CS-80 Filter for Mutable Instruments' Shruthi

oldcrow · Post by **oldcrow** » Mon Apr 27, 2015 7:56 pm

Hey folks, Crow here. One of the projects I managed to complete amid the ongoing crOwBX and Crowminius work is my filter board for MI's excellent Shruthi hybrid monosynth. I am ordering a set of boards for general sale in May, but I have three bare boards left from my prototype run I plan to offer for sale. Both board sets are the same revision level. My CS-80 filter board uses the same "mark II" V2164 circuit I implemented in the SynthTech MOTM-480 mkII, the upcoming SynthTech E480 and my CSR-80 voice card project. Like Mr. Gillet's filter boards, this one will also have an open-source hardware package offered on github. Once I have the BoM, and audio demo and the github repo prepared, I will place these up on my sales site.

For those who care to use some SMT parts, I've provided SMT and throughhole options on certain capacitors.

Update: an audio demo, http://www.cs80.com/shruthi/CS80_Shruth ... Demo01.wav

FYI,

Crow
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setsun8 · Post by **setsun8** » Mon Apr 27, 2015 8:57 pm

Wow this is awesome, will definitely pick one up. Can't wait to hear the demos

Luap · Post by **Luap** » Mon Apr 27, 2015 9:05 pm

Nice!

I've been waiting for this..

touyube · Post by **sduck** » Mon Apr 27, 2015 9:14 pm

Very cool! Could this be used in the Ambika? Or adapted for it if not?

ttown23 · Post by **ttown23** » Mon Apr 27, 2015 9:41 pm

sduck wrote:Very cool! Could this be used in the Ambika? Or adapted for it if not?

Same question here!

oldcrow · Post by **oldcrow** » Mon Apr 27, 2015 10:17 pm

Very probably. I do not have an Ambika though I examined Andrew's last week at AHMW. Looking at the voice card layout provided I can get two V2164s on there with some opamps and use their control signals, it seems pretty simple to do.

sduck wrote:Very cool! Could this be used in the Ambika? Or adapted for it if not?

kvitekp · Post by **kvitekp** » Mon Apr 27, 2015 11:43 pm

Very nice! I'm in for one.

/Peter

C14ru5 · Post by **C14ru5** » Mon Apr 27, 2015 11:46 pm

I'm also in for one!

sduck wrote:Very cool! Could this be used in the Ambika? Or adapted for it if not?

Based on how dense that Shruthi filter board looks, the answer would normally be 'no'. (On Ambika, the voice circuits are on the same board as the filter)
A possible exception could be if one uses SMD parts, but no one has made an Ambika filter board like that yet.

apoisontree · Post by **apoisontree** » Tue Apr 28, 2015 3:58 am

I'm in for one.

fcd72 · Post by **fcd72** » Tue Apr 28, 2015 7:29 am

Im in for one!

sammy123 · Post by **sammy123** » Tue Apr 28, 2015 7:34 am

Awesome. I'd take one for sure.

Also, If you need an Ambika for the development I could loan you mine.

pichenettes · Post by **pichenettes** » Tue Apr 28, 2015 8:39 am

Re Ambika: will need a bit of firmware work to add the cutoff 2 and resonance 2 parameters on the motherboard UI ; and on the voicecard to generate the two extra PWM signals (it might need some pins reassignment too). Actually we don't need the 405x routing junk if it's hardwired for HP->LP or LP->HP. If you only want the LP or HP half of it, you're already well served with the existing SVF board.

mmarsh · Post by **mmarsh** » Tue Apr 28, 2015 11:51 am

Hey Scott -

Very cool project, I'm in for one.

Mike

oldcrow · Post by **oldcrow** » Tue Apr 28, 2015 4:46 pm

Yes, I noticed there were only one cutoff CV and one resonance CV. I can still rig the filter for the CS-80 timbre using these and implementing a 2:1 tracking interval for the HP->LP and a trimpot-adjusted interval for resonance. I would remove the 4052 as I would need the space for the second 2164. We'll see what happens. --Crow

pichenettes wrote:Re Ambika: will need a bit of firmware work to add the cutoff 2 and resonance 2 parameters on the motherboard UI ; and on the voicecard to generate the two extra PWM signals (it might need some pins reassignment too). Actually we don't need the 450x routing junk if it's hardwired for HP->LP or LP->HP. If you only want the LP or HP half of it, you're already well served with the existing SVF board.

windspirit · Post by **windspirit** » Tue Apr 28, 2015 5:28 pm

Great idea! Interested in at least one, waiting for demos

oldcrow · Post by **oldcrow** » Tue Apr 28, 2015 8:32 pm

Here is a short demo, though I forgot to turn off the Lexicon.

http://www.cs80.com/shruthi/CS80_Shruth ... Demo01.wav

I'll put this into the initial forum post as well.

touyube · Post by **sduck** » Tue Apr 28, 2015 9:26 pm

pichenettes wrote:Re Ambika: will need a bit of firmware work to add the cutoff 2 and resonance 2 parameters on the motherboard UI ; and on the voicecard to generate the two extra PWM signals (it might need some pins reassignment too). Actually we don't need the 405x routing junk if it's hardwired for HP->LP or LP->HP. If you only want the LP or HP half of it, you're already well served with the existing SVF board.

Yes, it might be more trouble than it's worth. Actually the filter that I'd like to see ported to the Ambika the most is the MOTM 440 - don't know if that's one of your designs, Scott, but it would be a wonderful thing!

oldcrow · Post by **oldcrow** » Tue Apr 28, 2015 9:30 pm

The 440 was JH. It is the best discrete filter there is.

That said, I could adapt it to the Ambika, though I would be more motivated if I had one.

sduck wrote:Yes, it might be more trouble than it's worth. Actually the filter that I'd like to see ported to the Ambika the most is the MOTM 440 - don't know if that's one of your designs, Scott, but it would be a wonderful thing!

tubeohm · Post by **tubeohm** » Wed Apr 29, 2015 12:56 am

oldcrow wrote:Very probably. I do not have an Ambika though I examined Andrew's last week at AHMW. Looking at the voice card layout provided I can get two V2164s on there with some opamps and use their control signals, it seems pretty simple to do.

sduck wrote:Very cool! Could this be used in the Ambika? Or adapted for it if not?

Hi , is it possible to get one board for testing.
Can you contact me direct with Kontakt@tubeohm.com

Greets

Andre'

oldcrow · Post by **oldcrow** » Wed Apr 29, 2015 1:08 am

Just to clarify, I do not have Ambika voice cards with CS-80 filters (yet). This is for the Shruthi.

tubeohm wrote:Hi , is it possible to get one board for testing.
Can you contact me direct with Kontakt@tubeohm.com

Greets

Andre'

aburrows · Post by **aburrows** » Thu Apr 30, 2015 10:08 am

I'm interested too. I'm assuming you'll post here when they're available on your site Scott? Thanks!

oldcrow · Post by **oldcrow** » Thu Apr 30, 2015 7:46 pm

Yep, I always post at MW first.

aburrows wrote:I'm interested too. I'm assuming you'll post here when they're available on your site Scott? Thanks!

oldcrow · Post by **oldcrow** » Mon May 04, 2015 2:17 am

Hey folks, my BoM for the CS80 filter board for Shruthi is up at

If you have an SVF2 board and socketed the chips, they can be transplanted to the CS80 filter board to save on parts if desired. I will order boards this week.

--Crow
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Dude163 · Post by **Dude163** » Mon May 04, 2015 7:24 am

Awesome !! How much will they be Crow ?

oldcrow · Post by **oldcrow** » Mon May 04, 2015 8:22 am

These few I have on hand are $25 ea. When I order a larger batch they'll be $20 ea. --Crow

Dude163 wrote:Awesome !! How much will they be Crow ?

MUFF WIGGLER

MUFF WIGGLER

CS-80 Filter for Mutable Instruments' Shruthi

CS-80 Filter for Mutable Instruments' Shruthi