Hi Sidney

> Hello everybody. What is the most usual way of processing an external signal, such as a guitar or drum machine, using the A-100 filters. Do I need a special module with an external audio input

My answer is a little late - I was travelling for three weeks.

There are two aspects on the signal that you should obey:
1.) The (guitar-)signal as an source for modulation
2.) The (guitar-)signal as an audio signal to be worked on

The signal #1 should be as much dynamic as possible.
The signal #2 most times should be as less dynamic as possible (keep in
mind: a standard source signal in the modular system like a VCO isn't
dynamic at all!).

The A-119 (which york luethje recommended) is mostly thinking about the
signal #1. It amplifies the incoming signal to a suitable average level.
Then it derives an evelope voltage from the level of the signal (which
can be used to control a filter in the mannor of an auto wah), and also
it derives a gate signal, which again can be used for triggering
standard envelopes, S&H-circuits, ... etc pp.

You should always consider to use an audio compressor for the signal #2
because it reduces the dynamic of the original signal.

So in fact you might end with the following cabling setup example for a
autowah:
* Guitar -> input of A119
* audioout of A119 -> input of some compressor
* output of your compressor -> VCF audio input (this is signal #2)
* envelope out of A119 -> VCF control input (this derived from signal #1)
Of course an autowah is a stupid example, but it explains the basic
principle.

You also may achieve the function an audio compressor also with a
combination of three or four A-100 modules. But this would be wasting
money to my opinion, because any typical compressor (eg. the Alesis
3630) out there is cheaper than two A100 modules.


Florian