[A6] A6 filter wierdness

[Chad Gould]

> 1. some simple standard patches, without any prest modulations,  to use as
> building blocks

It would be nice to see building block patches, wouldn't it? I'm not happy
with a few things about the default patch. (Specifically how the folks set
up PWM.) Sometime when I get the chance I'll set up my own....

> 3. most importantly there is strangeness with the filters that seems
> different from ANY other synth I've used. On some patches they work as
> expected but on others they hardly affect the sound at all - as if the
bulk
> of the sound was bypasing them and just a small amount was being filtered.

Yeah, you have to check the actual filter configuration in the post filter
mix. 

Filter 1 is a multi-out filter, filter 2 is a Moog-inspired LP. Both are
available simultaneously in parallel or in series (having two filters is a
feature unique to the Andromeda, as far as polyphonic analogs goes). There
is also a pre-filter mix, like the CS-80 I believe but on few others.

Here's an attempted diagram of the routing:

OSC MIX OUT-> Filter 1 --+-- HP out Filter 1->|
  |              |       +-- LP out Filter 1->|
  |              |       +-- BP out Filter 1->|
  |              |                            P
  |         (toggle-BP,notch,)                O
  |         (or none)                         S
  |              |                            T-- Out
  |              v                            |
  |---------->Filter 2 ---------Filter 2 out->M
                                              I
Osc 1 Sin---------------+                     X
Osc 2 Sin---------------+---Pre-filter out--->|
Ring Mod----------------+                     |      

Yeah, it gets complicated sometimes. :)

There are a few things to look on at a patch to determine the filter
configuration:

1) Look at the post mix. That will both determine which knob will control
filter modulation, if any. If you see that pre-filter out mix setting (read:
unfiltered tone), you will know that the modifications might be slight. Or,
if you see filter two simultaneously with Filter 1 HP. 

2) The filter 1 -> filter 2 knob tells you a lot. 

BP or notch mode means *both filters* are being used. So you'll need some
additional tweaking sets. If its notch, the post-mix LP 1 / HP 1 out is
disabled, and controls the mix of the HP / LP - keep that in mind. :) 

If its none, Filter 2 is only used for resonant effects. (Filter 2 is
self-oscillating. Filter 1 is not though it can be pushed damn hard with
modulation. :) ) Tweak on filter 1.

If its parallel (what most patches probably will be set to), you'll have to
look at the post mix and see which filter is affected. Obviously it can be
filter 1, filter 2, or both depending on the volume settings.
__________
CHAD GOULD