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ChromaTalk Archives: August 2007

August Site Update

Chris Ryan [21030691]

No new article on the site this month; after completing the Programming Manual I decided to give myself a break for the summer. But I have posted the July ChromaTalk archives.

I hope everyone is having a good summer.

Alex Kretschmann


Alex Kretschmann,

melde Dich bitte wegen des von mir am 22.6. bezahlten aber bislang nicht ausgelieferten Rhodes Chroma!!!

Inzwischen kommen auch meine Mails an Dich als unzustellbar zurück, deshalb jetzt dieser Versuch über die Chroma List!


Ron Joseph [21030042+]

Translation anyone?

Werner Schöenenberger [21010114]

Volker asks Alex Kretschmann to contact him concerning a bought (and paid) Chroma which did not arrive!!!!! He has no contact anymore via mail and this is his trial via Chroma List.

Ron Joseph [21030042+]

Thank you Werner!

FS: two chroma's

Kevin Kelley [21030491+]

Hello to all on the list, I have two chroma's in good shape both have power supply issues that I would like to sell. I was hoping for around 1000 us for each please let me know offlist [e-mail address removed] if anyone is interested.

Chris Ryan [21030691]

I assume these are 21030491 and 21030713? Both are in the registry.

Wanted Rhodes Chroma Expander

Thorsten Pörschke [21030734]

Hello to all on the list

I'm looking for a Chroma Expander as a fellow for my Rhodes Chroma. If anybody is interested in selling one please email to [e-mail address removed]


PSU: L60V6

Werner Schöenenberger [21010114]

Hi list,

I am currently in repairing the PSU of a Chroma for a friend and as it has to be, the hard to find L60V6 is dead. So some questions arose:

  • does anybody know, where in Europe it is possible to find this voltage regulator?
  • Arti Haroutunian [21030388] wrote in 2004 that NTE4906 crosses to L60V6. Does anybody have experiences with the NTE?
  • it seems that the NTE also is hard to find. Does anybody have a source?

In the meantime, I will check the local electronic shops - maybe "luck is with me" Thank you in advance.

Riku-Sakari Kujanen [21030858]


How about if you swap the big capacitor to new one with higher voltage rating and leave the zener out. Old capacitor has over 20 years on it so replacement might be good idea too. I just did like this while ago encouraged by older posts on list.

Werner Schöenenberger [21010114]

Hi Riku-Sakari,

thank you for the hint. This might be an option I will check that.

John Leimseider [21030434++]

We have them at Cantos if you really want them... They aren't important is you put in the 16 volt filter cap...

Werner Schöenenberger [21010114]

Hi John,

thank you very much for the offer - I will check it out. It seems that the 16 volt cap seems to be the best solution. So maybe I try this way.

Werner Schöenenberger [21010114]

Hi John,

just one question for correct understanding: the original capacitor os a 47000 uF at 7.5V and a replacement of a 47000 uF, 16V would make the voltage protector obsolete. Is this correct?

John Leimseider [21030434++]

They are not really necessary if you have the 16 volt cap. If you feel better with it there, you can use it, but I've never seen a problem that the LV helps with...

Werner Schöenenberger [21010114]

Dear John,

that's good news. Thank you. So I definitely will go the path with the 16 Volt cap.

Erik Vellinga [21010286]

I might have one right here. I have replaced my power supply some time ago by a better one so my L60V6 is somewhere in the drawers. Don't know 100% sure I still have it.

Basically the 5V digital supply is protected against high voltage by means of this component. It works as a thyristor that immediately makes a shortcut between 5v and ground and blows the fuse if it is activated by too high voltage at it's gate. Better to put a 78L05 regulator to make another kind of protection than to leave the circuit unprotected. It is very easily fried.

Werner Schöenenberger [21010114]

Hi Erik,

thank you very much for your answer too. I was in the opinion that the L60V6 only should protect capacitor C3. So if I understood correctly, a regulator like the 78L05 would be inserted in a different way than the L60V6 (which is parallel to the capacitor). The 78L05 would be inserted serial between the output of the capacitor and the input of the digital 5V regulator.

Erik Vellinga [21010286]

Hi Werner,

Almost correct. It has to be a 78H05 or alike that can handle the current needed, i think it is about 4 A. I have to really look into this because it's 15 years ago that I last saw my original power supply. The L60V6 protects the 5 V regulator. If voltage goes above 7.3 volt it will short circuit and the Chroma does not power up, or blow the fuse I forgot.

If you disconnect it however, you will have a chance that the MOSFET in the digi-supply goes bang and you will have to replace a lot of CMOS IC's in the digital Chroma.

Instead you can mount above 7805 > 4A. on the capacitor and throw away the L60V6. 7,2 Volts in and 5 V out. Better option is to replace the whole @%#@$%^* power supply.

Funny thing is that I have a Hewlett Packerd medical power supply in my Chroma that uses the same idea of protection. Also it is an analog supply getting hot inside.

Riku-Sakari Kujanen [21030858]

Hi Eric and Werner,

Another solution for extra protection if C3 is replaced by higher voltage rating type is simple thyristor based crowbar protection fitted on on +5V digital output. If output is too high (miss adjusted voltage trimmer etc.) thyristor shorts and the current limiting circuitry on linear regulator pulls down the pre regulator. If something is totally wrong, shorted output should eventually blow the fuse.

BTW: is there any records of such failure where +5V digital output goes too high causing huge damages? Failing on low voltages seems more common problem.

Werner Schöenenberger [21010114]

Hi riku,

I think if the issue is to protect the digital 5V regulator against overload, then the protection at the output of the 5V regulator would "only" protect the rest of the cirquit.

But another question arose: Isn't the L60V6 a 6V protector (I cannot find any information about the component on the web) - at least based on the Chroma documentation and the identification (V6), I would assume 6V. Does anybody know?

Erik Vellinga [21010286]

That's exactly as I said and already being used in the original PSU.

Werner Schöenenberger [21010114]

Hi all,

one final question: What would you prefer to use instead of an L60V6, the 7805KC or the LM309. Both are easy to purchase for me.

Thank you in advance.

stereo output problem

Anders Elo [21010104]

Hi, this will be my first entry into this fantastic list!

I currently have an issue with the stereo output routing not working as I expect it to do.

For instance, when selecting unison link mode and pressing [Set] split-5 to route the split program to output-3 I get no sound from that program. And if using the two balanced XLR jacks I just get the same two mono channels as output i.e not stereo.

However, when routing to any other output, for instance output 2, it works fine but then I cannot use the XLR's as I'd like to do.

Am I doing something wrong here or is it just malfunctioning ?

Jesper Ödemark [21010135]

Welcome Anders, I hope the list can help since I fell short (and the mail was delayed too BTW). Great to see another swede on the list!

Werner Schöenenberger [21010114]

Hi Anders, welcome to the list and hope you have a good time here :-)

Well concerning the stereo outs, I only use the Chroma in mono, so I might not be a big help. As far as I understood from the manual, the set-split-5 switch should be enough. That it does not work, sounds strange. Anyway, if you want to use the XLR 3 output, you need to plug in the blind jack into Audio Inputs/Outputs 3, otherwise the routing to XLR will not happen. But if you do this and still do not get any signal with the XLR, I think, there is some issue with the Chroma (mabye only the wiring). If it works with the XLR but not with the Jack out, then maybe the Jack has to be cleaned.

Jack Colburne [21030142+]

Hi, and welcome to the club, Anders... :-)

We had a discussion a while ago about the multi-outputs and "stereo" applications [see Stereo Operation, November 2005]. The Chroma has no real stereo funcionality. The outputs are truly separate entities; you can't pan a sound across a stereo field within the Chroma. As Werner said, you have to remove the signal from the unbalanced 1/4 output #3 by plugging a "dummy" plug into it in order for the signal to show up at the XLR. If you don't have the original dummy plug you can plug a std 1/4 guitar cable into the #3 1/4 jack and leave the other end free. It should do the same thing.

The discussion there may help some and explain better.

Jesper Ödemark [21010135]

Maybe time to go stereo with the old girl? What's the easiest setup?

Jimmy Moyer [21030184]

(Discaimer, I don't play my Chroma live. Sequencer in the studio only.)

I find one of the best uses of the Chroma is to make huge stereo pads.

  • Choose your pad patch.
  • Select mono or poly all channels mode.
  • Record one pass.
  • Record another pass of the same sequence on another track.
  • Pan the two channels hard left and right.
  • Season with reverb to taste.

CC+ and multitimbrality?

Anders Elo [21010104]

To my disappointment I discovered that the kenton retrofit that I have doesn't support multitimbrality which the Chroma is able to handle. Therefore I'm thinking about acquiring the CC+ instead since I want to be able to fully utilize the Chroma's four outputs. Has anyone tested this kind of setup with the CC+?

Werner Schöenenberger [21010114]

I didn't do that, but based on the fact, that the CC+ does everything it promises and the routing is only controlled by the CC+, I would expect that this works. Anyway, from my point of view, the CC+ is THE recommendation for the Chroma and it is worth each cent, you spend for it.

David Clarke [21030085++]

Anders - the key element is just to be able to simultaneously control at least 4 different patches.

The CC+ will certainly do what you'd like.

If you don't currently require the other features also offered by the CC+, then the Syntech/KMX/Chroma Cult interface will also be able to take care of what you're looking to do.

(Thanks to Werner for his kind CC+ comments).

Anders Elo [21010104]

Thank you all for the responses and helpful suggestions. I've sent an email to Sandro requesting a CC+ board, hopefully he finds the time build one for me too. Regarding my stereo setup [see stereo output problem] I've managed to get it working by routing the link program to output 2 instead of 3. So maybe this problem is caused just as Werner suggested by a loose wire or perhaps even oxidation. I'll give a try and shower it with some isopropanol.

The Chroma sounds really massive in stereo, I think and it will definitely be my preferred setup when recording. :) A feature that I think should be very nice to have in the CC+ is to be able to have an alternating stereo mode, just like the old Oberheim OBXa when panning the board separately. This way you would be able to preserve 16 or 8 notes polyphony simply by routing each key either to the link or to the main channel. It also creates a very nice effect on arpeggiated sounds when the notes alternate between the right and left channel.

Fwd: FS: Rhodes Chroma Expander

Chris Ryan [21030691]

From Analogue Heaven:

From: Rob Belcher [16330123]
Date: August 21, 2007 3:42:49 AM PDT (CA)
To: "Analogue Heaven!"
Subject: [AH] FS: Lexicon 224 and Rhodes Chroma Expander

Rhodes Chroma Expander, (the very rare keyboardless Chroma) just come back from restoration by Roy Paynter (the UK chroma expert), midi, good condition. Comes with user manual. Im asking £2050. Im in the UK. I have lots of references in the archives!

new powersupply?

Anders Elo [21010104]

In order to preserve the Chroma a couple of years longer I'm planning to shift out the original PSU. I'm thinking of replacing it with a Doepfer PSU2 that is capable of delivering +-12V @ 1200mA. Do you think that would be sufficient to use or is it to small (I'm not going to connect the tapper) ? And I'd rather not use a switched supply since it could cause interference to the other circuitry. Also, does anyone know the amp requirements on the 5 V when having the CC+ board?

Jimmy Moyer [21030184]

I can only comment that three years ago, I replaced the stock linear supply with Power One MAP-80 switcher and I could not be more pleased.

No sign of any increased noise. No more of the increasingly frequent failures of the old supply. No more flakey, intermittent Chroma failures. Boards failing selftest, patches changing when the power amp is switched on, etc. No more buzzing noise and burning smell. I was also seeing permanent board failures every year or so. Now none in three years. Could still be a coincidence, but hope not.

Of course with the CC+, you could get by with a smaller supply. (I do have the CC+ and the MAP-80 continues to work fine.)