Is the SSM2040 back?

[Mark Hammer]

Pigtronix is releasing and debuting a new filter pedal for NAMM 2019, called the Resotron.  Their blurb states that the filter is "based on the SSM2040 chip found in the legendary Prophet 5 and Octave CAT synthesizers. This 24db/octave, state-variable filter provides the full gamut of familiar envelope filter sounds " https://pigtronix.com/product/resotron/

So is that a work-alike or has it been resurrected like the CEM3320 or the MN3005?

[Steve Newton]

Could be a copy chip:

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

[amz-fx]

Coolaudio V3320 Voltage Controlled Filter, Functionally compatible to CEM3320*

http://www.coolaudio.com/features-page.php?product=V3320

[Mark Hammer]

So you're saying the V3320 is not identical to a CEM3320, and the SSM2040 Pigtronix discusses is similar "not the real thing but an incredible simulation"? (as the promo for the Beatlemania show used to say)

Looks like I may have waited too long to sell the quintet of 2040s I bought from a guy in Dallas in 1982.

[amz-fx]

No, just adding a reference to the resurrected chip you mentioned as it is similar to the 2040 (but not exact).

There is enough reference material around that a 2040 clone could be made from discrete parts.

regards, Jack

[Mark Hammer]

It certainly could be mimicked from discrete parts, and the late great Jurgen Haible demonstrated that.  But what might be accommodated on a plug-in module in a big rack modular system is one thing, and what would be compatible with a surface-mount board in a compact pedal, like Pigtronix probably used, quite another.

Still, I don't wish to start any false rumours.  I just want some clarity on the matter.  And if my wildest dreams have come true, I want a price and a vendor! 

There are a few quad OTA chips presently available that could be shaped into filters or phasers, like the SSM2164 and its Coolaudio clone, and the V3320.  Not that a clone/reissue of the SSM2040 would be construed as "just another me too" chip.  But if one's interest in a 2040 is in putting together a filter or compact 4-stage phaser, there are existing chips that can also do that.

Which reminds me, where are the 3320 and 2164 phaser designs?  Smaller footprint that dual 13700/13600 designs, less problematic or labour intensive than FETs or photocells.  They're a little pricier than the parts for those other methods of phasing, but for what you gain in design simplicity and smaller package the small additional cost is worth it.

[jimbeaux]

"ALFA RPAR released the AS3310, AS3320, AS3330, AS3340, AS3345 and AS3360 in DIP and SMD packages."

https://en.wikipedia.org/wiki/CEM_and_SSM_chips_in_synthesizers#Curtis_Electromusic_Specialties

They're available from Synthcube, ModularAddict, Thonk,...

[Mark Hammer]

I see that SSI makes a 2044 clone, however it is a dedicated 4-pole lowpass filter, and not as flexible as the 2040.

[jimbeaux]

Mark - most of the phase shifter (3320) schematics I have are for synthesizer line level signals - but I have an article by C.R. Fischer (Modern Electronics 1988) phase shifter for guitar, bass,... - self contained LFO / 3 chip design (5532 / LM324) - does require bipolar power. If you're interested I can send you a pdf.

[Mark Hammer]

Thanks for the offer, but I found it already:  https://americanradiohistory.com/Archive-Modern-Electronics/Modern-Electronics-1988-10.pdf
That site is wonderful.  I was previously unaware of that magazine.  Thanks for the tip!

[ElectricDruid]

Pigtronix is releasing and debuting a new filter pedal for NAMM 2019, called the Resotron.  Their blurb states that the filter is "based on the SSM2040 chip found in the legendary Prophet 5 and Octave CAT synthesizers. This 24db/octave, state-variable filter provides the full gamut of familiar envelope filter sounds " https://pigtronix.com/product/resotron/

So is that a work-alike or has it been resurrected like the CEM3320 or the MN3005?

Schematics for a discrete version of the 2040 have been kicking around for some years as you know. JH was probably the first, but there's also a Rene Schmitz version, and there was (is?) a MOTM440 filter which is based on the same thing, and the Hearn-Morley module, which is an SMD board of the whole thing in a potting box.

But as far as I've heard, no-one has yet re-released the actual chip; not Alfa Rpar, not CoolAudio, not Sound Semiconductor, no-one. SSI would be the most likely candidate, but they haven't given any clues in that direction yet.

My guess is Pigtronix have based themselves on the available schematics and done it discrete SMD. You couldn't put a 3320 (either V3320 or AS3320) in it and then claim "based on the 2040", so those chips don't help you. You'd have a mob outside with flaming torches and pitchforks when people found out!

Tom

PS: To answer the other query about where are all the circuits with 2164 and 3320, I think the answer is "power supply". It's a faff to get a decent level bipolar supply together from a 9V input, and that's what those chips need.

[Mark Hammer]

Fair enough.  I guess the days of builder tolerance for supplies other than +9v or something you can easily squeeze out of 9V and a 1044 charge pump are gone.

Happily, some of us folks still welcome +/-12V supplies and rack modules.

[Scruffie]

I think CoolAudio are about to release one, they've alluded to such and with the synths Behringer are putting out it makes sense, so it is possible Pigtronix got early access.

[Mark Hammer]

That is a distinct possibility, though I'll put the kybosh on any rumours here, and just say it would be nice if it were true.  Do you hear me Uli?  IT WOULD BE NICE IF IT WERE TRUE.

[noisette]

If you haven´t seen this have a look (n0-n0nsense)
https://www.schmitzbits.de/rs2040.html

[Mark Hammer]

I've had that on my hard drive for several years now.  And believe me, I was thrilled to see Rene Schmitz' circuit, and Jurgen Haible's as well.  But I'd be more thrilled to see it in a 16-pin DIL or SOIC form, as would a bunch of other folks.

[~arph]

You can probably tame the transistor madness a bit with H bridge ICs like these:

https://www.diodes.com/assets/Datasheets/ZHB6790.pdf

[Mark Hammer]

Okay, Dave Koltai provided the answer to my question towards the end of this video he posted yesterday:  https://www.youtube.com/watch?v=DUcnN_Z7ufw

He indicates that some of the inspiration for the Resotron pedal came from his purchase of an Octave Electronics Cat synth, that used a 2040 for the filter section.  He then goes on to say that they used currently available analog parts to duplicate the functioning of the 2040.

Ah well, you win some, you lose some.

[noisette]

I've had that on my hard drive for several years now.

Ah, of course

You can probably tame the transistor madness a bit with H bridge ICs like these:

https://www.diodes.com/assets/Datasheets/ZHB6790.pdf