also... Re: [sdiy] SSM2044 Filter schematic??

[Magnus Danielson]

From: "Steve Ridley" <spr at spridley.freeserve.co.uk>
Subject: Re: also... Re: [sdiy] SSM2044 Filter schematic??
Date: Sat, 22 May 2004 10:05:12 +0100
Message-ID: <001901c43fdb$e4da0e60$d3a64c51 at default>

> > You might also want to check out Craig Anderton's MIF (Mulitple Identity
> > Filter). The original is based on the CEM3320, but the article states that
> > the tricks in the circuit can also be applied to the SSM2044. It is
> > definitely a VCF with all the bells and whistles.
> 
> Craig was referring to the SSM2040 as an alternative to
> the 3320 in the MIF article.  The 2044 is very different -
> the 2040 roughly approximates to four OTAs while the
> 2044 is more like a folded transistor ladder using
> current mirrors, so not a straightforward change.

The similarity between CEM 3320 and SSM 2040 is striking. The SSM 2044 is a
totally different breed altogether.

> I had planned to add differential amps across the
> caps on my Maplin 2044 board to produce something
> similar to an Oakley Super Ladder, but I misplaced the
> board during a house move.  It'll turn up one day...

Like I said, there is two methods to acheive different responses, feed-forward
and output-summing. The output summing method consists of sensing some or all
caps and then create different mixes of these outputs and possibly also the
input signal. The feed-forward method is if possible even easier, by sourcing
the input signal into the chain by means of resistors or capacitors. There's a
little exercise for someone who feel the need to do something odd.

Cheers,
Magnus