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ChromaTalk Archives: September 2009

Re: Awful Tuning Problems

Go to first message in thread, August 2009.

Randel Osborne [21030467] · Tue, 1 Sep 2009 11:18:06 -0400

I've replaced that pot with a 10-turn trimmer, and it keeps the breath-holding to a minimum.

How the Chroma Tunes Itself, and "Tuning Quirks"

Chris Ryan [21030691] · Tue, 1 Sep 2009 23:50:12 -0700

David Clarke [21030085++] has contributed another interesting technical article to the site. "How the Chroma Tunes Itself" details the tuning process: oscillator and filter scaling and offset, and "tuning quirks." David writes:

Several people have raised questions about how the Chroma seems to tune. Like Michael Grossman [21030350], some have seen that autotune may not result in exactly the same tuning every time it is used [see Resurrecting a Chroma, September-October 2008]. Also, you may find you're a little sharp or flat when playing across the keyboard.

In day-to-day use some of these items may not come up, but they can be pretty clearly seen when looking for them and using a tuner.

Interested myself as to 'why', I sat down a few years ago to try to figure out how the Chroma achieves its tuning - hoping in turn to understand what tuning performance could realistically be expected.

The result (which has been lingering on my harddrive for a long time now) is available on the site.

This is admittedly a dry read for most of us, but the hope is that some of the technical data may provide the basis for discussion on the Chroma list.

Also, the notes about some 'non-perfect' tuning performance of the Chroma are noted - to help set expectations of what the Chroma can do.

Please feel free to make comments or ask questions. I'd be pleased to change/update/expand topic, as required.

Thanks, David.

Flight Case on Los Angeles Craigslist

Chris Ryan [21030691] · Tue, 8 Sep 2009 07:46:26 -0700

$25. "The foam is deteriorating and needs to be replaced but it's a nice heavy duty road case."

[Posting ID 1363205774]

Items on eBay Germany

Chris Ryan [21030691] · Sun, 20 Sep 2009 20:09:51 -0700

Voice Board: Item #280397573545, "Buy It Now" price of £655.00, ends October 14. Functional, good condition.

Picture from the auction:

Programmierhandbuch (Programming Manual): Item #120463911876, price of £29.95. Original (not a copy), 55 pages, in German. A bit of dust or fading at the top.

Spielhandbuch (Performance Manual, I think): Item #120463910760, price of £24.95. Original, 25 pages, in German.

Händlerinformation (translates to "dealer information"—perhaps the Service Manual?): Item #120463911220 , price of £24.95. Original, 18 pages, in German. This book intrigues me, as 18 pages isn't long enough to be the Service Manual. Any ideas?

The manuals are a bit more than I want to pay, but if anyone here picks them up, photocopies would be appreciated, so we can get German translations of the manuals onto the site.

Joël Cordier · Mon, 21 Sep 2009 09:05:04 +0200

Just a question: Is one voiceboard worth 655 Euro ?

Lars Johansson [21030632] · Mon, 21 Sep 2009 09:08:16 +0200

No,

in that case a Chroma would be worth ( and cost ) 5500 Euros ( ca 8000 USD )

Not a chance....

Doug Terrebonne [21030114] · Mon Sep 21 02:08:17 CDT 2009

The ones I've seen have gone for 1/10th of that...

Christian Kleine [21030210] · Mon, 21 Sep 2009 09:10:23 +0200

the seller is known for very high priced auctions - 'worth' is relative of course.

Joël Cordier · Mon, 21 Sep 2009 09:12:37 +0200

I know a Chroma missing one board. Do you have a suggestion for a reasonable budget for one board?

Lars Johansson [21030632] · Mon, 21 Sep 2009 09:18:22 +0200

I'd say in that case up to 300 Euros.

Doug Terrebonne [21030114] · Mon Sep 21 02:24:43 CDT 2009

There's another voice board on ebay now at $79. Item # 270459336546.

Jesper Ödemark [21010135] · Mon Sep 21 02:58:31 CDT 2009

The manuals are a bit more than I want to pay, but if anyone here picks them up, photocopies would be appreciated, so we can get German translations of the manuals onto the site.

I guess it's a promo broschure with info on the Chroma - aimed at the different music store, so that they know how to present it as the great machine it is to a customer with a thick wallet.

:D

But it's just a fair guess...

I have the mentioned german manual too and it's a lot cheaper looking than the US manual. A xerox machine of the 90's would easily do the job.

See "Voice Board Ultra RAR!" on eBay, November 2009

Voice Board and EQ Board on eBay

Chris Ryan [21030691] · Mon, 21 Sep 2009 19:26:24 -0700

Dual EQ Board: Item #270459336501, starting bid US$35,00, no bids yet, ends September 26. "Even includes the original slider caps."

Dual Voice Board: Item #270459336546, starting bid US$79,00, no bids yet, ends September 26.

They are both being sold by a seller in Salt Lake City, Utah, United States. Descriptions are similar: "Board looks to be in good condition and appears complete. But I cannot test it and it is thus being sold as-is for parts. Board will only be shipped to a continental US address to your Paypal address."

Pictures from the auctions:

Chris Ryan [21030691] · Sun, 27 Sep 2009 13:09:15 -0700

Sold for USD$35.00 and USD$83.00 respectively.

Rhodes Chroma Scan with Jethro Tull's Peter John Vettese

Matrix [21030220] · Wed, 23 Sep 2009 10:11:50 -0700

MATRIXSYNTH: Jethro Tull - Peter-John Vettese - 1983

Chroma Polaris with brown and yellow color scheme.

Here is the picture. See also the E&MM Peter Vettese Interview.

Chris Ryan [21030691] · Wed, 23 Sep 2009 19:15:21 -0700

This was a production prototype. See Re: Red Chroma in the August 2001 list archive for what Tony Williams (one of the main designers of the Chroma; see Philip Dodds/Tony Williams Interview) wrote to me on this.

New Chroma replacement PSU

Rob Belcher [16330123] · Fri, 25 Sep 2009 18:19:33 +0100

Hi guys,

I'd like to buy one of sandro's new Chroma PSU kits, unfortunately i don't know who to contact about buying a kit..

I want to install one into my Expander? I assume they work in the Chroma expanders too? Could someone email me sandro's contact details?

Luca Sasdelli [21010226] · Sat, 26 Sep 2009 04:58:40 +0200

Hi Rob,

the SPSU kits belongs to my small production: Sandro (and David) are the makers of the (excellent!) CC+.

The SPSU kit could be installed even into Expander: it is a bit trickier than the Chroma itself, but it works. I've sent you a private mail with purchase details.

Blue Box: Rhodes Chroma

Chris Ryan [21030691] · Sun, 27 Sep 2009 12:39:41 -0700

There's an article on amazona.de about the Chroma. "Blue Box: Rhodes Chroma" has a number of pictures of what appears to be Chroma 21010100, which is in the registry but the current owner is unknown. There are some sound files available, but I couldn't get to them as registration is required and the site either isn't letting me register, or else my German translation widget is throwing me off.

Chris Smalt [21010280+] · Sun, 27 Sep 2009 23:30:54 +0200

I just managed to register and will send you the files.

Jesper Ödemark [21010135] · Mon, 28 Sep 2009 09:12:41 +0200

I just managed to register and will send you the files

No problem here either... though it was hard picking a short enough user name. :)

I'm interested in the history of that Chroma since my was originally sold in Germany and is only 35 numbers from Theo's.

Chris Ryan [21030691] · Mon, 28 Sep 2009 00:22:58 -0700

I'm interested in the history of that Chroma since my was originally sold in Germany and is only 35 numbers from Theo's.

Who is Theo?

Jesper Ödemark [21010135] · Mon, 28 Sep 2009 10:02:29 +0200

Who is Theo?

The man behind the Chroma article among other texts on the site.

When looking at his profile I see he has no Chroma himself, "just" a Polaris. But still... he has double Wasps so I forgive him. :)

Go to next message in thread, October 2009

Chroma and Brochure/Article on eBay Germany

Chris Ryan [21030691] · Sun, 27 Sep 2009 15:49:26 -0700

The expensive Touched By Sound Chroma is up for auction again (see Chroma on Ebay Germany, August), price unchanged at €3.499 (I'll take two). Item #350256605786, no bids yet (big surprise), ends October 4.

A brochure (can't tell if it's German text) and scans of the Synthesizer von Gestern article for auction: item #140347437335, first bid €1,00, no bids yet, ends October 1. I actually bid on, and won, an earlier auction for this, but money transfer and shipping to Canada would have been so ludicrously expensive that the seller was kind enough to back out of the sale and send me scans. I will transcribe, translate, and post this article at some point in the future if I can negotiate permission from the author.

Introduction and pressure sensor

Frank McGing [21010198] · Wed, 30 Sep 2009 14:23:05 +0100

Hi everyone!

I've just taken delivery of Chroma 21010198, originally from the UK, but now here with me in Ireland. If any of you are on the Analogue Heaven list, it was the subject of the 'DHL lost my Chroma' thread! Anyway, it's here now, and I've cleaned most of the foam off, which had fused with the wood.

It's not powering up properly yet - all that happens is a bunch of leds come on, but there's nothing in either of the displays. Apparently it did power up recently and tuned 5 voices, but then died after 90 minutes of use, after which it powered up as it does now. I'm hoping it's just the PSU, as I have one of Luca's SPSU kits here, ready to install, hopefully later today.

Regarding the pressure sensor part of this mail, I read some of the archives and saw that there was some discussion about producing a poly pressure retrofit. I would be really interested in one of these! I have also been in touch with Franklin Eventoff of Sensitronics, originally about retrofitting pressure sensors to a different synth (which I then abandoned due to complexity), but more recently to see if he could produce sensors for the Chroma. And he can! He has a number of designs available 'off the shelf', he can also produce custom short manufacturing runs, and he is interested if we can get a group buy organised. Btw, he's the guy who manufactured the poly pressure sensors for the Prophet T8 back in 1983, so he knows what he's doing!

Any interest in making this happen? In terms of design/development, where is the pressure retrofit at now?

Jesper Ödemark [21010135] · Wed, 30 Sep 2009 15:58:42 +0200

Frank McGing skrev:

Hi everyone!

Hi!

I've just taken delivery of Chroma 21010198, originally from the UK, but

It's not in the registry yet - Chris will be delighted. :) A cousin of my unit then, they're in the same hundreds. Good luck with the foam cleaning...

It's not powering up properly yet - all that happens is a bunch of leds

I'm keeping my fingers crossed for the SPSU. I hope it'll solve the problems. It sure solved mine which was similar to what you describe.

Regarding the pressure sensor part of this mail, I read some of the [...] organised. Btw, he's the guy who manufactured the poly pressure sensors for the Prophet T8 back in 1983, so he knows what he's doing! Any interest in making this happen? In terms of design/development, where is the pressure retrofit at now?

I'm always interested unless the price is way off the budget.

Arun Majumdar [21030348+] · Wed, 30 Sep 2009 11:15:34 -0400

Hi,

A while back I looked into a pressure for the Chroma - then, I fell upon the wonderful Haken Continuum.

So I've now saved up enough to get one and hopefully will put my order through by next month..

This is a simply amazing piece of gear to connect with the Chroma I think :)

On the other hand, I would be willing to contribute to a group kit, however, recent changes in my work status have left me even more limited free time. At present I am trying to restore my Digital Keyboard's Synergy (and I finally got all the parts, some of which I had to order from Thailand!).

Let me know if someone wants to pickup the trail and I will be glad to contribute financially to a project.

John Simmons [21030454] · Wed, 30 Sep 2009 16:37:08 +0000

Hi,

I've never contributed to Chromatalk before so hello to everyone! I own a partially working Chroma and am on Luca's list for the next run of CC+ which i am eargerly awaiting:)

I would definitely be interested in contributing financially to make this happen, so please let me know if there are any developements.

Chris Borman [21030194+] · Wed, 30 Sep 2009 15:17:41 -0400

I talked to Frank/Senstronics in the past about some other ideas I had. I agree they were kind of pricey for development as Arun mentioned in last springs forum [see Ongoing R&D on Pressure Sensor, April 2009].

I've got a two piece pressure sensor and small interface board Kit designed and will have a few ready ship in about 3 weeks. It's a real simple design and easy install. The Kit has everything you need including instructions and replacement damper felt. The interface has adjustable sensitivity. The only caveat is I choose to forgo sensors on the first and last keys to keep the cost down. That saved $80 off the sensor cost. I just sold my 2nd Chroma (21030869) to fund development.

The price for the self install kit is $345. Let me know if any of you are interested. You can Paypal me (+$10 for shipping anywhere in the US, email for international) at: [email address removed] or send a check to: [postal address removed]. I'd like to make a production run of 10 at a time which is where the qty price breaks start at Digikey.

Frank McGing [21010198] · Wed, 30 Sep 2009 20:41:24 +0100

Hi Chris

This is great news! Count me in for a kit. Out of curiosity, is it possible to pay the extra $80 and have pressure sensors for all keys? I'd have no problem paying the extra amount. I'd imagine it may not be that straightforward though...

I'll happily pay up now - can you email me with the shipping cost to Ireland please?

Arun Majumdar [21030348+] · Wed, 30 Sep 2009 16:25:47 -0400

Hey Chris,

I work in Maryland and was in Annapolis last weekend!!! I will write you separately, and yes, count me in! Money is on its way :)

Chris Borman [21030194+] · Wed, 30 Sep 2009 16:34:03 -0400

The interface board mux hardware is there for all 64 sensors. Really it was just an acceptable performance trade off to keep the cost down. That's fine if you or anyone else wants to pay for the super deluxe 64 key model!

Just send an address and I'll get Shipping/Export cost through UPS International to you.

Arun Majumdar [21030348+] · Wed, 30 Sep 2009 16:42:00 -0400

Count me in for that extra also! Email my other account when you get the chance so I can respond with payment (and I can come and pick it up so no shipping is needed if that works out for you).

Go to next message in thread, October 2009

Almost all LEDs on...

Frank McGing [21010198] · Thu, 01 Oct 2009 06:25:29 +0100

My Chroma saga continues! I installed the SPSU kit in the past few hours, and was really hoping that the Chroma would come to life, but alas, it still powers up with almost all leds on (except for 4 which remain off) and doesn't get any further than that. I trimmed the SPSU to get 5.05V, and also tried disconnecting all cables to the Kenton MIDI pcb, which won't work anyway, because I haven't reconnected its power yet.

I read the section on diagnostics on the website, and it would seem that the CPU board is next up for investigation. Has anyone here been through this and may be able to offer any advice? I'd really appreciate any help!

Go to next message in thread, October 2009