[sdiy] 1-2-4 !

[Magnus Danielson]

From: jbv <jbv.silences at club-internet.fr>
Subject: [sdiy] 1-2-4 !
Date: Sat, 17 Apr 2004 14:31:38 +0200
Message-ID: <408123AA.9353F156 at Club-Internet.fr>

> Hi,

Hi JB,

> Could someone be kind enough to point me to a
> web page or article explaining the differences
> between 1, 2 and 4 quadrant multiplier, not so much
> in terms of maths (mine are really poor), but also in
> terms of the differences in the signal...
> I've already done some google search, but haven't
> really find anything that could help me approach the
> problem as a whole...

Who needs Google when there is Synth-DIY? ;O)

As long as we are moving around in the linear behaviours, it's fairly simple.
This means that you need to have a DC component on either one (2-quadrant) or
both (1-quadrant) of the input signals. This allows for the other (or both)
signal to leak through. This means that you will hear both the summation and
difference signals as well as the two modulation waveforms. From an auditorial
point of view I think the 4-quadrant form is better, since then you have a
clean sound to use, and you are always free to mix in either or both of the
modulation waveforms, but the benefit is that you can decide their amount
individually.

To put it another way:
1-quadrant and 2-quadrant => Interesting, but you want "clean it up" to hear
the effect clearer.
4-quadrant => Faschinating... I'm off for the woods!

Cheers,
Magnus - who trimmed up a 4-quadrant multiplier on a Synthi-A Mk.I earlier this
week