I modified the abstract from DIY2 Pureverb, to make a reverse reverb, trying to emulate the "Reverse Gate Reverb" FX, from Kaoss Pad 3.

The original KP3 FX has also a gate... for the moment, I don't know how to add it. The original sounds has a abrupter finish of the reverb.

As I added 10 delay lines more... I would like to know if this would have a serious impact on CPU.

Comments, improvements... all accepted... well, asked!

EDIT: I added time value. from 0 to 500ms. It makes a noise when changing it... so, I think it should have fixed times (8, for example) and to have a little fade out and in, to avoid that noise.

http://www.pdpatchrepo.info/hurleur/mono-pureverb-reverse-gate.meh.pd

Got read of the noise by switching your delayread~s to vd~s.

http://www.pdpatchrepo.info/hurleur/mono-pureverb-reverse-gatemeh2.pd

I made a good abstraction for this ([earlyref~]), but it's on the expensive side and I'm not sure that anyone would bother to mess with it. The basic idea is that it's a multitap delay that randomizes the taps over time, and includes a unitary network that increases echo density without smearing out the impulse response as much as an allpass chain does.

It can be used for early reflection effects, gated and reverse reverb effects, etc. Changing the range or distribution of the delay times won't cause noise or glitches, since the delay taps are all faded out and updated one at a time. The quality should be as good as a high end commercial effect.

It's included in this: http://acreil.wordpress.com/2013/04/20/algorithmic-composition-of-acid-house-with-lo-fi-timbres/