Skip Navigation.
Section 0

ChromaTalk Archives: December 2012

Re: EPiCK for Chroma?

Go to first message in thread, November 2012

David Clarke [21030085++] · Mon, 03 Dec 2012 08:31:54 -0400

BTW: in case of such as a MIDI interface, would be possible to connect it someway to CC+ without occupy the external MIDI box?

The CC+ is built with only one MIDI interface - but:

  1. the straightforward way to avoid taking up the one-and-only MIDI interface would be to use a small MIDI merger, to allow more than one interface to input to the single MIDI IN.
  2. the CC+ still supports the DB-25 computer port in addition to its dedicated MIDI interface. So - you could (for instance) use one of the Syntech/Chroma Cult/KMX MIDI interfaces connected to the Chroma port for the add-on sensor, while using the main MIDI interface of the CC+ for your other processing.

Clone of the Chroma ?

Philippe [21010227] · Thu, 13 Dec 2012 03:19:26 +0100

Does anyone on the list know anything about what seems to be a Chroma clone or emulation displayed on the Facebook page of UVI ? Hard or soft ?

Analog or digital ?

Kroma

Chris Smalt [21010280+] · Thu, 13 Dec 2012 03:51:19 +0100

Haha, ridiculous mockup, but if it's a software emulation, I might buy me a new computer after all (since it's unlikely to run on a 2005 PPC Powerbook).

Mal Meehan [21010182++] · Wed, 12 Dec 2012 21:41:56 -0500

Looks like UVIs recent spate of sample based emulations of classic synths... this is just a CGI mock-up, its software based on their UVI Workstation VST Instrument.

I did one for Apple's Mainstage app many years ago, created a custom MIDI map and UI, using samples from my Chromas in Apple's EXS24 sampler (it says PPG, that's because I also did a PPG V version too).

ChromaEXSthumb

PPG_Mainstage_finalthumb

Mal Meehan [21010182++] · Wed, 12 Dec 2012 21:59:39 -0500

Looks like UVIs recent spate of sample based emulations of classic synths (Fairlight, Synclaviar etc).

This is just a CGI mock-up, its sample based software based on their UVI Workstation VST Instrument - you can see the left side is the sound creation screen and the right side is the effects and Sequencer.

Paul DeRocco [21030230] · Wed, 12 Dec 2012 19:09:02 -0800

Well, if they're trying to emulate the Chroma, they've got it all wrong. One of the important features of the Chroma is the use of two (or more) ADR envelopes to get more complex shapes than an ADSR. ADSRs suck. Oh, and so do mod wheels. At least they had the decency to call it a Kroma.

Mal Meehan [21010182++] · Wed, 12 Dec 2012 22:24:26 -0500

They have to work within the confines of the UVI Workstation software, so if that only has 2 ADSR envelopes that's what you work with.

Basically you sample some pure waveforms and use those samples as building blocks... the filter in this won't really sound like a Chroma's filter, not unless UVI have tweaked the actual VSTi emulation code to match the character of the original... You can do this in Kontakt to some degree, not sure about UVI Workstation (or the Mach5 Sample player which will also play this).

Not sure if this went through on a previous reply (images rejected because of size) [it did—see above] but I did something like this years ago in Apple's EXS24 sampler... I created a dedicated User Interface in MAINSTAGE with 400 patches sampled from my Chroma, If you left the EXS' filter off (or in 12db), it did actually sound very similar... and at the time because the Chroma was/is kinda locked out to hands on control it actually worked very well. My samples are 6 part velocity multisampled so playing from a piano weighted keyboard did actual sound expressive... so much so that due to emigrating and not being able to ship my Chromas, I was happy to sell them!! (shock!).

Mal Meehan [21010182++] · Tue, 25 Dec 2012 18:53:25 -0500

UVI Kroma

Thought this might be interesting to people here.

I bought the UVI Vintage Legends package primarily because I wanted to hear the Kroma... It's been a few years since I sold my 3 Chromas so the idea of being able to play a facsimile of one interested me.

I sampled 400 presets from my last Chroma (21030075, the joystick Chroma) and have them in Apple EXS24 format and on a weighted keyboard they play very well as they are all multilayered with 6 levels of velocity. I don't fiddle with the EXS' filter or envelopes so my samples really do sound very lively and organic... even pitchy where the unit was out of tune as the Redmatic software sampled it. The UVI Kroma sounds a little softer and far more in tune (colder) but strangely I could recognize some of the presets, some of the sounds that I created on my Chromas and then sampled for posterity.

Low and behold... after a few Facebook status updates and private messages it turns out that the Chroma UVI used to make the Kroma software synth was in fact #21030075. I sold it to Eric Inglebert and he allowed UVI to sample that Chroma, and his Synthex for the Vintage Legends product.

So I have my Chroma back in software form but to be honest I think my samples are better... the Vintage Legends product overall is quite good but the Kroma is perhaps one of the weaker instruments in the package.

Marais · Tue, 25 Dec 2012 19:20:27 -0500

Re: UVI Kroma

I really like UVI's Synclavier and Fairlight emulations as well.

Was the Chroma ever used on any well know Christmas recordings btw ? Garth Hudson and The Band Christmas Music Be Tonight perhaps ?

Merry Chroma Christmas.

Voice Board and Channel Board Recap & Rechip Kit on eBay

Chris Ryan [21030691] · Sat, 15 Dec 2012 10:33:27 -0800

Item #261140738639, USD$220.00. "The Rhodes Chroma is one of the greatest sounding analog synthesizers ever made. Unfortunately, many of the ICs used such as the 4000 series CMOS chips and linear ICs degrade over time and the polarized capacitors dry out. This kit replaces most of the IC ships (Kit does not include CEMs) and all of the polarized capacitors found in the Chroma voice cards and the channel board. Our recap/rechip kit includes over 200 IC's and 60 capacitors. This kit includes no instructions and assumes that the person installing the components is competent and has the proper equipment needed to do so. If you are not very comfortable installing components, soldering, and desoldering, then you should refer the work to a qualified technician. Power supply capacitors can be added to the kit for an additional fee, but we recommend that you install a brand new modern power supply for the best results. This kit does not address the CPU board or the I/O board in the Chroma. This is for the analog boards only!" From New England Analog.

Luca Sasdelli [21010226] · Sat, 15 Dec 2012 23:44:36 +0100

It sound interesting, but as per my own personal experience, I use the following rules when recapping/rechipping the Chroma:

  • high-quality IC sockets with each IC replacement; this does reduce the board stress and preserves CMOS chips from unwanted voltages
  • non-polarized DVB capacitors (VCO, S&H, VCF) are replaced with 5% (or better) PLYP capacitors (mainly Wima or Siemens made)
  • VCF feedback 1uF capacitors (C13-C14) are replaced with audio-grade ones
  • charge-pump VCO trimmers are replaced with 20-turns cermet ones (square case, horizontal mounted)
  • bigger CMB power filter capacitors (the 1000uF original ones could be easily replaced with same size 4700uF ones)

Keyboard Triggering Problem

Eric W. Mattei [21030443+] · Wed, 19 Dec 2012 13:08:45 -0800

Hello all

My tech friend has installed my new power supplies and we're experiencing two different symptoms on the Chroma that may be related.

  1. If you play various keys at random, after a couple of dozen times, a key does not produce sound. If you hit the effected key several times the note will eventually sound.
  2. If you play various keys at random, after a couple of dozen times, a random key will sound, but the sound does not stop after the key is released. If you hit the effected key several times the note will eventually sound.

Note that these symptoms don't happen with the same key or Voice Board every time. The symptom occurs randomly on various different keys and any Voice Boards.

We've cleaned all the key contacts.

Any suggestions?

Thanks in advance.

Paul DeRocco [21030230] · Wed, 19 Dec 2012 13:16:11 -0800

Try removing all but one voice board, and see if the problem persists. If it does, then it's not a voice board issue. It could be something in the keyboard scanning circuit. Try reseating the ribbon cable plug into the I/O board several times, to make sure there isn't crud buildup on its contacts.

Eric W. Mattei [21030443+] · Wed, 19 Dec 2012 17:40:47 -0800

Hi Paul and all

I neglected to mention: We're using the CC+ Set Split 37 Show Voice Allocations mode. The phenomenon appears to happen on a different board each time, randomly. It doesn't always happen on the same board. Doesn't that mean the problem is not a voice board issue? Do we still have to pull all but one voice board?

Also, we checked and re-seating the ribbon cable plug on the I/O board. It looks clean.

Thanks much. - Eric

Paul DeRocco [21030230] · Wed, 19 Dec 2012 17:58:13 -0800

Probably not a voice board then.

Hard to imagine what it could be, without poking around with a scope. I'd start by looking at the signals on the keyboard scanner, especially those on the ribbon cable. For instance, if the rise or fall times have gotten slow for some reason, it could cause one key to affect a key eight notes away, because they would appear consecutively on the same line.

Go to next message in thread, January 2013

Keyboard issue

Robert Vince [21030146] · Thu, 20 Dec 2012 09:55:09 -0800

Just wanted to let the board know that I'm experiencing the same thing since it came home from a CC+/Powersupply/Pressure sensor upgrade. Just thought it was another one of my little strange chroma gremlins toying with me.

Brian McCully [21030361] · Thu, 20 Dec 2012 10:09:41 -0800

Not sure about Eric's situation but I had key triggering strangeness that was a result of the crossbar being re-adjusted after the pressure sensor upgrade. The key contacts were ever so slightly not making contact (i.e. mostly triggering, but not every time). You might have to adjust the height/action to make sure that the contact leaves are being hit every time, but obviously not over-adjusting in a 'bend until fatigued' way. Takes some tweaking and close examination.

UVI Announces Virtual Chroma

Matrix [21030220] · Thu, 20 Dec 2012 10:45:45 -0800

Philippe [21010227] · Thu, 20 Dec 2012 20:28:29 +0100

After the Synthex, the Synthix & its Synthax demos, now the Synthox, can't wait for the Synthux ;)

Marais · Thu, 20 Dec 2012 14:51:13 -0500

Although I admire and have UVI's Synclavier and Fairlight applications, the Kroma sounds very much stacked and full of all effects, and very generic to me. Glad to have the real thing.

Paul DeRocco [21030230] · Thu, 20 Dec 2012 12:32:25 -0800

I notice a pop-up in the trailer when the Kroma appears that says "requires UVI workstation 2.0.8". I wonder if that means that it merely won't work with earlier versions of their workstation because of some bug or peculiar limitation, or that it's designed not to work with any other workstation.

Jesper Ödemark [21010135] · Thu, 20 Dec 2012 22:28:48 +0100

Phil a skrev 2012-12-20 20:28:

After the Synthex, the Synthix & its Synthax demos, now the Synthox, can't wait for the Synthux ;)

*haha* :)

Synthyx left after that. And then we can offer the swedish versions Synthåx, Synthäx and Synthöx. :D

(I hope that showed up correct, otherwise the joke is spoilt)

Brian McCully [21030361] · Thu, 20 Dec 2012 13:30:15 -0800

The 'Kroma by John Parkins' demo doesn't contain any sounds that are immediately Chroma recognizable to me. The flute thing, sorta. Yes it's very generic soft synthish.

If one was to load it up into the Mach5 v3 interface (a demo mode would be nice), it may possibly be interesting to program using the sampled waveforms and Mach 5's filter set, but from the simple screen shot interfaces shown it looks more like a Kontakt style plug-in ROMpler. Also in regards to Mach5v3, I submitted a bug report to MOTU's programmers (I owned the original Mach 5 and the latest v3) that has been open for over a year, since v3.0.0. It is a destructive bug where in the mono re-trigger mode the synth engine drops notes, and is like 3 step easily reproducible. This bug has yet to be fixed (lame lame lame), and basically renders standard mono synth emulation (bass, leads, etc.) useless. At least my real Chroma doesn't (currently...) drop notes.

Paul DeRocco [21030230] · Thu, 20 Dec 2012 14:19:06 -0800

From: Brian McCully

The 'Kroma by John Parkins' demo doesn't contain any sounds that are immediately Chroma recognizable to me. The flute thing, sorta. Yes it's very generic soft synthish.

The most distinctive things you can do with the Chroma, which you can't do on many other synths are two things: the "saws" wave shape, which has the inverse spectrum of the pulse; and the ability to create complex envelopes by adding two different ADR envelopes together, possibly with different touch sensitivities. There were some other odds and ends, certain keyboard algorithms, filter FM, odd-ball sweep shapes, etc., but I don't think they were used much.

But those are things of interest to synth sound programmers, not necessarily to performers. I suppose most people who buy any synth just play the factory presets, and those presets come to define the sound of the instrument

Chris Smalt [21010280+] · Fri, 21 Dec 2012 03:31:43 +0100

I suppose most people who buy any synth just play the factory presets, and those presets come to define the sound of the instrument.

There's a weird in-tune-ness about the Kroma demos. :-)

Jack Colburne [21030142+] · Thu, 20 Dec 2012 22:08:37 -0500

Sounds nice, pleasant. I like it. I'd use it.

But my interest in a virtual Chroma is specifically in the very aspects that this emulation does not include... I am not its target audience.

It's the depth and uniqueness of its architecture that is the reason I've owned Chromas. Lets face it, a JP-8 or an OB-Xa would have been a hell of a lot easier to cart around and keep in one piece. (I would still love to see a proper Oberheim Xpander/Matrix12 in software, tho)

To me, its niche/target is someone who would like some of the Chroma's unique sounds (like the percussive-attack-keyboard-type/emulation sounds.. the kind you can actually sit and "play"), but not necessarily a Chroma owner or, specifically, a programmer.

I think it will take a pretty impressive modeled emulation to ever come close to filling that position. But one that I would truly love to see and use.

J15 & J16 Ribbon Cable Ruined...

James Coplin [16330036] · Sat, 22 Dec 2012 00:19:40 -0600

On one of my Chromas, the panel has been acting increasingly flakey as of late. Tonight I opened up the J15 and J16 connectors where the ribbon from the front panel attaches. I was hoping to just clean up the exposed contacts on the cable a bit to see if that was the problem. Unfortunately, the metal is actually flaking off the plastic and in some places it is missing enough that entire tracks are gone. Am I completely screwed here or is there some sort of replacement/repair option available?

Chris Borman [21030194+] · Sat, 22 Dec 2012 09:33:20 -0500

I have the same issue with the Flat Flex Cables (FFC) that connect the Computer to the I/O board, but they still seem to work. The traces on the FFC to the keyboard are not separating, but occasionally crash the computer when I press a key. Especially so when I close the Front Panel. Sometimes the issue will go away after the unit has been on for awhile. I suspect the contacts are corroding. Need to look for new cabling or remove and replace the connectors with alternative connection h/w.

James Coplin [16330036] · Sat, 22 Dec 2012 09:14:24 -0600

Unfortunately, the J15 & J16 are the FFC that go to the front panel. Is there another connector up there or are they integral to the membrane? If so, what are my options now? Is there someway to splice FFC? Conductive epoxy to try and repair the lifted and missing metal traces? The use of FFC as an integral part of the panel seems like a super achilles heel for this instrument. Maybe it is time for some new Chroma replacement panels to be made.

Paul DeRocco [21030230] · Sat, 22 Dec 2012 08:47:58 -0800

The tails are integral to the panel. And they don't have "traces", in the sense of a strip of metal that could be glued back down. It's just conductive silver ink. As long as the Mylar tail is itself okay, and the ink is just flaking off, it should be possible to repair if you can get hold of some silver ink in liquid form, but it would be a delicate operation. I'm not sure where you can buy it in small quantity, but they still make membrane switches, so they still use silver ink. It might be possible to get away with a carbon loaded ink, which is also commonly used, but that's iffy.

The problem with making up new panels is that the tooling cost is high. It was worth doing for the Polaris, because they all go bad eventually. Unfortunately for you, there aren't a lot of Chromas with bad membrane panels.

James Coplin [16330036] · Sat, 22 Dec 2012 11:13:20 -0600

Looks like there are silver ink pens available from most of the major electronics outfits. Several explicitly state they are suitable for flexible surfaces and some can even be soldered after the fact. The cost is high, $40 for a pen that will do 100' or so of traces but certainly reasonable compared to the alternative. I wonder if conductive epoxy might not be a better choice. I'll keep the list posted with the experiment in case someone else ends up with the same problem.

On the other hand, I have toyed for years with the idea of replacing the panel with a knob laden surface that interfaced with the chroma interface. If the ink doesn't work, it might force my hand.

Doug Wellington [21030300] · Sat, 22 Dec 2012 11:00:32 -0700

James writes:

On the other hand, I have toyed for years with the idea of replacing the panel with a knob laden surface that interfaced with the chroma interface.

If you do that, let me know. I've been (slowly) working on a completely new front panel for my expansion chassis that will sit on top of my Chroma. My current design uses 5501 series E-Switches along with some rotary encoders and some potentiometers. FWIW, I'm currently using an MSP430...

Luca Sasdelli [21010226] · Sat, 22 Dec 2012 20:40:51 +0100

Wow! It sounds like a T8 panel :-)

Doug Wellington [21030300] · Sat, 22 Dec 2012 13:40:16 -0700

Indeed! My Chroma sits on a stand with my T8. :) Maybe I should get some T8 knobs for the Chroma panel... I've also thought about making T8 style pitch bend wheels for the Chroma. (Or I suppose I could make Chroma style levers for the T8, eh?)

Funny, I have the 5501 switches in red, orange, yellow and white (808 colors) in addition to the usual black. Too bad I don't have blue and green, eh?

I also have a T8 expansion chassis design that I'm building...

Paul DeRocco [21030230] · Sat, 22 Dec 2012 14:33:47 -0800

From: James R. Coplin

Looks like there are silver ink pens available from most of the major electronics outfits. Several explicitly state they are suitable for flexible surfaces and some can even be soldered after the fact. The cost is high, $40 for a pen that will do 100' or so of traces but certainly reasonable compared to the alternative. I wonder if conductive epoxy might not be a better choice. I'll keep the list posted with the experiment in case someone else ends up with the same problem.

My limited experience with conductive epoxy is that it isn't that conductive. You needs something with quite low resistance--a few kilohms is too much.

On the other hand, I have toyed for years with the idea of replacing the panel with a knob laden surface that interfaced with the chroma interface. If the ink doesn't work, it might force my hand.

Instead of destroying what's left of the panel, I'd be more inclined to set an iPad on top of it, and use a software interface.

Adrian [21040017] · Sun, 23 Dec 2012 13:16:57 +1030

I am in a similar position to James; my left front panel is non-functional (due to a short in the membrane somewhere in the unrepairable inner zone, rather than an issue the connectors). I am planning to (very carefully!) use a router to drill a small hole in the rear of the front panel metal (but not the membrane itself) behind each switch then mount tact switches on a custom PCB to replace the buttons. I have thought long and hard about it and I don't see why it shouldn't work, but I haven't actually done it yet due to FUD about hurting my beautiful Chroma. I don't see any other financially viable option really (there are a small number of NOS replacement front panels membranes available, but they're overseas and the purchase/shipping costs of getting one to Australia have held me back). Possibly a project for this January, we'll see. I'll document the process and my success or failure for the elucidation of future generations :-)

But I agree completely with Paul; with very few exceptions I wouldn't condone the retrofitting of controls on the front panel of any synth or module!

Fuzzy chips

Mike Todd [21010097] · Mon, 31 Dec 2012 20:14:49 +0000

Pulled my old Chroma out of the garage (where it sat for many years), and I'm contemplating getting it up and running (despite its being covered in foam "goo").

The PSU appears to be fine with all voltages present, correct and clean, and the front panel LEDs light up and don't reset - suggests the firmware isn't running.

The batteries have leaked a little, and a couple of circuit-board tracks have been damaged, but they should be easily fixed, although it will have to be in situ as the board interconnections are soldered, not socketed (as implied by the CC+ pages).

However, the 9 EPROMs and one of the IO-board chips have grown white whiskers. I know about chips growing whiskers internally, but I've never heard of them pushing through the packaging and extending 10mm+ all around the chip.

I believe that these whiskers are conductive, and so the chips will have failed (is that correct?)

The IO-board chip is easily replaced, but the EPROMs are more difficult. I actually have a bunch of 2732, but only a couple of 2716, and in any case no means of erasing/burning them.

One EPROM has had a couple of legs fracture when I was removing it, but I may be able to recover that by soldering it to a DIL header (assuming the whiskers haven't killed it).

If I knew that these were the only problems, I'd probably invest in the CC+ replacement CPU board, but it's a lot of money to throw into the project, only to find a lot more needs to be spent.

I wondered if any with more electronics experience than I have might comment on the above - particularly as I'm retired and my budget is very limited.

Thanks

Technician Larry [21030198] · Mon, 31 Dec 2012 15:02:21 -0800

Not good. Those little fuzzies and growies can exist under components and between DIP leads where you might not necessarily see it. This crud creates conductance paths where they are not supposed to be, and then traces and leads can corrode so badly that conductance gets eaten away as the metal rots.

You might check the clock pulses, interupt line and the signals on the address and data busses for clues. I suspect that you have problems other than, or in addtion to, bad EPROMs.

Some old Korg synths had batteries that leaked fumes, not liquid or goo, that digested traces and component leads. I've seen several of these that even still had good battery voltage but the board was destroyed. The CPU board on a Poly 6 was the worst layout I've ever seen. Not one, but TWO traces are routed between adjacent legs of DIPS making this board especially suseptable to open traces and extremely difficult to work on. The Chroma board can't possibly be as bad as that, but that corrosion can fester under components and between leads rendering it unreliable, even if it ever "wakes up" again.

Go to next message in thread, January 2013