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ChromaTalk Archives: August 2010

The Chroma Now Supports an External Alphanumeric Display

David Clarke [21030085++] · Sun, 01 Aug 2010 17:17:49 -0400

Following up to the ChromaTalk discussion in April of this year (Speaking of Chroma modifications...) we have created a firmware release to support an external display for the Rhodes Chroma/Rhodes Chroma Expander.

The hope is that easily understandable parameter data will allow a more fluid programming experience, and will make users more likely to modify existing patches, or to create new ones from scratch.

While there might eventually be a one-stop kit to add on the display, the initial addition of the capability is intended to be a 'do-it-yourself' project where interested users have the freedom to make up their own cables, decide their own display mounting locations and to choose their own display housings.

The specific details of this feature are provided on the Rhodes Chroma site (The Chroma CPU Plus (CC+): Alphanumeric Display).

Special thanks go to Tom Moravansky [21030431] who generously volunteered his time to review test versions of the firmware. Tom provided specific text for the Patch and Algorithm screens and also provided valuable input concerning the usability of the data.

As with all updates, the changes are intended to benefit Chroma users as a whole. We hope that all comments, questions or change requests will be shared here with the group for discussion.

Best regards,

Sandro Sfregola & David Clarke

Frank Hettlich [21030041+] · Mon, 02 Aug 2010 00:33:09 +0200

Dear Sandro Sfregola, David Clarke and Tom Moravansky,

you are simply GREAT! Doing this job in your spare time is more than anyone would expect.

Big thank you from Frank (owner of 2 nice Chromas, one of them being an original ARP)

Chris Borman [21030194+] · Sun, 01 Aug 2010 18:53:45 -0400

Wow...

Frank Hettlich [21030041+] · Mon, 02 Aug 2010 01:09:10 +0200

Just to clarify: A (hopefully well known) fact/story is that the first 50 Chromas were handmade by ARP employees before ARP was finally sold. One of which is in my hands others are still in existance, I am quite sure. Although Chris Ryan will know better for sure.

See First Fifty Chromas below.

Tom Moravansky [21030431] · Sun, 1 Aug 2010 21:27:12 -0400

A quick follow-up to the info.

I have been scouring the internet looking for a suitable enclosure for the LCD display. A company (Polycase) has something that is close, but it still needs a 'window' cut into the lid and different mounting posts. They can custom-make a case (basically modifying one of their stock items) to match the LCD specifications. However, I need to place a one time bulk order to get the best price savings. I don't know how others are thinking of mounting their display, but I just wanted to throw out that there is the possibility of a pre-made solution for reasonable money (under $10 each if we order 50).

I will try to get some pictures of a hacked up prototype version posted soon. There is also the possibility of a completely pre-made solution where the LCD is mounted in a case and cabled up ready for you to connect.

Finally - having a display with easy to read text and using it to build patches from scratch or modifying existing ones is a dream come true. It makes the Chroma orders of magnitude easier to use and it is a real joy to play again.

Jeffrey D. McEachin [21030073+] · Jeffrey D. McEachin

At 05:17 PM 8/1/2010 -0400, David Clarke wrote:

we have created a firmware release to support an external display for the Rhodes Chroma/Rhodes Chroma Expander.

Fantastic news! Well done, guys!

While there might eventually be a one-stop kit to add on the display, the initial addition of the capability is intended to be a 'do-it-yourself' project where interested users have the freedom to make up their own cables, decide their own display mounting locations and to choose their own display housings. (A picture of my display is attached).

I was hoping to use a red on black LCD to better fit with the Chroma's existing LED displays (see the attached picture). Unfortunately, Parallax doesn't appear to offer a choice of LCD colors. :(

It looks like the Parallax uses a standard LCD with a serial interface board tacked on the back. I'm tempted to buy a Parallax unit, desolder the green LCD from the Parallax, and replace it with this:

Jeffrey

PS please don't take my color preference as a criticism!

Luca Sasdelli [21010226] · Mon, 02 Aug 2010 10:00:59 +0200

Hi Jeffrey,

Crystalfontz makes several 20x4 serial dot-matrix displays: unfortunately I can't find red LED ones. There is only a 16x2 display unit with that colour.

David Gowin [21030611] · Tue, 3 Aug 2010 09:17:27 -0400

I've never heard of a more dedicated group as this. Many thanks for all the time and effort!

August B. Raring [21010148] · Tue, 3 Aug 2010 12:02:45 +0200

Rhodes Chroma User in Deutschland

Hallo liebe Chroma-Besitzer in Deutschland,

erwägt jemand von euch,seinen Chroma mit einem Display auszustatten? Leider habe ich keinen deutschen Händler ausfindig machen können,der das Parallax 27979 anbietet. Ein Kauf bei einem der US-Anbieter ist mit hohen Portokosten verbunden,allerdings ab 2Stck.portofrei. Hätte jemand Interesse an einem "group-buy"?

Könnte mir jemand ein Eprom mit der neuen Firmware,natürlich gegen angemessene Bezahlung,brennen?

August is asking if any other German Chroma users are considering the alphanumeric display, as he can't find a German dealer who offers the Parallax display mentioned above in the thread The Chroma Now Supports an External Alphanumeric Display. He's also asking whether someone could burn him a new EPROM with the latest CPU Plus firmware.

Christian Kleine [21030210] · Tue, 03 Aug 2010 16:29:46 +0200

Re: Rhodes Chroma User in Deutschland

Ich wäre interessiert - allerdings was würde das insgesamt kosten?

'I would be interested - but what would the total cost be?'

August B. Raring [21010148] · Tue, 3 Aug 2010 18:40:09 +0200

Re: Rhodes Chroma User in Deutschland

Hallo Christian,

ich habe jetzt doch noch einen deutschen Vertrieb für das parallax 27979 gefunden! Es sind die "Elektronikladen Partner" zu finden auf http://elmicro.com/de/contact.html Der Preis ist einer Pdf-Liste zu entnehmen und beträgt 37,90 € +MwSt. Leider gibt es nur Telef.Nr. der Läden,aber ich werde mal anfragen bzgl. Verfügbarkeit und Versandkosten und hier berichten!

August found a supplier and is contacting them regarding availability and shipping times.

Heinz Weierhorst [21010276] · Wed, 4 Aug 2010 18:24:53 +0200

Re: Rhodes Chroma User in Deutschland

Hello all.

Here another source for serial parallax displays in europe: Antratek Electronics. They offer it in three different colors: Green, yellow (you have to wait 1-2 weeks) and red (3-4 weeks).

David Clarke [21030085++] · Sat, 07 Aug 2010 13:44:41 -0400

While it isn't specifically mentioned in the write-up on the site, the display implementation tries to go beyond just a literal representation of parameter values on the parameter chart and also implements some of 'rules' in the documentation. For instance:

  • if Parameter 12 (Amplitude Modulation) is set to 12, 13, 14 or 15 (Delayed env), then if you attempt to modify Parameter 8 (Sweep Mode) there is an indication that regardless of what is stored in the patch, the mode is forced. E.g., the display will add-on:
    • Independent Key-Trig
    • Forced by Swp AmpMod
  • The Glide Rate text will know if the Glide Shape is Portamento or Glissando - and will update its output appropriately.
  • Parameter 34's values (Waveshape, width) differ depending on what the actual 'Waveshape' is, as selected by parameter 33.

It will be good to hear what people think when they try out the display capability.

Luca Sasdelli [21010226] · Sat, 07 Aug 2010 19:52:33 +0200

Excellent, David!

I should install the display asap: I'm quite impatient to test all its features, and to give some feedback. Is this "forcing" behavior already present in 214 release?

David Clarke [21030085++] · Sat, 07 Aug 2010 14:17:18 -0400

... Is this "forcing" behavior already present in 214 release?

Luca - in terms of functionality, the original Chroma code implemented the rules (like 'forcing'), but unless you were reading along in the programming manual as you're using the synth you wouldn't necessarily realize it (since the original display on the Chroma doesn't indicate this).

The current release of the firmware (e.g., the 214 release) contains the ability to display the noted points.

Luca Sasdelli [21010226] · Thu, 05 Aug 2010 19:43:44 +0200

Re: Rhodes Chroma User in Deutschland

Hi Heinz,

on mentioned website I can't find out infos about the red one. Is it a red-background or a red-character? (it should be red-character to integrate with Chroma displays I think...) How to specify the required colour?

I think that, as Chroma user group, we can ask the distributor for a special pricing on quantity supply, and to proceed as per usual subscriptions (i.e. one collects orders and payments etc).

P.S.: do you remember my NE5532 OAs on EQ board self-oscillation problem? The ceramic capacitors across pins 4 ad 8 didn't solve it, while by replacing the OAs with OPA2134s runs stable (and hopefully sounds better). Power supply on EQ board was improved with new elect capacitors and 2x22uF tantalum ones, other than the four ceramic caps as per above. Just to update.

Heinz Weierhorst [21010276] · Thu, 5 Aug 2010 21:54:44 +0200

Re: Rhodes Chroma User in Deutschland

Hi Luca.

Where the price is shown there's a green trafficlight. Hold the mouse cursor on that light and it will show the different colours available. In dutch of course: groen = green, geel = yellow, rood = red. I assume the backlight is red and the characters are black a the green one does. What I am wondering about is that parallax itself only offers green displays. Next the NE5532 problem. May its the brand. I only have Philips (Signetics) amps. Actually I use OPA 2134 too but with additional 0805 size 100nFceramic caps from pin 8 and 4 to output ground on each. Also replaced the 10uF with solid state tantalum. Does it sound better? I don't really know. May be it's a little bit less noisy.

August B. Raring [21010148] · Thu, 5 Aug 2010 22:15:32 +0200

Re: Rhodes Chroma User in Deutschland

Hallo Heinz, gemeint ist die "levertijd" (Lieferzeit)!!!

Translation: 'Meaning the delivery.'

Heinz Weierhorst [21010276] · Fri, 6 Aug 2010 13:09:06 +0200

Re: Rhodes Chroma User in Deutschland

Hallo August.

Vielen Dank für die Korrektur. Du hast recht.

'Thanks for the correction. You're right.'

Luca Sasdelli [21010226] · Thu, 19 Aug 2010 13:23:37 +0200

Display Installation

Hi all,

I'm not sure being the first in installing the display on CC+, but anyway I'd like to report that it works perfectly. The connection is made by re-using a 3-wires cable, directly soldered into the DB-15 plug; the display unit isn't boxed yet, so I'll try some solutions, putting it somewhere around and seeking the best location for viewing. A vague idea is to make a box with display on the front and MIDI connectors at the back or by side, having therefore only one cable coming from the Chroma; although the components aren't that deep, it should have enough stability to avoid displacement due to MIDI cables movements. I'll see...

A small note to other users: the display backlight switches on with a dedicated instruction and not with power; therefore, by simply powering on the display unit it doesn't illuminate (I was worrying my unit being faulty). The init string from CC+ 214 does the proper job.

I've bought the UART from RS Components, part no. 6865917. Again, great work guys!

Jesper Ödemark [21010135] · Thu, 19 Aug 2010 13:29:21 +0200

Re: Display Installation

Luca Sasdelli skrev:

coming from the Chroma; although the components aren't that deep, it should have enough stability to avoid displacement due to MIDI cables movements. I'll see...

Great news Luca, thanks!

If not sturdy enough, I see the perfect use for the original transformer here. The ultimate weight to keep things in place. :)

Luca Sasdelli [21010226] · Thu, 19 Aug 2010 13:44:52 +0200

Re: Display Installation

Great idea, Jesper! :)

A tiny question about the display: I see that keyboard tracking as control is reported as "Glide", thus making me a bit confused with Glide/Portamento parameters as shown in MIDI map. Is it a mistake or there is some reason for writing "Glide" instead of "Track" or "K-flw"?

Tom Moravansky [21030431] · Thu, 19 Aug 2010 08:34:26 -0400

Re: Display Installation

I'll get some pictures of my display in a case on-line Saturday evening.

I decided to run the wire from under the top lid and have the display case sitting just above the parameter buttons (just above the sweep and envelope params for example). I left the original CC+ MIDI connection in the back and ran a thin cable form J7 to the display.

Chris Smalt [21010280+] · Thu, 19 Aug 2010 15:10:31 +0200

Re: Display Installation

A tiny question about the display: I see that keyboard tracking as control is reported as "Glide", thus making me a bit confused with Glide/Portamento parameters as shown in MIDI map. Is it a mistake or there is some reason for writing "Glide" instead of "Track" or "K-flw"?

On the Chroma, glide has always been the name for keyboard tracking as modulation source. And if I recall correctly, you can choose between glide A and B, and the modulation signal actually responds to the two parameters in the glide section (rate and continuous/chromatic).

Luca Sasdelli [21010226] · Fri, 20 Aug 2010 17:35:49 +0200

Display - a wish

Hi all,

the new alpha display, being a totally programmable interface with the Chroma CPU, could be a near infinite source of informations. The one I guess could be nice is to use it as a sort of debug in troubleshooting failed autotunes; at the power-up and subsequent autotune, should a board fail, it could almost show which of the four tests failed (2xVCO, 2xVCF) thus narrowing the seek of the failure. I don't know the Chroma code, so I ignore if there are some more points to record during the autotune, to be notified on display as an help.

Uhm... perhaps I'm a bit influenced by a Chroma under repair with five failed DVBs <g>, but I think this should speed up the job anyway.

Tom Moravansky [21030431] · Sun, 22 Aug 2010 08:09:33 -0400

My Chroma display pix

here's the Chroma+display still on the workbench (still need to do overall cleanup and then tie down all cables before final reassembly).

(the display reflected some camera flash in the closeup)

Heinz Weierhorst [21010276] · Sun, 22 Aug 2010 18:18:22 +0200

displays

Hi all.

Another source for displays: Serial LCD Kit LCD #117 (formerly LCD #107) with Variable LED Backlight

The best is, he offers a pic controller for serial to parallel so that there are more choices to select a display of your wishes i.e. different colour/size .

David Clarke [21030085++] · Sun, 22 Aug 2010 13:44:49 -0400

Re: displays

All - just a reminder regarding displays (in terms of support for the CC+ Alphanumeric Display capability):

The CC+ needs to be aware of how to put the display into a known-mode, and expects to know how to position the display to the start of the screen.

Actions like turning off a 'blinking cursor', turning on the backlight, positioning the cursor, etc. tend to require different commands on different display controllers. As well, different displays have different requirements for the amount of time taken to service commands.

What this means is that while the basic text output from the CC+ is generic, the control-codes for the displays generally are not.

The control codes embedded in the current CC+ firmware are specific to the Parallax 27979.

If we decide that there are other displays that we want to support, then we would need to add specific startup code for those (if they didn't happen to specifically matches those of the Parallax 27979).

Because each display may have unique control commands, we would want to agree (as a group) on specifically which displays make sense.

Another consideration when evaluating display choices is one of power. The Parallax display is spec'd to take about 80 mA with the backlight on (20mA with the backlight off), which won't be much of a drain on the power supply - whether that is a replacement Chroma power supply, or the original supply.

Some displays may not be quite as gentle on the power supply - such as the 245mA 'typical' requirement of the Newhaven 4x20 line serial LCD display [PDF].

David Clarke [21030085++] · Sun, 22 Aug 2010 14:29:25 -0400

Re: Display - a wish

All - as has been discussed in the past, the applicability of CC+ features are really determined by us (the CC+ users, and would-be CC+ users).

Is this something which would be generally desired?

Side Notes:

As outlined in the tuning description, there are distinct set of steps performed to tune a channel.

The 10 individual tuning steps are below:

  1. Oscillator scale factor high end measurement
  2. Oscillator scale factor low end measurement
  3. Oscillator scale factor computation
  4. Oscillator offset measurement
  5. Oscillator offset computation
  6. Filter scale factor high end measurement
  7. Filter scale factor low end measurement
  8. Filter scale factor computation
  9. Filter offset measurement
  10. Filter offset computation

These steps are done in order, and (for a 'normal' tune) you only go to the 'next' step if the last step passed. For instance, if the oscillator scale fails on a channel, the filter scale is not attempted.

What this means is the code will detect the first bad thing which occurred on a channel. Therefore the error output only indicates what was detected to fail. It doesn't imply that other items later in the tuning process might not also have problems. The exception to this is that if the request was to ignore failures (e.g., Set Split 31) all 10 steps are attempted, even if failures are seen. In that case, up to 10 failures per channel could result.

So - a display could potentially identify that channel X didn't pass the 'pitch' autotune - but it wouldn't tell you 'why' it failed (e.g., it wouldn't tell you if the oscillator wasn't running, was running fast, if the wave shape setting didn't get set, filter setting wasn't activated, etc.).

Given that the user doesn't have any real control over the operation of the channel board and if an error is detected the operation of the board will likely still need to be reviewed for proper operation - would additional failure information (beyond the "Err  n" indication in the small LED display) have any useful benefit?

xref: Voice Board Test Controller

Luca Sasdelli [21010226] · Mon, 23 Aug 2010 03:57:29 +0200

Re: Display - a wish

Il 22/08/2010 20:29, David Clarke ha scritto:

The exception to this is that if the request was to ignore failures (e.g., Set Split 31) all 10 steps are attempted, even if failures are seen. In that case, up to 10 failures per channel could result.

This one could be the truly DVB diagnostic routine, where additional failure infos are useful.

So - a display could potentially identify that channel X didn't pass the 'pitch' autotune - but it wouldn't tell you 'why' it failed (e.g., it wouldn't tell you if the oscillator wasn't running, was running fast, if the wave shape setting didn't get set, filter setting wasn't activated, etc.).

Yes, this is true, but in respect with a generally "bad" DVB, a 'pitch' tuning failure helps in investigate within VCO hardware and relevant S&H portion, skipping the rest; a scope obviously can show clear steady waveforms (e.g. by looking at Z10/Z14 outputs) but not during the autotune routine: should a VCF fail when in self oscillation, this is hard to diagnose with measures. Almost, this by my own experience... :)

Given that the user doesn't have any real control over the operation of the channel board and if an error is detected the operation of the board will likely still need to be reviewed for proper operation - would additional failure information (beyond the "Err n" indication in the small LED display) have any useful benefit?

Of course this wouldn't be that useful to user (the autotune puts failed boards off mainly to allow him/her to perform anyway), while [SET SPLIT][31] is a specific tech routine, that IMHO could be greatly improved in diagnosing problems with the help of some display readings.

This is only my suggestion, hoping it could be useful to other users as well.

See New display, September 2010

First Fifty Chromas

Chris Ryan [21030691] · Sun, 1 Aug 2010 16:39:41 -0700

On 2010-08-01, at 4:09 PM, Frank Hettlich wrote:

Just to clarify: A (hopefully well known) fact/story is that the first 50 Chromas were handmade by ARP employees before ARP was finally sold. One of which is in my hands others are still in existance, I am quite sure. Although Chris Ryan will know better for sure.

See for instance the late Phil Dodds' comments on the first fifty Chromas produced. It's less clear precisely which instruments these were; I think we've all assumed that, roughly, 0001 through 0050 in the 2103 model range would have been the instruments in question, which would include your 21030041, Frank. Field Change Notice FCN2-001 hints that 0011 through 0060 may represent these fifty instruments, and indeed we don't have any 21030001 through 20130010 (or 21030011, for that matter) in the registry, Mark Smith's 2103-PT-002 being something of an exception. Serial numbers of less than 0050 in the 2101, 2102, and 2104 range would seem not to have been hand built; there are numerous overlaps in the last four digits of the serial numbers between models.

As far as obvious signs of these "special" Chromas, there are the ARP voice boards, which Frank, you indicated your instrument has. Of course, these can be swapped, so it's possible that some later instruments now have at least a few ARP boards. There's also been some indication that the first fifty instruments were the ones that had Poly/Mono rather than Footswitch Mode for parameter 2; had no vents on the top panel; had a discoloured or mismatched last key on the keyboard; and had different slider caps. At least one Chroma has been spotted sporting "ARP CHROMA" lettered above the keyboard (see Chroma stuff on eBay, October 2002), but this could have been added by an enthusiast.

Joe Porter [21030058] · Sun, 8 Aug 2010 19:58:41 +0000

Mmm. I wonder if mine is one of those (21030058). Has the mismatched key top and bottom note, and nearly all the boards are ARP ones (voiceboards and horizontal boards, except EQ, PSU & CPU which I changed when I got it). The top panel was replaced when I bought it though so couldn't say about the Poly/Mono parameter though.

Robb Witt · Mon, 9 Aug 2010 08:23:29 -0700

All –

Actually the first 50 were made by Fender employees at our Woburn Mass facility. It's true that all of us were "ex-arp folk", but Arp had gone bust months before and Phil had managed to sell us to CBS, who stuck us in the Fender org…. We would never have had the funds to produce 50 units as we'd been in Chapter 11 (then 7) at Arp for awhile. Fortunately CBS had some more change available.

That said, of course we used the board layout art etc. that was already available..

Details..details…

Tom Klepacki [21030025] · Mon, 09 Aug 2010 13:26:54 -0400

Hi Robb,

Can I have my 'ARP' front panel badge back? I bought my #25 Chroma with the 'ARP' badge, but it was replaced with a 'Rhodes' badge when I went to Woburn for servicing. Maybe you still have it?

>smile<

Robb Witt · Tue, 10 Aug 2010 12:43:18 -0700

Tom –

As it happens I DO have a couple of the chrome faced Rhodes badges kicking around in the bottom of a tool box somewhere. Weren't the ARP logos screened on the metal faceplate? Or are you talking about the oval brass ones? (That actually would be cool to have). My current ARP memorabilia is limited to a much worn baseball cap, and a full set of every version of the EP-16 piano membrane switches that were ever made. This is an embarrassingly large number of revisions, which we finally abandoned only when Tony Williams [see Philip Dodds/Tony Williams Interview] came up with the metal leaf switch replacements. My first object lesson in shotgun engineering. (Hey!! Let's try THIS!!) Yipes!

Jack Colburne · Tue, 10 Aug 2010 16:19:53 -0400

I think one of mine was one of the "pre-50, 50 Chromas". That mysterious 50 that were made before the original 50 were made in Woburn. Made of wood, twist-ties, and wires and its got all kinds of clips and stuff holding the keys on. and I think the "ARP" lettering above the keyboard is painted in... looks like, white-out.
...
...
ok.. i'm kidding.
:P

JLCooper ChromaFace on eBay

Chris Ryan [21030691] · Mon, 2 Aug 2010 18:37:40 -0700

Item #150475318430, ends August 9, starting bid £99.00, no bids yet. Sold from the UK. From the description: "The case has various marks & 2 of the screws that hold on the base are missing. Digital Ribbon Cable; Downloaded copy of the manual; new AC Adapter to provide 9v - only if you live in UK (the adapter has integral UK plug and is very heavy so it is not very practical to ship outside UK, so if you are outside the UK the adapter is not included and you must obtain a 9v supply yourself)."

There's some info about the ChromaFace available on the site, including the manual (which is included in printed form with the auction) and schematic.

Pictures from the auction:

Chris Ryan [21030691] · Sat, 14 Aug 2010 10:35:44 -0700

Sold for £99.00.

Just about potentiometers

Luca Sasdelli [21010226] · Thu, 05 Aug 2010 20:11:06 +0200

MIDI analog encoder for up to 96 pots

"This mini electronic board is a standalone controller for 32 potentiometers or analog inputs. It converts knob movement or voltage into MIDI. And it is expandable thanks to scanner input typical to all boards available here. You can connect numeric keypad for setting up all the features, or any of the keyboard scanners and use it as bot - note inputs, and numeric entry. You can also add a selection of potentiometer scanners in chain to get up to 96 MIDI controller knobs."

Well... I've bought an used Behringer BCR2000 for 80 euros, that's the total cost of POT32 and POT32X (expansion board to manage 64 analog inputs), but should one create a trimbox, even with the new display... :)

Michael Salmon [21030155] · Sun, 8 Aug 2010 11:57:25 -0700

there are lots of cool midi diy kits out there these days which would really make a lot of creative ideas possible. has anyone taken a look at the following and thought about "the ideal user interface" for the chroma? in other words maybe a mix of pots, buttons, sliders, x-way switches, etc in a compact style.

Livid Instruments Builder - $189 - "64 analog inputs, 179 Buttons, and 48 LEDs. "

Doepfer USB64 - 145 EU ($190) - 64 inputs, controls leds too (here's some examples built with this kit.)

Both kits have the buttons, etc all separate but still it makes me really interested. If there were a way to build something that fit right on the front of the synth over the 0-50 buttons it would be amazing.

Please remove for now

Ben Schwendener · Sun, 8 Aug 2010 16:05:05 -0400

I'll be back later!

Chris Ryan [21030691] · Sun, 8 Aug 2010 13:10:31 -0700

As a reminder to all, subscription management is available via the URL in the footer of list emails. [Or via the ChromaTalk page.]

Re: Error 45

Go to previous message in thread, June 2010.

Patrik Gudmundsäter [21010240] · Wed, 11 Aug 2010 20:06:25 +0200

Finally all 8 voice cards work perfektly, thanks to my technician Mr Sjöstrand!

Advice on keeping Chroma

Thomas Story [21030352] · Thu, 12 Aug 2010 13:43:19 -0700

Hello everyone ~ I'm toying with the idea of trading in my Chroma for a Prophet 5 3.3, no midi. My Chroma is pretty nice, upgraded power supply, CPU+, everything works except for some slight flakiness on one of the boards that can usually be rectified by swapping it with another one.

I've always lusted after a Prophet 5. There's someone selling one locally for 2800 (seems high? maybe not) no midi, but would also entertain trades. I love the keyboard on the Chroma, and if someone came up with a knob box that sat on top of the program 1-50 keys, I'd probably be more inclined to want to keep it (and knowing the way this group has been, I wouldn't be surprised if someone had one in the works!) - I have a BCF-2000 for it, but I really want the instant nature of something like a Prophet 5.

What are the downsides you see to this swap? I'm not convinced either way yet and would love some input. I do love the playability of the Chroma's keyboard, major plus. The membrane buttons, not so much.

Thanks for any and all advice.

Marais · Thu, 12 Aug 2010 17:03:46 -0400

Chroma has WAY more personality and depth then the Prophet 5 IMHO, especially a Rev 3.3.

The voice board should be easily fixable with a experienced tech.

BTW, do we see more board issues now with the upgraded psu's than originals ?

YMMV, M
Coming Late 2010: Chroma Enabler Patch Bank 101

Luca Sasdelli [21010226] · Thu, 12 Aug 2010 23:22:53 +0200

Several years ago I've swapped my Prophet 5 rev.2 with the Chroma I currently own. I did some mods on my Prophet to make it more stable (multi-turn tuning trimmers, better IC sockets, 2% capacitors within VCF circuitry and so on), it did in effect very well, but IMHO the sound of the Chroma, and its flexibility (the Prophet has only one sound structure) is far better.

Just in case, I can suggest to seek for a Prophet T8, still with wooden keyboard and polyphonic aftertouch, and similar audio structure as the P5. But the T8 is quite rare and expensive.

Paul DeRocco [21030230] · Thu, 12 Aug 2010 14:25:16 -0700

I'm about as biased as one can get, I suppose, but I wouldn't give up touch sensitivity and eight-note polyphony just to have a more convenient programming interface. I'd program the damn thing with 1's and 0's if I had to.

Luca Sasdelli [21010226] · Thu, 12 Aug 2010 23:29:18 +0200

Board issues with SPSU? I don't have any feedback about this. For sure, by replacing the original PSU with any other newer one, the reference voltage does change a little, so it has, as per recommendations on Chroma site, to be adjusted, as well as the I/O board and each voice board.

To summarize the adjustments:

  1. +5V Analog on SPSU PCB: adjust to read exactly +5.05V between regulator heatsink and ground
  2. I/O board: adjust the board trimmer to read minimum voltage between the two test points on same board
  3. Dual Voice Cards: adjust them as per on Chroma site (unreachable right now, so I can't point the right link)

David Clarke [21030085++] · Thu, 12 Aug 2010 19:41:32 -0400

... I'm toying with the idea of trading in my Chroma for a Prophet 5 3.3, no midi...

Tom - if you've not had a Prophet-5 before I'd suggest seeing if you can borrow one for a while, to play with it and see how it grows on you.

I know the first time I played one I was actually quite a bit disappointed - perhaps because my expectations were really high.

Over time I've come to enjoy it a lot - but as much I love my P-5 (Rev 1, w/MIDI) I find I gravitate back to the Chroma unless I'm looking for very 'synthy' sounding patches.

If you use the Chroma as more than one instrument via MIDI - then that is something you'd lose with the Prophet. As well, the keyboard on the P-5 really doesn't compare to the Chroma.

To me, $2800 is probably the going rate for the keyboard - but it would be high (for me), especially if had to add on MIDI on top of that (I'm a big user of MIDI.)

I think if I was going to shell out over $2k and wanted something Sequential-like (and couldn't find a T8) I might try out the Prophet '08 PE.

... What are the downsides you see to this swap?

I think the biggest down-side might be if you changed your mind after-the-fact (e.g., wanted the Chroma back after you've had the Prophet for a while). As the prices don't change that much, I think you'd end up with a lot less $$ in your pocket (sort of like trying to buy and sell a house in the same housing market.)

All that having been said - if it you a choice at all, I'd suggest having both a Chroma _and_ a P5. ;-)

Just my (biased) $0.02.

Matrix [21030220] · Thu, 12 Aug 2010 16:49:28 -0700

One thing to strongly consider is that Prophet-5s come up way more often than Chromas. Personally, I'd keep the Chroma and save up for a Prophet-5. If I needed the cash later, I'd sell when I needed to. I have both. The Prophet-5 feels more accessible, but the Chroma feels like it's on another level. The keyboard and velocity sensitivity makes the Chroma much more intimate. I couldn't sell either unless I absolutely had to. I love them both.

Jack Colburne [21030142+] · Thu, 12 Aug 2010 20:24:07 -0400

Tom, I think there are some questions to ask yourself...

What exactly do you want a synthesizer for?.. Meaning, what role does it play in your music/audio world?

Do you purposefully program patches, or spontaneously play with the sliders and knobs? (The Chroma lends itself well to purposeful, goal oriented programming rather than "grab the knobs and tweak" kind of playing... and, though you can do both types with either, the Prophet is clearly easier to "play" with)

What kinds of sounds do you prefer...meaning, what texture or character do you prefer, if any? (To me, a Prophet has a very particular kind of sound. As would a MemoryMoog, or CS-80... it is good to listen to and play with the Prophet before you choose. The PolyMod section of the Prophet is very powerful and fast way to get really cool unique sounds and effects. The Chroma's voice architecture is completely changeable and can create sounds the Prophet can't dream of.)

Do you want to be more portable? (A Prophet is far more portable than a Chroma. In fact it's far easier to get across the darned room)

And, it has to be said even if it is irrelevant; there is a element of recognition and fame associated with the Prophet that the Chroma never had.. tho it is certainly gaining, now.

I shouldn't judge, but $2800 is pretty expensive to me.

You are already aware of the velocity issues, the number of voices, and the keyboard itself.. (see first question above)

There are probably a dozen possible questions like these... But, in the end, it is your heart and desire that matter. Not ours. You have lusted for a Prophet for a long time. That makes a lot of input from us kinda irrelevant.

OK.. my real, personal, totally subjective answer?...

Put the Prophet on top of the Chroma... )))))

Chris Borman [21030194+] · Thu, 12 Aug 2010 20:25:07 -0400

The Chroma generates sound like no other and is really the reason we are all here discussing this (with Chris' help of course!). As far as any sonic upgrade to the Chroma, I want to try that OPAMP upgrade. I thought the demos really opened up the sound. If I were to get a P5, it would have to be a Rev 2 with the SSM audio Integrated Circuits and maybe Luca's mod's. The P5 3.x and Chroma both contain Curtis parts. A couple issues with the P5 Rev 2 and 3x is MIDI upgrades can be hard to find or not very flexible (No program dump/save, really? wtf?) I have seen a 2 with a good MIDI port. So, I think the instability of the 2 gives it's character...

Correct P5 sound or not, I would love a T8... I had an ARP 2600 I sold a few years ago. Yea, I kick myself daily for selling it but reasons were the potted pots were getting scratchy (hard to repair) and being a drummer, the 2600 is really a keyboard players performance machine once you get your sound patched up. Still wish I kept it.....

REALLY miss my Oberheim Xpander. That was the beast... - My fault there...

Dumped the Kurzweil K2000 but replaced it with a K2500/KDFX - Wow what sound and mod capability. Nice digital machine!

So, you already have one of THE greatest synthesizer instruments!

Yea, were out here thinking up the Knob solution for the masses… Hang in there.

Mal Meehan [21010182++] · Thu, 12 Aug 2010 21:13:19 -0400

Wow, sorry.... I can't believe anyone would want to swap a Chroma for a P5 (regardless of rev).

I have pretty much owned all the big vintage polysynths over the years and I have to say the Prophet 5 was my least favourite (I went through 2, both of which I sold on). It has a unique sound but I found it a little bit bland compared to the other synths I had at the time (too long to list)... perhaps in isolation it holds up better?

Yes, the sound creation is immediate with those knobs (compared to a Chroma or Matrix 12 etc) but it just doesn't have the organic nature to the sound that the Chroma has.. you don't feel connected to the sound when you play the P5's keys like you do on the Chroma, CS-80 or the SCi T8 (even though the T8's architecture isn't as complex as the P5, it still feels and sounds somehow better ), never owned a T8 as that was last on my vintage wish list before I decided to pack up collecting synths (what nonsense it is!).

If you are looking to do a swap, which better matches the quality of the Chroma I would suggest searching for an Obi Matrix12 for the similar complex architecture or an Elka Synthex, both of which will give you a huge analogue sound and real hand-on controls... again, I found the Matrix 12 to be too perfect and only hung on to mine for 3 years before I sold it and bought 2 more Chromas! (about the same time I bought an Alesis ION VA for gigging and discovered that the OBI filter in that unit could produce exactly the same tones that the Matrix produced... I did A/B tests and couldn't tell the difference because to me the Matrix was too good, it was too clean, too in tune... a VA could do a good result emulating one... if you get a chance to play an ION you'll see what I mean).

I think there have been some very good rational suggestions on this thread as to why the Chroma is far superior to a P5... the voice architecture, the velocity, and now aftertouch keyboard... the quality of the keyboard and the unit in general (although a P5 is quite nicely built too), the rarity of Chromas and the after market products that are now being built to help the Chroma last another 30-40 years.

If you have a craving for a P5 I would seriously look at the P08 and keep your Chroma... The Prophet 08 is a winner and has some of the old SCi Prophet quality to the sound.

Again, just my 2 cents

George Sarant [21030818] · Thu, 12 Aug 2010 21:14:34 -0400

Chroma vs. Prophet

I have both a Chroma and a Prophet 10 and I would say you get more wide-ranging sounds out of the Chroma. I also don't think that a Chroma and a Prophet 5 are an even trade. The Chroma is worth more.

Chris Borman [21030194+] · Thu, 12 Aug 2010 21:32:11 -0400

Chroma vs. Prophet

So what was it that ARP had over SCI? SCI was the first useable poly, but the ARP Chroma seemed to take it to another level. btw - The Xpander/M12 is THE last say in analog synthesis. MIDI, CV and all the direct knob or mod input's/MIDI outputs you could ever need. The Xpander I had seemed like what a P5 rev 2 would be. Unstable and VERY organic. Real nice pair with my Chroma.

RJ Krohn [21030455] · Thu, 12 Aug 2010 18:52:43 -0700

while i can't compare to the chroma, as my chroma is still at doorstop status, i thought i'd offer a few pros/cons of the P5.

pro: it sounds pretty awesome, and is really easy and fun to program. very immediate. stable, too. relatively easy to work on.

con: i find 5 voices to be very limiting.

i'd keep the chroma and kick the can on the prophet, personally. if your choice were to BUY the prophet, then i would say by all means, do it. good luck-rj

Ron Joseph [21030042+] · Fri, 13 Aug 2010 02:21:02 +0000

You could always buy a P10. :). Someone I know is looking to get rid of his.

Marais · Fri, 13 Aug 2010 01:01:34 -0400

Chroma vs. Prophet

I would say the Xpander has always been a great mate with the Chroma, that and the Yamaha FM synths.

Thomas Story [21030352] · Thu, 12 Aug 2010 22:39:30 -0700

Chroma vs. Prophet

OK - after all the great responses I've pretty much decided that I can't part with this thing. I have it fired up, running through Ableton Live, hooked up to my BCF-2000 and it just is so fantastic to play. The keyboard alone...

So, I'll keep my eyes peeled for a Prophet at some point in the future to complement...

IN the meantime, a couple of questions, what do you guys do to clean the membrane panel and keep it looking good? It's such a dust magnet and always looks grungy.

Has anyone written a map for the Novation remote zero? It sits nicely on top and would make a nice fit as a controller.

It seems like a knob box that incorporates the display, sits on top of or replaces the membrane panel (blasphemy?) and replaces the membrane switches and has knobs galore would be an amazing transformation...

An entirely new front panel, complete with new display, real push switches and knobs - fantasy? Looking forward to getting the aftertouch kit next and just continuing to play an amazing feeling keyboard.

Thanks for all the advice, kind of what I knew allready ; )

Luca Sasdelli [21010226] · Fri, 13 Aug 2010 08:34:25 +0200

Chroma vs. Prophet

Hi Tom,

about the set-top controller you mention, I'm currently designing (just for fun!) a small unit to embed knob programming, display and MIDI interface. I'm not very able in creating those stuff by hand: that high number of holes requires an industrial set to look properly, therefore I'm trying with Schaeffer Front Panel Designer software and service. The panel I'm working on right now is 1 meter wide and 10 cm high, holding 95 pots and the 20x4 character LCD, and its cost goes already beyond Euro 200,00- (front panel only!).

Moreover, there are the encoders to consider: 95 good quality pots, plus MIDI encoders (www.midi-hardware.com POT32 @ Euro 50,00, plus POT32X @ Euro 35,00), display and the rest of casing. Endless pots would be far better, but their cost should go too high.

With those costs, I guess the Mackie C4PRO should be the choice. Your Behringer BCF2000 isn't that suitable for the Chroma, because it has only 16 controllers per bank; IMHO the BCR2000 is far useable with 32 rotary controllers and the schema defined by Matt.

Jesper Ödemark [21010135] · Fri, 13 Aug 2010 09:44:29 +0200

... I'm toying with the idea of trading in my Chroma for a Prophet 5 3.3, no midi...

No, no... don't!

David Clarke skrev:

I know the first time I played one I was actually quite a bit disappointed - perhaps because my expectations were really high.

Same here... or even, I was _hugely_ disappointed. It really is a five voice pro-One without all the fun stuff of modulated mayhem of an analogue monosynth.

If you use the Chroma as more than one instrument via MIDI - then that is something you'd loose with the Prophet. As well, the keyboard on the P-5 really doesn't compare to the Chroma.

I couldn't agree more David. The keyboard of the P5's I've tested has been crappy indeed. Sure, the wood looks impressive, but underneath it's very much an off-the-shelf CEM-based synth. (I'm thinking of the v3 here.) I felt I managed to get that same sound from my VX-600 (and also gaining a lot of other good stuff the P5 don't have).

To me, $2800 is probably the going rate for the keyboard - but it would be high (for me), especially if had to add on MIDI on top of that (I'm a big user of MIDI.)

Over here in Europe I'd say the Chroma is worth at least 1½ times the money you pay for a P5.

I think the biggest down-side might be if you changed your mind after-the-fact (e.g., wanted the Chroma back after you've had the Prophet for a while). As the prices don't change that much, I think you'd end up with a lot less $$ in your pocket (sort of like trying to buy and sell a house in the same housing market.) All that having been said - if it you a choice at all, I'd suggest having both a Chroma _and_ a P5. ;-)

Amen! Try borrowing one. Maybe even trade for a few weeks with a friend or similar. Check it out and then decide. I bet your friend will be very pleased at least. ;)

Jesper Ödemark [21010135] · Fri, 13 Aug 2010 10:25:56 +0200

Chroma vs. Prophet

thomas story skrev:

IN the meantime, a couple of questions, what do you guys do to clean the membrane panel and keep it looking good? It's such a dust magnet and always looks grungy.

Armor All works on just about everything in the studio (except the end cheeks of the OSCar). Gives a nice finish and protects again stains and dust just slides off easily.

It seems like a knob box that incorporates the display, sits on top of or replaces the membrane panel (blasphemy?) and replaces the membrane switches and has knobs galore would be an amazing transformation...

I decided to have my knob box on a shelf just above (together with the Atari keyboard for the sequencer). The CC+ still make use of some button combinations (scratch pad etc) which makes it a bad idea to place something permanently on the button section imho.

An entirely new front panel, complete with new display, real push switches and knobs - fantasy? Looking forward to getting the aftertouch kit next and just continuing to play an amazing feeling keyboard.

I think it's too stylish to change.

Luca Sasdelli [21010226] · Fri, 13 Aug 2010 10:46:55 +0200

Chroma vs. Prophet

Il 13/08/2010 07:39, thomas story ha scritto:

It seems like a knob box that incorporates the display, sits on top of or replaces the membrane panel (blasphemy?) and replaces the membrane switches and has knobs galore would be an amazing transformation...

Back to costs, the attached draft is 312,76 EUR at Schaeffer (30% discount with 20 pcs), plus a realistic 300+ EUR for electronics; too much for my taste. (ok ok... I'm NOT a designer :-)) The .fpd file opens with Front Panel Designer.

An entirely new front panel, complete with new display, real push switches and knobs - fantasy? Looking forward to getting the aftertouch kit next and just continuing to play an amazing feeling keyboard.

Whew... an entirely new front panel, an entirely new Channer Motherboard... perhaps it would be easier to think to a totally new instrument; isn't it?

David Clarke [21030085++] · Fri, 13 Aug 2010 09:35:54 -0400

Back to costs, the attached draft is 312,76 EUR at Schaeffer (30% discount with 20 pcs), plus a realistic 300+ EUR for electronics; too much for my taste...

In the Winter of 2006 I figured I'd look to see how much it'd cost to make a new version of the one-off ChromaKnob.

The idea was to try to keep the size about the same, simplify the electronics and put it all on a circuit board, to see if it was actually viable to perhaps build a few for folks. It would also have a larger display (4 lines vs. two) to show more information.

In the end, the costs (and effort to put together at that time) made it so it didn't make sense for me to make more than just the one for me - but:

Two driving factors were the size of the panel, and whether or not it had to be engraved/plated.

In the end, I found it to be cheaper to make a smaller, blank panel out of less attractive raw materials - and then to put a colour 'control panel overlay' on top. In that way, I had much more flexibility with the graphics, the quantity of colours and cost.

Attached is the panel layout I used, which ended up being just under $100 in 2006 (but seems to price at just over $100 now).

The laminated and adhesive backed panel overlay was relatively cheap - about $37, including shipping. The overlay colours/text used is attached here as CHRMPN11.pdf.

The prototype panel, outside of its case, with knobs and overlay (and a less than well installed display), is shown here:

Once you add in the cost of the pots and the knobs and the electronics, the price does start to add up.

With the pre-made MIDI boards available today (which just needs the user to add knobs) - and the currently existing Alphanumeric Display capability with the CC+, it may not be too bad of a do-it-yourself project for someone to get their own panel, own overlay (with their desired graphics and layout), choice of knob colours - and then just use the Alpha Display and the commercial MIDI/knob/pot interfaces for the 'guts.'

Chris Borman [21030194+] · Fri, 13 Aug 2010 10:02:39 -0400

Chroma Knob Box

That is a very nice solution, but $800-$900 for a bank of buttons is a bit much for me as well. Maybe some folks might go for that!

My design is more conservative both electrically and physically by replicating and combining only the funtions of the existing PROG, PARAM, 50 right panel membrane buttons and the data slider into a single action per current A/B selection. Press the knob to select PROG 1-50. Spin the knob to modify PARAM 1-50.

Parts wise we're looking at 50 dual function low profile encoder/sw's with black knurled knobs. Two PCB's (approx 17" x 1/2") to mount and wire 25 encoders in the same physical arrangement as the right panel membrane button rows 1-25 and 26-50. Latched, mico LED's to indicate which button you last grabbed (Color?). All covered with a black plastic bezel on top to blend with the Chroma front panel, and peel & stick tape on the bottom to mount each sw assy directly below row 1-25 and row 26-50 front panel membrane buttons. Each sw array sits about 3/4" high with a discrete black ribbon cable to connect to a controller PCB mounted somewhere inside the Chroma.

The controller will have a single micro, DAC, some mux parts and ribbon cable or two to a desoldered part on the Chroma I/O board with a couple discrete wires for the Data slider. Not MIDI, the controller uses the existing front panel sw addressing of the Chroma. Function is transparent and parallel to the existing Chroma front panel. The Chroma functions 100% as it did before the mod. In my case, it would be more like 45%, which is where my Chroma is at right now...

Parts cost is down to $400-450 purchased in quantities of 10 kits. The 50 encoder/sw and knurled knobs is the main cost driver.

Anyway, That's my 40-45,000 cents worth... Working on it.

Chris Borman [21030194+] · Fri, 13 Aug 2010 10:11:56 -0400

Re: Chroma Knob Box

I forgot to add, it will work with the LCD stuff everyone has been discussing. Imagine to simply spin a knob and see textual descriptions of the PARAM scroll by. No more ambigious numbers! Maybe the CC+ folks can give us PROG text as well? Just need to figure out the best place to mount an LCD on the Front Panel. Might be easist to peel and stick a black low profile LCD case somewhere.

Luca Sasdelli [21010226] · Fri, 13 Aug 2010 18:01:47 +0200

Chroma vs. Prophet (Knob Box)

Ciao David,

it seems very good. BTW: where did you make the adhesive panel?

Matt Hillier [21010094+] · Fri, 13 Aug 2010 16:42:31 +0000

Chroma vs. Prophet

i strangely only have 2 analogue synths, a chroma and p5 3.3 and money wise i am not sure they are not an equal swap, depends alot on the country, p5's etc fetch 80% of there value in the us relative to the uk etc, sometimes not but the chroma is worth way more i feel and most definately much rarer. They are hard to find, p5 are not. P10? not sure.

Creatively the big issue is sliders / knobs and hopefully someone will address this in time for the chroma, i think if someone does do knob boxes for the chroma that match its hardware you could be looking at a rapid rise in value of everything chroma as thats whats stopped this becoming a very sought after synth.

Sound wise the chroma can't touch the p5 and the p5 can't touch the chroma, they are so different in tone, feel, depth of sound and where they sit in a mix and what eacy naturally does well, the chroma does have a much wider range of sounds, the p5 a deeper low end and depth sometimes and more silky tone sometimes.

The p5 is more fun for me, the chroma when i use it in sessions just has a vibe you cannot get elsewhere.

The big plus with the p5 is the knobs, its one of the best 'turn it on and tweak forever' synths i have ever used, the chroma isn't, with sounddiver the chroma is a great sound designer synth but it's a stop start process.

Which would i sell? an impossible choice. It would be easier to sell both!

Eric Inglebert [21030075] · Fri, 13 Aug 2010 21:37:14 +0200

The poly analog synths I currently own are Chroma, P5 Rev2, P5 Rev3, Matrix-12, Memorymoog LAMM, Synthex, Jupiter-8, OB8 and Andromeda. All equipped with Midi.

I would only trade a Chroma for:

  • Matrix-12 if I want more complexity, but I'd loose some punch, organics sound and versatility
  • Memorymoog LAMM if I want more organic and fat sound, perfect control in programming, but I'd loose versatility and playability
  • Synthex if I want perfect control in programming, to-die for analog chorus, but I'd loose fatness and playability
  • Jupiter-8 if I need a poly analog on stage every night and keep versatility, but I'd loose playability

Conclusion: I wouldn't trade the Chroma for any P5 on the planet, even my mid'ed Rev2. It's much too limited sound wise compared to a Chroma + CC+.

My 2 cents

Go to next message in thread, September 2010

Arun Majumdar [21030348] · Mon, 30 Aug 2010 09:45:20 -0400

Re: Chroma Knob Box

I just got back from a somewhat intensive work related project but now that I'm back, I can definitely see the value in a knob box: I can afford up to 1K on something like that as I use my Chroma and love its sound! Of course, if cost 500 then I would get two since I own two Chroma's.

Well, looks like I have some reading to catch up on this list!!!

My two cents worth is that maybe we should see how many folks would pay for this - count me in.

CPS Update and new stuff

Chris Borman [21030194+] · Thu, 12 Aug 2010 21:10:44 -0400

Finishing up the 2nd batch of Chroma Pressure Sensor kits this weekend. I have the major parts (fsr & PCB) for ten more, so let me know if anyone wants to be in the queue for this 3rd batch.

My next Chroma hardware offering to the group will be a pair of low profile 25 dual Encoder/Switch array strips that will peel and stick mount directly below both front panel membrane switch rows 1-25 and 26-50. Simply press the knob the select a program, or Spin the knob to change parameter value. All in real-time. No need to first press PARAM or PROG SELECT, or use the Data Slider. The Chroma membrane & slider will continue to function as normal. The encoders are detented and have heavy aluminum knurled knobs for a good solid feel. The hardest part of this install will be to clip out and desolder the pins of an IC and solder in a DIP socket on the I/O board.

Should work sweet with the current LCD display stuff I have been reading about. No more ambiguous numbers! You spin the knob and scroll though actual modulation descriptions! Just have to figure out where to mount the LCD. Our CC+ guys could add PROG names...

Jesper Ödemark [21010135] · Fri, 13 Aug 2010 09:49:37 +0200

Finishing up the 2nd batch of Chroma Pressure Sensor kits this weekend.

Nice! I almost forgot, having been buried in the repair of long lost shelved projects. (A Realton Variophon Gig with Keys for sale now!)

Chris Smalt [21010280+] · Fri, 13 Aug 2010 17:17:18 +0200

My next Chroma hardware offering to the group will be a pair of low profile 25 dual Encoder/Switch array strips that will peel and stick mount directly below both front panel membrane switch rows 1-25 and 26-50.

Very promising! As inobtrusive as they may be, wouldn't it be preferable to have them behind ( = above) the membrane switch rows? Cosmetically it would be odd to have them cover the text at the top, but if I picture them right, it would have an ergonomic advantage. That way, your hand wouldn't have to hover over two rows of encoders, while using the top switches.

Chris Borman [21030194+] · Fri, 13 Aug 2010 13:08:31 -0400

The two 25 encoder/sw arrays are completely separate. You could mount either one anywhere you like within ribbon cable distance to the controller. You would actually never have any reason to use the old program/parameter membrane switches.

You might not want to cover the existing text on the membrane.

Re: Mechanics

Go to previous message in thread, July 2010

Luca Sasdelli [21010226] · Mon, 16 Aug 2010 10:06:37 +0200

Hi all,

with the great help of Dan Levin, that purchased the hardware and sent to me from USA, now I've found some right screws to replace the outer ones of the Chroma, if weak or oxidated. Of course this is only my personal choice: McMaster sells 480.000 different items, therefore I guess there will be lots of even better choices!

All of them are Allen-head: I choosed this because are less prone than Phillips to damage, unfortunately with two different sizes: probably the merchant should have the right replacement to one of them, allowing the usage of only one Allen key for all.

The articles are as follows:

Line Quantity Item   Ships Unit Price Total Price
1 1 Pack 91253A153 Alloy Steel Flat Head Socket Cap Screw 6-32 Thread, 1" Length, Black, Packs of 25 after the holiday $10.11 $10.11
2 1 Pack 91255A153 Alloy Steel Button Head Socket Cap Screw 6-32 Thread, 1" Length, Packs of 50 after the holiday $9.61 $9.61
3 1 Pack 96006A253 Black Oxide 18-8 SS Socket Head Cap Screw 6-32 Thread, 3/8" Length, Packs of 50 (Same as 96006A555) after the holiday $5.16 $5.16
Merchandise $24.88

The flat-head screws are for the upper panel fixing, while the button-head ones for front panel holders; all of them fits fery well as per my personal taste (see attached image).

Unfortunately the merchant doesn't agree in exporting low quantities, because of USA paperwork complexity.

In Europe there are many Chromas, but that kind of screw thread isn't used; the screw boxes brings a Taiwan manufacturer label: I'll try to reach them and see if any distributor is available.

Joe Porter [21030058] · Mon, 16 Aug 2010 09:31:02 +0000

Like a lot of EU owners I'm sure, having those screws would be great. Thanks Luca.

Jesper Ödemark [21010135] · Mon, 16 Aug 2010 12:45:25 +0200

Luca Sasdelli skrev:

Hi all,

Hickup?

Luca's message came through to the list several times.

Luca Sasdelli [21010226] · Mon, 16 Aug 2010 12:52:05 +0200

Hi Jesper,

today I've encountered some issues between our mailserver and [the ChromaTalk list] ones; I hope they're solved now.

Sorry to the list for repeated messages.

Chris Smalt [21010280+] · Mon, 16 Aug 2010 14:00:31 +0200

Hickup?

Nah, it's like Plato said: "Twice and thrice over, as they say, good is it to repeat and review what is good."

Luca Sasdelli [21010226] · Mon, 16 Aug 2010 14:45:39 +0200

Or even "repetita iuvant" :) [repetition helps]

Chris Smalt [21010280+] · Mon, 16 Aug 2010 16:02:33 +0200

That's Latin for "I love techno music", right? :-)

Luca Sasdelli [21010226] · Mon, 16 Aug 2010 16:09:46 +0200

ROFL :)

BCR-2000 Chroma Issue

Thomas Story [21030352] · Mon, 16 Aug 2010 17:16:37 -0700

OK - situation is I have the BCR-2000 hooked up through both usb and Midi. Running through my Unitor8 for MIDI and hooked up to my Mac running Ableton Live 8.1 with USB.

Chroma is on CC+.

I have downloaded and transferred the preset that another list member made for the Chroma [see Chromatrol for Behringer B-Control], to the BCR through Sys-ex. I can see that it's transferred, the rez control goes to 7 on the dial. Correct.

The Chroma is not receiving control information, however the BCR can correctly control software plugins so I know it's working properly. I can see the midi information on the unitor being properly sent to the Chroma on the right midi channel. I can see it in LIVE that the information from the BCR is reaching the sequencer, and properly being sent. The Chroma however is not responding to control. I've even plugged it directly into the Chroma bypassing everything else and still no control.

WHAT am I missing? I had this working months ago, but for the life of me can not remember how, but it doesn't seem like I'm doing anything that different now.

Any advice?

Thanks kindly in advance!

Marais · Mon, 16 Aug 2010 22:50:27 -0400

Here are some notes I kept that got my BCR2000 (Chromatrol) to work with the CC+ Chroma. (tips courtesy of Dave Clarke [21030085++], Matt Thomas [21010021], and Randel Osborne [21030467]) .....

  • The CC+ interface has to be set to "CUST" (vs. "CULT") via Param 18 in config mode (Set Split 36)
  • And the mapping is default (e.g., select P20, and move the data slider to initialize the data). (set Split 36)
  • The other item to specially keep an eye on is that if the patch chosen (Parameter 1 on the Chroma) is the "16 channel mode", then all B parameters will be ignored by the Chroma (as all parameters are "A" parameters).
  • Also check [Set Split] [36], P6, This is the setting that decides whether Parameter Changes should be actioned or not. If this is set to "off", then neither the MIDI indicator light will flash for CC information nor will the values be accepted. You would want to have this set to "on"
  • You should see Midi in indicator activity when editing on the Behringer box.
  • Just a note to anyone doing this project, you will need to put the B Control into one of Global Midi Standalone Modes for it to work with the Chroma and to receive the Editor Profile sys ex file it seems.
  • Make sure the Behringer is set to the same Midi send channel as the Chroma CC+ and set to CC (Midi date type).

Luca Sasdelli [21010226] · Tue, 17 Aug 2010 09:09:31 +0200

Hi Tom,

just as a complementary help, I recommend BCmanager (Windows, sorry) as a setup software for BCR2000.

It is far better than the horrible Behringer software and it allows to configure each BCR' detail, e.g. encoder acceleration. It can also give you a very clear representation of the controller status.

Pay even attention to BCR2000 operating mode currently selected, and the MIDI cable(s) routing: see BCR manual page 8 onwards.

More BCR2000 "secrets."

2.14 upgrade - strange effect :)

Luca Sasdelli [21010226] · Tue, 17 Aug 2010 16:44:08 +0200

Hi all,

today I've upgraded the [CPU Plus/CC+] 2.13 firmware to 2.14, waiting for some display hardware to arrive. Just upon bootup, some leds flash all together in an odd way, and [NO LINK], [LINK UPPER] and [STORE] don't work at all; other buttons in left panel seems okay, and the whole right panel does work properly. No sound at all. I've reinstalled the previous and working Eprom, but the situation is still the same.

Therefore I'd like to know (David, Sandro or anybody else with CC+ knowledge) if a CC+ failure is to be suspected, or should I first investigate within key matrix logic. /SW7 on Z16 works okay by pressing mentioned buttons, therefore an electric fault shouldn't be.

Does the 2.1x firmware include some basic diagnostic routines (e.g. checksum)? Any suggestion before I'll replace Z16?

Many thanks

Luca Sasdelli [21010226] · Tue, 17 Aug 2010 18:12:37 +0200

Update: the same Eprom on another Chroma works fine. Therefore now I should check if the CC+ is okay, but I don't know how to do it :) Anyway, some 74LS244 are already on their way...

David Clarke [21030085++] · Tue, 17 Aug 2010 19:31:58 -0400

...today I've upgraded the 2.13 firmware to 2.14, waiting for some display hardware to arrive. Just upon bootup, some leds flash all together in an odd way, and [NO LINK], [LINK UPPER] and [STORE] don't work at all; other buttons in left panel seems okay, and the whole right panel does work properly. No sound at all...

Luca - based on this observation, it would be recommended you go into the config menu (Set Split-36) and to check the "P22" (panel mode) setting.

The changing of the 'no link' and 'link upper' functionality (as well as the lack of sound from the keyboard) would be consistent with the value set to "Pndr" (for an Expander) vs. "Chro" (for a Chroma).

Jesper Ödemark [21010135] · Wed, 18 Aug 2010 09:07:24 +0200

Luca Sasdelli skrev:

Update: the same Eprom on another Chroma works fine.

I just need to comment on that: Be glad you have another Chroma to test it in. :)

Luca Sasdelli [21010226] · Wed, 18 Aug 2010 09:59:04 +0200

Well, it was indeed a ...crossing-fingers task, because it's my one :-) The failed Chroma is under repair.

Luca Sasdelli [21010226] · Wed, 18 Aug 2010 10:02:39 +0200

Hi Dave,

you were absolutely right: the CC+ was into Expander mode. All firmware presets are corrupted, so I'm going to reinitialise them as per your instructions

Re: Enabler Finished

Go to previous message in thread, April 2010

Luca Sasdelli [21010226] · Tue, 17 Aug 2010 17:59:25 +0200

Hi Randel,

are the Enabler schematics being released to public? I'm interested mainly in the potentiometer encoding.

Randel Osborne [21030467] · Thu, 26 Aug 2010 10:50:19 -0400

Luca-

The enabler uses a mix of PC boards - one from another developer to do potentiometer-to-MIDI, and mine to do MIDI-to-display. I don't think that my schematics would be of much value.

Parameter Sticker for the Chroma Polaris?

Matrix [21030220] · Fri, 20 Aug 2010 10:45:37 -0700

Take a look at the top right of this Polaris.

Anyone know what that is?

John Leimseider [21030434++] · Fri, 20 Aug 2010 11:50:58 -0600

The Polaris II's had that chart on the right. There was also a version 2 power supply, but they were not exclusively in the Polaris II. Basically, they were the same machine… They could have mostly version 5 or version 9 (or version 9 star) software. Version 9 star has the better velocity table…

Matrix [21030220] · Fri, 20 Aug 2010 10:56:03 -0700

Interesting. Thanks! I never knew that.

David Gowin [21030611] · Fri, 20 Aug 2010 14:13:03 -0400

The Polaris II might have also had the Intel 80186 CPU, I believe the original had the 8086

Paul DeRocco [21030230] · Fri, 20 Aug 2010 11:23:09 -0700

The Polaris II might have also had the Intel 80186 CPU, I believe the original had the 8086

Nope. The only difference is that the early Polarises had an 6MHz 80186, until the 8MHz processor became available. There may also have been some variations in the amount of RAM, because the board supported either 2Kx8 or 8Kx8 chips.

Robb Witt · Fri, 20 Aug 2010 11:41:27 -0700

Pretty sure they all had 80186's from the start…. I recall we had some problems with heat as the chip ran hotter than the spec called for. At various times I think we experimented with gluing a variety of heat sinks directly to the processor body. Don't know if that made it into the final design or not.

David Gowin [21030611] · Fri, 20 Aug 2010 14:52:54 -0400

Hmm, cool, ok. I just remember going down to Fender and seeing a rep at Fender, was trying to run a Polaris user group newsletter and as a thank you, they gave me a new upgrade CPU for my existing Polaris.

Chris Ryan [21030691] · Fri, 20 Aug 2010 12:17:40 -0700

There are a few more pictures on the Polaris II (model 2123B) registry page. See also the thread Polaris Rev's from May 2003.

Still DVB not autotuning...

Luca Sasdelli [21010226] · Mon, 23 Aug 2010 19:52:35 +0200

Hello all,

I'm asking for some ideas to troubleshoot one.

The DVB I'm investigating on, after some IC changes to rewake it, has this behavior:

  • TP waveshape 50% duty cycle sharp
  • waveform on Z10, Z14 and Z17-1 is sharp and with same level of working DVBs
  • wave select work properly
  • if tuned with SetSplit31 it sounds perfectly in tune with the others
  • with max resonance, its VCFs sounds the same of working DVBs
  • all proportional controls (cutoff etc) does work fine on it

There are 1% correction metal film resistors in parallel with the thermal compensating ones. All connectors solderings have been unsoldered and re-done from clean. Swapped slot but same result.

Does anybody has some hints to do?

P.S.: excellent the SetSplit37 (voice allocation display): it helped me a lot!

Tom Moravansky [21030431] · Mon, 23 Aug 2010 14:05:01 -0400

I had a voicecard like that. I changed the CC+ board to insert the 2 second pause after boot up (and before the tune routine) and I do not have a problem with it passing tune. For some reason, the quick tuning of the standard Chroma did not give it enough time to stabilize, but the 2 second delay makes it work perfectly.

Heinz Weierhorst [21010276] · Mon, 23 Aug 2010 20:27:13 +0200

Hi Luca.

I've had that problem too. The trouble was that one OSC failed to tune but was very close to the working OSC. Playing over the keyboard shows he was not tracking right. The fault was a 4052 switch so that the computer could not "listen" to that OSC during Autotune. Have you changed the places for that DVB just to make sure it's not the CMB?

Luca Sasdelli [21010226] · Tue, 24 Aug 2010 08:28:48 +0200

Thanks Tom,

unfortunately on this Chroma the 2" delay doesn't change the status. Moreover, by invoking the auto-tune with the instrument already warmed up, still set the DVB off; the only way to have it playing is to use SetSplit31.

Heinz Weierhorst [21010276] · Tue, 24 Aug 2010 18:29:26 +0200

Hi Luca.

Is that DVB calibrated? Setting the charge pump current should be done at low frequencies. So choose a preset where both OSCs are set to square, bank 1 prog. 17 (wooden pop) for example. With edit A & B on set para 26 to "0". Next select transpose 1 octave down. Set para 3 to "4" (unisone). Make sure there are no frequency modulators i.e.by footpedal etc. Now play low "C" . That's the lowest note on the Chroma under normal conditions - about 16Hz. With a scope to TP1 and TP2 set charge pump trims to 50% duty cycle. When you have a scope with digital readout it's done in a fly.

Luca Sasdelli [21010226] · Tue, 24 Aug 2010 18:56:56 +0200

Hi Heinz,

yes, the DVB was calibrated. Unfortunately I don't own a scope with digital readout... but my ear is still good enough to recognize a 50% square wave with only odd harmonics :)

Anyway, the saga continues: a DVB fixed yesterday and one more today! Now are four playing DVBs and something is already listened. The timbre appears greatly improved using the Burr-Brown OPA2134 both in CMB and EQ board: more deep tones and more definition at same time.

A quirk: the EQ board didn't output nothing because R25 was *never* soldered at one side, thus leaving the instrument in a permanent muting. The owner told me that the instrument was never sold and has been kept all this years within the shop.

Impressive the number of replaced components till now... it's like if that Chroma got a lightning.

Heinz Weierhorst [21010276] · Tue, 24 Aug 2010 20:10:59 +0200

Hi Luca.

As I mentioned before the the charge pump current or as I call it "HiEnd trim" should be set a low frequencies. Set OSCs waveform to saw and look at Z10 pin 1 and 7 and adjust for a perfect (double frequency) saw. About the OPA2134 amps. I also noticed less noise. My Chroma is connected to a T.C. M350 and after that to Behringer 2030 Monitors. When I remove the Chroma from that chain noise stays the same (Chroma volume in middle position). In up postion the noise from the Chroma gets more dominant. I choose OPA2134 cause they are much faster and have low distortion.

August B. Raring [21010148] · Tue, 24 Aug 2010 21:43:33 +0200

Hello Luca,

Anyway, the saga continues: a DVB fixed yesterday and one more today!

For interest: What had to be fixed?

Luca Sasdelli [21010226] · Tue, 24 Aug 2010 22:53:16 +0200

Hi August,

indeed the causes are multiple. Originally this Chroma was totally out of order: wrong PSU voltages, no boot and of course totally mute. Gradually I've brought it at a working status, repairing I/O board (1 buffer), EQ board (1 VCA and 2 OAs) and Channel Motherboard (lots of logic ICs), and there was only one working DVB and another one destroyed by verdigris (there are a few pics in a previous mail of this).

Till now I've found several faulty CMOS switches (4051/52/53), some TL082 as S&H buffers with O/P shortened to one voltage, a couple of faulty CEM3360 (VCA), one faulty CEM3350 (VCF) and some data latches. All Z19, Z20 and Z25 have been replaced as per http://www.rhodeschroma.com/?id=diagnosisrepair#repairingfaultyvoiceboards

All ICs are mounted now on high-quality IC sockets (same type found on CC+). All desolderings have been done with vacuum desoldering station to minimize damages to the boards.

I find very useful for faultfinding:

  • SetSplit31 (tune all cards including faulty ones)
  • SetSplit39 (scratch patch: init all parameters to a known state)
  • SetSplit37 (show voice allocations)
  • check Z14 O/P (pins 1 & 7), then Z10 O/P (pins 1 & 7) with scope
  • check output switches (Z17 & Z18) for proper paths
  • check S&H buffers O/P for obviously wrong voltages
  • amp all the time connected to Chroma output

not strictly in this order.

Maybe I'll build four connector extender cables, to easily operate on DVBs and to reduce mechanical stress on CMB (if not introducing problems within timings).

August B. Raring [21010148] · Tue, 24 Aug 2010 23:09:07 +0200

Thank you very much for this detailed description, Luca! I think it will be very useful for my own repairing attempts,having also troubles with two of my DVBs.

Luca Sasdelli [21010226] · Thu, 26 Aug 2010 18:02:32 +0200

Ciao Heinz,

unfortunately even by following your instructions about DVB tuning didn't clear my issue. Now I've got two DVB with this failure: with SetSplit they're tuned, with good waveforms, but autotune fails. They're the latest on this terrific damaged Chroma: now it plays with 5 DVBs, while one is destroyed by verdigris.

Front Panel on eBay

Chris Ryan [21030691] · Tue, 24 Aug 2010 16:25:04 -0700

Item #250687444386, "buy it now" price of US$799.00, ends August 31. Edited description: "Auction includes one fully populated Chroma front panel with all circuit boards (EQ board, I/O board, computer board) and display. These are spare parts that were sold to me several years ago (2004ish) as working by someone I trust, but I never installed them to test so they are untested by me but believed to be functional. They have sat bubblewrapped and unmolested on a shelf since then and now I'm cleaning out the parts bench. I did swap out my Chroma's I/O board a few years ago when it was starting to have issues but the problem turned out to be with the power supply. My original I/O board is the one installed on this panel and is believed to be working since it was just fine before the power supply started going south. The CPU board is missing some ICs so that will obviously not work as-is. There are a few mounting screws (for mounting the PC boards to the standoffs) that are missing as they have been donated to my Chroma."

A few of the pictures from the auction:

Go to next message in thread, September 2010

Chromatrol

Marais · Fri, 27 Aug 2010 17:50:16 -0400

My Chromatrol project finished, minus getting a little spray glue in one or 2 knobs and on the template paper lol

David Hillel Wilson

Tom Hughes [21030251+] · Sun, 29 Aug 2010 15:43:31 -0400

I just saw the post on Matrix Synth that Dave Wilson passed away. I believe he developed a Chroma voice card troubleshooting device, is that correct?

Chris Ryan [21030691] · Sun, 29 Aug 2010 12:50:15 -0700

Yes. See Voice Board Test Controller.

Sad news.

Matrix [21030220] · Sun, 29 Aug 2010 13:36:50 -0700

You can also see talk about it at 3:27 in part 2 of the 3 part video in the post. Really sad about the news. I didn't know him personally but he was just one of those guys you liked knowing was out there.

Paul DeRocco [21030230] · Sun, 29 Aug 2010 13:56:02 -0700

I went to his "museum" once. He was a moderately interesting guy, who was certainly obsessed with synthesizers, but the museum consisted of piles and piles of old synths filling several rooms of his dark, dusty, ramshackle house. And I mean "filling"--he was quite the packrat.

He had a lot of pretty ordinary synths, but a fair number of valuable things, too, like an old ARP 2500 and a bunch of custom modules for it. Separating the wheat from the chaff, there could be some good stuff in there for a real museum, but I'd hate to be the guy to have to clean the place out and sort it all.

He didn't show me the tester, though, or even mention it, which seems odd.

Peter Forrest [21010096] · Sun, 29 Aug 2010 23:22:16 +0100

That is very sad news. David was eccentric, to put it mildly, and the collection was poorly organised and in many cases badly looked after, in a ramshackle, leaky building. But the bottom line was that he was extremely generous with his advice and help, and altogether an unselfish and decent person.

Rob Belcher [16330123] · Sun, 29 Aug 2010 23:30:35 +0100

very sad RIP dave