Korg MS-50 filter

widdly · Posted: Wed Jul 16, 2008 12:34 am Post subject: Korg MS-50 filter

Anyone know anything about the Korg ms-50 filter?

There is a schematic here..
http://machines.hyperreal.org/manufacturers/Korg/MS-synths/schematics/ms50filt.gif

Looks kinda interesting

v-un-v · Posted: Wed Jul 16, 2008 2:21 am Post subject:

I used to own an MS50- it was a lot of fun, probably more than the MS20 (which I still own), but I don't remember the filter being really remarkable. Personally I would save your energy, and build Ian Frijitz's Threeler instead Smile

widdly · Posted: Wed Jul 16, 2008 3:10 am Post subject:

Of course I should build a Threeler. I should also get the resonance in my late ms20 filter working.

..but you can never have enough filters.

The arrangement of diodes in the schematic just looks strange to me. The rectifier in the middle bit. no quite a ladder.

v-un-v · Posted: Wed Jul 16, 2008 3:30 am Post subject:

I imagine that the rectifier is there to keep the feedback (resonance) in check?- Similar process to the Trancendent 2000 design by Tim Orr?

Everybody in the 70's had a way of trying to get round Moog's then patented transistor ladder- using diodes was just another way- very similar to the EMS synthi filter I suppose? But before you say "Hey that filter was really unique"- think for a moment why it was unique.... because I think the EMS filter was unique because of the way it handled modulation signals, and not necessarily the sound.

If you want a really unique sounding filter, then its gotta be the Threeler or Steiner one etc. Wasn't it a rogue capacitor in the EMS modulation input that gave it that weird response that could sound really nice and bubbly??

bubblechamber · Posted: Wed Jul 16, 2008 2:38 pm Post subject:

i'm finishing up a layout for the ms20 filter and i should be posting it over the weekend, if anyone is interested.

a.b.o.z. · Posted: Wed Jul 16, 2008 3:12 pm Post subject:

post it in PCB layout sub-forum.
great, thnx!!

Peake · Posted: Thu Jul 17, 2008 9:28 pm Post subject:

I remember MS50 filter as being a bit noisy. It obviously uses the peskily expensive CA3019, but I suppose that one could match diodes in its place.

vtl5c3 · Posted: Mon Jul 21, 2008 8:07 am Post subject:

I built a couple of them about 10 years ago. The CV rejection is pretty bad, so it's no good for sequenced CV control (unless you like that clicky sound). For pads it is kinda nice, has sort of a "glassy" type sound that reminds me a bit of things I've heard done with the EMS synthi. I'd say it's not a "must have" VCF...

macumbista · Posted: Sun Jun 28, 2009 10:35 am Post subject:

Bringing this thread back from the dead... I'm actually interested in the VCA in the same schemo (Jessica Rylan raves about this diode bridge VCA!). I won't be using it with sequenced CV, only as AM modulator in dual VCO setup.

So, three questions:

1) Anybody have any impressions good or bad?
2) Anybody try to build it? Looks simple enough (excpet diode IC).
3) Any tips for matching diodes to get rid of 3019 IC?

Thx!
Derek

fonik · Posted: Sun Jun 28, 2009 2:28 pm Post subject:

macumbista · Posted: Sun Jun 28, 2009 2:32 pm Post subject:

Yeah yeah. I found some stuff on Google 10.3 seconds after I posted that question Wink

fonik · Posted: Sun Jun 28, 2009 2:36 pm Post subject:

macumbista · Posted: Sun Jun 28, 2009 2:57 pm Post subject:

Is it something like a Sonic Screwdriver?

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

fonik · Posted: Mon Jun 29, 2009 11:38 am Post subject:

frijitz · Posted: Mon Jun 29, 2009 12:46 pm Post subject:

fonik · Posted: Mon Jun 29, 2009 1:43 pm Post subject:

thank you very much. i wonder where do you learn such things...

creekree · Posted: Mon Jun 29, 2009 4:01 pm Post subject:

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

I have been scanning old EFM projects for the archives, and it so happens that this weekend I had found the MS50 clone I was riffing off of. It's a nice starting point.

VCF5a_schem.jpg

Description:

Filesize:

87.63 KB

Viewed:

653 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

VCF5a_pcb.jpg

Description:

Filesize:

104.73 KB

Viewed:

343 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

VCF5a_top.jpg

Description:

Filesize:

154.07 KB

Viewed:

347 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

macumbista · Posted: Tue Jun 30, 2009 7:06 am Post subject:

Did you make a stab at the VCA too?

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

macumbista · Posted: Tue Jun 30, 2009 8:20 am Post subject:

I'm all in for inarticulate droning! I just wanted to use the multiplier in the circuit for rough AM/ringmod action... I have an allergy to sequencers, or maybe that's just to boring, mechanistic repeating patterns in general. Give me chaos and mutation any day Wink

CJ Miller · Joined: Jan 07, 2007 Posts: 368 Location: 127.0.0.1

Here's a later version of Tom's EFM VCF5. Got to split!

VCF5b.jpg

Description:

Filesize:

161.23 KB

Viewed:

679 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

forbin · Posted: Mon Oct 26, 2009 1:13 am Post subject:

Interesting! Has anybody any experience with the EFM VCF5? It is certainly a bit of a different topology from any of the other VCF's i have looked at. I have done a SPICE simulation and it looks OK. Not super sharp at 12dB/oct but could be worth the effort nevertheless...

ms50_vcf.jpg

Description:

SPICE Model of MS50 VCF

Filesize:

283.78 KB

Viewed:

478 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.