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Curtis chips: Prophet 5 & the classics?
Old 2nd June 2008
  #1
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Dirty Halo's Avatar
 

Curtis chips: Prophet 5 & the classics?

For my education, what is it about the "Curtis" chip that makes it special and gives it that sound?

And what are the alternatives? What do they sound like or can be characterized?

-andrews
Old 2nd June 2008
  #2
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Quote:
Originally Posted by Dirty Halo View Post
For my education, what is it about the "Curtis" chip that makes it special and gives it that sound?

And what are the alternatives? What do they sound like or can be characterized?

-andrews
Bump? Please.

-andrews
Old 2nd June 2008
  #3
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I know very little about EE design, so I couldn't tell what makes the Curtis chips sound the way they do. But like you know, most of them have a sort of "brash", "brassy" quality to them. Not all Curtis synths sound the same, as it's not just the chips that define a synth's sound, but all Curtis-based synths share something tonally.

Alternatives? Well... Besides discrete electronics, way back in the late seventies / early eighties, there weren't a lot of other options for compact synth design. Besides Curits, Solid State Music (SSM) were the only other widely available option for inegrated filter, oscillator, vca and envelope chips. Prophet 5 rev 2, Korg Trident / Polysix and RSF Kobol are probably the most famous SSM synths. Some people argue that compared to CEMs, SSM chips have a more organic sound to them.

Roland (and Yamaha?) had their own chip designs, had their own sound, but these were not available for other manufacturers. And nowadays, there are also Alesis' ASIC chips.

- CM
Old 2nd June 2008
  #4
thx1138
Guest
It sounds good, that's all you need to know heh
What do you mean by alternatives? There aren't that many chip manufacturers out there... the only one I can think of are the SSM chips which were in the first models of the Prophet 5. I like that one a tiny bit better, but they are different.
Old 2nd June 2008
  #5
Deleted 8456dd3
Guest
Curtis chips are used throughout old analogue polysynths. Mostly famous i guess for the 3340 vco chip and 3320 filter chips.

The 3340 is the vco design in the Sh101, Pro One, OBXA, OB8, Prophet 5, Memorymoog and others..

The 3320 is the filter chip used in the Synthex, Pro One, OBXA, OB8, Prophet 5 and others.

SSM were the other big "synth" chip manufacturer, of their range the most significant were probably the 2040 and 2044 vcf chips, those were used in the Polysix, the early version of the Prophet 5 (Revision 1 and 2's used the SSM 2040 filter chips) and also the PPG Wave (SSM 2044)

The CEM filters in particular do have a sound. They are becomming increasingly more difficult to source spares for today..
Old 2nd June 2008
  #6
Doepfer uses Curtis chips in many of their filters.
A forward somewhat agressive sound. it can go deep too, but is less "relaxed" than moog, and less "psychedelic" than ARP etc.
the A-111 oscillator uses a CEM3340.
Old 2nd June 2008
  #7
Gear Maniac
 

there's alot more to it than the chip. circuit architecture has alot to do with sound.

thus, mono yamaha cs's dont sound like 1 note being played on a cs80.

obxa vs. p5 vs synthex. got all 3, lots of difference.

and yes, who cares-it doesnt matter. find what you like and jam.
Old 2nd June 2008
  #8
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The "sound" of a Curtis chip?

Quote:
Originally Posted by rjd2 View Post
there's alot more to it than the chip. circuit architecture has alot to do with sound.

thus, mono yamaha cs's dont sound like 1 note being played on a cs80.

obxa vs. p5 vs synthex. got all 3, lots of difference.

and yes, who cares-it doesnt matter. find what you like and jam.
No doubt... I'm just curious what it is specifically about the Curtis chip that gives it its sonic characteristic versus another chip... and what is it about how the differ that make them sound different?

I know that a Prophet 5 with the same architecture sounds different depending on the chip, ergo est, the chip has "a sound."

I'm curious and would like to learn.

-andrews
Old 3rd June 2008
  #9
curtis: mean, sharp, direct
SSM: brutal, wide, more phased

both have a nice edge. the differences are marginal but existent
I favour the SSM sound, but that's just personal opinion.

hope my dribble helps
lol
Old 3rd June 2008
  #10
i always felt these adjectives to do it for me:

curtis (cem): direct, focused, ripping, sizzley/brassy in the highs, cutting resonance..

ssm (e-mu*): wide bandwith, smooth, organic, warm, liquidy resonance..


however, within each group, it does depend on the circuit implementation. for example, filters: 2044 in Trident leaves those in Polysix and MonoPoly in dust IME. 24dB 3320 in Rev3 P5 and Wave2 trumps the OBXA in 24dB setting. again, OBXA's 3320 surpasses OB-8 at 12dB setting etc etc.. it goes on.

also generations n revisions of chips matter too: i do feel the earliest 20x0 series of SSMs sounds bigger and more organic than the second, 2031/2044/2056 series used in Korgs etc. and that the second generation of curtis (337x) is just so smoother and less agressive/brassy than the early ones (3340,3360,3320).



*ssm are indeed e-mu chips, designed by Dave Rossum, for their late, chip based modulars, and ill-fated Audigy. made for sci rev1 and 2 prophets, until 1980 when Dave switched to CEM. later revisions were adopted by korgs, ppgs 22/23, fairlights, kobols. also used in emulatorII, sp12 and emax etc... "SSM" or "SSMT" was a company that mass produced them.
Old 3rd June 2008
  #11
Quote:
Originally Posted by clusterchord View Post
.....snip...
*ssm are indeed e-mu chips, designed by Dave Rossum, for their late, chip based modulars, and ill-fated Audigy. made for sci rev1 and 2 prophets, until 1980 when Dave switched to CEM. later revisions were adopted by korgs, ppgs 22/23, fairlights, kobols. also used in emulatorII, sp12 and emax etc... "SSM" or "SSMT" was a company that mass produced them.
I always felt they should've used an SSM stage in those last EMU command stations (being the grandchild of the audigy - sort of). that and a direct sampler function, and they would've made the perfect workstation. but it's got inserts, so I'm not complaining much.
heh
Old 10th June 2008
  #12
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dan p's Avatar
 

Rip Doug Curtis.A few months back doug passed away but his design will stay forever.


Dan P
Old 13th June 2008
  #13
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[h1]Soul of the Machine [/h1]
By Marcus Ryle | April, 2007
In January of this year, the synthesizer world lost one of the most important and least known synthesizer pioneers of the 20th century, Douglas R. Curtis. For those in the know, the term “Curtis Chips” might ring a bell. But for most, Doug’s work was hidden behind the scenes. While great pioneering names like Oberheim, Sequential Circuits, Roland, Korg, Moog, Ensoniq, Rhodes, PPG, and countless others graced the front panels of many amazing instruments, Doug’s chips delivered their soul.

The practice of analog circuit design is a mysterious art, but Doug was one of its true wizards. His natural gift for physics and mathematics, coupled with his early fascination and love of synthesizers combined to create his calling. He started building his own analog synthesizers in high school, and continued through college. After attending Northwestern University, Doug managed to win a contest (and a job) at the company Interdesign with an innovative VCA chip design, which he also patented. Doug’s winning design was published in an electronics magazine, and caught the attention of Tom Oberheim. In the mid-’70s, Tom asked Doug if he would be able to design a voltage-controlled envelope generator that he could use to make the Oberheim 4-voice programmable. Of course, Doug was able to design the chip, and Curtis Electromusic Specialties was born. Before long, Doug had designed dozens of versatile and great sounding chips that would lead the analog synthesizer world for decades.

I had the good fortune of working with Doug during my days at Oberheim from 1980 through 1985. Tom was my first boss and mentor, and Doug quickly became a mentor to me as well. Tom, myself, Doug, and Michel Doidic (another analog wizard) would sit around dreaming up the ultimate in analog synthesizer capabilities, and Doug would go off and design some more magic oscillator and filter chips to make it all a reality. Products like the Oberheim OB-8, Xpander, and Matrix-12 (to name just a few) would not have been possible without Doug. The sounds of these instruments live on, thanks to his designs.

Doug wasn’t interested in being in the spotlight for his work; he was a unique mix of technical brilliance and humble kindness. But despite his relative anonymity, his permanent mark on the musical world is undeniable. In recognition of this, Doug was inducted last year into the San Jose Rocks Hall of Fame for his technical contributions to music. Sadly, at the young age of 55, Doug lost a brief but fierce battle with pancreatic cancer. He is survived his wife, Mary, and two daughters, Ashley and Julia.

Chips off the old Block
A partial list of instruments that contain Doug’s chips:

• Dave Smith Instruments Evolver
• Roland Jupiter-8
• Oberheim OB-8
• Akai: AX-80, AX-60
• Banana: Poly Synth
• Cheetah: MS6
• Crumar: Spirit, Bit 01, Trilogy
• Dave Smith Instruments: Evolver, Poly Evolver
• Elka: Synthex
• Ensoniq: ESQ-1, Mirage, SQ-80
• Fairlight: CMI II
• KeyTek: CTS-2000
• Korg: MonoPoly, Polysix, Poly-61
• Linn: Linndrum
• Moog: MemoryMoog
• Oberheim: OB-Xa, OB-SX, OB-8, Xpander, Matrix-12, Matrix 6, Matrix 1000
• PAiA: Proteus
• PPG: Wave 2.0, Wave 2.2, Wave 2.3
• Rhodes: Chroma, Polaris
• Roland: Jupiter-6, Jupiter-8, MKS-80, SH-101, MC-202, MKS-20
• Sequential Circuits: Prophet-5 (Rev 3), Prophet-10, 600, 2000, 3000; T8, Pro-1, Six-Trak, MAXStudio 440, VS
• Simmons Drums: SDS8, SDS9, SDS800, SDS1000
• Steiner: EVI
• Synton: Synrix
• Waldorf: Wave, Microwave

Dave Smith Remembers

I worked with Doug since the late ’70s, when I redesigned the Prophet-5 to use his circuits, simply because they worked better. From then on we used his parts exclusively in all Sequential products. When I started designing hardware synths again five years ago, Doug was the first person I spoke to; I wanted to once again have his magical analog circuits as the backbone of the Evolver sound.

I also was lucky to have Doug as a great friend; over the years we have skied, backpacked, mountain biked, and climbed pyramids in Mexico together. A great loss to us all, but his legacy will carry on in all the instruments with his sound, not only the highly-prized vintage synths (how many on the list do you want?), but also in the Evolvers and more new instruments still in the design phase. -Dave Smith
Old 13th June 2008
  #14
Quote:
Originally Posted by Reptil View Post
I always felt they should've used an SSM stage in those last EMU command stations (being the grandchild of the audigy - sort of). that and a direct sampler function, and they would've made the perfect workstation. but it's got inserts, so I'm not complaining much.
heh
well u could sorta aproximate this by getting one or two old emax-es, that have SSM filter n vcas, and pair it w a cheaper standalone mpc-style sequencer.. 16 poly of lofi hybrid goodness.

Quote:
Chips off the old Block
A partial list of instruments that contain Doug’s chips:
.
.
• Roland Jupiter-8
• Korg: MonoPoly, Polysix
.
.
these do not contain any curtis chips. monopoly is all SSM, Polysix part SSM part original Korgs thyristor vco design. Jupiter 8 is discrete vco/vca plus Roland's proprietary IR series of analog chips. Fairlight CMI II had SSM2044 filters, tho im not sure about vcas..
Old 13th June 2008
  #15
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Quote:
Originally Posted by clusterchord View Post
these do not contain any curtis chips. monopoly is all SSM, Polysix part SSM part original Korgs thyristor vco design. Jupiter 8 is discrete vco/vca plus Roland's proprietary IR series of analog chips. Fairlight CMI II had SSM2044 filters, tho im not sure about vcas..
That has very little bearing on the overall gist of the post; would've been more interesting to have shared positive thoughts, vs. some desperate need to demonstrate extreme trivia lol
Old 13th June 2008
  #16
Gear Maniac
 

Quote:
Originally Posted by analogbass View Post
That has very little bearing on the overall gist of the post; would've been more interesting to have shared positive thoughts, vs. some desperate need to demonstrate extreme trivia lol
A "desperate need to demonstrate extreme trivia"? I think perhaps he is offering some valuable constructive corrections.

Your post was lovely, by the way. RIP Doug Curtis.
Old 13th June 2008
  #17
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Quote:
Originally Posted by Clem Snide View Post
A "desperate need to demonstrate extreme trivia"? I think perhaps he is offering some valuable constructive corrections.
Absolutely. Considering that article/obituary is from Keyboard magazine, I'm a bit surprised to hear that there are mistakes in the gear listing. If anybody should be responsible for getting it right, it's those guys!

Despite the errors, that is still one helluva an impressive list!
Old 13th June 2008
  #18
Deleted 8456dd3
Guest
Couldnt agree more.... Great story. Big respect to doug, tom and dave (and of course others..bob moog etc)

Quote:
Originally Posted by analogbass View Post
That has very little bearing on the overall gist of the post; would've been more interesting to have shared positive thoughts, vs. some desperate need to demonstrate extreme trivia lol
Old 13th June 2008
  #19
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Quote:
Originally Posted by clusterchord View Post
these do not contain any curtis chips. monopoly is all SSM, Polysix part SSM part original Korgs thyristor vco design. Jupiter 8 is discrete vco/vca plus Roland's proprietary IR series of analog chips. Fairlight CMI II had SSM2044 filters, tho im not sure about vcas..
Great info as always Cluster. You positive that Keyboard made a mistake with those listings? Were there any revisions that may have used the Curtis chips?
Old 13th June 2008
  #20
Quote:
Originally Posted by analogbass View Post
That has very little bearing on the overall gist of the post; would've been more interesting to have shared positive thoughts, vs. some desperate need to demonstrate extreme trivia lol
of course, indeed i shared my thoughts 6mo ago, when Doug passed away. it was nice to repost what u did. but why on earth would u feel offended by a mere correction of data?? is it god given just bcs you posted it? is the world coming to an end?

how terribly inconsiderate of me.



@JazzPunk: Fairlight III did use later Curtis "voice processors". not sure what the first one, the CMI I used, its kinda like a white rhino.. ive heard CEM, but dont know for sure. no CEMs ever in Jupiter8 or Polysix (or trident, or monopoly). bk then, Korg was traditionally oriented towards SSM. and Roland hasn't ventured into Curtis designs until MC202/SH101 and Jupiter 6 in '83.
Old 13th June 2008
  #21
Quote:
Originally Posted by clusterchord View Post
well u could sorta aproximate this by getting one or two old emax-es, that have SSM filter n vcas, and pair it w a cheaper standalone mpc-style sequencer.. 16 poly of lofi hybrid goodness.
...snip..
that would be nice. not extremely portable but very nice.thumbsup
got a korg ES1 paired with some doepfer filters for the crunch
going to fire it up now
thumbsup
Old 14th June 2008
  #22
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Acid Hazard's Avatar
Quote:
Originally Posted by Jazzpunk View Post
I'm a bit surprised to hear that there are mistakes in the gear listing. If anybody should be responsible for getting it right, it's those guys!

Keyboard mag is always making mistakes. I remember about 10 years ago they ran an article on analogues. Something like the top 10 maybe? I don't quite remember, but they mentioned the SH-101. According to them, it had MIDI.
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