ChromaTalk Archives: April 2014

• My Chroma Restoration Journey and a Big Shoutout to RC (5 messages)
• Load single sysex from a computer (3)
• Rhodes Chroma Multitrack (6)
• IO-board and CC+ LCD (8)
• Chroma on Ebay UK
• Ganged channel editing and the "Data Entry" slider via CC function? (4)
• iPad app editor (3)
• One key not working (4)
• Chroma Polaris questions (9)

My Chroma Restoration Journey and a Big Shoutout to RC

William Santana [21030244] · Tue, 1 Apr 2014 12:37:31 -0700 (PDT)

Hello RC fans. I have owned my Chroma for about 8 months now. I bought it from an individual who was the original owner. It had all of the usual issues being the foam rot, the failed power supply and nearly all of the dual channel cards had failures in some way. I have been a synth tech for over 20 years so I knew what I was getting into when I purchased it. Once I started the journey of my Chroma restoration I was curious why there was so much undying devotion to this instrument and devotion by some very intelligent people too. My first interaction was with Luca Sasdelli [21010226]. He has designed and made available a wonderful, modern, drop-in replacement power supply module specifically for the Chroma. As it turns out, the original PSU for the Chroma was the true "Achilles' Heel" of the Chroma as has even been admitted by the original designers of the Chroma. However, Luca has chosen an excellent switch-mode power supply and has designed a PCB and populated the PCB so that his SPSU module drops right in and hooks right up. Thank you Luca! Your work is the real lifesaver for the future of many more Chroma to come!

Once I had my unit turning its wheels and the CPU was firing, I began to go through the unit. The original CPU has a 2 x AA battery clip on board to deal with patch memory retention. AA batteries seem harmless enough but when left in a circuit for decades, likely the worst will happen. They will leak and when this happens they will destroy what they come in contact with. Surprisingly, the way my Chroma was situated in its case made the leakage run directly off of the CPU which was good. The CPU was actually functioning despite the leakage! The bad news, however, is that it dripped onto the upper contact board and then onto the dual channel card behind it and then oozed onto the motherboard. But it pretty much stopped there. When the Chroma was first released onto the world, there was a problem with the process that the ARP team were being forced to use by Fender to remove excess flux from the PCBs during the manufacturing process. This led to many customers getting extra dual channel boards to replace the many of the original dual channel PCBs that shipped in the Chromas since their oscillators were proving to be unstable because of this de-fluxing process. Because of this, I had received a box of goodies that came with the Chroma. Inside were, all of the pedals some cables, some data cassettes and 2 additional dual channel cards! From there, a lot of cleaning took place. I had to thoroughly strip all corrosion, repair any disintegrated traces and I even replaced the headers on the one corroded dual channel slot on the motherboard. Once I got passed all that, I now had a "complete" Chroma. So, I turned it on then started to understand what all of those cryptic little numbers meant on the display. They were telling me most if not all of the dual channel cards are not good enough to be used by the CPU! And so, the arduous process started of going through each card to work through the many problems each one had. Yes, some had multiple problems. But, what I discovered while working with the voice cards is that the Chroma design is absolutely brilliant. The multiplexing is handled on the dual channel board itself, which means; There are no active CVs passing through the headers on the motherboard. Which means, stability.

I began to develop a lot of respect for this instrument, Phil C. Dodds (R.I.P.) [see Philip Dodds/Tony Williams Interview] and the rest of the design crew. There was nothing this sophisticated happening at the time of its development. Had there been more time to develop the concept, who knows how it would have affected the modern synthesizer.

Back to my journey,

After countless hours of dual channel card surgeries and occasionally pulling some parts off of the 2 extra cards I mentioned earlier, I was starting to get this old beast to settle into something more civilized. I had a Lithium battery sitting around and decided to put it in place of the old AA battery clip so I could start working with the unit. I loaded a bank of patches to start to get an idea of what this thing could do. I started noodling with parameters haphazardly and kept stopping and staring down the parameter chart in bewilderment. "Wow! This thing is really deep!" I was totally in awe of it since it seemed to have nearly every parameter I had ever wanted on any other synth at one time or another when they would fall short. On the other hand, I was feeling frustrated.....frustrated at the interface.! Oh wait! This is an ARP after all. You have to think like an ARP engineer for this thing to make sense. So, I went to get my lab coat and my pocket protector, sat down with the parameter chart and started to really "understand" the Chroma. I went back and forth between the chart and the Chroma for weeks to confirm my understandings and work through what they were intending to convey with some of their odd nomenclature. Also, the original chart has some improper labeling on it to boot.

By now, I am invested into the RC site and start reading and chatting with the RC folks about what it all means. There have been 2 revisions of the parameter chart BTW. The newer charts come with all of the corrections for the previous chart as well as the access info for the CC+ replacement CPU. I felt as though I had just reached a plateau after finally getting my Chroma working right. Did I need to upgrade the CPU too? Well, to put it plainly, that was the moment when I decided whether or not to be a Chroma Devotee. After all of the time into the unit to get it running, the amount of time to understand its potential had me at a fever pitch to my synth buddies about how this synth is better than all of the others hands down. I had to stand up for what I knew was right. So, I ordered the CC+. The individual responsible for the brilliantly thought out and executed product is David Clarke [21030085++]. Now, being this a product for a very limited number of total units in existence, I could not have expected the level of excellence, thoroughness and quality of detail from David on the part of customer service and the CC+ itself. Obviously, this man is intelligent and has very high standards. Thank you David Clarke for your work. Once I received my CC+ and got it installed, which only took about 20 minutes, my Chroma immediately seemed at ease with its functions. There are 4 banks of 50 patches already loaded into the CC+ and they are all substantial. There's brilliant work from several individuals in there, I am sure. So, here I am with an amazing machine and I still get people who look at me odd when I try to talk about its merits to people. I get a lot of, "I don't think I would like something that complex" which we all know is not entirely true. What I keep looking at with the Chroma is how it really suffered in the same way Yamaha's DX7 suffered. If the PSU was Achilles' right heel, then the lonely data entry slider was the left one! I have played a lot of synths and I have watched the market value fluctuate. All of which is telling me what drives desirability.

It seems most people need immediacy in the sonic sculpting process. There are too many other things to do while the inspiration is ripe. Looking into solutions, I came across the Enabler by Randel Osborne [21030467] with Redshift Consulting. This was an all-out, no-expense-spared programmer to put every parameter of the Chroma on a larger-than-life, heads-up panel. You literally never have to look at the parameter chart again. The Enabler was a "knock out of the park" in terms of the ultimate programmer for the Chroma. I contacted Randel and, unfortunately, he has no interest in producing any more of the Enablers. The initial batch that he produced at $3750 a pop and a 1-year tun around, that would be a purchase for only the most devotedand well-funded Chroma owners.

With all being left to my own efforts, I started noodling on paper and came up with an idea that would be more cost focused but still giving every bit of functionality as the Enabler. With my concept now in its latest revisions, I will be slowly putting together a 93-knob, 32 button programmer designed eliminate the need for the parameter chart and to make the Chroma easy to use.

Also, since so few synths are equipped with polyphonic pressure sensitivity, it should be known that the Chroma was originally designed to support poly pressure yet few units actually contained the original option. A fellow named Chris Borman [21030194+] has recently finished another batch of his poly pressure kits for the Chroma. I should be receiving mine sometime next week. I have no doubt that I will be blown away by the quality and sophistication of his product being he already has all of his technical documentation available for the CPS kit.

Last but not least, Chris Ryan [21030691] is man who has been maintaining his website devoted specifically to the Rhodes Chroma. There is not another vintage synth that has as much support in one place as Chris' website. You, Chris Ryan, are the real reason why the Chroma will survive in greatness. And now, after that journey, I can honestly say that the Chroma is the best vintage analog polyphonic synth ever made. The rest of the synth world may not know it yet but with a support network like the Chroma has, it will be one of the longest lasting synths from the golden years of synthesizers. Thank you Everyone!

Bruce Sklar [21030660] · Wed, 2 Apr 2014 07:35:33 -0400

I am an original Chroma owner, that I bought before I had kids.

Learning to program the Chroma took time, but I found that if I had a sound in mind and went for it (for hours on end), it forced me to think in depth about all the possibilities the Chroma offered, and proceeding this way also was actually EASIER using the one data entry slider. It reduced option anxiety so to speak, and forced me to think in a more linear fashion that my jazz pianist self normally proceeds.

I should mention that I had taken a 12 week course nights a Brandeis University while in high school that had a modular ARP with 2 keyboards and about 100 modules. And a Buchla in the next room so I had a good understanding of flow. BTW for anyone wanting to get a handle on analog synthesizer concept, the ARP 2600 manual is a classic textbook for learning and its there online to be found.

What I got out of the experience beyond getting sound out of the chroma that even some developers of it didn't think it was capable of, was that I became a monster a programming anything with multiple sliders

A word of caution- I have a Dave Smith Polyeveolver- and I would have preferred sliders to knobs. Like the Polaris. Just a thought.

Bruce Sklar

Moretown VT ( got the Chroma while still living in Newton Mass.)

David Clarke [21030085++] · Thu, 3 Apr 2014 20:38:48 -0300

... I ordered the CC+. The individual responsible for the ... product is David Clarke...

William - thank you for the kind words. I can't take full responsibility though.

While he's been engaged with other projects recently (and so has not been able to be as active on Chroma related items), Sandro Sfregola [21010294] is due as much credit (if not more) than me. The CC+ owes its existence to him and his keen development efforts.

The CC+ is also somewhat the product of the Chroma community. It is a bit uncharacteristic in that it was not created to 'make money.' Instead it was created in order to allow the continued and effective use of the Chroma's. Over time, the features added have been based on input and observations from members of the Chroma community.

It's good to hear that you're enjoying the Chroma as well as the inputs available from the community available here.

Best regards,

David Clarke

William Santana [21030244] · Fri, 4 Apr 2014 09:22:08 -0700 (PDT)

Thank you again David. If you have time, I may be wanting to talk about a couple of features that I would like to recommend as addition to the CC+ firmware.

David Clarke [21030085++] · Fri, 4 Apr 2014 14:15:10 -0300

... I may be wanting to talk about a couple of features that I would like to recommend as addition to the CC+ firmware.

William - recommendations are always welcome. Given the relatively small pool of CC+ users, I generally suggest that the discussions of potential new features be done here (on the list).

That allows would-be users of the features to provide their voice, both in terms of desired implementation and perceived utility.

David Clarke

Load single sysex from a computer

Enzo Bodo · Thu, 3 Apr 2014 12:57:40 +0200

Hi !

I’ve got a Chroma with CC+ extension and I want to make personalized banks.

So I selected interesting presets by dumping them with « Set Split 36 » + « 21 ». Every Sysex file weighs 136 bytes.

However nothing happen when I want to load them on the Chroma from my computer using Sysex librarian.

A dot appears on the program number’s display, proving that the Chroma understands there is activity, but the « program modified » light witness doesn't turn on and the preset doesn't load.

Nevertheless I can load Sysex with 50 presets and one preset from the internet weighing 126 bytes.

I found a method to bypass this by dumping with « set split 20 » to dump the preset 0.

Unlike the « Set Split 36 » + « 21 » method, it creates a 126 bytes Sysex (like those on the web) that I can load as preset 0, then use the store function to record it in the Chroma

Did someone run into the same issue ? Is there a parameter I can modify to make it possible ?

Can I convert my Sysex files ?

It would be perfect if I could avoid to dump again 200 preset chosen in dozens of banks

Here is some example of both dumping method

• setsplit20.syx
• setsplit36+21.syx

Thanks for your help

Brian McCully [21030361] · Thu, 3 Apr 2014 10:33:38 -0700 (PDT)

I suggest studying this:

The Chroma CPU Plus (CC+): User's Guide - MIDI System Exclusive (SysEx)

There are 118 data bytes per program, plus the sys-ex header and footer (8 more bytes), per program for the single dumps.

I seem to remember that 136 bytes was for another kind of dump - like the MCM dump. You may be requesting/dumping the wrong thing.

Brian

David Clarke [21030085++] · Thu, 3 Apr 2014 19:58:25 -0300

I seem to remember that 136 bytes was for another kind of dump - like the MCM dump. You may be requesting/dumping the wrong thing.

Brian's reply is correct.

[Set Split 36][21] asks the CC+ to perform a "MCM SysEx Dump."

The 'MCM' is the MIDI Controller Map. That map controls how MIDI continuous controller messages are handled in the CC+ and doesn't actually contain patch data.

If the patches you're interested in are already in the Chroma, and you want to make personalized banks - then one way will be to simply use the features available directly on the front panel. For instance - you might decide to decide to make patch bank 4 your 'custom' bank. You can then find the patches you want, select them, and 'store' to the location you want in bank 4 (or whatever bank). Once you have the full bank of patches that you like, you can dump them all to the computer via a full bank dump.

As you note, using [Set Split 36][20] to get the current patch is also an appropriate way to save off individual banks (that you can then later and save into whatever patch locations you like).

It would also be possible to use a patch librarian on the computer.

David Clarke

Rhodes Chroma Multitrack

Pontus Hagberg · Thu, 3 Apr 2014 18:58:38 +0200

I made a Youtube video with only Rhodes Chroma sounds.

Some are presets and some sounds are inspired from the Yamaha CS-80 using HPF and LPF in series.

I am applying polyphonic pressure from a Roland A-80 but I am , of course on the wait list for a pressure sensor kit to the Chroma itself too :D

Best Regards
Pontus
Sweden

Peter-Jan Kleevens [21010014] · Thu, 03 Apr 2014 19:13:03 +0200

Very nice !!!! Congrats !

PJ
Holland

William Santana [21030244] · Thu, 3 Apr 2014 10:57:31 -0700 (PDT)

Cool track. It is nice to hear the Chroma being used for more percussive sounds. Let's hear some more!

Jack Colburne [21030142+] · Thu, 3 Apr 2014 19:00:01 -0400 (GMT-04:00)

Pontus,

Excellent, lovely. We talk a lot about tech and history and such, but don't get enough chance to really hear how it can sound. Thank you for the music and video.

-Jack

Daniel Rickenbach [21010172] · Fri, 4 Apr 2014 01:21:31 +0200

very beautiful

thanks

Daniel

Tim Siefkes [21030850] · Fri, 4 Apr 2014 06:38:52 -0500

Nicely done, I enjoyed that too. Although I sold my Chroma in 2012, I remain a lurker on this list and still enjoy following the Chroma news and developments. (Mine sadly fell into disrepair and was beyond my means and capabilities to restore, but it is in good hands now).

IO-board and CC+ LCD

Roel D. [21010092] · Tue, 8 Apr 2014 00:52:32 +0200

Hi all,

I'm working on my Chroma, and it's working. (New PSU and CC+ installed this month, but 4 voice boards are faulty.)

However, I'm working on the IO board now. The only problem that's obvious is the tapper that never stops, even if I disable it. (Didn't really started debugging that. Just disconnected the tapper itself.)

Anyway, my question; which of these modifications are done by the manufacturer?

1. The capacitor in the left upper corner seems to be C32. (This corner is bottom right in the IO Assembly document, C32 has a place on that board, but not on mine.) My guess is that this is done by the manufacturer.

2. Also visible in the first picture, but this one is close up. R68 is either cut or broken. Here my guess is that I should repair that, the sooner the better. Right? My analog electronics background has been taking quite a nap the last 15 years...

3. This one seems more adventurous, my guess is that some logic failed and this was the 'easy' way to repair it. Although the floating pcb has some writing underneath, I'm doubting on this one. Anyone seen it before?

And apart from that: I have the LCD working with an Arduino Pro mini as a serial display adapter. In short, couldn't find the serLCD backpack with decent postage fee, and found a device that's Arduino compatible and has the firmware online. (Watterott device). So I adapted the code to work on an Arduino Pro mini that I had lying around and to be fully compatible with the sparkfun device. If anyone is interested, just ask! The Arduino Pro Mini clones can be found on Ebay for around 2€ easily. (Don't expect too much, I had to burn the bootloader myself on this one.)

Thanks,
Roel

David Clarke [21030085++] · Mon, 7 Apr 2014 20:30:26 -0300

...which of these modifications are done by the manufacturer?

1. 1) The capacitor in the left upper corner seems to be C32. ...

This one is likely intentional. You can refer to the details of Field Change Notice FCN2-005 to confirm.

3. This one seems more adventurous, ...

This was also intentional - it is referred to in Field Change Notice FCN2-004.

2. Also visible in the first picture, but this one is close up. R68 is either cut or broken. ...

While I don't currently have a Chroma open to double-check, I'm not aware of this being an intended mod, and expect it should be corrected.

... I have the LCD working with an Arduino Pro mini as a serial display adapter.

Great!

Paul DeRocco [21030230] · Mon, 7 Apr 2014 22:32:57 -0700

From: Roel Das

I'm working on my Chroma, and it's working. (New PSU and CC+ installed this month, but 4 voice boards are faulty.)

However, I'm working on the IO board now. The only problem that's obvious is the tapper that never stops, even if I disable it. (Didn't really started debugging that. Just disconnected the tapper itself.)

There is one common CPU crash mode that fires the tapper at 2MHz/65536. But if the CPU is running, then an erratically firing tapper usually means you've got an unstable power supply, causing the A/D converter to think the parameter slider is constantly moving. That should be easy to track down if you've got a scope--and somewhat harder to track down if you don't.

David Clarke [21030085++] · Tue, 8 Apr 2014 19:57:12 -0300

... if the CPU is running, then an erratically firing tapper usually means you've got an unstable power supply, causing the A/D converter to think the parameter slider is constantly moving...

Roel - when you've indicated that the issue occurs "even if [you] disable it", is that a reference to [Set Split][9]?

Paul - assuming it is, wouldn't you agree that that should rule out a jiggling parameter value - since the tapper should be 'off' (as far as the software is concerned)? In that case it would seem that the issue is a write strobe/tapper logic issue. Again though - a scope at/near Z38, Q1 and Z41 of the I/O board should quickly show you what's going on.

David Clarke

Paul DeRocco [21030230] · Tue, 8 Apr 2014 16:38:45 -0700

If that's what it is, then nothing else will work, so you couldn't do [Set Split][9] to try to disable it. Oh, I suppose you could press those spots on the panel, but it would be pretty obvious that the CPU wasn't paying any attention.

But if that's the issue, a scope may not help diagnose why, either. When EPROMs are that old, they may start dropping bits, and all it takes is one to crash the CPU. Fortunately, this doesn't mean the EPROMs are defective, it just means they need to be reprogrammed, and they'll be good for another 30 years.

Jerry Leonard [21030100++] · Tue, 8 Apr 2014 23:40:45 -0700 (PDT)

I'm curious to know. How many of you have implemented the FCN mods. Of 8 I/O boards, I've only come across one that had the mod with the raised platform.

David Clarke [21030085++] · Wed, 9 Apr 2014 12:02:24 -0300

... Of 8 I/O boards, I've only come across one that had the mod with the raised platform.

Most of the Field Change Notices will have an 'effectivity' section which outlines which serial numbers might need to the field change.

As a general statement, if the Chroma isn't on the serial number list (or didn't have parts swapped into it from one that was originally on the serial number list) - then the notice doesn't apply (e.g., newer cards would automatically have the new circuitry included in the circuit board itself, hence not need to have an add-on modification).

In the case of the raised platform, you can review the I/O board to see if Z55 is physically present or not. If it is present (as shown in the 'current' schematics - xref: Schematics and Drawings) then the 'fix' is already present.

If you don't find Z55 (e.g., nothing connected to pin 7 of the 0809 ADC - such as is shown on the original ARP branded schematics of the preliminary service manual) - then the end-of-convertion modification would apply.

Roel D. [21010092] · Fri, 11 Apr 2014 19:56:43 +0200

If that's what it is, then nothing else will work, so you couldn't do [Set Split][9] to try to disable it. Oh, I suppose you could press those spots on the panel, but it would be pretty obvious that the CPU wasn't paying any attention.

But if that's the issue, a scope may not help diagnose why, either. When EPROMs are that old, they may start dropping bits, and all it takes is one to crash the CPU. Fortunately, this doesn't mean the EPROMs are defective, it just means they need to be reprogrammed, and they'll be good for another 30 years.

As I have the CC+ installed and the synth is working, I think I can rule out the EPROMS. With disable it, I indeed meant [Set Split][9]. So I assume that it's not the jiggling parameter issue either.

My scope is at least as old as the synth, so I don't really have good faith in it. And I'm just getting the hang of it all again after being mostly a musician for the last 10 years. But next week I can take home another scope that might help me have a look at it. I'm guessing a write strobe/tapper logic issue or tapper driver (Z38) issue seems most logical for now.

Chroma on Ebay UK

Jesper Ödemark [21010135] · Tue, 08 Apr 2014 15:06:34 +0200

[eBay item #261442937680]

Don't know if it's been mentioned or if anyone here is the seller... but here it is anyway.

From the description: "You are bidding on a used and fully rebuilt Rhodes Chroma synthesiser, overall condition is incredible. Only 3000 units were ever produced [sic]. This unit has had a full overhaul including new power supply and full calibration, it also has a rare internally mounted midi interface. It also comes with the original Anvil full flight case. ... this Rhodes Chroma has been used on countless sessions for many artists including Herbie Hancock and Michael Jackson." Unfortunately I missed the pictures on this one; it doesn't look like it sold: "This listing was ended by the seller because the item is no longer available." — Chris

Ganged channel editing and the "Data Entry" slider via CC function?

William Santana [21030244] · Tue, 8 Apr 2014 15:05:20 -0700 (PDT)

Would it be possible and desirable for Chroma owners to be able have access to the ganged channel editing feature as well as a "Data Entry" slider feature via control change or sysex control? If it is possible, I would certainly see an advantage to having these features on an external controller.

David Clarke [21030085++] · Tue, 8 Apr 2014 20:45:59 -0300

... Would it be possible and desirable for Chroma owners to be able have access to the ganged channel editing feature as well as a "Data Entry" slider feature via control change or sysex control?...

William - I'll let others chime in on whether they'd see these as desirable - but a few comments (that hopefully won't dissuade others from sharing their thoughts)

I would suggest that the 'ganged' approach is already implemented by some users today via the external tools they use for interfacing with the Chroma.

Specifically, software editors will typically let you 'link' controllers together so that when you change one it will also change others. Those implementations though are not restricted to just changing A & B of the same parameter at the same time - but instead allow more flexible linkage (e.g., have filter mod depth change as frequency changes, have more than 2 things linked, etc.)

I've personally never done much with 'Edit A' and 'Edit B' both on at the same time - but if it were to be implemented, the 'easiest' way is to have the external controller do exactly what the Chroma does internally - which is actually to send two different controller messages (e.g., simply send the A and B CC if you wished to have a single knob control both).

If it was desired to have the Chroma somehow automatically do this (e.g., to treat every A parameter change as an A&B parameter change) there'd have to be agreement as to how the Chroma would know about this mode and how it gets turned off/turned on.

The 'Data Entry' approach is technically possible, but is confirmed not there today. That said - if added, there would need to be some discussion about how it should 'work', keeping in mind that the slider on the Chroma today internally scales itself for the number of parameters. So - let's assume that an alpha dial that needs to be rotated 360 degrees for a full mod-depth range. If you then went to a parameter like filter mode - would you need to rotate it 180 degrees to change from LP to HP - or 5 deg? If someone already has a dedicated knob for a given parameter, would they see utility in having a physically separate "data entry" capability beyond the one that is already on the front panel of the Chroma? Is the desired functionality essentially to add MIDI support for a "Data Increment" and "Data Decrement" functionality (e.g., what is often implemented as MIDI controller ID 96 and 97)?

Chris Smalt [21010280+] · Thu, 10 Apr 2014 00:05:26 +0200

Would it be possible and desirable for Chroma owners to be able have access to the ganged channel editing feature as well as a "Data Entry" slider feature via control change or sysex control?

Ganged channel editing is essential when controlling (serial) filters, and also for the oscillators.

To me, the Chroma's two assignable levers, two assignable continuous pedals, and an assignable data entry slider (the active parameter is saved along with the program, remember?) have always provided plenty of real time control options. I became pretty quick changing the active parameter on the fly. I did try some remote options, and was rather underwhelmed by, for instance, an external controller mapped to filter frequency, because it didn't sound as smooth as modifying parameter 41, 43 or 45 (A *and* B) on the Chroma itself.

I remember sending "ganged" controller messages from Opcode Vision's faders back in the day, which worked very well and was quick to set up, but there don't seem to be many standalone control surfaces that do this.

William Santana [21030244] · Wed, 9 Apr 2014 16:55:54 -0700 (PDT)

My main interest for desiring these features is for the added benefit it would add to a dedicated programmer I am developing [see Chroma Programmer, March]. Having a data entry encoder rather than using the original data entry slider means that 1) you would not have to wear out the original Chroma part and 2) I could have the data entry encoder next to the CC+ supported display so, the current params on the display would be able to be edited quickly without having to look away from the display.

iPad app editor

Sam Shepherd [21010117] · Fri, 11 Apr 2014 02:17:18 +0100

Hi There,

I've been searching around but having trouble getting this amazing iPad app of Leon [21010301]/Matrix [21030220] to work out with my Chroma, midi is definitely sending to the Chroma from the app but no response.

It responds to note-on messages over midi, but doesnt pickup any of the CC commands from the ipad.

I understand that the chroma may have to be in a special mode using a set-split function, but i've recently had some trouble with the interface & it can be a little erratic at times!

I have a CC+ kit on my chroma 21010117. (also, is it normal that midi isn't sent as standard from the chroma?)

thanks for the help everyone, and thanks Matrix and Leon for these amazing apps, Looks like it's taken ages to do this and so grateful for your efforts

all the best

Sam

David Clarke [21030085++] · Fri, 11 Apr 2014 07:51:47 -0300

... It responds to note-on messages over midi, but doesnt pickup any of the CC commands from the ipad. ... is it normal that midi isn't sent as standard from the chroma?)

There may be settings available to adjust operation, but with the CC+ installed, MIDI note on/note off information (at least) should be sent from the Chroma, by default.

If problems are seeming to be had receiving data from an external controller (like the iPad setup), then the following settings are some items to check/consider:

• Go into the configuration menu via [Set Split 36]
• Select [P6] - Ensure set to "On"
• Select [P18] - Select "CUSt"
• Select [P20] - Move "Parameter Control" slider
• Select [P24] - Select "Prog"
• [Set Split 36] (to exit the configuration menu)

If expected operation is not seen hen the next attempt is made to receive external note/controller data, a review can be done of the green LED on the MIDI interface box (or the one of the small decimal LEDs in the large 2-digit program number display on the Chroma) to see if they light in response to incoming MIDI data or not.

Sam Shepherd [21010117] · Sat, 12 Apr 2014 02:34:15 +0100

David, you star! works like a dream! thank you.

i've started to make a copy of this controller with lemur. It can save presets! that might be a cool function to have, Unlikely to happen soon, but ill post the result should i get it working.

thanks again for the help :)

Sam

One key not working

Pontus Hagberg · Sun, 13 Apr 2014 23:03:44 +0200

There is one key not working properly on my Chroma. If you play a very soft but fast staccato note you will get it work , sending out a very low velocity value. If playing harder there will be no sound or the note will hang. The particular note works when playing from a MIDI Masterkeyboard It is the #F just below the Parameter 32 select button.

Any ideas ?

Best Regards
Pontus

Paul DeRocco [21030230] · Sun, 13 Apr 2014 14:46:26 -0700

From: Pontus Hagberg

There is one key not working properly on my Chroma. If you play a very soft but fast staccato note you will get it work , sending out a very low velocity value. If playing harder there will be no sound or the note will hang.

Since they're visible mechanical leaf switches, they're not hard to figure out. One contact could be slightly bent, so that it doesn't make reliable contact. Another possibility is that the key itself doesn't have sufficient dip, because of misadjustment at the balance rail or at the front of the key. A more likely issue is some persistent crud on a contact.

What I use to clean contacts is a narrow strip of plain paper dipped in alcohol, inserted between the contacts while they're open, and then dragged back and forth while they're closed.

Michael Röpsch [21030816] · Mon, 14 Apr 2014 00:11:42 +0200

Hi Pontus,

maybe a mechanical problem: One of the key contacts seems to be out of shape. Open your Chroma. The distances of the contact springs should be the same overall - and they are critical. If an aberration is visibly recognized you can try to bent the spring to correct form (carefully! and the Chroma turned off!) - but this is difficult... Also try to clean the contacts with a contact cleaner.

If the contact spring couldn't get the correct shape - and if it is the upper one: Perhaps it's possible to mount a screw (HAS TO BE plastic material !!!) near to the spring mounting to press it slightly down without fixing it hardly. I did this years before - and if you need I'll send a pic.

On the other side it could be an electronic problem with the stack switch board

Good luck

Philippe [21010227] · Mon, 14 Apr 2014 01:37:38 +0200

Definitely sounds like the middle leaf doesn't go back in contact with the bottom leaf when the key is released. So it fails in the process to inform the voice board that you released the key, therefore the voice board behaves as if you are still pressing the key, reason why the note will hang (or be silent because the sound has ended) since your "imaginary finger" is still pressing on the key. This means either the lower leaf is not resting up enough or the middle key is not resting down enough. First thing I would try (after making sure visually there is no obvious physical twist or damage to any of these leaves) is to press lightly up the lower leaf until it is in permanent contact with the middle leaf when key is at rest. You might need to apply this pressure a few times before it puts the leaf back into proper place.

Of course it could be another reason, yet this would be my most obvious first suspicion...

Good luck,
Phil

Chroma Polaris questions

Frank Hettlich [21030041+] · Sun, 13 Apr 2014 23:44:19 +0200

Hello Chroma Polaris users,

a couple of questions arised when I was playing with Chroma Polarii again trying to dig deeper into them:

1. Checking the Polaris' OS revision

David Clarke once wrote:

"If you're not hooked up via midi at the time, you can also get the revision level from the keyboard itself. Just hit LF-D-2, and the flashing number LED will represent the version number." [See Polaris, OS revisions and more, April 2002.]

-> I just did that:

• first Chroma shows first a shortly flashing "5" and then jumped to a steadily flashing "D".
• second Chroma shows first a shortly flashing "9" and then jumped to a steadily flashing "D".

What does that mean? First has version 5 and second one version 9 installed?

2. Differences of Polaris revisons

Are there any major differences when it comes to the installed Polaris os and what is the latest one (my understanding is that is version 9)? Does it make sense to update an older version?

3. Volume attack

I get different attack behaviors when using different voices from nearly 10 seconds (probably less) as mentioned in the manual to rather short 2-3 seconds. The most common behavior are quite short attack values (unfortunately).

4. Two of the CEM3372 chips in one of my Polarii are dead. They are labelled:

• CEM3372
• 8402 3160A-01

and

• CEM3372
• 8408 3160A-01

whereas most other CEM3372 have version 3160B-01 instead of 3160A-01

My friend google gives some interesting results that basically say that there are indeed differences between these versions (3160A-01, 3160B-01, 3160C-01, 3160D-01). Symptoms are e. g. a different VCF behavior (not only with the Polaris but also when installed in the Akai AX-80).

Did anybody ever check his CEM3372? What is the "standard" CEM3372?

Thanks a lot

Frank

David Clarke [21030085++] · Sun, 13 Apr 2014 20:47:41 -0300

first Chroma [Polaris] shows first a shortly flashing "5" ... second Chroma [Polaris] shows first a shortly flashing "9" ... What does that mean? First has version 5 and second one version 9 installed?

Yes, exactly - the first has Rev 5 and the second has Rev 9 firmware.

2. Differences of Polaris revisons

Are there any major differences when it comes to the installed Polaris os and what is the latest one (my understanding is that is version 9)? Does it make sense to update an older version?

There may be some exceptions - but generally speaking, the only reason there's a newer version of firmware is to correct behavoiurs of the earlier versions. Unless you see something in the older firmware that you specifically wish to maintain, I would generally recommend the Rev 9 firmware.

Insofar as I know, that was the latest formal firwmare - with the possible exception of '9*' (which is 9 plus a Rev 5 velocity table - xref: Polaris sys ex broken, January 2011)

(I'm not aware of all the details of changes between versions)

3. Volume attack

I get different attack behaviors when using different voices from nearly 10 seconds (probably less) as mentioned in the manual to rather short 2-3 seconds. The most common behavior are quite short attack values (unfortunately).

If not already done, I would recommend going through the adjustments and setups - expecially the Volume Offset and Key Sensitivity settings - noted here: Polaris Service Manual: Adjustments and Checkout.

4. Two of the CEM3372 chips in one of my Polarii are dead. They are labelled:

... My friend google gives some interesting results that basically say that there are indeed differences between these versions (3160A-01, 3160B-01, 3160C-01, 3160D-01).

A link discussing this is: Akai AX80 problems, please help - Gearslutz.com.

...Did anybody ever check his CEM3372? What is the "standard" CEM3372?

I don't know if the Polaris always used the same revision - but I can confirm that my current Polaris (S/N 300831) uses RevB (3160B) parts.

David Clarke

John Leimseider [21030434++] · Sun, 13 Apr 2014 23:55:56 +0000

I got a bunch of the rev B CEM3372's from Fender, indirectly. My Polaris has that version, too. The different versions need different resistor values in a synth that doesn't do software calibrations.

The version 9 software added a bunch of extra MIDI functions. There may be others that I never noticed.

Doug Terrebonne [21030114] · Sun, 13 Apr 2014 19:45:55 -0700 (PDT)

As I mentioned in that Gearslutz thread in the AX80 it is critical to match the CEM3372 revs but I don't think that's the case in the Polaris.

I have rev A and rev B CEM3372s in stock if you need any. I can also provide a programmed EPROM of the v9 Polaris firmware.

Doug

www.synthparts.com

Paul DeRocco [21030230] · Sun, 13 Apr 2014 23:11:18 -0700

From: David Clarke

There may be some exceptions - but generally speaking, the only reason there's a newer version of firmware is to correct behavoiurs of the earlier versions. Unless you see something in the older firmware that you specifically wish to maintain, I would generally recommend the Rev 9 firmware.

Insofar as I know, that was the latest formal firwmare - with the possible exception of '9*' (which is 9 plus a Rev 5 velocity table - xref: Polaris sys ex broken, January 2011)

(I'm not aware of all the details of changes between versions)

That velocity table is the thing to watch out for. I like the newer version, but lots of people preferred the older version. Of course, if you have access to an EPROM eraser and programmer and a little time, you can try them both out.

I also have a rev 10, which was never released. Since I don't have source code for the earlier versions, I don't remember what change there was. I think it may have a little extra code to allow the use of a 24MHz CPU with a 12MHz crystal.

Frank Hettlich [21030041+] · Mon, 14 Apr 2014 15:00:56 +0200

Thanks a lot to all who replied with tips and tricks - this the most friendly and knowledgable user group I am aware of!

One of my Polaris has only 3160Bs installed (and all are working fine), the second one had 5*3160A (2 of them are broken) and one 3160B - for whatever reason there is this mixture as I bought it as "new/spare".

Today I took the advice to calibrate (especially the volume offset) and diagnose the second one:

1. I was able to set the volume attack rather equally - great!

-> Though the attack time is nowhere adjustable between 0-10 seconds as stated in the manual but more like 0-2 seconds (and that is the case with the other Polaris as well, so my guess is that the 10 seconds were on the "to-do-list" for the programmer but never went into reality or there are technical reasons. Other user experiences are welcome!)

2. There definitely IS a (slightly) audible difference between the 3160A voices and the 3160B voice. Playing with different cutoff and resonance settings I was always able to tell which one the 3160B voice was - funny!

-> So Doug, I would like to get 3*3160A (will contact you privately) and may offer the 3160B for sale or keep it - just in case.

The Polaris with mostly 3160As has a lower serial number 2123-300199 than the 3160Bs which has sn 2123-302651. So the manufacturer might have used those chips which were the actual ones at that very moment. I guess that Curtis produced those CEM3372-3160A-D in that order.

Anyone has new spare nuts for the backpanel sockets which seem to be always rusty after all these years and maybe more durable metal sockets for the 3 output sockets (high, low, headphone).

All the best

Frank

Paul DeRocco [21030230] · Mon, 14 Apr 2014 11:30:31 -0700

From: Frank Hettlich

1. I was able to set the volume attack rather equally - great! -> Though the attack time is nowhere adjustable between 0-10 seconds as stated in the manual but more like 0-2 seconds (and that is the case with the other Polaris as well, so my guess is that the 10 seconds were on the "to-do-list" for the programmer but never went into reality or there are technical reasons. Other user experiences are welcome!)

Since I'm "the programmer", I'll speak to that one. My Polarises have exactly 10-second attack times on both envelopes. I suppose it's possible that this was a bug in earlier revs, but it's not like it takes special software to get 10-second times. So I wonder if perhaps there isn't an analog problem resulting in your not getting the full range of your sliders. Try pushing other sliders all the way up, and seeing if they have the expected range. Try master tuning--it should go up a semitone. Try sweep rate--it should go up to about 10Hz. If you find a problem, there is an internal adjustment on the ADC, and an adjustment procedure detailed on p6-2 of the service manual.

Anyone has new spare nuts for the backpanel sockets which seem to be always rusty after all these years and maybe more durable metal sockets for the 3 output sockets (high, low, headphone).

The difficulty with those jacks is that some of them have a larger-than-usual bushing, requiring a larger-than-usual nut. The panel hole is also larger-than-usual, making it difficult to replace with a more conventional jack. I looked around for some sort of ring that could take up the space between a standard 3/8" bushing and the larger hole, but came up empty.

Frank Hettlich [21030041+] · Mon, 14 Apr 2014 22:34:49 +0200

Paul,

until yesterday I had 3*Polaris (2 left that I will keep) and all of them show the same behavior.

The filter attack when opening the filter (cutoff) works like expected (means the sound is flowing in in a very nice smooth/linear slowly movement) but with the volume attack when at max (no filter modulating at all) the perceived sound is like starting with a certain value (half volume) rather quickly (1-2 seconds as seen on my volume metering in my RME UFX) and then it takes some time (maybe until 10 seconds) to fully achieve full volume. I just checked my quite new Novation Bass Station 2 and it works nearly the same - so no worry. This question came up by the buyer of the Polaris who wondered about this behavior.

Thanks for explaining why it is not easy to get replacement sockets. What was the reason using those output sockets back in the days?

You once mentioned considering writing a new os for the Polaris. What´s on the feature list you would like to implement? I would like:

• individual volume levels for each oscillator
• higher speed and more waveforms for the lfo
• second lfo
• more configurable ring modulator (volume levels for carrier and modulator)
• different filter modes (lp, hp, bp)

Thanks again for your help

Frank

Paul DeRocco [21030230] · Mon, 14 Apr 2014 14:06:01 -0700

This discussion really belongs on the Polaris list.

From: Frank Hettlich

The filter attack when opening the filter (cutoff) works like expected (means the sound is flowing in in a very nice smooth/linear slowly movement) but with the volume attack when at max (no filter modulating at all) the perceived sound is like starting with a certain value (half volume) rather quickly (1-2 seconds as seen on my volume metering in my RME UFX) and then it takes some time (maybe until 10 seconds) to fully achieve full volume. I just checked my quite new Novation Bass Station 2 and it works nearly the same - so no worry. This question came up by the buyer of the Polaris who wondered about this behavior.

If the volume doesn't rise slowly from zero when you've selected a long attack on the volume envelope, then you've got misadjusted volume offset (LF, A, 9).

Thanks for explaining why it is not easy to get replacement sockets. What was the reason using those output sockets back in the days?

Dunno. That's what they chose at Fender of Japan.

You once mentioned considering writing a new os for the Polaris. What´s on the feature list you would like to implement? I would like:

• individual volume levels for each oscillator
• higher speed and more waveforms for the lfo
• second lfo
• more configurable ring modulator (volume levels for carrier and modulator)
• different filter modes (lp, hp, bp)

The only thing I'd consider doing to the Polaris is a Digital Polaris. Since the control panel is what it is, I wouldn't change the basic parameter structure, except maybe to add a few adjustments to the assignable slider by pressing two switches at a time (e.g., Volume + Volume Pedal = Reverb Level). What I'd probably add would be stereo output, reverb, 64 voices, multi-track sequencer using Standard MIDI Files, 132 sequences, and modern connectivity including USB and Ethernet. But I'm not promising anything, since I haven't quite finished the Digital Chroma [see Digital Chroma, January].