[LAU] Filter envelope

[Leigh Dyer]

On 11/03/11 06:17, Q wrote:
> Hello
>
> I'm looking for a resonant filter that's switchable between lowpass,
> bandpass and highpass and which has a traditional ADSR envelope
> controlling it. I'm wanting something that can be used in JACK Rack or
> something like that, or which could be used as a plugin in Ardour, in
> order to process incoming audio in real time.
>
> There are plenty of LADSPA filter plugins, but they all seem to be
> either static or swept by an LFO or similar. I thought someone, at some
> point, might have made a filter and envelope triggered by an incoming
> signal, in the way that a synth's filter does.
>
> It looks like all the building blocks are probably there in various
> LADSPA plugins, but I can't figure out how you'd connect them together.

AlsaModularSynth could probably do exactly that. However, I'd also look 
at PHASEX -- it's a synth, but like many hardware synths it has the 
ability to turn off its oscillators and process an external signal (from 
a JACK port) through its filters, using its envelopes and LFOs for 
modulation.

> I'd also consider a hardware solution (but only a cheap one, as finances
> are very tight at the moment) and in some ways it would have some
> advantages. I thought there was bound to be a guitar stompbox that would
> do that (and no doubt a cheap Behringer knock-off version as well!), but
> so far I've not turned up anything suitable.

Nothing cheap that I know of, but Moog's MF-101 does fit the bill, if 
only for a low-pass filter:

http://www.moogmusic.com/moogerfooger/?section=product&product_id=5

Thanks
Leigh