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ChromaTalk Archives: July 2012

TouchOSC iPad Template Modifications

Chris Ryan [21030691]

I've posted an article by Leon van der Sangen [21010301] that modifies Matrix's iPad template so it can be used without the need for a dedicated computer. Leon is looking for feedback on his work.

Leon van der Sangen [21010301]

Hi Chris,

Thank you for posting my iPad TouchOSC editor template. The iPad TouchOSC editor template can be found at this link.

Marais

Thank you for doing this Leon. I have a older iPad mkI and Alesis I/O dock I am hoping to dedicate to using with it, do you think that will work? The thought of having a Enabler and iPad to edit the Chroma is awesome sauce! To all would a midi merge of the Enabler and iPad going into Chroma at the same time be kosher ?

Leon, please let us know when the finished version is ready

David Clarke [21030085++]

... To all would a midi merge of the Enabler and iPad going into Chroma at the same time be kosher ?

I can't see any reason why it wouldn't be OK.

David Clarke [21030085++]

... Leon is looking for feedback on his work.

Leon - in the posting you note: "...There are 2 or 3 parameters for which I don’t know the continuous controller number and range..."

As/when you get back to working on the template, just let the list know as I'm certain we can provide any info you might need in terms of MIDI CC assignments.

Marais

Anyone get to try this out yet?

Marais

Touch Osc Editor template Modified

Success! : ) Thank you Leon and Matrix. If anyone has any questions about the process let me know (TouchOSC Mac editor, TouchOSC Ipad ipad, Alesis I/O). A few notes, you will not need OSCulator now, and TouchOSC for Ipad is 4.99 now, the Mac editor is free.

touchoscmarais

Next up Enabler v Touchosc. Stay tuned.

Adrian [21040017]

I had a quick go a couple of weeks ago but no luck :-(

I have everything loaded in the iPad side and my CC+ midi interface LEDs flash for both send and receive, but the Chroma does not audibly respond. I tried all midi channels and all the options and things I could find on the ipad, even restarted it a few times to be sure. I've used TouchOSC via wireless networking to a Mac before.

However my Chroma is only just in a working state - I have my left front panel unplugged and individual switches soldered in on long wires, to work around an internal short within the panel membrane *sob*. I haven't had it going at 100% since I bought it - so there's a better than even chance I'm doing it wrong.

Marais

See Matrix's [21030220] trouble shooting notes at the bottom of this page [New Rhodes Chroma TouchOSC Templates Complete], perhaps that can help. Good luck.

Matrix [21030220]

Re: Touch Osc Editor template Modified

On Tue, Jul 31, 2012 at 7:29 PM, Marais wrote:

Success! : ) Thank you Leon and Matrix. [...]

Awesome! You are welcome! :)

CPU - I/O board cables

John Leimseider [21030434++]

Does anyone have the part number for the cables that connect the CPU board to the I/O board? Thanks!

David Clarke [21030085++]

These are AMP "Flat Flex" 0.100" cables.

While they don't have the shroud on the end, P/N A9aat-1502f-nd from Digikey will do the trick.

Different lengths are also available, xref: P0074.pdf (at digikey.com).

Paul DeRocco [21030230]

The shrouds are separate pieces that snap onto the flex strips. If you have a bad cable, I believe it's possible to coax the old shrouds off without ruining them, but I don't recall how. It might have involved judicious use of a razor blade to pry with, or something like that.

Chris Ryan [21030691]

Perhaps in the Service Manual's Parts List or Replacement Parts?

Voice card standalone repair unit?

RJ Krohn [21030455]

hey all, i've got a few voice cards i'd like to repair here (two that are outputting faulty sound, one passes autotune but isn't actually IN tune). there was talk of a DIY unit that would host a card for easy repair. does anyone have one built, or know the status of that? if anyone has one built, would they like to rent me one? id gladly pay a deposit, or whatnot. thanks, rj

Arun Majumdar [21030348]

I am also interested in the voice card tester / repair helper units. I think it was Luca that has that? I have a second Chroma and I have been planning on refurbishing it mainly because it has a few voice cards that are not functioning as they should, and, it will need a new SPSU unit. I've been busy rebuilding the studio (and I have one of Randel's [21030467] amazing Chroma Enablers!) - so time has been a bit short but I would like to know if there are plans for the voice card tester.

Thanks!

Luca Sasdelli [21010226]

I've built a Voice Board Controller upon David Hillel Wilson's project.

I've already started to work on an upgraded version, with some improvements to the original design and hopefully a simpler assembly strategy (e.g. a PCB, most of mech switches assisted with CMOS ones etc.)

At present the unit it still quite delicate (because of wirings etc.) and I'm not intended to rent it, sorry.

Arun Majumdar [21030348]

Hi Luca,

If you do put a kit together or share your design notes I will be happy to purchase or build one depending of the situation :)

If you do plan to release a kit please let us know!

Thank you,

-A

Review of the Chroma on Ebay

Jesper Ödemark [21010135]

Not sure, but I couldn't find this on the site based on the images in the article: [eBay item #230822698592, later relisted as item #230828647378].

Pictures from the auction:

eBay230828647378

Chris Ryan [21030691]

I'm mobile right now but this was for sale previously and I believe it's the International Musician review.

Re: Discussion on Possible CC+ Feature: Sync'ing Chroma Sweep via MIDI

Go to first message in thread, June 2012

David Clarke [21030085++]

From a MIDI sync implementation perspective, what is more important to users:

  • less drift over time (e.g., more accurate sync timing)

or

  • an ability to more quickly respond to dynamically changing MIDI tempos (with much less sync timing accuracy)?

James Coplin [16330036+]

Less drift over time. Definitely. If the timing isn't accurate, what's the point?

Paul DeRocco [21030230]

How does a bad implementation manage to introduce drift over time, when MIDI clocks are being transmitted continuously?

David Clarke [21030085++]

The general problem is that:

  • the MIDI timing clock is expressed as a number of 'ticks' per note

but

  • the Chroma's sweep is an actual rate (e.g., 'time').

If we were only talking about an arpeggiator, then having it be clocked by MIDI precisely would be more or less straightforward (since you can equate so many midi clock to the advancement of a 'note') - but since we're really talking about a sweep rate (and not a note advancement), you need to effectively measure the frequency of the MIDI clock, and then convert that into a 'time' that the sweep code understands.

This also allows the 'rate mod' code in the Chroma to still operate as it does today, even when the base rate is derived from MIDI.

The drift over time would come into play due to the accuracy of the 'time calculation' vs. the actual real life run-time of MIDI.

Calculating over a longer period gives better accuracy, but at the expense of not being able to instantaneously be able to react to a tempo change.

Calculating over a short period of time gives better responsiveness - but at the expense of accuracy.

In practice, any drift is likely going to be of most concern when either triggering the same arpeg over a very long period of time or when running the sweep in a free-running mode (the 'key sync'd sweeps are somewhat self-correcting, as as long as the frequency is close, the triggering of a new note should bring the start of the sweep back in line.)

Paul DeRocco [21030230]

What would probably work best is to set the sweep phase increment to a value calculated from the time between MIDI clocks, and also force the sweep phase value on each clock. Any error in the former would result in tiny discontinuities in the latter, but these would probably be inaudible if one had an arpeggiator or sweep pattern running.

Unfortunately, the original Chroma doesn't have a very versatile high-res timer. I don't know if the CC+ added a better timer.

Thinking about shoehorning that sort of stuff back into the ancient Chroma code gives me a headache. I'm glad it's someone else's project.

August B. Raring [21010148]

less drift over time (e.g., more accurate sync timing) ! Because I`d mainly use it for arpeggiator sync.

David Clarke [21030085++]

... What would probably work best is to set the sweep phase increment to a value calculated from the time between MIDI clocks... Unfortunately, the original Chroma doesn't have a very versatile high-res timer. I don't know if the CC+ added a better timer...

Hindsight is 20/20, and if I knew then what I know now, it would have made sense to try to include an additional hardware-based timer on-board in the CC+. Unfortunately, that wasn't the case - and so the timing resources available are just the ones in the Chroma.

As you noted, the timer in the Chroma does what it needs to do for the core Chroma operation - but it really isn't a 'general purpose' timer and so doesn't easily lend itself for other uses. As that timer is also used for the main processing of the Chroma, we can't easily take it over just for sync operations either.

Some other practical considerations:

  • A 120 BPM tempo means 0.5s/quarter note. At 24 PPQ, that would mean the time between MIDI clocks is 20.833mS. For 121BPM, you'd have 20.661mS between clocks. That means, to have at least 1 BPM resolution near 120 BPM, the internal timer would need to be able to at least resolve to 170uS. If you want to be able to support a clock up to 200BPM or so, then you'd need to be able to resolve down to 62uS for a 1BPM difference. 62uS is very fast for a software-based system.
  • Per the note above, while the 'timing' could theoretically change every 62uS the Chroma only recalculates a channel's next sweep value every 20mS and so changes faster than that are going to be 'lost' anyway.
  • The 'highest resolution' timer, easily available inside the Chroma runs around 1.25mS.
  • If the best timer is 1.25mS, you can't necessarily afford to calculate the time between every MIDI clock; rather, you'd need to count a certain number of MIDI clocks and see how many '1.25mS' 'ticks' occurred during that period. This is the mathematical reason why there's a tradeoff between the accuracy and the latency. To be more accurate, you'd want to average over more 'tick's of the clock' - to be more responsive, you'd need to average over fewer clock ticks (but then suffer with the inaccuracy).

Based on responses to the list, it does indeed seem that the preference is for accuracy over short-term responsiveness (which is also my preference).

The sync feature will be in the next firmware release but perhaps we'll call it an 'initial release' so people can try it operationally, see whether it is sufficiently useful - and then make comments on how/if it needs to change.

What would cause a voice card to be out of tune after passing autotune?

RJ Krohn [21030455]

hey folks, sorry if i'm rehashing an old problem, but i've hit a wall on getting this last voice card working. here's the rough specs:

  • Z19,20, and 25 have all been replaced.
  • the card will usually not pass autotune for the first 5-10 minutes, but then often will pass autotune, but OSC B will be noticeably out of tune. off by almost a half step, making it unplayable.
  • i've traced the waveform on a scope from Z10, but to my eyes, the outputs look fine, so i dont see anything different.
  • i have found that on the faulty card, if i trim the waveshaper trimmer for OSC A to be spot on in tune(it's usually only out by less than 10 cents), and then run the autotune, that change in pitch will STICK, i.e. the autotune function will not send OSC A's pitch back to its previously (slightly out) pitch. HOWEVER, it WILL send OSC B's pitch back to its previous (VERY out) pitch. in essence, trying to trim the pitch via the waveshaper trimmer for this card WORKS for OSC A, but not for OSC B. autotune sends OSC B right back to being very out of tune.

i've got sockets, and enough IC's to essentially shotgun the whole OSC section, but i'd much rather not do that. i can't seem to get any further with a scope(doesnt help that it's virtually impossible to reach the bottom side of an IC when it's seated in the machine).

does anyone have an idea of a likely cuplrit in the OSC section? (ps-all these tests were done using the scratch patch). thanks, rj

Paul DeRocco [21030230]

Usually, if an oscillator passes auto-tune and then sounds out of tune, it's because there is excessive leakage in its sample-and-hold. This results in a small sawtooth or scallop (filtered sawtooth) wave superimposed on the control voltage, which gets averaged out by the oscillator. The sample-and-hold update rate, however, is different during auto-tune, resulting in a different offset.

You've already replaced the CMOS switches. I'd try replacing the TL082 op-amps and/or the sample and hold capacitors. (Make sure you use low ESR low leakage caps.) It's also possible that there's some crud on the board that's causing leakage, but I assume that when you changed the 4051 chips, you cleaned all the solder flux off. You did do that, didn't you?

My order of attack would be: look at the PITCH A and PITCH B control voltages with a scope, AC coupled, with the gain cranked up, to see if they've got more than a couple millivolts of ripple at the 50Hz update rate. If not, then the problem lies elsewhere. If they do, I'd try a thorough cleaning in that area, on both sides of the boards. If that doesn't fix it, I'd replace the caps, because they're easier. If that doesn't fix it, I'd replace the op-amps.

David Clarke [21030085++]

Do you have an alphanumeric display attached to your CC+ and do you have the ability to program an EPROM?

If so, then we can provide a tuning-debug version of the firmware which will at least identify what portions of the auto-tune are failing (and hence will let you focus on something unique to VCO A, B, common circuitry, etc.)

[Note to all - while some individual CC+ users have already been provided with an unofficial 'voice card debug' version of firmware, this capability will be added as part of the standard release, starting in the next firmware.]

RJ Krohn [21030455]

alas, i dont have an alphanumeric display. but i do have CC+ in there. looks like i've got a good route for a working card.

i noticed another bizarre trait of OSC B on this card. after letting it sit on for an hour, and recalling the scratch patch (set split 39), this OSC B's pitch would drift DOWN after triggering. so it would initially be in tune, but would drift down quickly, as if i was doing a pitch bend down. does this sound like a capacitor not holding a charge consistently, echoing the sample and hold section theory?

Paul DeRocco [21030230]

Not surprising at all. On any sudden pitch change, channel 4 in both Z19 and Z20 turn on, to charge both capacitors up. On subsequent samples, only Z19 is used, so that any modulation will be smoothed by the RC time constant. If there is any current leakage on the node connecting C36, Z23-3 and Z20-1, it will develop an offset voltage across R104, which would account for the pitch droop--and your auto-tune problem. Again, it could be any of those three parts, or it could be board leakage.

looking for one working voice card, sale or trade.

RJ Krohn [21030455]

hi folks, im 1 voice card away from having a fully working chroma, and would love to put the repair side of this thing to bed. im looking to either purchase outright, OR trade+cash-i have 2 complete, non-working voice cards and one complete, non-working channel motherboards. let me know if anyone out there is interested or has anything available. thanks, rj

Doug Terrebonne [21030114]

How far did you get in repairing the non-working cards? They are usually pretty simple (CMOS chip failures most common, sometimes CEM chips)...

Voice tuning repair

Matt Hillier [21010094+]

Hi guys

i have a chroma here that has just started booting and showing '# err 1 ' which i think means voice card 1 won't tune ?

I have tried swapping out all the cards and it just shifts the err to another number / voice ) so my guess is the card needs fixing.

I have tried the ' set split / 50 trick ' but nothing changes.

The Chroma sounds perfectly in tune though on all voices.

Can anyone advise on repair this may need / cost and who to use for this in the uk ?

Luca Sasdelli [21010226]

Hi, it could be a board adjustment set; please check on the site the voice board tuning procedure (50% pulse wave) to see if this does solve.

Should the board being repaired, you can send it to me in Italy.

Luca Sasdelli [21010226]

More in detail: Service Manual: Calibration & Checkout

Remembering Phil Dodds...

Chris Borman [21030194+]

Watching Close Encounters of the Third Kind on SciFi network. The Phil Dodds scene coming up shortly!

I wonder what Chris’ focus would have been had Phil not sold CBS/Fender Rhodes on the Chroma? Still can’t believe he lived less than 5 miles from me and my two Chroma’s in disrepair... Would have been a fun meet!

Chris Ryan [21030691]

I wonder what Chris’ focus would have been had Phil not sold CBS/Fender Rhodes on the Chroma?

Maybe a PolySix site, or more likely OB-8. Traded in the former for the latter, and when the Oberheim just couldn't be repaired I swapped it for the Chroma.

Marais

OB Xpander would of been nice

Chris Borman [21030194+]

I absolutely agree with that Marias!

Chroma, Xpander, T8, K2600, Quadra, 2600... All would be nice!

Chris Ryan [21030691]

Chroma, Xpander, T8, K2600, Quadra, 2600... All would be nice!

Well, one such effort is enough for me. But if someone else wants to start a site for one of these instruments, I'd be more than willing to provide some advice.

Back to the original topic, for those who may be relatively new to the list, in the early noughts we put together a list of questions for Phil Dodds and I did an "interview" with him via email.

Marais

My experience btw the is that the two synths that layer the best with the Chroma are the Xpander and any DX-7 or similar.

Chris Borman [21030194+]

I could see that. The DX7. Digital frequency modulation (FM) synthesizer in its roughest of early implementations. My guitarist friend had one and recorded a great CD with it, Jaco tribute and all!

My Son was playing my drum set w/ Super Sensitive Snare. So he decided to jam the stick into the well seasoned head and popped it open. Quite a few years getting that head there shot to hell! Of course I was pissed and taught him a few adult words... But, later I put on a Weather Report CD and was hand drumming along with the busted snare head. It was magical what I did with that busted snare head. To quote ex ST6 guy Chris on One Man Army, ‘The operator should not be intrigued by any one weapon. Truly the weapon is the mind’ (or something like that). True with any instrument including synthesizers.

Paul DeRocco [21030230]

Chroma, Xpander, T8, K2600, Quadra, 2600... All would be nice!

Let's skip the Quadra, okay? If I never hear another one of those, it'll be too soon. I think that was Dave Friend's baby, certainly not Phil's or mine. Dave's been a smidgin more successful since turning his attention to other things.

Chroma vs. other polyphonic analog synths

Tobias Menguser

Hi all,

I'm new to this list and would like to say hello and post a few first questions.

I own several great synths like the Jomox Sunsyn, NED Synclavier, DSI Poly Evolver etc., and think about adding the great Chroma to my studio setup to produce trailer and electronic soundtracks.

I have an offer to get a Chroma with new wood but without midi for 4000EUR, what do you think about the price? Another candidate on my wish list for polyphonic analog synths is the Xpander, which is cheaper.

Any (comparison) comments from owners of a Chroma and a Sunsyn or Xpander?

Thanks for your feedback!

Best,

Tobias

Marais

Hello,

Here is a very nice demo of some Chroma sounds. Rhodes Chroma Demo, Part 3

I would say the Xpander complements the Chroma. Also keep in mind many of the current add on's available for the Chroma like CC+, new power supply, Enabler Programmer iPad editors, aftertouch kit, etc. and the top support from this list you get to keep a vintage instrument up and operating.

Enjoy and let us know if you pick it up.

Tobias Menguser

Hi M.,

Thanks for your reply.

Here is a very nice demo of some Chroma sounds.

Thanks, I know these demos already.

I would say the Xpander complements the Chroma.

How would you compare the sound?

Any owners of a Chroma and a CS80 who can describe the sound differences?

Also keep in mind many of the current add on's available for the Chroma like CC +, new power supply, Enable >Programmer Ipad editors, aftertouch kit, etc. and the top support from this list you get to keep a vintage instrument up >and operating.

Thanks for this information. I think the unit has a new power supply next to the new wood. Do you think 4000EUR is a good price?

Enjoy and let us know if you pick it up.

I will!

Best,

Tobias

James Coplin [16330036]

Tough call. I have both the Chroma and the Xpander and I use them both constantly. I prefer programming on the Xpander and I think you have more complexity and depth to the Xpander due to the massive number of filter types and the extensive modulation options and sources. However, I do think the Chroma "sounds" better. Which is completely subjective and it can hardly be said the Xpander sounds "bad" as it of course sounds amazing as well. All of that being said, I picked up a second Chroma last week but I don't have any plans for a second Xpander. ;)

Jesper Ödemark [21010135]

Thanks for this information. I think the unit has a new power supply next to the new wood. Do you think 4000EUR is a good price?

The price is fair. Not extreme in any way, but I would make sure the PSU is new. The original one is the number one problem in the Chroma. If the synth is in good shape with all new wood as you describe and a fresh PSU added to it 40 grand is OK. You could argue it should include the CC+ too but on the other hand, new wood is a lot of work too. With old PSU and/or refurbished old PSU it's not worth half for someone who plan to use it professionally (IMHO).

The Chroma is my main polyphonic machine so I cannot compare to those you mention. But having owned a few of the older Roland's, the PS-3200 etc the Chroma sure kicks a**. My only other analogue poly is the VX-600 and they surely complement eachother. The VX-600 is colder, precise, snappy and "tough". The Chroma is a lot more organic, alive, warm and "expensive" sounding.

Chris Ryan [21030691]

Do you think 4000EUR is a good price?

I've been tracking prices; see the Price History.

Tobias Menguser

Hi James,

Thanks for your helpful feedback,

Due to Chroma programming: Can I program the Chroma via MIDI CCs when having the CC+ update?

Best,

Tobias

Tobias Menguser

The price is fair. Not extreme in any way, but I would make sure the PSU is new. The original one is the number one problem in the Chroma. If the synth is in good shape with all new wood as you describe and a fresh PSU added to it 40 grand is OK. You could argue it should include the CC+ too but on the other hand, new wood is a lot of work too. With old PSU and/or refurbished old PSU it's not worth half for someone who plan to use it professionally (IMHO).

The Chroma is my main polyphonic machine so I cannot compare to those you mention. But having owned a few of the older Roland's, the PS-3200 etc the Chroma sure kicks a**. My only other analogue poly is the VX-600 and they surely complement eachother. The VX-600 is colder, precise, snappy and "tough". The Chroma is a lot more organic, alive, warm and "expensive" sounding.

Hi Jesper,

Thanks for this helpful feedback as well!

Anybody who compared a Chroma to a CS80?

Best,

Tobias

Jesper Ödemark [21010135]

Due to Chroma programming: Can I program the Chroma via MIDI CCs when having the CC+ update?

Yes! :D

I have a Doepfer Drehbank hooked up to mine and it's amazing to have everything at your fingertips.

Matt Thomas [21010021]

Hi,

I have both & fwiw I'd probably sell the CS-80 first. Heresy I know, but both are superb instruments. It just happens that the CS80 is really a keyboard player's synthesizer (i.e. the best of it comes from the nuanced performance that it allows) whereas the Chroma is more of a programmer's delight, with still excellent performance features. I'm not the best player in the world, so the greater sonic palette & the MIDI parameter control via the CC+ means that the Chroma would stay if I had to ditch one.

Tobias Menguser

Great to hear that Midi CCs work!

I would like to use my Lemur for Chroma programming.

Best,

Tobias

Marais

I have had a CS60 and 80, I would say the Chroma can be nearly as organic sounding as CS series, and perhaps just a tad less expressive (ribbon, and the best implementation of aftertouch ever on CS) and intuitive (control panel on CS). But much more reliable once the usual issues are dealt with (power supply stabilized, voice board issues dealt, key contacts cleaned, etc.) and the CC + update is added.

I would say James summed up nicely the sonic differences The Xpander is more complex in the fiter types and modulation matrix but the Chroma is bigger sounding. I would say both do texture well, neither having fast envelopes but this is never a issue for me personally. I find both benefit from a nice analog chorus. Both are a tad harder to program than a simpler synth like a Prophet, Juno, and Jupiter. This can be made easier on with a external programmer (yes w/ CC+ on Chroma) such as a iPad and midi interface and iPad editor app, a computer editor, a cheap Behringer midi knob box and Chroma profile, or the epic Chroma Enabler box. Both will put smiles on your face if you like to program sound. If your not a tweaker they may be a bit overwelming.

RJ Krohn [21030455]

here's my thoughts re: chroma, CS80, and xpander....

chroma sounds better than xpander (i'm using matrix 12 as my comparison here fyi), IMO, but not by much. poly AT is a bigger difference. i was just thinking the other day that the chroma sounds closest to a slightly beefier matrix 12, to me.

programming the chroma in its stock form sucks. xpander, really a joy in its stock form. however, with upgrades (i'm using dual BCR2000's with labelling), the chroma becomes more fun to program, and easier in ways. again, YMMV.

comparing to the CS80 is tough; it is hands down my favorite synth of all time, for reasons i'm not fully sure of (it makes my insides feel the best?) chroma is up there though. it also depends on what you want: if having a bunch of sounds is a big deal, go chroma or xpander. 80% of the CS80 presets suck, personally. but the interface is the best interface of any poly synth i've ever played, and it sounds unlike any other-when in tune.

one other thing to consider: depending on your playing style, 6 voices may be an issue. when my chroma doesnt tune all the cards, and im stuck with 5 or 6, i get into voice stealing hell, and i do not enjoy being in that location, personally.

good luck.-rj

Tobias Menguser

Hi Matt,

I have both & fwiw I'd probably sell the CS-80 first. Heresy I know, but both are superb instruments. It just happens that the CS80 is really a keyboard player's synthesizer (i.e. the best of it comes from the nuanced performance that it allows) whereas the Chroma is more of a programmer's delight, with still excellent performance features. I'm not the best player in the world, so the greater sonic palette & the MIDI parameter control via the CC+ means that the Chroma would stay if I had to ditch one.

Nice summary, thanks!

I'm not the best player as well, so the Chroma seems to be the right choice. ;-)

Tobias Menguser

Great to hear that the Chroma can be nearly as organic sounding as CS series!

Thanks for the feedback on sound tweaking with external controllers, I like this a lot!

Tobias Menguser

Hi,

Thanks for your thoughts on the three synths, which helped me again (like other posts) to focus on the Chroma now. I think it's more than worth the 4000EUR investment, but I have to find out more about the condition of the Chroma unit which was offered to me.

Best,

Tobias

Brian McCully [21030361]

Best synths to layer with Chroma

Chroma with JX-8P (or MKS-70, double the voices) - the 'strings' of both.

Chris Borman [21030194+]

Re: Best synths to layer with Chroma

The precision of the K2500 with the growl of the Xpander makes my sound bank!

Paul DeRocco [21030230]

What do people actually like about the Chroma?

The "Chroma vs. other polyphonic analog synths" threads is interesting to me, since I was the original designer of the Chroma, but also because I've been tinkering with soft synth simulations of the Chroma. So I'd be curious how what I'd like from a modern version of the instrument matches up with what other people might like.

When I resurrected my Chroma a few years back, I quickly became frustrated with it, and decided I wanted something better. I still like the basic sounds and feel, but I wanted more. Here's what I felt limited by:

  1. Only eight voices. I want to be able to hit the sustain footswitch and play an glissando across the whole keyboard, and not have any notes drop out.
  2. Dry mono output. I want stereo with a nice reverb. I'd like to have panning that can be modulated, or the ability to route the A and B channel outputs to opposite sides.
  3. Poor tuning. I don't want a dry phase-locked sound, but I think the Chroma couldn't tune itself accurately enough, and needed auto-tuning too often.
  4. Detuning A and B is a fixed pitch detune, which sounds unnatural. The Polaris is designed so that the beat frequency doubles about every two octaves, which is more natural sounding.
  5. Primitive voice allocation. I want to be able to change programs, and then play on the new sound while the notes from the old sound are still sustaining.
  6. Insufficient resonance levels. It would be nice if resonance could be modulated as well.
  7. Tone controls should be program parameters.
  8. It lacks the selective pitch bend feature introduced in the Polaris. All lever and pedal based modulation should have selective options.
  9. Envelopes are too slow. The shortest sound you can make is the duration of one 20ms scan cycle.
  10. Limited wave shapes. I'd like to have some simple FM sounds, and maybe even a few sample sets of percussion sounds.

Unrelated to the sound, my other complaints are:

  1. No MIDI. What I'd really like is full speed USB MIDI, and the ability to play different sounds on all 16 MIDI channels, while playing independently on the keyboard.
  2. Sounds are stored in CMOS RAM. I'd like them stored in files on a flash drive, with multiple banks of course. I'd also like them stored as text, so that an external program editor could add descriptions or screen layout information. I'd like to support an external flash drive, in lieu of the cassette interface.
  3. I'd also like to be able to get at the programs, or upgrade the firmware, via Ethernet.
  4. I'd like a clock/calendar to timestamp the files, and to be able to show the time in the display.
  5. The display is purely numeric. I'd like an alpha display that can show (in admittedly tiny letters, because the holes in the panel are tiny) the meanings of the parameter values.
  6. The instrument is too heavy. If I could replace the guts with fewer guts (getting rid of the power supply and all those channel boards), it would be meaningfully lighter, and consume less power.

All this begs the question: do I really want a Chroma, or do I just want a really nice soft synth to run in my laptop? Well, actually, I DO want a modern Chroma. I like a self-contained instrument, which I can use untethered to a computer, that has a decent keyboard. The Chroma's UI isn't great, but it's not too hard to use, and I could double the number of parameters by using SET SPLIT as a prefix. But maybe I'm just old-fashioned, and the rest of the world would prefer a good Chroma VST plug-in.

On the other hand, maybe I'm not old-fashioned enough. Is it possible that a lot of Chroma owners really want analog oscillators and filters, and would turn up their noses at a digital simulation? What aspects of the old analog sound would people want to see accurately imitated?

Marais

Re: What do people actually like about the Chroma?

Mr. D,

This reminds me a little of the story of the great album cover artist for Blue Note records Reid Miles who created some of the most beautiful and revered cover art of all time and when he would get his Lp copies from Blue Note would trade them in for Classical records.

I think what you did is create a true musical instrument, like Bob Moog said he was always wishing he could do. I believe he came over at the NAMM show and told you in some way ? For me it does capture that certain magic that not many did, like the feeling a violinist gets when playing a top notch instrument, with a level a expressibility, playability from the keyboard and a warm organic sound that transforms into musical inspiration despite it's limitations, like a Steinway does. I think you hear this when you hear what Hancock, Zawinul, Garth, and Mays did with it. Hope I didn't overstate it too much. : )

Maximum respect, M

Jack Colburne [21030142+]

Re: What do people actually like about the Chroma?

For me, the difference was never strictly one of a superior "sound". It was, in the end, the playability, physically, literally. (and, yes, the programming flexibility). And that was more than the keyboard.. there was something about how the original velocity tables (in particular), the keyboard itself and the responses of modulation sources(envelopes)made this particular synth sound like a unified, organic instrument. Clearly a synth and electronic, but that word "organic" is one that I could not separate from the beast.

It does not feel or respond as a keyboard triggering a synth.. it plays like as single entity. I did not have to "pretend" or "act" like I was playing, creating the emotion and laying it on the instrument... it was IN the instrument.

That being said, at the time, the depth and flexibility of programming was the most interesting aspect of the beast.. and in that aspect I love just about all entries in your list. (I later was a Kurzweil K2xxx series guy and recognize several things on the list that speak "K series" behavior to me. Still have my K2000RS and K2500. Would not get rid of them as i would not get rid of the Chromas.)

The programming power was the reason I got the beast. But as I learned and played it more, the playability was the reason I fell in love with it.

If you did develop a soft synth version that emulated the Chroma accurately (with all the great additions and "fixes" you list), the best way I could describe why it would be special for me would be that I would most likely ALWAYS play it with my 88 key piano action controller... not the plastic "semi-weighted" controllers or synth keyboards.

That would help make it a "Chroma" for me.

Dave Blees [21030552]

Re: What do people actually like about the Chroma?

Jack - I was in the process of composing a message so much like yours, after reading yours I decided not to bother! I would only add that if such an instrument as a Chroma (Mark II?) were developed with all the feature tweaks Paul listed, and the keyboard could especially emulate the feel of the original (with possibly an equally elegantly simple action design), I would buy an *88-key* model in a heartbeat - forget about the other controller keyboard, the Chroma's the best controller I ever had, with its only shortcoming being the less than full key complement. Please put me on the Beta tester list, Paul!!

Jesper Ödemark [21010135]

Re: What do people actually like about the Chroma?

Paul D. DeRocco skrev 2012-07-30 00:44:

On the other hand, maybe I'm not old-fashioned enough. Is it possible that a lot of Chroma owners really want analog oscillators and filters, and would turn up their noses at a digital simulation?

Yepp! :D

Marais

Re: What do people actually like about the Chroma?

Just don't let Arturia do it please, it will be buggy. : )

Luca Sasdelli [21010226]

Re: What do people actually like about the Chroma?

Well... The Rolls-Royce Phantom II didn't had neither GPS nor ABS/ESP, phone etc., but still it's a very beautiful car! :-D

Perhaps isnt' that a matter of old-fashion or not: simply IMHO the Chroma has limits, I know them and I'm happy to play it within those limits.

Marais

Re: What do people actually like about the Chroma?

The Beatles had 4 and 8 tracks. Limits are good in music. : )

Although a modulatable stereo out would be nice : ) David .C, in theory could this be something added to CC+ with a hardware mod?

Luca Sasdelli [21010226]

Re: What do people actually like about the Chroma?

Stereo output needs a new Channel Motherboard, that could balance single board (A+B channels!) output across stereo landscape. The two-channels together is a limit, because with independent voice patches the channel separation will have 2+2+2+2+2+2+2+2 voices to distribute among L+R channels; to overcome this, a new DVB design would be needed, to bring out osc A and B signals on separate buses, so having 16 voices to spread across stereo front.

I know Heinz [21010276] already has such as a design (I think it should be some hard-balanced stereo distribution... am I wrong?).

A custom panning requires extra hardware (VCAs on CMB) and software to control and store it within presets.

RJ Krohn [21030455]

Re: What do people actually like about the Chroma?

2nd that. i've got enough VI stuff. none of it is exciting like an actual instrument.

Paul DeRocco [21030230]

Re: What do people actually like about the Chroma?

2nd that. ive got enough VI stuff. none of it is exciting like an actual instrument.

If you're unexcited by your virtual instruments, is that because they don't sound good, or because you don't like the inconvenience of not having everything in one clean physical package?

Part of my question is whether people are snobbish about real analog circuits, the way they are about tube amps or vinyl records, or whether they would appreciate an actual Chroma whose guts were replaced with digital, as long as it sounded like good analog.

There are a lot of bad ways to do digital simulations of analog. It's hard to bandlimit sawtooth or pulse waves so that you don't get aliasing up high, especially with Sync sounds. And it's hard to make a filter that doesn't clip horribly when it self-oscillates and has a wave going through it. And one must take steps to ensure that the oscillators aren't so perfectly in tune that they sound dry. But there are good ways to do all these things, too.

Paul DeRocco [21030230]

Re: What do people actually like about the Chroma?

The Beatles had 4 and 8 tracks. Limits are good in music. : )

Their early stuff was recorded in mono. Later, computer magic managed to separate the sounds to create pseudo-stereo.

Paul DeRocco [21030230]

Re: What do people actually like about the Chroma?

Jack - I was in the process of composing a message so much like yours, after reading yours I decided not to bother! I would only add that if such an instrument as a Chroma (Mark II?) were developed with all the feature tweaks Paul listed, and the keyboard could especially emulate the feel of the original (with possibly an equally elegantly simple action design), I would buy an *88-key* model in a heartbeat - forget about the other controller keyboard, the Chroma's the best controller I ever had, with its only shortcoming being the less than full key complement. Please put me on the Beta tester list, Paul!!

The trouble is, all I can do is make replacement electronics. I'm not in a position to create a brand new instrument with a new keyboard. That would take major backing, something that companies like Roland, Korg, Yamaha would be unlikely to tackle, since they're wedded to their own architectures and engineering departments.

Eric W. Mattei [21030443+]

Re: What do people actually like about the Chroma?

I bought my Chroma in 1982 because it was the most powerful polyphonic multitimbral analog synthesizer under digital control ever sold. Thirty years later, it still is. At this point, I like the idea of having real live honest to gosh analog oscillators and filters in addition to digital synths and VI's.

Also, the Chroma's action is, of course, in a whole other class compared to the typical plastic and spring keyboard. My hands are insured for tens of dollars. :) But I've always found the Chroma so much easier to play than any other synth I've seen.

So what more could I ask for? Well, under MIDI control, the Chroma's multitimbral capability is awesome. But the lack of dynamic voice allocation is frustrating.

Marais

Re: What do people actually like about the Chroma?

Agreed, actually the most recent digital things that exited me were iPad apps (Animoog, and StepPolyArp, Funkbox, etc.) Although the new software version of the PPG is nice. Although I am not into them the new hardware and DIY modular synth scene is crazy.

Marais

Re: What do people actually like about the Chroma?

Part of my question is whether people are snobbish about real analog circuits, the way they are about tube amps or vinyl records, or whether they would appreciate an actual Chroma whose guts were replaced with digital, as long as it sounded like good analog.

I would say both here. Sound is always a little plastic sounding and let down, and working on a computer synth is not inspiring to me in most cases.

Marais

Re: What do people actually like about the Chroma?

yes, can we get fake stereo for the Chroma ? : )

Chris Smalt [21010280+]

Re: Chroma vs. other polyphonic analog synths

Jesper wrote:

If the synth is in good shape with all new wood as you describe and a fresh PSU added to it 40 grand is OK.

Hey guys, anyone interested in one of my Chromas at only 39 grand (euros)? ;-)

Chris Smalt [21010280+]

Re: What do people actually like about the Chroma?

  1. Dry mono output. I want stereo with a nice reverb. I'd like to have panning that can be modulated, or the ability to route the A and B channel outputs to opposite sides.

On big shows, I used to route four Chroma outputs to four mixer channels, so that each sound would have the right effects and panning. On the other hand. I didn't mind playing the Chroma totally dry in small concerts. It still blew all other synths out of the water.

On instruments with built-in effects, I always thought editing those was a drag, and there was no real time control. Or rather: editing effects parameters while playing would cause clicks and stuff.

  1. Detuning A and B is a fixed pitch detune, which sounds unnatural. The Polaris is designed so that the beat frequency doubles about every two octaves, which is more natural sounding.

I have always added a touch of keyboard tracking to one of the oscillators to adjust this to taste.

On the other hand, maybe I'm not old-fashioned enough. Is it possible that a lot of Chroma owners really want analog oscillators and filters, and would turn up their noses at a digital simulation? What aspects of the old analog sound would people want to see accurately imitated?

If an emulation sounds different, I'll program it a little differently to make up for it, or add some effects etc. I would love a VST Chroma. I have no trouble at all making my computer gear sound lively and powerful.

I know many people seem to have an allergy for virtual keyboards. But then their real Wurlitzers, Vox Continentals, Hammonds and Rhodes pianos sound fairly stuffy to me. So I guess Jack's "unified, organic instrument"-notion is at work here - if it feels good, it is good. Personally I'm much happier playing, say, a Wurlitzer sound from a good master keyboard than using a real one.

What I like about the Chroma was that it doesn't *sound* limited, even though the architecture restricts you in many ways. This is what makes it a real instrument, instead of some do-it-all keyboard.

David Clarke [21030085++]

Re: What do people actually like about the Chroma?

...Perhaps isnt' that a matter of old-fashion or not: simply IMHO the Chroma has limits, I know them and I'm happy to play it within those limits...

My sentiments line up pretty much with Luca's Rolls-Royce analogy. I used to own a 1957 Chevrolet. By today's standards the car came with poor brakes, windshield wipers that moved quicker the faster the engine went, an AM-only radio, bench seats, etc.

It is of course possible to modify the car to have power windows, power seats, put in a different engine, take out sheet metal to make it lighter, etc. At some point though the car really stops being a what a '57 Chev was and becomes a modern car that looks like the original.

I'm not saying that the new car would be bad - but it really isn't what it started out as either.

I personally wouldn't mind having both of those cars. That said - if the only way to get the latter is to sacrifice the former, I would prefer to keep the original as is.

So - I'd be pleased to be able to get something that had all of the earlier mentioned features - but I'd prefer to have the option of getting it as a standalone unit vs. needing to 'gut' a Chroma to get it.

I understand a new keyboard chassis might not be viable, but perhaps a compromise (that is in line with past ChromaTalk discussions) would be to produce a new 'expander' module that had all the features discussed. Because it would only be a module - it would be used tied to the Chroma's keyboard - or separately controlled via MIDI. By doing this sort of thing you now get 100% flexibility as to how to implement the electronics and MIDI.

Tom Hughes [21030251+]

Re: What do people actually like about the Chroma?

Dare I say?... Bring on the C2!

Jack Colburne [21030142+]

Re: What do people actually like about the Chroma?

In the spirit of David's hardware description/conversion, if a software emulation was viable and truly "a Chroma", it would be a nice touch to design it to work like the GForce MiniMonsta with a more authentic emulation mode, and an "UberChroma" mode incorporating the barrel of features that might otherwise turn it into a "not-Chroma"... "a modern car that looks like the original."

It would be slick to have the original 1966 Batmobile built from a 1955 Futura, but be able to flip a switch and have a new armored, mega armed 21st Century version too.

Marais

Re: What do people actually like about the Chroma?

I route my Chroma permanently to a Roland Dimension D chorus, instant Stereo : )

Jesper Ödemark [21010135]

Re: What do people actually like about the Chroma?

Paul D. DeRocco skrev 2012-07-30 21:13:

Part of my question is whether people are snobbish about real analog circuits, the way they are about tube amps or vinyl records, or whether they would appreciate an actual Chroma whose guts were replaced with digital, as long as it sounded like good analog.

As I said earlier: Yepp!

I have no problem being called snobbish with 6000 vinyl records and somewhere in the region of 60 synths (57 or so analogue). ;)

Jokes aside, I can still hear what people use when presented to new tracks and I still think the best sounding overall sound (not individual tracks which more heavily rely on musician/productions skills) comes from analogue gear. I read this article: The Sizzling Sound of Music which summed it up good for me. When the CD came, people said the vinyl was dead due to imperfections. The same was true for the analogue/digital world of musical instruments. Both things proved to be wrong. In the article I can read that today's younger audience not just only miss out on the differencies in mp3 quality, they even prefer lower quality 'cause their ears are used to it. This will not help me though, I prefer the cracks and pops on vinyl prior to CD "perfection" and I would probably never settle and be happy with a digital "Chroma". Example: I downloaded the virtual MiniMoog from Arturia this summer 'cause it was free. It was fun for three minutes (just like the Google Doodle was when they remembered Bob's bithday). On the other hand, my faithful #4740 have seen hundreds of times more use in just the short span after those three minutes.

But, there might be a market for one, especially for those interested in "new" digital instruments which live up to 95% of the genuine machine's standards and who aren't interested in hunting CEMs and tracking hairline cracks and dry joints. :S I wonder how well the Memotron have sold... just a thought.

Sorry for bordering on off-topic. :)

Tim Siefkes [21030850]

Comparing Chroma to CS80...

On 7/29/2012 10:40 AM, tobias.menguser wrote:

Anybody who compared a Chroma to a CS80?

I have both Chroma and CS-80 (well, I should say "HAD" the Chroma, which I finally sold just last week to James Coplin... hi James!) I bought each one brand new when they first appeared on the scene (ca. 1978 and 1982 respectively). They were both "must have" instruments for me in the day, and I gigged for years with each of them, but oddly never both at the same time. I always felt the CS-80 was the most "fun" to play, with it's true polyphonic after-touch, ribbon controller, and all the controls/sliders you could grab and adjust in real time on the fly, sort of like grabbing the Hammond drawbars at will. Throwing in a quick touch of Ring Modulator for instance as an accent... and getting right back to the regular sound you were using was fun. I guess the CS-80 was the most expressive to play, for me. But it had a more limited sound set (like Brian Eno once commented, something to the effect that the CS-80 has only about five or six great sounds that it does those REALLY WELL). It worked well in my prog rock and 80's synth-wave bands (think UK, Ultravox, Gary Numan type stuff).

Chroma on the other hand was a much deeper instrument, with a wider array and palette of sounds to choose from. Much more could be done with it in terms of sequencing and just wild effects and internal modulations. It could be MIDI'd with other sound modules. You could split the keyboard. I loved having the Apple ][ sequencer to play with, and to be able load various banks of sounds into it as well. But it was also just less intuitive to adjust sounds on the fly during the live performance. I felt more locked in to the presets, though the presets were very good! But, simply not quite as adjustable during the live set. I tended to stick more with the sounds as they were programmed. I used it more for funk & reggae.

Both sound great, and of course there's no one instrument that's perfect for absolutely everything. Both have their strengths and weaknesses and both are monster machines in their own ways. I feel privileged to have had both! As I said, my Chroma is now in the good hands of Mr. Coplin, and I still have the CS-80 but it is harder to move it around now. (When I gigged with it, my band had the benefit of a small road crew and a truck... and the CS-80 has it's own enormous Anvil ATA case on wheels). It will be harder for me to part with that one... there's a stronger emotional attachment there I guess. They might just have to pry it out of my cold dead hands...

RJ Krohn [21030455]

Re: What do people actually like about the Chroma?

thanks for your thoughts on this, paul.

i have sample sets of novachord, jupiter 4, and VP330 that sound amazing. they are indistinguishable from an "in the flesh" analog synth to my ears. when it comes to things like reaktor/CS80V/other VI's, it's both sound and interface that are a problem for me. a big part is that tweaking filters or whatnot by dragging and clicking is soul crushingly annoying, to me at least. i haven't found one that on sound alone beats the real thing, and as someone lucky enough to be privy to the real thing, it's an obvious choice-now. i don't doubt that they'll get close enough-if they haven't already-as far as sound quality goes. that help?

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