DIY SSM Synth

rdemon · Post by **rdemon** » Wed May 23, 2007 5:11 pm

I'm looking at the expensive costs of buying a P5 SSM synth and the fact that it has some reliablity issues and considering doing a DIY SSM synth.

I do a lot of work with microcontrollers and have a full electronics workshop and an EE/CS degree at my disposal.

Can you recommend some DIY SSM synth designs and a source for SSM chips (lots of them)?

Ron

metrosonus · Post by **metrosonus** » Wed May 23, 2007 5:50 pm

as long as you went by the schematics of the chips you'd allright. you'll just need to code your own os, midi interface ect. I'm reaserching the same thing with CEM and i'd rather just leave it modular anyway..

rdemon · Post by **rdemon** » Wed May 23, 2007 5:57 pm

Do you know where I can get the schematics of the various SSM chips.

If you build the SSM chips using discrete components, won't they sound different than the original IC. I think IC circuits has different electrical characterstics than discrete.

Also, I would think the various discrete component you buy today would have different sonic qualities than the ones made back then. I know a transistor is a transistor but I bet the transistor material is different today.

The OS and Midi are pretty straight forward for me.

metrosonus · Post by **metrosonus** » Wed May 23, 2007 6:11 pm

synthtech.com has some .. if you manage to obtain an SSM chip, you can use the schematic of the pinout and other data as a starting point is what I meant.. it's actually alot simpler than it seems as Im finding out. I said in another post though I aint gonna touch the microprocessor and other stuff though. At least that way I wont hit a brick wall with my project and also so i can build up an array of modules.. and by connecting them this way and that i can somewhat mirror the voicings of other synths.. system 100, sh101 for example.

steveman · Post by **steveman** » Wed May 23, 2007 6:17 pm

Some discrete SSM clones:
http://www.uni-bonn.de/~uzs159/

http://home.debitel.net/user/jhaible/hj.html
There's an SSM clone filter design somewhere on his site.

SSM chips (lots of them)

You'll be lucky, hen's teeth are abundant by comparison

This guy occasionally has them I understand, but you'll probably have a very long wait.
http://www.synthtech.com/cems.html
Wine County will have spare SSMs too, no doubt cost an arm & a leg.

TBH it'll probably cost nearly as much to buy the chips as it will a P5

, never mind the rest of the circuitry, pots, casing etc...

The P5 is the one synth I'd really like to own, but it's the whole thing, looks, sound feel etc.

metrosonus · Post by **metrosonus** » Wed May 23, 2007 6:21 pm

heh.. I may have to try the clone.

synthetic88 · Post by **synthetic88** » Wed May 23, 2007 11:11 pm

Why not go modular and use the MOTM filter module (440 I believe). Doepfer also has an SSM filter, big surprise.

I sure wouldn't want to fry one of the last xxx SSM chips on the planet in my DIY project. That would be one long cry in my beer.

rdemon · Post by **rdemon** » Wed May 23, 2007 11:20 pm

The rarity of these SSM/CEM chips is crazy. Who owns the intellecual property? If the chip is basically a set of integrated transistior, resistors, and caps why can't some produce a pin comparable replacement? This is just 1970's manufacturing here, there has to be something more to it.

The only business reason I see is that the demand may not be there and the whoever owns the IP won't give it up.

I'm tempted to try reverse engine an SSM chip and layout an IC design myself!

metrosonus · Post by **metrosonus** » Wed May 23, 2007 11:58 pm

I think because to reproduce them would only appeal to a niche market. They're no longer considered industry standard and analog synths have been relagted to the botique/niche market. Id ont know what goes into making one of those ICs, but without a contract from Korg or something, I doubt it's going to happen. Till then we can recycle and attempt discrete clones.

rdemon · Post by **rdemon** » Thu May 24, 2007 12:08 am

metrosonus,

I do electronics design and it isn't that difficult (it's not trival though). If the schematic for chip was availible then I'm sure I can find a chip house to run the design on some sample chips that are pin capability. The individual chips would be very expensive (100-200 per chip) but it is doable.

metrosonus · Post by **metrosonus** » Thu May 24, 2007 12:14 am

well .. yea. it's a matter of capital as well. I'd rather buy a recycled one from someone for my hobby / DIY projects for 30$ than 100$

Its ceartainly not impossible.. i didnt mean that. I just meant it's going to take more capital than the average synth nut is willing to put up to make it feasable.

gojira · Post by **gojira** » Wed Aug 22, 2007 9:20 am

I've been doing a bit of research on availablilty of NOS CEMs, SSMs and other useful chips for synths, etc. To be honest some of them aren't as rare as they seem, just difficult to access for individuals.

Many exist in inventory and can be sourced from various obsolete component brokers, however these are strictly buisness to business brokers, and some do have quite a high minimum order. On the other hand some do not.

Chips like the SSM2044 are quite abundant and available at a decent price. Some of the other not so widely used SSMs are harder to get, but it is possible, and if you can deal with a reasonable broker, you should be able to get fair prices.

As far as i know the IP for some (maybe all?) SSM chips is owned by Analog Devices, but no longer manufactured, although they did produce them at one time).

The same goes for CEMs in terms of availability, some are harder to find than others (for e.g. the 5530/5508 seem very hard to find). I think OnChip owns the IP for all (?) of the CEMs. The minimum order to get them to do another run is pretty high though.

I'm trying to work out the feasability of buying some hard to access ICs/OTAs/OPAMPS/matched transistor pairs etc. so that people can buy replacments for thier broken synths and also use them for DIY projects (for example Digisound modules).

I think the really difficult ones to find (maybe impossible) would be things like Yamaha's custom IG series chips used in some of the CSxx line of synths.

Just out of interest, does anyone have any experience in processes involved in making drop-in/pin compatible replacements from discrete parts? What kind of starting information is required? Will there be much difference in sound between the IC and discrete versions? Also, what is involved in the production of analog ICs these days?

VJ.

atkbg · Post by **atkbg** » Wed Aug 22, 2007 1:27 pm

Try here.
http://www.synthdiy.com/view/filecat.asp

Theres quite a bit on there.

DIY SSM Synth

DIY SSM Synth

Why can't someone produce new SSM/CEM chips!