Return of the IR3109?

I can almost see Olivier cringing from here :wink:

Anyways, I figured this may be of interest to some folk around here…
‘Guest’ is a clever chap who I believe helped design the x0xb0x(?) successfully reproduced a BA662 clone, is now working on an IR3109 clone.
The IR3109 being the IC central to many of Rolands rather nice sounding filters, as used in several of their popular analog synths. And rumour has it… there was once an IR3109 based Shruthi filter board!? :wink:

http://www.muffwiggler.com/forum/viewtopic.php?t=126397

Now if he could also make some CEM replicas…

What about a LM13700 clone? Oh wait…

^ I guess its aimed at folk replacing original chips that don’t want some hacky abomination tacked on to their PCB… If it’s anything like his BA662 clone, it will rather less kludgey than that.
Im sure if it were as simple as substituting it for an LM13700, then he wouldn’t be wasting his time doing this.

The main reason to clone any of these old chips is to ensure it has the same pin out for vintage synth repair while hopefully keeping costs down. If you want a brand new IR3109, get a Ripples.

“If you want a brand new IR3109, get a Ripples.”

Both are quite similar indeed, and both are certainly very nice filters. But arguably not quite identical… Although I admit this perhaps makes me a professional hair splitter!

Still, ‘Guest’ seems to have made some interesting discoveries already while researching his clone project.
Assuming he completes the project and puts them on sale, then i’d certainly be curious to try one, for comparisons and hoardings sake of course :stuck_out_tongue:

It makes sense as a “spare part” for repairing Jupiter-8s and more importantly MKS-10s.

But this part is just 4 OTAs (= 2x LM13700) and one expo converter. The “round Roland sound” comes from the circuit built around it, with low signal levels and lots of headroom.

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