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ChromaTalk Archives: November 2008

New Registry Page: Model 1611 (Computer Interface)

Chris Ryan [21030691] · Sat, 1 Nov 2008 10:53:17 -0700

The instrument registry has been a popular part of the site; in addition to the more than 500 Chromas and Expanders listed (over 200 of which were supplied directly by owners), it accounted for over 5500 page views during the last twelve months, more than 7200 if the Polaris registry is included.

A lot of the instruments in the registry came from Fender's warranty list, a copy of which was supplied by Ken Ypparila [21030229]. This list also includes the serial numbers of the computer interface kit, Model 1611, which were registered by owners. This kit comprised the Fender Music System and the interface card for the Apple II computer. I thought it would be interesting to start a new page for this part of Chroma history. For now, the list contains the interfaces for which registration cards were returned to Fender, along with the serial number for my interface (which was stolen along with my computer over twenty years ago), 27 in total. The highest serial number in the list is 16110219, which was mine; so it seems that this was a production run far more limited than even the Chroma—which is perhaps not surprising, as this was among the first computer interfaces for any such musical instrument.

If you have, or had, the Chroma Computer Interface, feel free to send me the serial number, if available (as I no longer have my interface card, I'm not sure whether the number appears on it; but it is shown on the diskette), and some information about it. It would be interesting to know how many of these kits still exist, and if any of them may even be in use. (If any are, I have one or two diskettes I could supply with some original patches I haven't heard since the 1980s.)

Dave Bradley [16330135] · Sat, 1 Nov 2008 18:05:56 -0600

I still have my interface card along with the sequencer librarian manual and the software in a box somewhere. I don't think I ever returned the warranty card for it though.

Åke Danielson [21010068] · Sun, 2 Nov 2008 18:16:10 +0100

Hi Chris,

No. 16110106 is living with me. Well... it actually died (the card) a couple of years ago, but it is still in my old Apple IIe.

audio input

Michael Salmon [21030155] · Sun, 2 Nov 2008 10:10:11 -0800

hi folks

was wondering if there's a way to get audio inputs to actually get filtered by the synth like you can do with some other analog synths (korg ms-20 for example)?

Luca Sasdelli [21010226] · Sun, 02 Nov 2008 19:46:05 +0100

Hi Miguel,

the Chroma audio section is in fact 16x complete mono synthesizers spanned over 8 voice cards; Korg MS-20 belongs to a mono synth generation, thus the incoming audio is processed by a 6dB/oct HPF and a 12dB/oct LPF. To allow an external signal being processed by Chroma, it should first be fed into a given half-voice card and this is difficult to manage by the software, that in this case should control only 15 audio chains, leaving the 16th for the ext audio. Not to mention the filter control signals, e.g. VCO, envelope(s) etc.

The single audio path is based on a 12dB/oct filter; two channels could have their filters paired in series, reaching a 24dB/oct LPF/BPF/HPF, very close to the ARP 2600 VCF, so I think is easier to build up a brand new one: google for "ARP 4075" to find out some infos about.

Moreover, you can look for a spare ARP Omni Synthesizer board: it includes all you need, e.g. ARP 4075 VCF, LFO, ADSR on a single card.

Which sort of audio do you like to process?

Andrew Dalebrook [21010180] · Mon, 3 Nov 2008 10:07:13 +1300

Hi

Surely one could use the insert loops to process audio?

Dave Bradley [16330135] · Sun, 2 Nov 2008 16:57:19 -0600

Only through the master EQ section, I believe.

Leonardo Ascarrunz [no serial number] · Sun, 2 Nov 2008 19:02:32 -0700

Actually i have been thinking about making a mod to allow audio to be fed into the chroma programs. You would have to route the signal with a cable to the motherboard and disable one of the noise sources.

Jesper Ödemark [21010135] · Mon, 03 Nov 2008 17:02:25 +0100

As Luca said - it's a lot messier to modify the Chroma that much compared to building some kind of clone. Many monysynths have external inputs but few polys do and there are reasons for that.

On a mono you basically replace a VCO with the signal. A poly has more voices and more complex control mechanisms.

But the _idea_ otherwise is great! :D I love filtering through all my monos...

Michael Salmon [21030155] · Mon, 3 Nov 2008 07:56:01 -0800

hi luca,

you're much smarter than me about this stuff :) but can i just plug a line level signal into the audio input and somehow route it to the synth? i just wish i could pass an audio signal through the chroma and use it like a moogerfooger pedal, minimoog, ms-20, etc. I have cc+ installed by the way not sure if that helps.

It would be amazing if this feature existed, then I could setup a pedal patch change sequence that would have different synth settings, and during a song change the patch by pressing the foot pedal to change the audio input filtering.

Luca Sasdelli [21010226] · Mon, 03 Nov 2008 17:35:54 +0100

Hi all,

indeed I think that by simply filtering an audio signal thru one of Chroma VCF could be an excessive technical effort in respect to what we could get from that; probably, by using a cheap effect stomp box e.g. a Behringer Filter Pedal, we could approach a similar result.

The Chroma "sound" is caused mainly by the oscillators quality and instrument architecture: the filter role is a precise harmonics shaping, but it doesn't necessarily "create" the sound.

A different way could be the one suggested by Leo: by feeding an external signal in place of noise generators (i.e. sent to ALL filters at the same time) could allow to "play" filters in polyphony and to obtain sure excellent effects. I'll have a look about.

As per almost each Chroma mod, the main problem is to have a way to switch back to the original setting when needed.

Bruce Sklar [21030660] · Mon, 3 Nov 2008 11:38:12 -0500

Im fairly sure the chroma inserts are trs meant for effects and come back in post synth.

I own a poly evolver however and it does do this. Chroma beats the evolver though.

Im the original owner, used it out extensively in an R&B band here in the wilds of vermont.In the Northeast Kingdom, in 1983 or so the voltage wasnt always 110 and it just wouldnt go on. And on snowy cold days, a hair dryer to the vents would be necessary to get it to go.

But that was 1983-1991 and I wasnt 52 and dont own a van any longer.- replaced it and the 88 rhodes with a polaris and a roland rd300. I now use RD 700x, Vk8 and the Polyevolver. Current band is Grippo funk Band, which will be a familiar name to phisheads....

Chroma has place of honor in the home studio. David White, ANALOGKEYS in Boston is a genius repairman, (ad in keyboard mag every month) but after my Chroma, he may want to retire- it was worst case scenario.

Michael Salmon [21030155] · Mon, 3 Nov 2008 08:38:30 -0800

Just out of curiosity, what would be the most simple solution to do this? Is there a way to use CC+, or would you have to alter the voice circuit board to patch an audio signal in place of 1 of the 16 VCOs and silence the other VCOs?

Sandro Sfregola [21010294] · Mon, 3 Nov 2008 19:33:56 +0100

The easiest way to implement an external audio input on the Chroma is by the noise generator path; this requires a simple mod of the channel motherboard and the addition of a simple buffer/preamplifier module; for the physical input, one of the existing rear panel jacks can probably be used.

When time permits, I will try to draw a circuit for site publication.

Leonardo Ascarrunz [no serial number] · Tue, 4 Nov 2008 12:36:45 -0700

Ideally you would route the noise signals to the buffer circuit and use a switching 1/4 inch input jack to enable the noise whenever there is nothing plugged in. No need to cut traces either. Just remove c14 and c15, and add these to the noise signal path in the buffer circuit.

This would give a total of 2 separate audio inputs with no functionality loss.

I've been thinking about doing this mod myself for a while now.

editor

Bruce Sklar [21030660] · Tue, 4 Nov 2008 14:57:42 -0500

my apologies to the guys talking about the input mods- I have zero electronic circuit skills. Didn't mean to add irrelevant stuff...

I'm wondering, as I do have the midi interface, what's out there for editing programs for the Chroma. Is there one which would allow for multiple parameter tweaks using for example an m-audio 8 slider keyboard?

Jesper Ödemark [21010135] · Wed, 05 Nov 2008 09:59:06 +0100

In my answer I assume you have the CC+ midi interface. Otherwise you have to specify _which_ midi solution you have in order for us to be able to help.

Jesper Ödemark [21010135] · Wed, 05 Nov 2008 09:51:44 +0100

As long as you can program the M-Audio keyboard what to send it should work great. Most people know that I use the Doepfer Drehbank since I wanted knobs for _everything_ but it works well with solutions with fewer controls too (I tested the Doepfer Pocket Dial forst which has 16 knobs). You just have to map the correct.

Bruce Sklar [21030660] · Wed, 5 Nov 2008 06:16:18 -0500

Sorry- browser froze..

I have the syntech interface which i got from Ken Ypparila [21030229] in 1986.I certainly would be open to uprading further . Everything is original in my chroma, Ive had it recently refurbished but power supply etc is all original Again apologies if multiple emails- I use an old mac at 6 in the morning. spinning beach ball of death every minute or so.

Jesper Ödemark [21010135] · Wed, 05 Nov 2008 12:30:45 +0100

OK, as I recall there are a few things that it allows you to control, but others on the list are more informative I guess. Mine came with the EES-interface and an Atari editor and that allows for sysex dumps but no realtime control. Since then I've upgraded to the CC+ which I can only recommend you to do too if you want as much external control as possible.

Michael Salmon [21030155] · Thu, 6 Nov 2008 08:29:44 -0800

I'm wondering what people would do, if building a chroma user interface from scratch what would they would make it look like? In other words if you words what would be the nicest way to interact with the instrument from a visual and tactile perspective? Has anyone redesigned, even on paper, an interface beyond knob banks that lets the user control all parameters, save and retrieve?

Jesper Ödemark [21010135] · Thu, 06 Nov 2008 22:06:04 +0100

I'd love a set of knobs the size of the memory panel, grouped like it with knobs instead of switches. Also with the same colour scheme etc.

One day I'll make a new panel etc for my Drehbank. Black with black/green/white etc.

Leonardo Ascarrunz [no serial number] · Thu, 6 Nov 2008 16:39:35 -0700

Actually i have been thinking about making a dedicated programmer. It would be on the midibox platform, and most likely use sliders and knobs. I would also like for it to connect to the chroma via its computer interface since i do not have the CC++ upgrade. I might get started on it this winter.

Chris Smalt [21010280+] · Mon, 10 Nov 2008 00:54:50 +0100

Who needs knobs when you can have a huge touchscreen? I'd like it to have virtual sliders. The advantage of virtual sliders instead of knobs is that you can choose to jump to a value, or gradually change the existing value. Also their position gives you an indication of the values.

Jesper Ödemark [21010135] · Mon, 10 Nov 2008 08:32:30 +0100

I prefer knobs or rotary encoders. This whole touchscreen thing just reminds me of the ribbon controller used instead of bend wheels on some old Moogs... horrible solution since it's hard _not_ to jump in values, though practical in some live situations.

Chris Smalt [21010280+] · Mon, 10 Nov 2008 22:57:44 +0100

I think with the right design (bigger center detent, the right curve) the ribbon would have worked fine. Of course playing it takes some practice, but so do knobs...

Michael Salmon [21030155] · Mon, 17 Nov 2008 08:19:31 -0800

touchscreen could be interesting, but what exactly would it look like in your mind? multi-touch would be preferred but is much more expensive

another idea - would there maybe be any use for a digital patch panel interface that was used to make synth routing changes?

Chris Smalt [21010280+] · Thu, 20 Nov 2008 04:34:36 +0100

touchscreen could be interesting, but what exactly would it look like in your mind? multi-touch would be preferred but is much more expensive

The most important aspect for me is to have a choice: gradually change a value, or instantly jump. A software slider, mouse-controlled or touchscreen, lets you do that. A hardware button doesn't. Some on-screenbuttons allow you to jump, others don't. I'm a fan of sliders also because they display the value by their position - you don't have to read numbers to get an instant snapshot of the readings.

I don't like hardware buttons with little led indicators for their values. Most are only readable at a 90 degree angle, and your hand hides the readings also.

another idea - would there maybe be any use for a digital patch panel interface that was used to make synth routing changes?

I've always been fairly comfortable with the Chroma's system - the routing is more or less fixed anyways, and I have a clear picture in my head of the routings. The less onscreen icons and pictures, the better, as far as I'm concerned. I still see the old Samplecell software by Digidesign as an example of great interface programming: everything was huge on screen, so it was visible from across the studio and easy to mouse, everything worked with either sliders or a graph with breakpoints, and there were simple keyboard shortcuts for the pages, so that you could navigate quickly without having to memorize how.

Chroma 21030348 For Sale on eBay

Chris Ryan [21030691] · Wed, 12 Nov 2008 23:53:37 -0800

Looks like Richard has reversed his decision made back in January to keep his Chroma, after considering selling it. #21030348 is for sale on eBay, this time for a "buy it now" price of US$3300. It's item #110311622177, ends November 19.

Chris Ryan [21030691] · Mon, 17 Nov 2008 22:19:03 -0800

Looks like this ended early, without a sale.

Richard Willoughby [21030348] · Tue, 18 Nov 2008 05:49:35 -0800

Yep, I had offers as high as $3300, and if I was patient I believe it could sell for about $3700..... but I changed my mind again after a late night jam session with friends........ sort of had a battle between synths......and the Chroma won no contest......

and in my opinion the DSI PolyEvolver took second....

lots of fun...

Chris Smalt [21010280+] · Wed, 19 Nov 2008 02:37:44 +0100

That brings back a lot of good memories - anything recorded?

Richard Willoughby [21030348] · Wed, 19 Nov 2008 05:58:02 -0800

not yet, but I am planning on having one of my buddies come over soon to do some improvised playing on the Chroma and the Andromeda with me and multitracking some of the soundscapes we come up with on the fly....... those two synths sound very good together in my opinion......... hmmmm....Chroma in Andromeda....has a nice ring......

Jesper Ödemark [21010135] · Wed, 19 Nov 2008 22:18:35 +0100

Sounds like porn to me! ;)

Chris Smalt [21010280+] · Fri, 21 Nov 2008 18:36:25 +0100

This message ended up in my spam box - had to fish it out manually!

Jesper Ödemark [21010135] · Fri, 21 Nov 2008 19:36:22 +0100

*haha* Sorry, couldn't help myself. I guess I need to get into a relationship again (not counting the Chroma). :D

Richard Willoughby [21030348] · Mon, 24 Nov 2008 06:15:49 -0800

Well, me and my buddy recorded a CD's worth of noise-making with just the Chroma and the Andromeda, pretty much no effects on the Chroma whatsoever......and the results are pretty interesting, esoteric and dare I say beautiful in parts.......listened to it in my car this morning driving in the snow......... I laid out a track listing and am titleling it "A Devil Between Mirrors"........sounds overall like what I imagine the journey after ones death might sound like.....at times quite discordant, but with striking moments of harmony and peacefulness thrown in........if it doesnt trance you out, it is bound to give a headache.......not for everyone thats for sure.....;)

all created/recorded in one spontaneous take......... if anyone wants a CD mailed to them, let me know......

SPSU kits

Luca Sasdelli [21010226] · Wed, 19 Nov 2008 23:05:02 +0100

Hello all,

this just to inform you that I'm about to start a new batch of SPSU Chroma kits. Should you be interested, please drop me a line, just to estimate the quantity of PCB to order.

Bruce Sklar [21030660] · Thu, 20 Nov 2008 10:59:01 -0500

What are these kits?

Jesper Ödemark [21010135] · Thu, 20 Nov 2008 17:06:15 +0100

They solve the issue with the original PSU being too weak to handle the load. After changing mine for one of Luca's the Chroma always tunes every voice and there are no crashes...

BTW Luca, do you live on the second floor? ;) (bet you haven't heard that one before)

Luca Sasdelli [21010226] · Thu, 20 Nov 2008 17:14:45 +0100

Hi Bruce,

it is a power supply unit replacement kit; the original one is linear-based and, with the time, it begins having voltage drops, unstable performances, buzzes, stray magnetic fields and vibrations. A typical issue concerns the big capacitor C3 and/or the limiter installed on its top, causing severe voltage drop or tuning problems.

The kit I prepared is based on a diagram from Sandro Sfregola and allows an average user to replace the old PSU with a new switched-mode PSU and a small board with voltage regulator and reset circuitry. Moreover, a metal bracket is supplied to allow easy installation, by reusing existing transformer holes in the Chroma case.

More details at this page.

Bruce Sklar [21030660] · Fri, 21 Nov 2008 07:19:12 -0500

I would get one of these.

I wish Id had one when i moved to Vermont in 1983 where the voltages were sometimes in the 90's range and the Chroma wouldnt turn on except for a brief flash. And because of extreme cold and condensation issues in clubs, Id always have to travel with a hair dryer to get it to work.

EES Chroma interface on german ebay

Jesper Ödemark [21010135] · Mon, 24 Nov 2008 09:46:54 +0100

See EES MIDI Retrofit. Item #270303970566; here is the picture:

I miss my Chroma, can anyone help

Mark Yurkovic · Fri, 28 Nov 2008 22:02:31 +0000

I was an original Chroma owner in 1984. I paid $3200 for it!! I bought the Syntech midi box and loved it. Eventually, I couldn't find anyone to help me fix it to keep it going and I sold it. Now I miss it and was wondering if anyone would consider recording audio/wav files of the original factory presets for sampling. Can anyone help?