwise unlisted components);
  • identifing a source for all components on a dual channel voice board, including web addresses and cost;
  • validating the schematic in the service manual;
  • generating a set of gerbers that can be used to produce a replacement circuit board, etc.

Is there any interest/desire to see some/all of this info either as an article for the site, or sent out via the mailing list?

Henry Salvia [21030307]

Absolutely! Even those of us less inclined to hack hardware could use this information to hire the job out. Thanks.

Matt Thomas [21010021]

I think it would be an invaluable resource, particularly as these old monsters get become increasingly unreliable.

Josue Arias [21010162]

Hi David,

That info would be very interested! My chroma have a faulty voice and that will save me lot of time, please post the info at Chroma site.

John B. Rotondi [21030185+]

Dear Mr. Clarke-

I cast my 'Yay' vote for the dissemination of your voice card build information. I am sure there are many list members who have errors caused by voice card failures. I myself have 2 Chromas that I am in the process of restoring, with several voice cards needing rework. This information you have documented, would be greatly appreciated, as was the power supply retrofit info previously posted. Keep up the excellent work!

Murray Macdonald [21030276+]

Ho David,

My voice cards are fine (at the moment), but I would still sleep better knowing that I had an extra card or two, or that the artwork to produce replacement cards was somehow accessible. It must have taken some effort to ensure your cards fit the form factor. Nice job. They look great.

Robert Shanks [21030301]

Any interest in . . . YES!

Yes! Yes! Yes! Please do

Thanks - Robert

Jimmy Moyer [21030184]

Another yes vote.

(I do have one board that fails self-test at the moment, though if I enable it, I can't notice any thing wrong with the sound, so not high on my list of emergencies.)

Luca Pilla [21010218]

Yes, yes, yes! I hawe two worng voice card :-( Let me know
Luca, from Italy

David Gowin [21030611]

I would think the ability/knowledge to make any replacement parts or at least the most common replacement parts (such as the power supply and voice boards) would be a huge asset to community!

Many thanks for all the work you've done for everyone here!

David Clarke [21030085++]

Any interest ... (thanks)

Thanks to all for the feedback (regarding interest in the voice card build details).

I'll work with Chris R. to see what's do-able for the site. In advance of that, if anyone gets stuck (e.g., has an immediate need to get a replacement connector for the bottom of the card, etc.) just let me know and I'll dig those specifics out for when you need them.

cassette interface cable configuration

Mark W. Heckert [16330114]

Is there anyone out there who can tell me the configuration of the cassette interface cable that came with the chroma?. At the chroma end is a 5 pin connector(Midi type) and it teminates to three mini type jacks. Do you happen to know what size(in inch increments) the jacks are and also what pins on the 5 pin each jack terminates to????.....

Chris Ryan [21030691]

See David Clarke's info in his January 2001 post "Info on Chroma Cassette Cable."

Mark W. Heckert [16330114]

Thanx Man you saved my life.......

MIDI 9 Retrofit

Chris Ryan [21030691]

I received the following information from Jack Butler at MIDI 9 (formerly Gulbransen, well known to Chroma history buffs).

For background information on the Gulbransen factory's role in Chroma history, see

I stumbled on your Chroma page searching for MIDI Rhodes. The systems available from my company, MIDI 9, may be ideal for the Chroma. I admit that I know nothing about clearance issues under the keys of the Chroma.

We bought out Gulbransen recently, and we are actively pursuing the vintage retrofit market. Here are some of the new features we have recently added:

Standard KS controller features:

  1. full velocity sensitivity
  2. selectable MIDI channel
  3. MIDI volume control
  4. MIDI mute
  5. individual note velocity sensitivity

Advanced KS controller configuration software features:

  1. keyboard split
  2. keymap (custom pedal board setup)
  3. aftertouch
  4. second touch
  5. Intelligent MIDI merge/thru for embedding control information
  6. MIDI installation analyzer
  7. one touch set-ups for Rhodes, double manual organs, CP70 Yamaha, Wurlys
  8. Velocity curve adjustable for each MIDI zone
  9. Five types of velocity curves
  10. Release velocity for each MIDI zone
  11. Trigger point adjustable

Here is a link to our leading East Coast Rhodes MIDI installer:

Not exactly sure how the product works, how it would be installed (how much clearance is required), or what advantages it would offer over a Chroma with the Syntech/Chroma Cult MIDI retrofit, I asked for more information. He responded:

Our systems require about 1/2" vertical clearance under the black keys, when they are at rest. The way the sensor strip works is this: Each key gets 2 lights beams to detect velocity. Our feather-light tiny plastic spring-loaded fingers (nessies) ride under the keys and cut the beams.

We ship sensor strips fully assembled, so installation is usually very fast. I was told today by Steve Hayes at Speakeasy Vintage Music that the Chroma has a very different action from a Rhodes or a piano. It is possible that our system may not fit, we don't know.

As far as advantages, I don't know the Syntech/Chroma system at all, but here are new features we added today to the KS controller configuration software:

  1. keyboard splittable into four zones
  2. five types of velocity curves
  3. selectable MIDI channels per zone
  4. MIDI mutes per zone

Below is an info email I recently sent out:

This email is to officially announce our new company name change and our new velocity sensitive piano and organ MIDI retrofit systems.

Recently the former long-time owner of Gulbransen sold our Digital Hymnal business, along with the Gulbransen name to QRS Music. We will continue manufacturing only MIDI systems, not Digital Hymnals. We have now emerged from the transition period with new products and a new company name: "MIDI 9." (The origin of the new name is explained at the web site.) This new MIDI System business is now owned by Dave Starkey, the original inventor, and Walter Chung, a past president of Gulbransen.

Here is a link to our new web site:

Our new product line includes:

  • KS-61 specifically designed for single manual 61 note organ applications
  • KS-122 designed for double manual organ applications (includes two 61 note sensor strips)
  • KS-73 designed for 73 note Rhodes and Yamaha CP70 pianos

All of our products are velocity sensitive and do not change the feel of your keyboard.

We also are continuing to offer:

  • KS-1 for standard 88 note pianos
  • Orchestra III for 61, 73, or 88 note length, includes onboard sequencer and sound module

We have also reduced prices, the new factory direct prices are:

  • KS-1 $795 (includes 88-note strip and damper sensor)
  • Orchestra III $1295 (includes one 61, 88, or 73-note strip plus damper sensor)
  • KS-61 system is only $795. (includes 61-note photo-optical sensor strip)
  • KS-73 system is only $795. (includes 73-note photo-optical sensor strip)
  • KS-122 system is only $995. (includes two 61-note strips)

Quantity discounts are also available.

Add $20 UPS Ground delivery for all single sensor strip orders, $30 for double strip order)

Systems are in stock and ready to ship.

Feel free to email or call me directly to order or for more info.

Jack Butler
(formerly Gulbransen Inc)
ph 800-757-MIDI (6434)
fax 619-469-1456

There seem to be a couple of interesting capabilities (multiple zones etc.), but of course no sysex. Anyone know if this would even fit in a Chroma?

Rich Hilleman [21030351+]

Hi Chris,

I have one of these on order for my Suitcase 73. Peter Miller at CAE Sound will do the installation. He did the restoration of my Chroma and Expander and is restoring my other Chroma for his own use. I'll see if he can write a note about the applicability.

By the way, we have found a way to restore keyboard contacts that none of the usual service proceedures fix. I found that 1000 grit sandpaper (available at hobby stores for modeling work) would fix the upper contact when nothing else would. Treat the contact with cleaner after and it will last longer.

Go to next message in thread (July 2003)

Pix of Chroma with Natural finish wanted

Vincent Russo [21030433]

Hi, We would like to refinish our Chroma and perhaps go with a natural finish. Anyone done this and have photos to see ?

David Clarke [21030085++]

There was someone on the list that had given their Chroma a 'blonde' finish (and had either posted pictures - or a link to a site with pictures.) A quick poke through the old messages might be worthwhile.