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Subject: Re: Fixed Filter Bank

From: "coyoteous" <satori@...>
Date: 2002-03-08

--- In motm@y..., "jhaible" <jhaible@d...> wrote:
> The graph: That's the 907's frequency response with all pots
up. (!)

Wow, I take it you mean all the way up, or at the center?

> Originally a "design fault" (intentional or not, I do not know,
> and it's a sensitive topic, so don't quote me on that ...), there is
> a lot of cancellation going on between the bands.

I guess I just did (quote you, that is) <g>.

> BUT this produces a wonderful coloration of the signal, and I
> like it so much that I actually cloned it twice. (The first shot
> wasn't good enough in SNR, but the second one is fine.)

I'm sure the phase plot is equally bizarre. I remeber it sounding
nice. As with most Moog modules, I usually attributed the
"niceness" (and the noise) to the discrete circuitry. Though it
seems a lot of vintage synth character in general has more to do
with design quirks - in the studio I call them "happy accidents."

> Separate outputs are contrary to the Moog Filter Bank's
topology.
> (I know that Wendy Carlos had hers modified with individual
> outputs, but this cannot be done without compromise on other
> aspects of the design.)

Okay, no individual outputs. How about an inverted output? That
would be nice to blend with the source for cancellation effects.

> The EMS filter bank is nice, but very different. Designed without
> that "fault", it has a very flat response when all pots are up.
> A "better design" than the Moog, but less character.
> I have made a clone of the EMS FB many years ago for my
> personal use, but I would not contribute to a commercial
> version (MOTM) of this one, or any other direct copy of EMS
> products.

Why? Are there patents still in effect, or because EMS is still (sort
of) in business? They don't make the filter bank anymore, do
they? I notice the "D" brand is probably pulling their yet to ship
diode filter, because of a licensing hassle. Modcan have an
"EMS type" filter, I wonder if it's licensed. Drifting even further off
topic, how different is the Roland diode ladder from the EMS?

> But apart from this "ethical" aspect, the Moog FB is the ∗really∗
> interesting one anyway, because of its special character and
> coloration.

Cool, bring it on!

Barry