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ChromaTalk Archives: November 2010

Re: question on envelope min-max timing

Heinz Weierhorst [21010276] · Mon, 1 Nov 2010 16:05:13 +0100

Go to first message in thread, October 2010

Hi all.

Take a look to the programming manual [specifically, Panel Parameter Descriptions]. The envelope parameters say 1=1msec. 30=10sec. So there can't be a linear relationship! I think it's done in an exponential manner. 1=10msec. 10=100msec. 20=1sec. and 30=10sec.

Paul DeRocco [21030230] · Mon, 1 Nov 2010 10:42:00 -0700

Attack is different from decay and release, because it's linear instead of exponential. Decay and release are identical, except that a decay parameter of 31 is an infinite hold, while a release parameter of 31 is just a longer release. The relation between parameter values and times is roughly exponential, and is done through table lookups. These are the tables:

pv ramp decay
1 65535 255
2 32768 128
3 27087 105
4 22390 86
5 18508 71
6 15299 58
7 12647 48
8 10454 39
9 8641 32
10 7143 26
11 5905 22
12 4881 18
13 4035 14
14 3335 12
15 2757 10
16 2279 64
17 1884 53
18 1557 43
19 1287 35
20 1064 29
21 879 24
22 727 20
23 601 16
24 497 13
25 411 11
26 339 9
27 281 7
28 232 6
29 192 5
30 158 4
31 131 3*

*(release only)

The pv column is the parameter value. The ramp column, divided by 65536, is how much of the total distance is traversed in each control signal sample period, where the distance is computed once at the start of the attack. The decay column, divided by 255, is how much of the distance is to be traversed in each sample period, where the distance is recomputed each time. I seem to recall the sample rate is about 50Hz.

Chroma for sale

Erik Vellinga [21010286] · Sat, 6 Nov 2010 21:03:17 +0100

Hi guys,

Just to let you know:

A couple of days ago I put my Chroma on the local Dutch auction site www.marktplaats.nl. I am however considering to put it on Ebay. She has been with me for more than 20 dedicated years but I have to let her go due to private circumstances. The wooden parts have been refurbished, she has a switched-mode PSU inside, rev. 1.4 EPROMs, well tuned, no ERRORs and a Cult interface. What would be a good price to ask ? Since yesterday the current bid is at € 2000,- but I consider that a bargain.

Going through all the soundpatches I have in order to make a nice demo-bank she doesn't make it easier to sell…

If anyone of you is interested, you can watch the advertisement at [obsolete url removed]

Regards,

Erik

A couple of pictures from the auction:

Ivan Hirländer · Sun, 07 Nov 2010 09:28:06 +0100

Hi Erik,

you have another bid at 2200Eur, do not forget... :)

Doug Terrebonne [21030114] · Thu, 11 Nov 2010 21:10:49 -0800

Did you also put it on ebay? Is this yours or a scammer?

[eBay item #320614969358]

Claes von Heijne[16330008] · Fri, 12 Nov 2010 08:53:43 +0000

Nice price :)

The USD is low, but 5500 is good.

Doug Terrebonne [21030401] · Fri, 12 Nov 2010 02:35:58 -0800

wheels mod

By the way I like the mod wheels. I'd like to have those instead of the dinky levers on the stock Chroma. Can you tell us about it and maybe give us some internal pics of how they mount inside?

Jesper Ödemark [21010135] · Fri, 12 Nov 2010 11:40:28 +0100

Re: wheels mod

Wow, I totally missed those when watching that picture originally.

Erik Vellinga [21010286] · Fri, 12 Nov 2010 12:06:14 +0100

Did you also put it on ebay? Is this yours or a scammer?

Yes, that's eh…was mine. Sold for 5500 US !

Chris Borman [21030194+] · Fri, 12 Nov 2010 06:43:01 -0500

Re: wheels mod

I want to install a set of these Wheels in my Chroma: Synthwood backlit wheel box for our Pro-One conversion kit

Jesper Ödemark [21010135] · Fri, 12 Nov 2010 13:03:15 +0100

Re: wheels mod

I consider the Chroma too stylish for that. But if you're going to do it I vote for red/green to match the panel graphics. :)

Dave Bradley [16330135] · Fri, 12 Nov 2010 09:22:39 -0600

Re: wheels mod

Sacrilege!

The Chroma/Oberheim levers rock! I HATE wheels!

Robb Witt [21030230] · Fri, 12 Nov 2010 11:16:40 -0500

Re: wheels mod

Thank Warren Ames!

Paul DeRocco [21030230] · Fri, 12 Nov 2010 10:12:04 -0800

Re: wheels mod

Sacrilege!

The Chroma/Oberheim levers rock! I HATE wheels!

I'm glad someone says so, since I spec'ed 'em in the first place. With a lever, you can easily do true electric-guitar-style above-the-pitch vibrato. I've never seen a wheel that could do that.

Rob Witt · Fri, 12 Nov 2010 13:23:12 -0500

Re: wheels mod

Paul -

Sorry if I incorrectly attributed to Warren... I remembered him working out details with the springs and "key-levers", and believed it was his design.

Paul DeRocco [21030230] · Fri, 12 Nov 2010 10:32:49 -0800

Re: wheels mod

Oh yes, he did the design, but I had been arguing for vertically oriented spring-loaded levers since the days of the PPC on the Odyssey back at ARP. So I specified that the instrument would have them, and he specified exactly how they would be made.

Rob Witt · Fri, 12 Nov 2010 13:37:38 -0500

Re: wheels mod

Good call then.

Patrik Gudmundsäter [21010240] · Fri, 12 Nov 2010 19:39:28 +0100

Hi Claes. I got one! I also now got the MK 7 active :)

Doug Terrebonne [21030114] · Fri, 12 Nov 2010 13:56:04 -0800

Re: wheels mod

Well one big advantage with a traditional mod wheel is you can leave it any position to add modulation without manually holding a lever.

John Leimseider [21030434++] · Fri, 12 Nov 2010 14:56:51 -0700

Re: wheels mod

That's one of the nice things about 2 programmable pedals, isn't it?

Doug Terrebonne [21030114] · Fri, 12 Nov 2010 16:15:14 -0800

Yes, that's eh…was mine. Sold for 5500 US !

Wow that must be a new record! Was it an EU buyer? Also, did you have any info on the wheel mod?

Chris Smalt [21010280+] · Fri, 12 Nov 2010 23:52:43 +0100

Re: wheels mod

The Chroma/Oberheim levers rock! I HATE wheels!

I love the levers, particularly the way they stay glued to your fingers! I can't say I hate wheels, but to me, the standard direction of wheels is counterintuitive. Pull = more modulation works for me. Same for pitch.

Dave Bradley [16330135] · Sat, 13 Nov 2010 10:47:17 -0600

Re: wheels mod

Well one big advantage with a traditional mod wheel is you can leave it any position to add modulation without manually holding a lever.

That's what mod pedals are for!

Doug Terrebonne [21030114] · Tue, 16 Nov 2010 23:31:55 -0800

Erik, was there any info you can give us on the wheels mod?

Chroma 21030223 for auction at VEMIA

Peter Forrest [21010096] · Sun, 7 Nov 2010 16:27:33 -0000

Hi Chris and everyone.

There's a nice Chroma for auction at VEMIA, ending November 13.

[Item 8179]

Here's the description:-

Classic poly analogue with weighted action keyboard and velocity sensitivity. Serviced and calibrated on 2nd November 2010 and in full working order with original factory presets installed and tape storage system working (can be used with any DAW to upload and download presets as audio files.) It's cosmetically very good apart from some abrasions on two of the keys and minor gaffer tape residue on one of the wooden side cheeks. Sounds amazing with a very individual tone unlike other classic poly's and with the velocity sensitivity it really is a player's instrument. I'm selling this reluctantly as need the space. Will be delivered to VEMIA after the auction for onward delivery / expert packing and shipping.

Serial number 21030223; first bid 520GBP, no reserve, plus 10% buyer's premium.

Rhodes Piano Sound

Patrik Gudmundsäter [21010240] · Sun, 7 Nov 2010 19:27:41 +0100

Does anyone have a Realy Good Rhodes Pianos sound for the Chroma?

I had one, but it's now gone after all the work we made on it :(

Chris Ryan [21030691] · Sat, 13 Nov 2010 14:40:35 -0800

Patch 26 from Factory Set 1 is not bad.

(By the way, for those replying to the digest, editing the subject line to something other than "Re: [ChromaTalk] ChromaTalk Digest [etc.]" will help those of us receiving individual messages to sort through the threads.)

Jack Colburne [21030142+] · Sat, 13 Nov 2010 18:15:00 -0500

Yeah, If i remember correctly, patch 26 or a tweaked version is what i used to fill the gap after the suitcase 73 and before the Roland MKS-20.

Chris Borman [21030194+] · Sat, 13 Nov 2010 18:26:58 -0500

Run that 4 voice in Stereo through a reverb/room processor . Very organic.

Bruce Sklar [21030660] · Sun, 14 Nov 2010 06:49:12 -0500

wow. I also went from rhodes to mks 20 with a gap-1987 maybe, had a Polaris too, and used it for the tine effect with the Chroma for the body of the sound. External chorusing is best- otherwise you sacrifice the tonal color for two same-tuned oscillators

Dave Bradley [16330135] · Sun, 14 Nov 2010 10:08:27 -0600

Must have been something in the water. I gave up using the Chroma rhodes sound too when the MKS-20 came out!

Marais · Sun, 14 Nov 2010 12:04:23 -0500

What did Zawinul use for those fat tines Sportin' Life's Indiscretion ? Could it of been Chroma or FM ?

Jack Colburne [21030142+] · Sun, 14 Nov 2010 14:35:48 -0500

lol, great minds and all that... And I still have and use the MKS-20. Like the Rhodes piano, it now has a life and sound of its own. That is one wonderful thing about vintage music gear like that.. originally intended to emulate or "replace" item "A", it ends up being something emulated itself. The MKS-20 also replaced my CP-70. How many sample players have CP-70(80) patches?? One that I own has several.

The list of that gear is almost endless.

... though i do, now, wish I held onto the Rhodes.

CC+ MIDI Map

Matrix [21030220] · Fri, 12 Nov 2010 20:44:42 -0800

I just installed the CC+ upgrade with the MIDI extension kit. It responds to not On and Off fine, but I seem to be having trouble getting it to respond to MIDI CC. According to MIDI Controllers Map in the User's Guide it states:

"The default MCM which is installed with Enhanced Programming (Set Split 36, P20) is below. This map attempts to provide a direct mapping for all the standard front-panel parameters on the Chroma."

What does the P20 mean? I hit "Set Split" followed by 36, what do I do after that? Or is it Set Split, 20? Once it's set, should the "Table 1" mapping work?

Matrix [21030220] · Fri, 12 Nov 2010 21:25:21 -0800

Actually, I think it means hit Set Split, followed by 36, followed by 20. It doesn't seem to be working in all cases. What's interesting is there is an LED in the MIDI expansion box that indicates if MIDI messages are coming in. In some cases it lights up, in some it does not. In all cases my midiman UNO lights up that MIDI OUT is going out... If anyone has any ideas, let me know. I'll continue to work on it...

Matrix [21030220] · Fri, 12 Nov 2010 21:33:30 -0800

It looks like it's the MIDI extension kit? I tested it with an E-mu Xboard49. The keys and mod wheels light the MIDI extension kit LEDs, but the knobs do not. Any ideas?

David Clarke [21030085++] · Sat, 13 Nov 2010 10:16:22 -0500

... I seem to be having trouble getting it to respond to MIDI CC...

It should be the default state it was shipped in, but you'll first want to ensure that MIDI CC's/Parameter changes are enabled.

  1. Press [Set Split] and then [36]. That will get you into programming mode.
  2. Press [6]. If this says 'Off', move the slider under it says 'On'. {This turns on Parameters}
  3. If you are wanting to gain access to the full list of Chroma controllers (vs. the subset available with the Syntech MIDI interface), you'll want to select the Expanded MIDI controller map. As you're still in the programming mode, select [18]. Move the slider to have the display show 'CuSt'.
  4. If you want to be 100% sure you're using the default expanded MIDI controllers map, select [20]. Move the slider (this will cause the INIT to be performed).
  5. Exit programming mode by pressing [Set Split] and then [36].
At this time the interface is set up to use the mapping shown in Table 1.

The LED on the cable set/in the display will only flash when the Chroma has received MIDI data that it recognizes. It will not flash for all messages. If you (for instance) send data for a different MIDI channel - or to a controller which is not defined in the Chroma, then the LED won't flash. If the LED is not on for some messages one the wire, then that is telling you that the Chroma doesn't believe those messages are for it.

... I tested it with an E-mu Xboard49. The keys and mod wheels light the MIDI extension kit LEDs, but the knobs do not. Any ideas?

Looking at the on-line manual for the Xboard 49, it looks like the knobs are programmable, and there are several different modes for the data they send. That being the case, the 'devil may be in the details.'

To debug, the recommendation would be to set a specific knob to a specific controller from the table above (on a specific channel), and then work with it to see what messages are/aren't being received by the Chroma (as evidenced by the MIDI activity light on the Chroma).

... What's interesting is there is an LED in the MIDI expansion box that indicates if MIDI messages are coming in. In some cases it lights up, in some it does not...

The default shipping setting for the CC+ is to have the unit in Syntech compatibility mode. In that mode, the original Syntech CC mapping is used - and it does leave quite a few holes in the controller map. That being the case, it would be expected that only some controllers would be received by the Chroma, as noted in Table 1: Chroma Parameters to MIDI Controller Translations in the Syntech/Chroma Cult Manual.

Performing the change to the MCM Mode Selection (as in Step 3 above) will implement the full parameter mapping.

Matrix [21030220] · Sat, 13 Nov 2010 09:17:45 -0800

Thanks David, walking through your steps did the trick. I am now able to edit my Chroma. Woohoo!!! :)

For those interested, here's something I am working on:

It's about 99% done. I have a page/screen for each major group of parameters: Wave A/B, Filter A/B, ENV A, ENV B, Glide & Sweep A/B, Volume A/B & Tune, and Controllers. All I need to do now is test it over the weekend and make some adjustments.

Aside from the direct control, the one other thing I love about this is I no longer have to refer to the parameter chart sheet! It's all there on the screen next to the controls. In the screen you can see the modulation sources printed out and numbered with the numbers next to each additional mod bus.

As for the color coding, green is for parameter labels, orange for values, and red (all the sliders) for control objects.

Once it's ready, I will make it available to others, for free of course.

Aside from the one to one mapping of controls, I'm going to add some track pads on it like the KORG KAOSS Pad controllers. I was messing with another app called S1 MIDI Trigger last night and it was pretty incredible. I had a pad mapped to various note settings and pitch. Let's just say some crazy stuff was coming out of it. :)

With the CC+ upgrade and the iPad, this synth is really going to open up for me.

New Power Unit

Stéphane Roux · Tue, 16 Nov 2010 11:52:50 +0100

Hi Gents,

Do you know if the new power unit is stil available ?

I would need one to repair my old fellow ...

Luca Sasdelli [21010226] · Tue, 16 Nov 2010 12:14:12 +0100

Hi Stephane, yes the power units Are available: I'll let you know details soon.

Stéphane Roux · Tue, 16 Nov 2010 12:25:00 +0100

Good news for me... Let me know, and put me in your list...

TouchOSC Template for the Rhodes Chroma

Matrix [21030220] · Mon, 15 Nov 2010 13:00:54 -0800

See MATRIXSYNTH: TouchOSC iPad Template for the Rhodes Chroma for screens and a link to the templates.

It's done for now. Everything seems to be working ok. It's nice to be able to control the Rhodes Chroma in real time with sliders. The one thing a little annoying with TouchOSC is that the pads on the last page of the template do not spring back when released. So you can't go nuts with it, let go, and have it go back to where you were before you started. This is OK for the filter and resonance, as it's relatively easy to get back, but not so for pitch. S1 MIDI Trig supports snapping back to place, so I will give that a try next.

Marais · Mon, 15 Nov 2010 16:41:30 -0500

1980's super analog synth controlled by iPad, amazing job !!!

A video would be very cool of the rig in action if you can.

Thomas Story [21030352] · Mon, 15 Nov 2010 14:11:41 -0800

Nice! I was working on my own template, I've been on the road alot and haven't had a chance to finish it, so it will be fun to compare what you've done with what I've done.

It really is amazing just how much it opens the machine up!

Matrix [21030220] · Mon, 15 Nov 2010 16:20:25 -0800

I'll see what I can do this weekend in regards to video. If anyone tries it out and can do video feel free to as well. BTW, the template isn't locked, so if anyone expands on it, feel free to share. I just wanted to get it out there. I did basic testing and tweaking with what time I had, but haven't had a chance to really sit down and use it from practical perspective. There were some odd quirks. For example the Mod Amounts on the Chroma for things like the filter go from -63 to 63, but when I set the range to this it didn't quite work as expected. With sweep (LFO) set as the source for example, there was no effect at +63 and it gradually went to full effect as I went down to -63, so to get it to "feel right" I set the range from 63 to 0 in reverse. Also, the buttons on TouchOSC are independent of each other, meaning you can't set up a range of buttons for the modulation sources and use them to select which one you want active. Instead, I'm guessing the last one selected wins. Because of this I decided to just use a slider, so you set the slider to the level corresponding to the mod src. It's not perfect, but it works. There might be other quirks, so if anyone catches anything, let the list know. It is a start though.

I think I'm going to tackle S1 MIDI Trigger next as you don't need the PC in between if you have a Line 6 MIDI Mobilizer which I do. Only thing is the current version does not support text outside of control labels, so you can type out your mod sources like with TouchOSC. I did talk to the developer and it is coming.

One last thing worth noting is a group of people are working on a wireless MIDI interface for the iPad called, The Missing Link. Initially it will be TouchOSC to MIDI out, so you'll be able to use it instead of OSCulator on a PC. As I said it will be wireless as well, so you'll be able to just sit it somewhere, hook up your Chroma and other synths for that matter, and use the iPad to control them. Hopefully it will support MIDI in in time as well so other apps will work with it. Hopefully I'll get to test it out soon.

Matrix [21030220] · Mon, 15 Nov 2010 16:23:06 -0800

In regards to S1 MIDI Trigger and labels, that should have been "so you can't type out your mod sources like with TouchOSC. "

Matrix [21030220] · Sun, 21 Nov 2010 16:23:43 -0800

Video added:

Not a performance. :)

David Clarke [21030085++] · Mon, 22 Nov 2010 18:36:11 -0500

This almost makes me want to buy an iPad :->

Frank McGing [21010198] · Tue, 23 Nov 2010 01:15:28 +0000

Me too... :-) Great work Matrix!

Mal Meehan [21010182++] · Mon, 22 Nov 2010 18:41:40 -0500

I have an iPad but sold all three of my Chromas... now I want one again!!!

Matrix [21030220] · Mon, 22 Nov 2010 19:18:25 -0800

The iPad really is remarkable. Who would have thought there would ever be a dedicated Rhodes Chroma interface like it - and one so "treky" at that. The iPad literally becomes it and nothing but it when you run the program. It's surreal when you think about it. The magic is in the OS and how it becomes whatever it is you are running on it. At first it seems limiting - a device running a limited OS, but then when you are forced to accept it as the device it becomes, it is pure magic. A dedicated controller for the Chroma, or a perfect dedicated lounge synth. And the synths for it are relatively cheap! A KORG ER-1 for $9.99, the iMS for $15, Reactable Mobile for $9.99. The "Little MIDI" analog style step sequencer is FREE!

MATRIXSYNTH: Free Analog Style Step Sequencer for the iPad Now Available

It really is a no brainer and a revolutionary device if you think about it. Note the MIDI stuff does require either a Line 6 MIDI Mobilizer, or now that MIDI support was just released today with iOS 4.2, another device, but they are cheap considering.

The multitasking for synths may not be there yet, but when you consider what you get for the price, it really is an amazing deal, but never, ever get rid of your classic synths. :)

Matrix [21030220] · Mon, 22 Nov 2010 19:22:51 -0800

Just in case you don't click the video link, check this out:

MATRIXSYNTH: iPad Analog-style MIDI Sequencer app, sequencing an Andromeda A6 synth

This app is free. It makes me want two iPads, one for the sequencer and one for the TouchOSC editor. The new OS supports multitasking, but I'm away from my iPad at the moment to see if I can run the two at the same time.

Chroma Pressure Sensor - Final production run?

Chris Borman [21030194+] · Mon, 15 Nov 2010 19:09:20 -0500

Just shipped the last of the CPS orders plus a repair part from my last production run this morning. I do have sufficient remaining parts to complete eight additional CPS Kits. I would like to get 10 folks to commit so I can make another qty purchase of the major PCB and FSR components to keep this train rolling a bit longer. 7 folks (one just today) have expressed an interest in getting a CPS Kit since we started this little venture last December but have yet to commit for various reasons.

Maybe somebody out there who has one installed can put up a video demo of the CPS in action? That might entice a few more folks to go Polyphoinc After Touch!

Just my thoughts for the group.

Paul DeRocco [21030230] · Mon, 15 Nov 2010 16:17:59 -0800

Okay, I'll bite. How do I place an order?

Thomas Story [21030352] · Mon, 15 Nov 2010 17:50:05 -0700

I can be put on the list also!

Stéphane Roux · Tue, 16 Nov 2010 12:26:40 +0100

Hello to all,

i would be also interested by a kit. Nevertheless, i would also appreciate to see a demo of it before buying ..... any you tube demo or else ?

Stéphane ROUX to be added in your list ! thanks

Stéphane Roux · Wed, 17 Nov 2010 12:20:49 +0100

CPS demo

Hi all,

Chris, please note that i am interested in a kit.

But seems that several others owners would appreciate to hear it (or see) it in action. Does any one have a video of a working system ? just to appreciate the changes ...

Would be , i think, very appreciated by all of us.

Marais · Wed, 17 Nov 2010 11:35:02 -0500

Re: CPS demo

same here please

Chris Borman [21030194+] · Thu, 18 Nov 2010 17:03:56 -0500

So far I have had a few confirms but not enough yet... If anybody with a CPS kit installed could provide some performance feedback to the group that would help the guys on the fence. (only positive reinforcement please...) Really an A/V demo would be the bomb! Come on guys make one! Show your Stuff!

Paul DeRocco [21030230] · Thu, 18 Nov 2010 16:22:20 -0800

So far I have had a few confirms but not enough yet...

Am I on the list? I expressed interest here on the mailing list, and asked how to order, but didn't hear any acknowledgment. I just want to make sure you know I'm definite about it.

Chris Borman [21030194+] · Thu, 18 Nov 2010 19:35:50 -0500

You are on the list Paul. To order, all you have to do is ask! Just shoot me an email with your address.

Chris Borman [21030194+] · Mon, 22 Nov 2010 09:34:53 -0500

Chroma Pressure Sensor - Last of the Kits

I sent invoices to the 7 folks who have responded. I have parts for just 4 more. Last call for anyone else who wants Polyphoninc Aftertouch in their Chroma...

This video demostrates Polyphonic Aftertouch on the Sequential Circuits T8. The hardware used for this particular synthesizer was designed by Frank Eventoff. Frank helped with FSR design for the Chroma Pressure Sensor Kit:

Marais · Mon, 22 Nov 2010 10:16:42 -0500

Re: Chroma Pressure Sensor - Last of the Kits

Is it possible to post a simple audio mp3 of a Chroma unit using the pressure kit. Also some more feedback from users on how the kit works, how it is to install, tweek, effect on the current keyboard etc. would be helpful.

Luca Sasdelli [21010226] · Mon, 22 Nov 2010 16:08:28 +0100

Re: Chroma Pressure Sensor - Last of the Kits

Hello Marais,

I've installed two of them and I can confirm that the whole kit is very well designed and built, so the installation task is quite straightforward (see my feedback on Chroma site). There is some tweak to do about the mechanical positioning between support bar and key weights, to suit the player' feelings.

Its use during playing is reactive and immediate, allowing a quite wide range for generated control data, very usable in driving pitch, cutoff, mod amplitude etc. in an effective manner. The separation between key pressure areas is excellent, therefore is possible to have a key with near maximum value and the neighbor areas totally clean from the effect.

About the video I'm quite busy right now, but if I find some spare time I can arrange for it. Anyway, it's... a polyphonic aftertouch :), so IMHO there is nothing really special in it.

Chris Borman [21030194+] · Mon, 22 Nov 2010 10:26:20 -0500

Re: Chroma Pressure Sensor - Last of the Kits

Basically It functions just like the plain old Modulation Wheel, only you don't have to take you hand off the keyboard and in this case every note has one of its own! The modulation effect can be Volume, Pitch, Resonace/Filter effect, etc. I recall some mentioned that you can even trigger alternate sounds with Key Pressure.

Stéphane Roux · Mon, 22 Nov 2010 16:39:57 +0000

Re: Chroma Pressure Sensor - Last of the Kits

Hi

understand that it is well designed.... But, to have a musical description of the system ... well, it will convince more people than words..

Some keyboards are equipped with aftertouch, but the effect is not always let's say "musical".... Some are equipped with, and it sounds that the instrument is designed espacially for aftertouch effect ...

Not sure i am very clear about this ... This also depends on the sound you are playing also... Vangelis typical sounds will for sure be improved with aftertouch....

I think some of us are only interested to see the system working, and also to hear how musical is the effect... Does the Chroma worth this modification ? what is the imporvement in term of sound for example ? what can it offer as this was only an option for chroma ?

just some questions ....

Thanks whatever for the link to the prophet 8 demo.

John Leimseider [21030434++] · Mon, 22 Nov 2010 09:49:15 -0700

Re: Chroma Pressure Sensor - Last of the Kits

I've had the pressure kit in my Chroma for many years… It is amazing. I'm assuming that Chris' kit will work the same. To be able to control so many functions independently for each key puts the Chroma in a different league. I also have a CS80, and each of them gives you different and musically useful applications for the pressure. The thing to keep in mind, for me at least, is that it takes practice. Just like adding velocity to a polysynth changes what you can do, poly pressure adds more nuances to your playing. I really like it for filtering, but also for pulsewidth control. I have a patch I did where the aftertouch fades in an octave as the fundamental fades out, so it does great "guitar" harmonics.

What I'm saying is that the pressure won't help until you spend a little time learning to program for it, and then using it. I think it's great that Chris went to all the trouble. The Chroma community should support him on this. Everyone should order a kit. It's a real bargain!

Luca Sasdelli [21010226] · Mon, 22 Nov 2010 18:07:03 +0100

Re: Chroma Pressure Sensor - Last of the Kits

Hi Stéphane,

I find very hard to answer to your "musical" questions... :) The personal taste and feeling is something... personal, and there is nothing as the real instrument feel to check it.

Anyway, just to try in feeding some answers: polyphonic aftertouch has each single key as a complete expression world, in terms of both velocity and after-pressure; some channel-aftertouch equipped keyboards tend to express the aftertouch more as an "instrument dash" effect instead of a note-wise one: this is not the case of the polyphonic aftertouch, where you can apply the desired effect for each individual key. I don't experience any fatigue in doing this, but of course it depends on the aftertouch sensitivity, that could be adjusted via the on-board trimmer and the software values.

On the other hand, I can't feel unwanted aftertouch effects while playing: this the reason because I judge this kit as very well designed. As an example, I own a Yamaha AN1X and its (channel-) aftertouch is terribly invasive...

I can't understand why you do ask about some degradation (???) of Chroma sound with the kit; the key action is near the same (not exactly the same, because at the end of key travel now there is a soft damper), velocity expression is as before, and there is no reason to suspect that the sound could have any issue with the kit installed. Think that original Chroma firmware already has the polyphonic aftertouch control embedded (old CPU board does work with it as-is), therefore the instrument has been designed with this tool in mind.

Why most of Chromas were built without the pressure sensor? Do you think this was a quality-based choice? I don't know; maybe the ex-ARP guys could answer properly. I guess this was caused because of costs, or maybe late manufacturing times and subsequent delivery delays.

Matrix [21030220] · Mon, 22 Nov 2010 11:51:24 -0800

Re: Chroma Pressure Sensor - Last of the Kits

A few questions for me:

  1. With the CC+ upgrade will the Chroma transmit poly aftertouch with this mod so you can use the Chroma to control other synths that support it?
  2. Can you choose between poly and channel or is it always poly?
  3. How difficult and forgiving is the installation? Is it something a "novice" can do with some patience? If you make a mistake is it easy to recover or is it the sort of thing where you need to be super careful to get it right the first time?

Jesper Ödemark [21010135] · Tue, 23 Nov 2010 00:11:00 +0100

Re: Chroma Pressure Sensor - Last of the Kits

Mine is the kit waiting for a spare part (on it's way over the pond) so I've just tested the working bits (i e 97% of the keys) but I've used the aftertouch on my old FZ-1 sampler for years. Controlling for example my MS-20 LPF with velocity and HPF with aftertouch is modulation heaven. The difference is of course that the Chroma is polyphonic and the keyboard so much better. I've tested my pressure sensor and it's a delight to play (and I'm no key wiz!). It's best suited for textures (think Vangelis) and modulation mayhem effect style, but as John points out below. There are no real limitations to the possibilities.

I see the CPS as a great addition to a splendid keyboard. I'm quite sure that it adds to the second hand value too. So if you have the spare cash I strongly recommend getting one!

Peter Forrest [21010096] · Tue, 23 Nov 2010 00:18:50 -0000

Re: Chroma Pressure Sensor - Last of the Kits

John's absolutely right. If you like playing a synth pianistically (if that's a word), then poly aftertouch can give you more variation, control, touch, feeling, than the best acoustic piano in the world can give you.

The kit I bought isn't yet installed, but please Chris can you put me down as a definite for another one (for some future Chroma).

Matrix [21030220] · DATE

Re: Chroma Pressure Sensor - Last of the Kits

Hi Chris. Please put me down for one. Do you take Paypal?

Chris Borman [21030194+] · Mon, 22 Nov 2010 19:33:54 -0500

Re: Chroma Pressure Sensor - Last of the Kits

Nothing like having stuff waiting around for the oppourtunity. I have lots of that! I will save my last Chroma for you.

Norman Fry · Tue, 23 Nov 2010 00:51:27 +0000

Re: Chroma Pressure Sensor - Last of the Kits

How much are these kits, again please?

Chris Borman [21030194+] · Mon, 22 Nov 2010 19:56:55 -0500

Re: Chroma Pressure Sensor - Last of the Kits

$345, $15 Domestic (USA) or $30 International

Brian McCully [21030361] · Mon, 22 Nov 2010 12:47:24 -0800

Re: Chroma Pressure Sensor - Last of the Kits

Hi - I'm new to the group (I have 21030361) and recently have been asking (i.e. pestering Chris B with) many of the same questions.

regarding the last email:

A few questions for me:

  1. With the CC+ upgrade will the Chroma transmit poly aftertouch with this mod so you can use the Chroma to control other synths that support it?
  2. Can you choose between poly and channel or is it always poly?

A quick search on the Syntech and CC+ parameters on the site yielded:

P16 - PRESSURE MODE: (syntech & cc+parameter)

This parameter is only relevant if you have a pressure sensor in your Chroma. This determines whether you want to transmit the pressure as poly key pressure or as channel pressure. Most keyboards only recognize channel pressure. The selections are "p01" and "chan".

P26 MIDI Pressure Transmit (On/Off) (cc+ only parameter)

If set to 'On', pressure commands will be sent via MIDI (if they are generated from an installed pressure sensor). If set to 'Off', pressure commands will not be sent via MIDI, regardless of whether a pressure sensor is installed.

So in regards to P16 - I guess (I hope) for MIDI Out, that somewhere that (monoAT) channel pressure is interpolated between all the possible (and multiple) key presses or is just the highest value out of any/all of the fingers pressed...because probably not many of my synth modules will respond to polyAT.

I've gone ahead and ordered the pressure sensor upgrade (today) as well as the CC+ and switching power supply. There's only one current keyboard on the market that I'm aware of that has poly pressure (the new Rhodes) and it seems like a very cool option (and I'd rather retrofit my Chroma for ~$350, than drop $5k on a new, heavy keyboard). I played the Sequential T8 at one point and it was wonderful. One of the Ensoniq's offered polyAT and it was pretty cool. MonoAT is indispensible for my playing style, so I'm hoping my Chroma with polyAT turns out just as well, or better!

David Clarke [21030085++] · Mon, 22 Nov 2010 18:21:18 -0500

Re: Chroma Pressure Sensor - Last of the Kits

  1. With the CC+ upgrade will the Chroma transmit poly aftertouch with this mod so you can use the Chroma to control other synths that support it?
  2. Can you choose between poly and channel or is it always poly?

Following up on this point, as of CC+ Firmware Version 213, Poly Pressure MIDI transmission is supported: see Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

At present, Channel/Mono Pressure transmission is not supported.

Recall though that the CC+ feature set is driven by community need - and so if pressure sensor users deem this to be a needed setting, just bring it up for discussion on the list and it could be considered for a future firmware update.

Doug Terrebonne [21030114] · Mon, 22 Nov 2010 18:52:02 -0800

Re: Chroma Pressure Sensor - Last of the Kits

Does a Chroma with CC+ receive polyAT over MIDI if it doesn't have the pressure kit?

David Clarke [21030085++] · Mon, 22 Nov 2010 22:11:07 -0500

Re: Chroma Pressure Sensor - Last of the Kits

Yes - a Chroma with a CC+ will receive both Poly Pressure and Channel Pressure over MIDI, and will action those commands, regardless of the presence or absence of a pressure kit.

Received Poly Pressure (as you'd expect) will directly affect a channel/voice (e.g., the note in question).

As with the Syntech interface, received Channel Pressure on the CC+ will get sent to the Chroma as Pedal 2 commands.

Jesper Ödemark [21010135] · Tue, 23 Nov 2010 14:25:50 +0100

Re: Chroma Pressure Sensor - Last of the Kits

Brian McCully skrev 2010-11-22 21:47:

...because probably not many of my synth modules will respond to polyAT.

But if you hook them up so that the left part is sent to one synth and the right part of the keys to another it still might be very useful. :D

Go to next message in thread, March 2011

Brian McCully [21030361] · Mon, 22 Nov 2010 17:06:53 -0800

mono (channel) AT, with CC+ or Syntech...?

Hello, David Clarke wrote:

Following up on this point, as of CC+ Firmware Version 213, Poly Pressure MIDI transmission is supported: see Re: Pressure Sensor and Rhodes Chroma CPU Plus (CC+)

At present, Channel/Mono Pressure transmission is not supported.

Recall though that the CC+ feature set is driven by community need - and so if pressure sensor users deem this to be a needed setting, just bring it up for discussion on the list and it could be considered for a future firmware update.

Question 1: Does anyone know if the Syntech interface outputs mono (channel) AT, when a pressure sensor is installed and P16 is in this mode? (I hope it does...)

Question 2: Since I'm new in the group, I'm not sure of how to get the ball rolling on any given firmware feature set (is there a poll somewhere?), but I'd be all up for requesting that mono pressure be implemented on the CC+. I didn't see the 'this isn't working yet' note until just now, for P16... Since Chris Borman is about to deliver a new batch of the pressure kits, the demand may be a little higher.

For implementation, I'd guess that the 'hardest pressed note' out of the maximum of any given 16 keys would be the easiest way to convert polyAT to monoAT(?).

PolyAT can be a big MIDI bandwidth hog - it is used in the HUI (Mackie control surface) protocol extensively, where a dedicated MIDI I/O port (not thru'd or shared) was necessary for glitch free operation. PolyAT (or sometimes monoAT even) is generally (and historically) a primary data type that sequencers would like to have filtered out - hence all HUI-type (or compatible) devices are assigned as 'Control Surfaces' -separately- in sequencers, because if polyAT was shut off globally, the Control Surface wouldn't work. PolyAT was partially chosen as a primary controller type for HUI, because it was/is lightly implemented, as far as the MIDI spec goes (I co-wrote the HUI protocol).

Since I've never sequenced with polyAT, it will be interesting to see how smoothly playback (of polyAT) works. Although hopefully it should work fine, as the HUI spec has survived as a standard MIDI control surface protocol (relatively glitch free for automation sake).

Since I can have both the Syntech and CC+ interfaces co-existing (I believe), I'll volunteer for guinea pigging (uh, beta testing)...

David Clarke [21030085++] · Mon, 22 Nov 2010 22:03:03 -0500

Re: mono (channel) AT, with CC+ or Syntech...?

Question 1: Does anyone know if the Syntech interface outputs mono (channel) AT, when a pressure sensor is installed and P16 is in this mode?

Brian - yes, it does.

Question 2: Since I'm new in the group, I'm not sure of how to get the ball rolling on any given firmware feature set...

You've just done it.

The ones who use the CC+ are generally on this list - and so if someone is interested in having the CC+ firmware/feature set changed I recommend that it be raised here on the list to see if others agree/disagree/would find use in it.

Where appropriate, we may even want/need to agree on the details of how a would be feature should operate (as per below).

... I didn't see the 'this isn't working yet' note until just now, for P16... Since Chris Borman is about to deliver a new batch of the pressure kits, the demand may be a little higher.

The interface was always able to receive and respond MIDI pressure - but it originally didn't transmit any.

As there were only a few original pressure sensors out there, and nobody has asked for transmit support, it didn't seem worth the effort to add it in at the beginning.

When Chris started with the pressure kits, the ability to transmit pressure was added. The Chroma natively produced poly pressure commands - and so those messages were the most straightforward to transmit as MIDI.

For implementation, I'd guess that the 'hardest pressed note' out of the maximum of any given 16 keys would be the easiest way to convert polyAT to monoAT(?).

This would be a point we could discuss in terms of how to best implement channel pressure.

For instance, if you're using a mono patch, and you've just pressed another key (that isn't going to sound), should you still use that key data to contribute towards the channel pressure?

If not, the internal 'smarts' to collect the pressure data will have to be aware of the keyboard algorithm being used.

If so, it would seems that perhaps we couldn't realistically limit to a 16 key selection; rather, we'd have to cater for any number of keys.

If you implement the function in terms of the 'hardest note pressed', what do you do when you release that hardest note, but others are still pressed? Consider Key 1 at Pressure 25, and Key 2 at Pressure 50. If both keys are being pressed, then the 'hardest note' would be 50. If key 2 is released, but Key 1 is maintained at Pressure 25 - will you need to produce channel pressure messages to show the decrease from 50 to 25?

Just thinking aloud, is there a way to avoid needing to keep a 127-note table recording pressed/not-pressed status, and the current pressure of that note - and then doing math on the pressure of the pressed notes?

Since I can have both the Syntech and CC+ interfaces co-existing (I believe),

Yes you can.

Brian McCully [21030361] · Mon, 22 Nov 2010 23:04:08 -0800

Re: mono (channel) AT, with CC+ or Syntech...?

David Clarke wrote:

If you implement the function in terms of the 'hardest note pressed', what do you do when you release that hardest note, but others are still pressed? Consider Key 1 at Pressure 25, and Key 2 at Pressure 50. If both keys are being pressed, then the 'hardest note' would be 50. If key 2 is released, but Key 1 is maintained at Pressure 25 - will you need to produce channel pressure messages to show the decrease from 50 to 25?

Through these archives, I was reviewing how the Chroma responds to pressure and it seems to look at a maximum of 16 notes. How they are detected or processed (in memory, for 'dissection') is beyond me, but I get the jist of why 16 was the number. I don't think you can play more than that with 10 fingers, regardless of the sustain pedal state. Or sostenuto, or other 'hold' functions if there are any.

My first question would be is how did the Syntech interface deal with polyAT to monoAT(?)

In (application) a typical monoAT (channel pressure) application, either someone is using one hands, or two hands, to somehow lean onto the keybed to initiate the pressure - whatever finger, hand, or set of clustered notes is pressed hardest yields the end result of channel pressure value. I don't think it's a very complex or interpolated value - it certainly can jump from 50 to 25 in a flash. Relative to firmware, buffer and scanning questions, I don't know if hysteresis questions come to hand, or any buffering for any amount of time is necessary to keep things 'stable'.

Some examples: when I am trying to perform a (e.g.) single note pitch bend via monoAT, I would just hope that: a) there's a smooth (high resolution) pitch bend; b) it's easy to press, to get to the bend within range (and max value as often as not may not be the desired value at any given time) and c) that it doesn't warble once it's at the desired pitch, unless I want it to.

For multiple notes, if there's already a held value and something comes in higher, it is overtaken and high value wins. If the high value drops out and the lower value is still held, then the lower value is the current value.

Using one hand, (for pitch bend, multi-note, mono voice) I may press my thumb down and trill between thumb and third (or any other) finger(s) while varying the thumb press to do a whammy or pull-off type bend. The thumb is the governing force and any other lesser values will not 'count' in the output.

For opening a filter via monoAT, e.g. using two hands, I may hold a big fat multi-note chord and press down whatever was convenient in the left hand, while (e.g.) changing fingering on the right hand - the left hand acting in the role as being the 'heavy' in determining the overall modulation amount.

This is all interchangeable between one or two hands, and any fingers, just comes down to hardest press. This is something in standard monoAT application that every keyboardist is used to (and rarely thinks about the mechanics), but in the polyAT world we aren't used to it.

I thought originally that interpolation (between various key presses) may come to play, but I think the answer is that it is just a matter of whatever key is max value pressure, for monoAT. thanks, (...for addressing my other questions as well...), -Brian

Paul DeRocco [21030230] · Mon, 22 Nov 2010 23:58:09 -0800

Re: mono (channel) AT, with CC+ or Syntech...?

From: Brian McCully

Through these archives, I was reviewing how the Chroma responds to pressure and it seems to look at a maximum of 16 notes. How they are detected or processed (in memory, for 'dissection') is beyond me, but I get the jist of why 16 was the number. I don't think you can play more than that with 10 fingers, regardless of the sustain pedal state. Or sostenuto, or other 'hold' functions if there are any.

For internal playing there is no reason to measure the pressure on anything other than the notes that you are hearing, of which the maximum number is 16. The software cycle goes through 16 channels in about 20ms, and it reads the pressure on 16 keys in that same period of time.

Some examples: when I am trying to perform a (e.g.) single note pitch bend via monoAT, I would just hope that: a) there's a smooth (high resolution) pitch bend; b) it's easy to press, to get to the bend within range (and max value as often as not may not be the desired value at any given time) and c) that it doesn't warble once it's at the desired pitch, unless I want it to.

Pressure is generally harder to control than a lever, which gives both force and position feedback, or even a pedal, which only gives position feedback. I find it primarily useful for controlling volume or brightness, not pitch, since tiny variations in the latter are very audible.

Brian McCully [21030361] · Tue, 23 Nov 2010 09:46:21 -0800

Re: mono (channel) AT, with CC+ or Syntech...?

Pressure is generally harder to control than a lever, which gives both force and position feedback, or even a pedal, which only gives position feedback. I find it primarily useful for controlling volume or brightness, not pitch, since tiny variations in the latter are very audible.

Hi Paul, I use monoAT quite often for pitch bend applications on the Yamaha Motif XS6 (set for +/- 2 semi-tones). The Motif's keyboard action is average to good, but the AT works surprisingly well, definitely one of the best AT actions I've ever used (and the audio pitch resolution is really good too, stepping is almost inaudible). Prior to owning the Motif I rarely used AT for pitch bend, and I totally concur with what you state in regards to the other standard applications. One of things I'd hope that polyAT would be good for, is pitch bending for pedal steel type applications.

Tapper

Jeffrey D. McEachin [21030073+] · Wed, 17 Nov 2010 15:34:18 -0800

Does anyone know what could cause the tapper to tap continuously? When I installed a CC+, the tapper went crazy. I hesitate to blame the CC+, though, because the old CPU board didn't work. I'm guessing it's power related, but I haven't had time to slap a meter on it yet.

David Clarke [21030085++] · Wed, 17 Nov 2010 19:54:34 -0500

Jeffrey - I'd make a clean program selection on the panel and then watch the Program Modified flag (decimal point) in the large LED display. If this flag is behaving as though a parameter is changing, then the tapper may actually be reacting to what it believes is a changing parameter. By watching the program number in the display (small or large) you can likely tell 'what' is changing (e.g., if it keeps swapping between P9 and P36, then one of those two membrane buttons keeps on thinking it is being pressed).

If the keyboard otherwise seems to work fine (e.g., no retriggering of the Prog Mod. flag) then something is otherwise telling the tapper to fire, and tracing along will help find out what that is.

(A brute force approach to help rule out the CC+ would be to install the 2nd unit to see if the same or different behaviour results).

Paul DeRocco [21030230] · Wed, 17 Nov 2010 17:57:14 -0800

I've generally found this to be some power problem affecting the A/D converter on the I/O board, causing it to believe that the parameter slider is being jiggled up and down.

Chris Smalt [21010280+] · Thu, 18 Nov 2010 13:28:13 +0100

That happened to my Chromas all the time after being in storage for some time(with random parameter changes in the display). It would go away (and stay away) after a couple of hours of warmup.

Chris Borman [21030194+] · Thu, 18 Nov 2010 08:58:57 -0500

Same here. My Chroma does not wake up happy after a long sleep.

Yellow/Orange Chroma For Sale

Leonardo Ascarrunz [no serial number] · Thu, 18 Nov 2010 08:51:36 -0700

I have decided to try to sell my Chroma so I thought I would check the list first for potential buyers. This particular unit has the Orange/Yellow color scheme that was used on the prototypes and has no serial number. All voices work, and the only internal modification is the install of a switching powersupply. Unfortunately at some point in its life someone decided to cut a hole on the cover to install a fan, so a square hole is present in the upper left corner. Besides the hole, the unit is in good shape. Some pictures are available on the instrument registry, and I can take more on request. I also have a midi interface box for it. Please email me for further details.

Re: Looking for a Rhodes Chroma

Go to first message in thread, October 2010

Odysséas Tsakas-Grigoriadis [21010242] · Thu, 18 Nov 2010 23:59:19 +0000

Hello again list,

I'm sending this message to let you know that I finally found and bought a Chroma, and it arrived 2 days ago. It's in very good condition, except for the wood panels which have some deterioration due to the anvil case's foam. Everything is original on the Chroma, except for the PS which was changed by previous owner. The price I paid for it was 2100 euros, and along with the Chroma, received all pedals and manuals. I'm currently ordering the CC+ upgrade for this new lady. As for the voices, 2 of them do not work, but as the seller told me everything was ok before shipping, I'll have to check if the failure is somewhere else than the voices circuitry.

Regards to the list,
Odysséas

Peter Forrest [21010096] · Fri, 19 Nov 2010 00:05:26 -0000

Congratulations, Odysséas! I hope the two voices spring back to life.

Lars Johansson [21030632] · Fri, 19 Nov 2010 01:08:02 +0100

I'm not jelaous, no I'm not.....

Odysséas Tsakas-Grigoriadis [21010242] · Fri, 19 Nov 2010 00:14:13 +0000

Thanks Peter! I also kept an eye at VEMIA's auctions, and saw the Chroma appearing :) . At that time however, I had already ordered mine. Hope everything went just fine for you and your site with this auction round!

Marais · Thu, 18 Nov 2010 20:02:29 -0500

Try "goo[d] gone" product form the hardware store for cleaning the side panels, but you may have refinish the wood as well at some point.

Try reseating all the voice cards or switch there positions as the simplest place to start.

Marais · Thu, 18 Nov 2010 20:05:32 -0500

sorry spell check in action when you do not want it.... : )

"Goo Gone" product

Daniel Rickenbach [21010172] · Sat, 20 Nov 2010 11:49:45 +0100

Hi

The rotten foam can be cleaned with pure alcohol too. The varnish is soluble with acetone. My Chroma was over and over with this foam rot, and then first I have cleaned with alcohol, after this I cleaned only the wooden parts with acetone. After this, I put on a new clear acrylic varnish. I didn't have used any sandpaper, only fine steel-wool to polish after the first and second painting. The only difference between the original color and now: Original the chroma wood is a little bit reddish, now it haven't anymore, but for my opinion, it looks well.

Odysséas Tsakas-Grigoriadis [21010242] · Sat, 20 Nov 2010 14:40:19 +0000

Thank you for your help on this M. & Daniel. I will take a shot sometime next week, and will post photos to show the work. However, I'll make a small investigation prior to this, as I would like to keep that "reddish" color on the wood.

Voice card fixed and CC+ installed

Doug Terrebonne [21030114] · Thu, 18 Nov 2010 18:11:00 -0800

Here's an update on my Chroma - Got it all working now. The bad voice card turned out to be a bad RC4151 voltage-to-freq chip on OscA. Also got the CC+ and installed it and it's working great!

Tempco resistors again

Greg Montalbano, Analog Synthesizer Service · Tue, 23 Nov 2010 15:27:25 -0800

Once again, time to track down a few 1.87K tempco resistors. Anyone have a source?

Paul DeRocco [21030230] · Tue, 23 Nov 2010 15:55:57 -0800

What goes wrong with them? I'd never seen one fail in all the time I worked at ARP and Fender.

Greg Montalbano, Analog Synthesizer Service · Tue, 23 Nov 2010 16:01:56 -0800

They die. I've had a couple die on Chroma voice boards, and several more die in Odyessys; they show infinite resistance (open circuit).

Jeffrey D. McEachin [21030073+] · Tue, 23 Nov 2010 17:07:38 -0800

What goes wrong with them? I'd never seen one fail in all the time I worked at ARP and Fender.

I recently found 3 that failed. They go open circuit, for whatever reason. I'm not sure why, if they're rated at 1W. Bad winding, perhaps?

As for a source, you have to "roll your own" using SMD resistors. See ModularSynthesis - Parts (scroll down to "Tempco Resistors"). On the plus side, they're 3300ppm/°C like the original, unlike the more common 3500ppm/°C tempcos. On the minus side, they're only rated at 1/10W, HOWEVER, if you're running that much current through the CA3046 or CEM3350, then something is seriously wrong and you'll probably blow up other stuff, too.

I'm looking at buying the parts to make 100 and having my repair tech assemble them. Cost will depend on how fast he solders. Is anyone interested in buying them at, say, 1 for $5, 5 for $20?

David Clarke [21030085++] · Tue, 23 Nov 2010 20:33:18 -0500

I'm looking at buying the parts to make 100 and having my repair tech assemble them. Cost will depend on how fast he solders. Is anyone interested in buying them at, say, 1 for $5, 5 for $20?

The last time I had a need for tempco's in quantity I went to the original manufacturer (KRL/Bantree).

These are the folks that made the original "KRLP-1C" parts, and so they'd be a reasonable group to approach for a price and availability.

The last order I had (which was for a minimum order of 50) worked out to about $3/part.

Temperature Compensating Wirewound Resistors | KRL Bantry

Paul DeRocco [21030230] · Tue, 23 Nov 2010 17:52:28 -0800

From: J.D. McEachin

I recently found 3 that failed. They go open circuit, for whatever reason. I'm not sure why, if they're rated at 1W. Bad winding, perhaps?

Well, okay, I guess I'd better hang onto the four I've got!

As for a source, you have to "roll your own" using SMD resistors. See ModularSynthesis - Parts (scroll down to "Tempco Resistors"). On the plus side, they're 3300ppm/°C like the original, unlike the more common 3500ppm/°C tempcos. On the minus side, they're only rated at 1/10W, HOWEVER, if you're running that much current through the CA3046 or CEM3350, then something is seriously wrong and you'll probably blow up other stuff, too.

Power isn't an issue, because they never have more than a couple hundred millivolts across them.

I expect that a 3500ppm resistor would work fine. After all, you don't run the Chroma over a very wide temp range anyway.

Alternatively, if you can find leaded TC resistors with a larger TC, you can always combine them with one or two regular resistors to reduce the TC and adjust the value. The equation solving is left as an exercise for the reader.

Greg Montalbano, Analog Synthesizer Service · Tue, 23 Nov 2010 17:58:45 -0800

David Clarke wrote:

The last time I had a need for tempco's in quantity I went to the original manufacturer (KRL/Bantree).

These are the folks that made the original "KRLP-1C" parts, and so they'd be a reasonable group to approach for a price and availability.

The last order I had (which was for a minimum order of 50) worked out to about $3/part.

Thanks. I'll get in touch with them & see what the current price would be.

Martin Pavlas [21030450] · Wed, 24 Nov 2010 08:59:50 +0100

Approx 6 months back I was in need of getting around 200pcs of them. KRL/Bantree did not even respond to my (several) requests from a quotation. Eventually I got them from Microohm (200pcs of 1.87K 1W 1% 3300PPM/C at $4.25 each). I had also a good offer from German Weltronic, but the physical dimensions of their parts were not ok. I have contact emails for their sales ppl, if anybody is interested I can provide that info, or check the websites. Communication with Microohm was easy, and I was able work with the price there. They started with $8 per piece ;)

Eprom information

Thomas Story [21030352] · Thu, 25 Nov 2010 12:18:51 -0800

I'm looking at upgrading to the Pressure kit, but notice that I need to upgrade my OS to the latest to get it to work with pressure, I'm on 211.

I'm on a mac, and notice that pretty much all the programmers are for PC. I can run virtual pc, and try the Willem pcb35 and see if that works, but does anyone on the list have access to a programer to burn the new OS in exchange for money? Or any advice to doing it myself would be greatly appreciated.

Thanks!

Greg Montalbano, Analog Synthesizer Service · Thu, 25 Nov 2010 13:15:42 -0800

Hola Tom -- I can program them for you, if you can point me towards the relevant files.

David Clarke [21030085++] · Thu, 25 Nov 2010 18:52:02 -0500

... I'm looking at upgrading to the Pressure kit, but notice that I need to upgrade my OS to the latest to get it to work with pressure, I'm on 211...

Tom - just to clarify, newer firmware is needed to provide the ability to send pressure data via MIDI but if you were only concerned with having the pressure data available locally (e.g., playing the Chroma and having the Pressure data acted upon), then the older version of the firmware would be OK.

Thomas Story [21030352] · Fri, 26 Nov 2010 22:00:33 -0800

Hola Tom -- I can program them for you, if you can point me towards the relevant files.

Hey!

Thanks for the offer, I'll take you up on it soon. Hey - do you have any interest in helping me with my Sequential Circuits Studio 440? It's my baby and it looks like the power supply is taking a dump and needs to be or should be replaced. Did I mention that it's my baby and I'm seriously bummed right now? I can point you to some specs on the original power supply and schematics. The yahoo groups has a Studio 440 group that has all the info.

I'd really like to get this back up and running as soon as possible. Let me know if you have time. More important to me than a 7 voice Chroma.

Expensive JL Cooper MIDI Interface

David Clarke [21030085++] · Thu, 25 Nov 2010 19:01:18 -0500

It would be interesting to get a copy of the listed 'accessory order form' for the site, but I can't see that being that much of an extra draw such that someone would want to pay over $120 US for a JL Cooper MIDI interface:

[eBay item #320621271326]

If they were just looking for MIDI, it would be a much better investment for someone to get a Syntech interface for $100.

The auction included a ChromaFace; RCA/DIN cable the seller "built to load patches from storage;" audio cassettes of factory patches; program printout books; a Chroma Accessory Order Form; the Performance Manual; and the Service Manual ("in rough shape but useable"). Pictures:

Go to next message in thread, December 2010

Any news about the Chroma Enabler?

Odysséas Tsakas-Grigoriadis [21010242] · Sun, 28 Nov 2010 12:04:12 +0000

Hi list and hello Randel,

Just wanted to know how is it going with the Chroma Enabler? Could you at some point provide us with a video of it in action? Also, I saw in older posts that you was thinking of building more Enablers, what about it?I think many people on the list would be interested in the idea of acquiring one (I know I am:) ).

Go to next message in thread, December 2010

CPS - new odd behaviour

Jesper Ödemark [21010135] · Mon, 29 Nov 2010 10:36:42 +0100

Hi list,

the first CPS I received from Chris had two fault pressure pads (i e, two keys not responding to pressure (keys 40-41)) on the right pressure PCB. I received a spare a few days ago and after installation I detected new problems. A set of keys in the middle of the board don't respond to pressure now. First I thought it was about the height of the bar. But after removing it and confirming with an analogue Ohm meter this is the result: key 1-17 are OK (E1-G#2), key 18-34 don't work (A2-C#4) while keys 35-64 are OK (D4-G6).

I've measured both with the MUX-board attached and without and it is the pressure boards that is faulty. The strangest thing is that the problems are spread across both boards now and across two IC's on the MUX. I'm quite positive there was no problem with the left pressure board before. Can I be the source of this and if so, what the hell could've happened?

This is so depressing since it's so great to play the keys that do work. :(

Jesper Ödemark [21010135] · Mon, 29 Nov 2010 11:48:14 +0100

And a quick update:

I removed the replacement board altogether. Instead of the expected 35-40K Ohms I read 15-25K on the first two pressure sensors of the new right board. But still the problems of the left board remain (key 18-32). I can't get the needle to move even (except on key 18 where I get a lousy 2-3K Ohms and key 4 that rather show a tendency to move into the negative).

Have I received all the monday copies? Can stuff have happened in transit that shows up now (I'm thinking PCB cracks etc)? If there are any cracks they ought to be on the bottom (glue side) of the PCB so I cannot trace anything.

Chris, you wanted the fault board back for testing. Should I return the other(s) too and leave the problem to you?

/j. - sad and a bit fed up

Chris Borman [21030194+] · Mon, 29 Nov 2010 06:33:32 -0500

Jesper,

Please send back the entire CPS assembly including the replacement sensor board so I can take a look. Also include photos showing the installation and a view of the CPS mounted on the damper bar.