[sdiy] Re: [AH] Korg MS 20 Filter Differences

[Kyle Stephens]

The Doepfer A-106 (http://www.doepfer.de/A106.htm), based on the MS-20 filter (dunno when it came out as to take a guess if it's OTA or discrete), has an interesting resonance loop external send/receive feature.

If you're hip to the Yo Dawg internet meme, it'd go something like "Yo dawg I hear you like filters so I patched a filter in your filter so you can filter while you filter" etc. ;P

I've an on-the-shelf MS-20 filter project that will have several selectable diode configurations, pre and post the resonance buffer/variable gain element.

If ever you've DIY'd a guitar effect or done a mod to an existing one, you'll know different diodes definitely sound different, and from Tim's analysis he concludes the clipper diode position in the filter makes an analytical difference. I've heard, if not in person , that it's an audible one too. I've only heard one MS-20 live, and didn't know the version - sounded cool in any event!


_Kyle


--- On Wed, 11/4/09, Paul Perry <pfperry at melbpc.org.au> wrote:

> From: Paul Perry <pfperry at melbpc.org.au>
> Subject: Re: [AH] Korg MS 20 Filter Differences
> To: "matrix" <matrixsynth at gmail.com>
> Cc: analogue at hyperreal.org
> Date: Wednesday, November 4, 2009, 12:27 PM
> For the record, the Frostwave
> Resonator is the mk2 (OTA) design. here's why:
> 
> 1. the differences in sound between various MK1 units, and
> the
> difference between various MK2 units, is greater than the
> average difference between a MK1 and a MK2.
> I've owned a number of MS20s, and heard plenty more.
> The mileage of others may vary, of course.
> 2. You can get the parts. A the time I started making the
> Resonator, the MK1 design was still a mystery.
> 
> If anyone wants to tweak up a MS20 type filter, I think the
> place to
> attack is the diodes in the resonance feedback loop.
> 
> As for the whole MS20, I think the (very unusual) VCA is a
> likely source of inter-MS20 variation. The transistors are
> specially selected - never a good sign! - and I believe it
> is the source of the high noise level as well.
> I'm not a musician, but if I were, I would seriously
> consider
> replacing the VCA with something else - or at least
> providing the option.
> 
> The only change I made to the filter was provision of
> voltage control of the resonance. Not something one needs
> every day -
> but a remarkably handy thing sometimes!
> 
> But having said this, it remains that I have never heard a
> MS20
> filter that I didn't like ;D
> 
> paul perry Melbourne Australia (Frostwave)
> 
> > I'd be interested to know which the Frostwave is based
> on and why.
> 
>