Probably the next filter board

This was absolutely not scheduled, but somehow I couldn’t resist…

(partly breadboarded, not tested, waiting for the chips, but they come from a trusted source, also I’ll have to redo the drawing cause I highly doubt half-toning will look great on the final boards)



Going for some SH-101 fun? Those Roland chips are a huge pain to find. You got a good connection :slight_smile: I mean sometimes S at vintage planet has some, but I have not seen lately, but MUST HAVE! Hehee :slight_smile: Frankenstein shruthi coming along well looks ugly next to it’s brother, it’s mainly waiting for it’s backplane connectors to arrive :stuck_out_tongue:

Yeah Baby, count me in! We need a FilterSwitchBoard… (4052!)

has some, $40 a pop tho!

Not sure about the audio jacks Pin base, I can’t easily find a datasheet, but I’ve been curious, why the switch to the Neutrix on all the Shruthi’s?

They are way easier to source than the original part used in the Shruti which was available only from Farnell ; and I don’t need the stereo / insertion detection switches thingies anyway. The Neutriks can be found from Farnell, Mouser, and while I haven’t had a look at this, there are similar parts made by a couple of factories in the East.

Just curious. Thanks.

mmm, i’ve got a bit of a soft spot for those roland filters.
i’d like to end up with a full set of filter boards, even just to look at, i’m up for one please :slight_smile:

BTW, how easy would it be to use one of your boards as a standalone filter? I.e input and output only.



  • >VCA to +5V (or to 0 / 5V linear pot if you want a fancy volume control).
  • >OSC to GND
  • a 0 / 5V linear pot to >FREQ
  • a 0 / 5V linear pot to >Q

and that’s it - someone here did it for the CEM3379 filter board.

Should be easy, you only need to simulate the VCA + Filter signal (connect the VCA, F + Q signal via a 10 K Potentiometer used as a voltage divider). Maybe Oliver could give you a hint where tu use a linear/exp Type.

Sadly, the source of IR3109 turned out to be not as reliable as I thought. I have not lost much on this - but the quantity of genuine IR3109s I am in possession of is too small to consider the production of this board.

Shit - but you could relabel whatever you got as CEM 3398 . . .

Oh well… Moog transistor ladder filter anyone?? :smiley:


How about the ARP VCF?

^ Oddly enough, it was that guys Moog vcf clone I was looking at that made me wonder about a Moog filter in a Shruthi…