Curtis/SSM clones?

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stickjam

Well-known member
Joined
Jun 17, 2004
Messages
325
Location
Grand Rapids MI
Anyone aware of any current or past efforts to clone any of the CEM or SSM synth chips? 

Obviously demand would probably never justify resurrecting the artwork and tooling to reproduce the original silicon, but I'm wondering if pin-compatible hybrids could be fabricated with SMD technology?

The sonic character of some of those chips would be great for some ideas I have rattled around for a while, including some bits I prototyped back in the 80s.  Yeah, I let the magic smoke out of my share of Curtis chips when they were plentiful.  I couldn't in conscience use real CEMs for new stuff. 

Perhaps having some pin-compatible clones--even if they needed a couple stacked SMD cards to keep close to the original form factor--would enable some of those old scavenged warhorses like OB8s come back to life.

 
No relation... ;)

I'm not aware of any single-chip or pin-compatable plugin modules that would sub for those IC's, but over at Electric Druid there are PIC-based lookalikes for the CEM3312 envelope generator.  They spit out the ADSR envelope via PWM, which is then lowpassed to create the smooth waveform.  The amount of support circuitry required to get the envelope out of the chip (20MHz crystal, dual opamp, handfull of resistors and caps) probably prevents the full thing being small enough to drop in place of the real deal, but it does get the DIY thoughts a-buzzin'.

This page supposedly describes a temperature compensated VCO based on the same principles that make the CEM3340 tick, but there's no way you're going to get it to fit in a DIL socket.
 
I've been wondering about this myself. I think EMU build custom replacements for part of the final batch of their SP-1200 reissue when they ran out of filter chips. It wouldn't be easy nor cheap to track one down though.
 
Actually there's one chip I really want to construct a clone of using chips that are likely to be around for a while (as opposed to endangered species like CA3080/3280, LM394, and the like)  It doesn't have to be package pin-compatable--just function exactly like the original in any given circuit. 

That's this one:

CEM3320 VCF

By the block diagram, does this chip look easily reverse engineerable through measurements taken on a known working original chip?  (By asserting various DC and transient levels on the input and monitoring the output pins, then produce a model based on that)



 
No idea if anything is or becomes available in the portfolio of the 'semiconductor leg' of Behringer ? (forgot their name)

Regards,

  Peter
 
stickjam said:
Anyone aware of any current or past efforts to clone any of the CEM or SSM synth chips? 

I wondered if anyone here ever did synth related stuff - I've got two toes in here, one toe in synth diy, and the rest of me busy a @#% w/ work and kids ;)

Here is someone who has a clone of the SSM2040 VCF IC.  Not a drop-in, but claimed "equivalent":

http://sites.google.com/site/hearnmorley/products/hm2040

Just found it the other day - He says he doesn't have any currently and is waiting to get more.  I was going to order one of his ADSR modules for a new project, so I'll let you know if I find him still active and replying to orders :) I don't know how up-to-date the page is, etc...

I had a few other similar links too - I'm not at home but when I get a chance I'll dig up some more links...  I wanna say I did find someone working on a curtis based discrete clone too... not sure which IC.

Lots of "new" discrete designs too for VCF/VCO/etc in general these days - probably many inspired by the SSM and Curtis schematics and patents floating around, but you may already be up on that...  I was out of the synth DIY loop (and this place too) for a bit and was amazed at the growth in the community and the number of small operations making interesting DIY stuff...  sort-of like the 500-series surge in this corner of the DIY world.  You can still get NOS of some of the later chips too (SSM2044, etc). Schematics are also pretty easy to come by for Curtis/SSM stuff.  Let me know if you need any of that info.

Good luck and let us know if you find anything...

Cheers!
jt

 
jh2040.gif


Here is a product that does a semi discrete version of a SSM2040
http://www.analoguehaven.com/division6/filtareseiii/
 
I wish someone would clone the Yamaha IG series chips used in the Yamaha CS series synths... Keeping my CS-80 going is a bit of a job.
 
A late reply, but perhaps it is of interest to someone:

There are 2 ssm2040 discrete clones availeable, one designed by J. Haible and sold by Synthesis Technology for a modular:

http://www.synthtech.com/motm440.html

The other is by Tip Top Audio, also for modulars (Z2040).

In the net there are at least 3 schematics for ssm2040 clones floating around, 2 on J. Haibles site and the other by Rene Schmitz, also one from a japanese diy-synth site. ( I can provide the links but i don't have them here)

As a side note, there is one german manufacturer (Schippmann) who is going to release a discrete VCF module soon. His filters (in the Ebbe und Flut) are supposed to be some of the best sounding analog filters, would be nice to see a diy-project with his filters...

Greetings,
Nils

 
Oh, i forgot, there is another ssm2040 clone by mattson mini modular, designed by Jim Patchell and George Mattson...
 

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