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ChromaTalk Archives: January 2010

Panel Colour Themes

Chris Ryan [21030691]

I've put together a page reviewing the design and origin of the "Halloween" and gold monotone instrument themes. See Panel Colour Themes. One thing that remains a bit hazy for me is the subsequent history of the Halloween-themed Chroma and Expander played by Herbie Hancock on Saturday Night Live. Are these the ones you have now, Mark?

Have a good 2010, everyone.

Mark Smith [2103-PT-002]

I have a Chroma made from early production parts. I was assembling it when the Halloween switches were being experimented with and I got a set. I have parted out the expander and sold the case to someone in CA. It had no serial number. I don't know how Herbie Hancock got his.

Ron Joseph [21030042+]

I finally have a better camera so I'll try and take a few better shots of the panels. A few minor points: The gold and Halloween overlays have FSW for parameter #2 just like the stock Chromas; the original panel from the first 50 Chromas have Poly/Mono for parameter #2 and the original blue/green color scheme. So all told there are 4 possible panels: 1st 50, stock, Halloween and gold. Also, you might like to point out that the Gold set is only an overlay with no membrane panel underneath it; it needs the same membrane panel as the Halloween Chroma. This is a problem as I'd have to disassemble a Halloween panel in order to use it or have a new membrane panel made (I'm leaning towards the later option)...Happy 2010 everyone.

Chris Ryan [21030691]

Thanks, Ron. I've added a couple of notes to the page to clarify. It would be great to have more pictures.

Robb Witt

All –

Regarding the color schemes on all panels manufactured before the original Woburn team departed Fender....

While it's generally true that there are probably 3 or 4 major "families" of color schemes, it's absolutely true that the number and variety of panels that could potentially exist out there is a bit larger. As the guy who made all of them, with the exception of the Blue production Polaris panels, and some later blue/green versions for the Chromas that were possibly made in Hoopeston, I can state with authority that we were constantly "tweaking" both the colors themselves as well as the color layouts. We'd mix up a batch of "earth toned" ink and print up a half dozen panels... and then the next week do a different run to see if Shykun liked it more. I also dimly recall doing a couple of "special runs" for people at the shop (Mark Smith I think, and maybe Mike Shea [no serial number]) That was the benefit of having a full blown production shop at the dev facility. In general I think the story is something like this:

  1. The original layout was done (I think) by Warren Ames, who also designed the switch panel underlays. The colors on these were probably derived from the colors Arp was using on the Quadra, at least that's the only blue/green color combination we used at Arp that I can think of. We probably made a minor adjustment or two to the panel labels before we went into pre-production. I'm pretty sure I manufactured the original display prototype that we used at Arp (all the original publicity photos), and am positive that I manufactured all the "first 50" panels, as well as those used for demos, in-house, spares, production, and the like. This is the layout that should, I think, be considered the standard "production" layout and color scheme. I am relatively sure that all panels using this scheme were manufactured at the Cummings Park R&D facility in Woburn that we set up when we exited Arp. The only reason I say "relatively" is that I heard a rumor years ago that after I left Fender (about the same time Phil, Bob Hartford, and a number of others left) the guys in Hoopeston decided to outsource making the panels for production. That may or may not have happened, I can't say.
  2. So-called "Halloween" units. (BTW, the first time I ever heard this term used was here. We never called them that at Fender, regardless of what Phil D. apparently reported). As has been noted elsewhere, we started fooling around with the Chroma color scheme while we were designing the Polaris in response to a request by John Shykun. After more or less settling on a color scheme for the Polaris, we decided we'd similarly "retrofit" the Chroma. So as Mark Smith has commented, the idea was to switch the Chroma production over to the new scheme when we released the Polaris. (I was gone by the time that finally happened, so can't tell the story on how/why those plans were changed, as they obviously were). Once we decided to do that we tried to "fix" a couple of other problems that folks had reported with the original layout. So that's the reason the position of the numbers in the parameter boxes was changed (moved up), and the descriptors changed from black on a colored ground to white on a black ground. (We'd been told, and duplicated via experiment, that under certain combinations of stagelighting the original labels more or less "vanished". That obviously made programming on the fly even harder that it normally was, and it was easy enough to fix...). With the new layout in hand, as well as a new switch layout underneath (again courtesy of Warren Ames), any number of variously colored "non-standard" panels were fabricated. My fairly faulty memory says that Mark Smith and I both had Chroma's with this color scheme, and I'm pretty sure I would have given any of the in-house tech's who asked (Mike Shea for example) a set. Then of course there were our in-house demo units (Chroma and Expander), as well as Herbie Hancock's units. We may also have sent some panels out to particularly "friendly" customers or shops. I'm not sure. I guess my point is that there could be a 3 or 4 more of these lurking around out there, as well as any number of replacement panels. (As for my old unit, which had no serial number... I'd love to know if it ever surfaced. I sold it in '91 to someone in Colorado I think. A much regretted action.)

As far as the gold-toned set goes; Mark Smith might recall that I made a special "gold and black" switch panel for the 82 key "Grand" version of the Arp electric piano that we had. (The case had a top that opened to a sort of faux Steinway look. Boy I'd love to know where that ended up!). I don't have a specific memory of doing the gold Chroma panels that Mark had, but it's obviously something we would have easily done in our spare time. This group should not be astonished if another one-off color scheme crawls out of the woodwork at some point either.

Anyway, that's what I know 'bout that!

Chris Ryan [21030691]

Thanks for the clarifications. A couple of notes on what you write:

... the idea was to switch the Chroma production over to the new scheme when we released the Polaris. (I was gone by the time that finally happened, so can't tell the story on how/why those plans were changed, as they obviously were).

Is this perhaps because production of the Chroma seems to have stopped (early 1984, I believe) before production of the Polaris really got going (it was reviewed in the December 1984 issue of Keyboard)?

(As for my old unit, which had no serial number... I'd love to know if it ever surfaced. I sold it in '91 to someone in Colorado I think. A much regretted action.)

See Earth-Tone Chroma Identified? from July of 2008. It seems that Leonardo Ascarrunz is likely the owner of your instrument (no serial number in the registry).

New Parameter Chart Update

Chris Ryan [21030691]

It's taken me ages to get back to this, but I've posted a new version of the redrawn parameter chart. I've made some revisions based on feedback from last March (see New Parameter Chart): most significantly, I've reversed the order of the parameter lists to correspond with the original chart. Exceptions are PATCH [1] and the modulation routings. I've also added a small legend for the colour coding: orange for stock Chroma, grey for parameters and functions for which an upgrade is required (pressure sensor, CPU Plus, Syntech MIDI). And there are a couple of other minor fixes.

Please let me know what you think, and if you have any more feedback. Also, when finalized, do you think the original version should live alongside this one, or should this "version 2" chart replace it?

Chris Smalt [21010280+]

Looks great. A tiny consistency thing: for parameter 50, it says "- Pedal 1" and "- Pedal 2", while in other occurences of reversed scaling, it says "-Deep", "Concert +4.5 Octaves" and "Concert -1 Octave" without a space after the minus.

Chris Ryan [21030691]

Fixed—thanks!

Dave Bradley [16330135]

I find the main pitch/cutoff param block listed between the rows confusing. It is laid out 0-3, 8, 10, 12, 14 in the top row, then 4-7, 9, 11, 13, 15 in the bottom.

In keeping with the other vertical columns layout approach, I would do something like this myself:

0 4 8 12
1 5 9 13
2 6 10 14
3 7 11 15

Then since the volume params block would no longer fit underneath, I would pull those back to the right above the volume block.

Dave Bradley [16330135]

Looking at the layout you set up again, I see why you laid it out that way - with outgoing arrows from the blocks pointing to the blocks they represent. But for me, this just confuses things. I'm sure others will feel differently.

Chris Ryan [21030691]

As this is the crux of the new design, I'd like to know what others think. I suppose a similar horizontally-oriented design is possible, but probably not as clear, and makes it more difficult to arrange the arrows to the destinations while probably still not completely addressing your concern about readability:

Dual pedal - leaf switch repair success

Frank McGing [21010198]

I believe that the leaf switches in the dual pedal assemblies have a tendency to break. I've just managed to replace one on my dual pedal using a common computer part. It's the spring section from a bracket that's used to mount a DVD/CD drive in an ATX case. It took a bit of drilling and cutting, but it fits very well, and appears to be strong enough to last for a long time.

I can post more details and some pics if anyone is interested.

Chris Ryan [21030691]

Yes please!

Frank McGing [21010198]

For anyone who may be interested, here are some pics to illustrate how I fixed my dual pedal leaf switch.

  1. The broken leaf switch

  1. The donor part (bracket used to mount a DVD/CD drive in an ATX computer case)

  1. Various parts (broken leaf switch, working leaf switch, and spring removed from bracket)

  1. New leaf switch shaped and cut to size

  1. Pedal fixed

The bracket spring is an excellent fit. The screw holes are already in the correct places and just need to be drilled out a bit. The length of the spring is also perfect (quite uncanny actually!) and just needs to be bent a little into the correct shape. The final step is to cut back the excess metal in order to fit the new leaf switch into the pedal switch assembly.

I have more pics of the process if anyone wants them, but this is already a sizeable email and I don't want to annoy list members with too many pics!

Paul DeRocco [21030230]

I'm not sure that a piece of a bracket will make a reliable long-lasting switch contact. However, if you Google "leaf switch" you may be able to find some actual switches that can be scavenged for replacement parts. For instance, I came up with this for starters in about 15 seconds.

Frank McGing [21010198]

That's a good point. If my solution doesn't work out, I'll definitely do as you suggest. I think it'll be fine though - the spring from the computer bracket is flexible and much stronger than the original leaf switch contact.

Paul DeRocco [21030230]

It's not just whether the leaf doesn't break, but whether the contacts are plated with something that doesn't go high-resistance when it oxidizes, and whether you get good wiping action to cut through pollution deposits.

Frank McGing [21010198]

Now there's an aspect I hadn't considered at all. Thanks for pointing this out!

Re: Knob Boxes

See Chroma Knob Boxes and sub-thread Knob Boxes, December 2009.

Matt Thomas [21010021]

I finally had some time again to caress the old lady in the studio yesterday and would like to add: No matter which solution you chose to edit with knobs, find one. :D

It's amazing to just reach for the cutoff, the release, the modulation depth or whatever. I even managed to sequence some 303-ish bassline on the Chroma and that felt odd, but fun indeed!

I finally got around to finishing my own long delayed Chroma knob box project - behold, the Chromatrol!!!

OK, it's just a Behringer B-Control with my own custom Chroma trim but I like it :) I'm going to send the BCR presets and the panel graphics to Chris for any other BCR users out there who might like to try it.

See Chromatrol, added to the site in February 2010, which includes presets and panel templates.

Dave Bradley [16330135]

That's beautiful! We need a closeup pic of just the knob box, please!

Mal Meehan [21010182++]

Yes... close up photo please...

That looks like the best solution ever - well done!!!

Thomas Story [21030352]

Yes please on the presets! Nice I just picked up a BCR2000 for next to nothing and have been excited to get it hooked up to the Chroma. They are cheap enough to dedicate to the Chroma alone. Nice job!

Jesper Ödemark [21010135]

Matt Thomas skrev:

I finally got around to finishing my own long delayed Chroma knob box project - behold, the Chromatrol!!!

Nice work! Similar to what I'm planning for the Drehbank. How did you do the print? Laminated colour print? Print on adhesive plastic?

OK, it's just a Behringer B-Control with my own custom Chroma trim but I like it :) I'm going to send the BCR presets and the panel graphics to Chris for any other BCR users out there who might like to try it.

...and there I got a reminder too. Damn, I need to fix the Drehbank settings on my old computer and upload those.

Marais

Anyone interested in making some of these up and reselling them ? Some of us are not DIY. : )

Michael Krewitsky [21030504+]

I can do this, I believe, with the correct input information...sounds very interesting and, of course, I want one myself... Let me know who's interested and let me see what is entailed....

Robb Witt

Way cool. I love the fact that you changed the graphic to put the nomenclature in white.

Matt Thomas [21010021]

Some of us are not DIY. : )

Trust me Marais, nor am I :)

Well a few of you asked for it, so here's the close-up of the Chromatrol. The front panel isn't as smeary and reflective as it looks in this pic but I now realize I should have used semi-gloss photo paper - cos that's all the front panel overlay is :) It's a thick-card gloss photo paper, cut out by me with scissors and stanley knife. Total cost about 20 pence. I designed the graphics in Photoshop, stealing liberally from Chris's website and parameter chart - thanks for doing all the hard work Chris :)

The wooden end cheeks were pretty simple to make, I simply unscrewed the BCR2000's plastic end cheeks, held one end against a piece of paper and then drew around it. That gave me the necessary minimum size, then I just drew a more angular/square shape around it that looked more like a Chroma end cheek. One of the nice coincidences is that the depth of the BCR and the depth of the Chroma's flat top panel were a pretty perfect match.

I cut out my shape and took it to a nearby sawmill that makes furniture, staircases etc and asked them to cut me two pieces of wood from my template, the same thickness as the Chroma end cheek. The guy who did it told me it was the smallest job they'd ever taken on :) They only had oak, so I took oak. Total cost about £16. I'll try and find my end-cheek template and mail it to Chris.

Varnishing - I bought a golden oak and a cherry red. Total cost about £10. Made a total guess mix in a tupperware box (so I could keep it without it drying out) and tested it on what would eventually be the hidden side of the cheek. Let it dry, added some more red, tested again and decided that that was close enough for jazz. Put three coats of varnish on over a few evenings. End result was too red so added another layer of just golden oak.

I had to take a hacksaw to the edge of the BCR as there is a small plastic lip protruding about 2 or 3 millimetres along the edge when the original end cheek is removed. Then it was time to screw the wood to the BCR. I'm sure there is a sane and sensible method for working out where to drill in wood so that it lines up perfectly with screw holes beneath - but I don't know it. Let's just say you don't want to see the hidden sides of my wooden end cheeks.

So that was it. With the cost of the BCR and the materials it was about £140 and a lot of little bits of evenings scattered over about 6 months (I get easily distracted). Having used it on & off now for several weeks I don't think that it's necessarily the perfect solution but it's probably the best for the price. The degree to which it opens up the Chroma is staggering.

I've learnt quite a lot about what would be desirable (even essential) in a custom controller box but I'll save that for another email as it's getting late.

Dave Manley [21030547]

Hi Matt,

I'm a bit ignorant on how these operate. If you have a midi interface on the Chroma, can the BCR send control info directly to the Chroma (based on the BCR presets you've defined), or is a computer running some program needed in between. I guess the question is: once the BCR is configured, will it operate as a standalone knob box?

Matt Thomas [21010021]

Hi Dave,

The BCR is a really staggeringly flexible little box so the answer is yes, absolutely. It transmits MIDI data straight out of its two rear MIDI sockets and down it's USB cable.

It can also act as a MIDI merge for incoming MIDI events and add them to the controller messages it's generating - thus you can set up the whole Chroma - BCR - sequencer loop whichever way you fancy. I use Chroma with Local Off, transmitting MIDI notes to the BCR, the BCR merges the notes and controller messages then sends them into the sequencer which instantly loops them back to the Chroma where they play and modulate the synth engine. Sounds long winded written down but it's just adding a BCR into the same set-up 99% of people use for MIDI sequencing.

I think the BCR manual is online if you wanted to get a handle on any specific things it can & can't do.

Paul DeRocco [21030230]

So you're saying that this only works with a CC+? Or does it work with a Syntech converter and a regular Chroma?

Matt Thomas [21010021]

The BCR will work with any Chroma MIDI interface that allows for mapping of CC messages to Chroma parameters. In your case I think you'll need to edit the presets I've set up so that the BCR transmits the appropriate CC number to correspond with the Syntech's assignment of CCs to Chroma parameters. Might take you about twenty minutes to read about how it's done in the BCR manual and another twenty to do it - easy :)

Chris Smalt [21010280+]

The BCR will work with any Chroma MIDI interface that allows for mapping of CC messages to Chroma parameters.

I was just done writing a similar response, about when I used to route four faders of my Roland master keyboard to modulate various Chroma parameters on the fly, when I realized that maybe Paul was asking about the option that Matt described to work with the Chroma in local off mode. It's been a while since I used my Syntech, but in the manual. I haven't been able to find the option to set the synth to local off. I seem to remember I used to set the Chroma to a muted mono instrument to get around this while working with a sequencer.

Marais

Matt, Can u please pass on the BCR presets, panel graphics, any other info, etc. ?

Andrew Dalebrook [21010180]

About three years ago I posted my setup with a BCR2000 and a Syntech interface: see my post in the thread Re: MIDI Controllers.

It has the BCR settings files along with a MIDIOX "MIDI translation" to convert the BCR's CC into ranges that the Syntech can use. I.e. where a parameter has a range of 64-127, the BCR spits out 0-63, this is amended by MIDIOX and goes into the Chroma. This way you can use the full range of the LED ring.

Hmmm, or you could just set the range from 64-127on the BCR...

Anyway, it's there if you need it.

Dave Manley [21030547]

Hi Matt,

One more question: how do the LED rings get set? For example, if you change to a new patch on the Chroma, will the LED rings get updated with the associated parameter values in the patch?

Matt Thomas [21010021]

Hi Dave

One more question: how do the LED rings get set? For example, if you change to a new patch on the Chroma, will the LED rings get updated with the associated parameter values in the patch?

In a word, no. The BCR / Chroma combo is no worse than many old analogue polysynths in that respect but it is one of the shortcomings. Personally I find it's a niggle rather than a deal breaker. There are two ways round it but one I haven't tested and the other would require some additional firmware functionality be added to the CC+.

The first option is Snapshot Send: "A Snapshot Send lets you send all current controllers values in order to transmit the B-Control settings to the connected MIDI device. Press the "< PRESET" key while the EDIT key is kept pressed. The B-CONTROL now sends the current controller settings."

I haven't tested this but hopefully can this week.

Second option is Data Request: "Current value settings of the MIDI device connected to your B-CONTROL can be transmitted to your B-CONTROL using the data request function (provided that the MIDI device supports this function, and a request command was defined using the editor software). In this case, the MIDI device doesn't send data; the B-CONTROL requests them instead. Press the LEARN key while the EDIT key is kept pressed. The request takes place, and the B-CONTROL indicates the controller values of the receiving MIDI device on the LED rings"

This is clearly the preferable option as it would draw the settings of the current Chroma patch into the BCR but I'm guessing the CC+ doesn't have the functionality to respond the BCR's data request - I tried a couple of times with no result.

One additional issue - I use two BCR presets, one for Chroma voice A, the other mapped to voice B. Thus either option (data request or snapshot send) would need to be performed once for each BCR preset.

Doug Terrebonne [21030114]

I thought you didn't want a Behringer anywhere near your Ferrari? :) Anyway as I suggested last month the BCR is a great value - glad someone came up with a preset/overlay for it...

Daniel Benoit [21030109]

behringer ferrari...

Now that Berhinger has bought Klark-Tecknic AND Midas it as makes them go up in the social class... ;-)

dbm
Ferrari Owner... hoping for good bottons for its "dash board"

Paul DeRocco [21030230]

In a word, no. The BCR / Chroma combo is no worse than many old analogue polysynths in that respect but it is one of the shortcomings. Personally I find it's a niggle rather than a deal breaker. There are two ways round it but one I haven't tested and the other would require some additional firmware functionality be added to the CC+.

Doesn't the CC+ transmit a Program Change when you change sounds? And then can't the knob box read the program out of the Chroma and decode the parameters from it?

C2?

Bruce Sklar [21030660]

Just wondering if C2 is still is still being considered.

Tom Hughes [21030251+]

Good question... and timely, seeing as how 2010 is looking to be the Year of the Chroma...

Sandro Sfregola [21010294]

The C2 is coming... slowly; more on this soon...

Marais

What is it btw ?

Chris Ryan [21030691]

See The Chroma CPU Plus (CC+): Postscript.

Marais

hmmmmm......

"a new instrument, the C2 module"

Perhaps Sandro, any more info please?

Heinz Weierhorst [21010276]

Hi Sandro.

I just finished the layout of a new chanelmotherboard with some extensions.

  1. the synthdatabus is eight bit wide.
  2. a feature was added to make the Chroma "Stereo", with eight panpots which route to output 3 and 4.
  3. it's possible to make one or two external input(s) by switching off the noise sources.
  4. an active temperature compensation was added.

The amount of parts is reduced. The digital part is done by two Mach4 and three HCxx ICs.

The obsolete noise generator is replaced by a tiny eight pin PIC. See Electric Druid.

The rest are some HC4052 and some Opamps.

Dimensions of the board is 305 X 129 mm and will fit old dual voice boards as well as new releases.

Now some thoughts about the C2:

The charge pump VCO design is good and very linear and should be preserved.

A great amount of the Chromas sound is in my opinion the CEM3355 Filter design an should also be preserved. I had worked out a replacement with LM13700, but at the moment the Q-control must be revised.

There is a simple trick even with the CEM3355 to add two aditional filter modes: A 6dB Bandpass or an Allpass. One of the bad things in the original Chroma design is that one VCO is killed when selecting a noise source. So noise mixing is also simple to do.

But!!!! - only on hardware level, a lot of software is to do.

Dave Bradley [16330135]

I love this crowd.

Bootup problems

Bruce Sklar [21030660]

I had my Chroma refurbished- basically cleaned, few components maybe replaced, and possibly the tech put a new battery case on the logic board. David White, who has had the big ad in Keyboard for years, in Boston did the work.

It was functioning, then sat for 3-4 months, but not in a damp place or anything damage inducing. David did say not to let it sit, turn it on every day, etc. It would then power up and after multiple attempts tune all 8 boards, but then started to go blank after playing a few notes. (freeze up, or mostly all lights off)

Now, one blink and nada. The tapper softly taps quickly until it peters out. Immediate repower up does absolutely nothing. Power Supply is original. I was thinking of getting cc+ and new PS any way, but..

Any thoughts out there? I am NOT a tech , but feel comfortable enough with the cover off.

This instrument used to shut down regularly when I first moved to Vermont in 1984, (sub 110 volt situations common then) power supply transistor on the big blue cap was what Bill Thomas or Steve Gromm always suggested replacing , which I did a few times. It served me well 5 nights a week for 10 years. But I'd love to have it in the place of honor, functioning, in my studio.

Jesper Ödemark [21010135]

I'd say: Get the new PSU. It sounds like that's the villain. My machine went through similar behaviour and after a PSU-swap it was cruising down the highway again.

Bruce Sklar [21030660]

Thanks Jesper. ChromaTalk makes email bearable, it's a great thing!!

David Clarke [21030085++]

... Power Supply is original ... This instrument used to shut down regularly when I first moved to Vermont in 1984,... power supply transistor on the big blue cap was what Bill Thomas or Steve Gromm always suggested replacing , which I did a few times...

Bruce - while I'm not of fan of 'quick fix' suggestions, if the big blue power supply cap is still the originally baby-blue Mallory one, then the quickest stab-in-the-dark would be to just replace it and see how/if the behaviour improves.

I have yet to find an original Chroma which hasn't developed a problem with the big 47000uF cap. While some Chromas may still run OK most of the time, they get flakier and flakier with age. A new capacitor can be gotten as a drop-in replacement for about $30.

I used to recommend Digikey part number P10074-ND (Panasonic P/N EEG-A1E473FGE). Digikey P/N 338-1253-ND looks to be a similar part.

Doug Terrebonne [21030114]

Do you know what all was included with the "refurbishing" that was recently done? You should have gotten a complete report of repairs and replaced components. Was any battery leakeage detected and traces repaired? That's the most common problem I've seen with flaky Chromas. I've also never heard of a properly refurbished synth needed to be powered up every day...

Paul DeRocco [21030230]

From: David Clarke

Bruce - while I'm not of fan of 'quick fix' suggestions, if the big blue power supply cap is still the originally baby-blue Mallory one, then the quickest stab-in-the-dark would be to just replace it and see how/if the behaviour improves.

I have yet to find an original Chroma which hasn't developed a problem with the big 47000uF cap. While some Chromas may still run OK most of the time, they get flakier and flakier with age. A new capacitor can be gotten as a drop-in replacement for about $30.

I used to recommend Digikey part number P10074-ND (Panasonic P/N EEG-A1E473FGE). Digikey P/N 338-1253-ND looks to be a similar part.

The physical density of capacitors has increased dramatically over the years. I don't recall exactly what size the original was, and I don't want to open up my unit just to find out, but Digikey part 565-3327-ND looks about the same size but with a much higher voltage rating, and probably a lower ESR, and it's only $16.64 in onesies. ESR is a pretty important parameter in this application, because the design runs higher peak currents than the typical linear regulator.

David Clarke [21030085++]

... I don't recall exactly what size the original was, and I don't want to open up my unit just to find out, but Digikey part 565-3327-ND looks about the same size but with a much higher voltage rating, and probably a lower ESR...

Before any order is placed, it is recommended to make a quick measurement of the unit currently in the Chroma as sizes aren't necessarily all the same for different brands/ranges of capacitors.

The height of the unit likely won't be an issue but it is recommended to measure the diameter of the part (to make sure the replacement will fit in the holder that's in the Chroma) as well as the lead spacing (to make sure the replacement will match the holes in the screw-on circuit board).

Bruce Sklar [21030660]

My plan is to remove the cap, which is large and baby blue, and take it to You-Do-It Electronics in Newton, Mass (huge) and get a suitable replacement, bringing these reccommendations for reference. You guys are awesome...I've got a daughter at Berklee, always looking for a good reason for a Boston road trip. (I'm an hour from the Canadian border.)

Paul DeRocco [21030230]

I dunno, it wouldn't surprise me if You-Do-It doesn't have low ESR caps of that size, and that's what you really want. I suggest doing what Dave said, measure the diameter and terminal spacing, and if the low ESR cap I mentioned from Digikey matches, buy that. You can drop the part number into the search box and download the data sheet, which will include the measurements. They ship same-day, and even overnight shipping is a lot cheaper than two tanks of gas.

Bruce Sklar [21030660]

Got it. I have their website up and will proceed.

Again, thanks for the well informed help!!

Chroma Pressure Sensor update

Chris Borman [21030194+]

Sensitronics LLC called and said the production FSR will ship this week. I had recieved samples from them a couple weeks ago in various resistance values to validate the circuit. The CPS MUX and Trans PCB's also due in this week. All other parts are here and ready. Made a change to the sensitivity adjustment circuit to limit current to 340uA at the lowest setting. Modified the FSR and MUX/TRANS circuits for consistent sensor contact orientation and interface uniformity. Changed to through-hole technology parts to make assembly eaiser.

That all said, I will get updated installation documentation and actual install pictures to Chris for the website [see Pressure Sensor Retrofit Kit] and should start shipping kits within two weeks.

Dave Manley [21030547]

Chris,

That sounds great! Thanks for the update.

Chris Borman [21030194+]

CPS update

First CPS sensor assembly and only 83 more to go! I tried it with the prototype OPAMP circuit. Great sensitivity and no crosstalk at all between sensors even with the 3/16" felt damper strip.

Jesper Ödemark [21010135]

Re: CPS update

Great news - keep up the good work!

drehbank template

Jesper Ödemark [21010135]

Hi Chris and the list,

finally... here it is, my promised Doepfer Drehbank Chroma setup as used in my studio.

Note: The downloadable Drehbank Editor can be found at doepfer.de and works but I couldn't find a way to use it under Windows Vista and had to retreat (I'd almost call that an upgrade!) to Windows XP.

I've grouped the upper row of 25 Chroma controls in the top two rows of the drehbank. The lower row is connected to the bottom two rows of the drehbank. The bank switch allows for switching between edit modes.

I've intentionally left the right eight knobs unused even though you could argue to group the controllers differently. These are left unused for now 'cause they are connected to eight cv inputs on the back. Hence I plan to use them for pedals, switches, windcontrollers and the like one day in the future.

I hope someone can save time and effort by using this. :) I've attached a picture of my drehbank too, to show the current and ugly look. A new front panel will be designed... one day. :D

Peter Forrest [21010096]

Thanks Jesper! I'll be trying this once my Chroma is fixed.

Chris Smalt [21010280+]

finally... here it is, my promised Doepfer Drehbank Chroma setup as used in my studio.

So both banks can be active at a time? That nicely duplicates the original Chroma behaviour! It *is* an ugly mother indeed, but that's Doepfer design for ya...

Jesper Ödemark [21010135]

No, just one at a time unfortunately, but if you use a setting to edit both simultanously you can use bank A to edit both, so it's basically Chroma style.

And yes... Doepfer design indeed. :( There was another incarnation in dark grey that is better looking, but this was best economy when I found it on Ebay.

Anyway, I will make a new faceplate like the Behringer one we recently saw. If I feel really into it then I might even rearrange the knobs and place them in groups of five. :)

Chris Smalt [21010280+]

That's a shame - it wouldn't have been too complicated for Doepfer to implement that.

Jesper Ödemark [21010135]

Probably not, but the Drehbank came out years before anyone thought about using 2x50 knobs for _one_ synth. :)

The banks are intended to use with two separate setups, i e synth + mixer or two or more synths etc.

There are dozens up templates for various machines available though, so they sure put some effort into it when it was new.

Marco Rosano [21010197]

Very nice!

Is there a way to load your setup with an Apple?

Jesper Ödemark [21010135]

I'm not sure, I've kept an ancient old crap-PC just for updates like this one. Here's Doepfers page about the Drehbank editor. You might understand more of it than I do. :)

Marco Rosano [21010197]

Thanks Jesper,

very psychedelic page!

I have tryed the mac SoundDiver software some times ago but it is so complicate and confusing.

Maybe the only way is to ask to a PC friend some help...

Jesper Ödemark [21010135]

I bet it is. I'd gladly help if I could. It was easier during hte years when all you had to do was to ship an eprom. :)

Chris Ryan [21030691]

I have tryed the mac SoundDiver software some times ago but it is so complicate and confusing.

Not only that, but it was discontinued years ago (though you can still get a copy; check the entry on the Mac OS X Editors & Librarians page).

I assume that the Editor for PC includes uploading the .dbp file to the Drehbank? If so, I wonder if SysEx Librarian would be able to accomplish this on the Mac.

Jesper Ödemark [21010135]

I cannot answer all the tech stuff since I'm not comfortable in those digital domains... ;)

...but once you've loaded the editor, you simply open the chroma file and then transfer it to the Drehbank. I remember that it was a lot easier than I'd originally expected. I remember testing to send a setup with just cutoff control before going through the pain of programming all the knobs and assigning them to the correct CC value, positions and scale.

Marco Rosano [21010197]

drehbank template for mac

Hello Chris!

My test of opening the .dbp Chroma template document with SysEx Librarian failed.

But it was a good idea, what kind or format is .dbp?

Is there any midi software, other than the Drehbank editor, who can open it?

Jesper Ödemark [21010135]

Re: drehbank template for mac

Marco Rosano skrev:

My test of opening the .dbp Chroma template document with SysEx Librarian failed. But it was a good idea, what kind or format is .dbp?

My guess is "Dreh Bank Patch".

Is there any midi software, other than the Drehbank editor, who can open it?

I haven't heard of any.

Marco Rosano [21010197]

Re: drehbank template for mac

Hello Jesper,

maybe the PC Drehbank editor can "save as" or "export" or "convert" the .dbp document in .syx or .mid format?

We can always dream... :-)

Jesper Ödemark [21010135]

Re: drehbank template for mac

It's a very simple program from back in the days when windows 95 was the new hip thing. :)

Chris Ryan [21030691]

Re: drehbank template for mac

On 2010-01-25, at 6:06 AM, jesper wrote:

It's a very simple program from back in the days when windows 95 was the new hip thing. :)

I wrote to Doepfer about the information on this page and they replied:

Sorry, but Drehbank is discontinued a long time and also the premium support for that device and as you've seen SoundDiver also many years ago.

Best idea is try to run the PC editor f.e. on an older PC or an PC emulator on Mac.

But we could not give you any advice/support for Mac nor for the editor.

Also the site you mentioned is from 2002 and also outdated a long time ago, think we've forgotten to delete all links to this site - I've now deleted it for clearness.

Thanks for the hint!

I have used both VMware and Parallels; these are decent solutions for running Windows on an (Intel) Mac. I can't help but think, though, that there must be some way of sending the information from a Mac to the Drehbank.

Foot Pedal on eBay

Chris Ryan [21030691]

Item #270520197471, starting bid USD$22.99, no bids yet, ends January 26. From the description: "A pedal that I used with my Chroma years ago. It used to work just fine, but I can't test it anymore so I am selling it as is."

Picture from the auction:

Chris Ryan [21030691]

Sold for $22.99.

Dual Footswitch on eBay

Chris Ryan [21030691]

Item #170438836864, current bid USD$50.00, ends February 7. From the description: "The item is in perfect working condition. I sold my Chroma a while ago and I couldn't find the pedal that goes with it. Now I found it. The pedal has lived in my house, a temperature controlled environment, free from dust and smoke."

Picture from the auction:

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