Opposite of noise gate?

[MACHINE MEDIA]

> Hi all.  I just bought a compressor/gate recently and after playing with it I
> thought it'd be cool to have a gadget which did the opposite of a noise gate. 

Actually in my mind (your mileage may vary) a limiter is the opposite of 
a gate -- the ideal gate lets all amplitudes above a certain threshhold 
through, an ideal limiter lets no amplitudes above a certain threshhold 
through.

> That is, instead of the gate opening when triggered, the gate would close. 
> I'm thinking it'd be interesting to hook it up to the trigger out of a drum
> machine to produce choppy stuttering-type effects.

So, you want to duck a drum machine??

> In typing this I guess this sounds a bit like ducking. I can think of a couple
> of differences though:

OK :)  Perhaps we can come up with methods of gain reduction named after 
other popular waterfowl -- so you could say "goose" a snare drum :)

> a) both the noise gate and ducking both depend on the level of the source
> signal (at least with my compressor/gate).  I'm talking about an external way
> to trigger the gate (i.e. drum machine).

This is called an external key input -- a very popular feature in a gate.

> b) usually a ducker will reduce the level of the signal.  I'd like to be able
> to stop the signal altogether perhaps with adjustable gate attack & release
> times.

This is adjustable on any ducker I can think of.  A high setting (eg. 
90db) should render the signal nearly inaudible.  If it isn't inaudible 
enough for you, you can run the output of the  ducker through another 
gate.

> Is there such a thing already?  

Yes, absolutely.

> If not, anyone have any ideas on how to build one?  I can read a schematic 
> and put stuff together but I'm no EE.

Most commercially available gates are solid-state devices built using 
IC's.  Analog Devices' three man SSM team has several excellent chips that 
can be used that require few external parts and more on the way.  You 
might also want to contact THAT Corporation (they are big on VCA chips). 
What you might find out is that the metalwork necessary for a low noise 
design is more costly than the electronic parts.  

Aphex, Dbx, and several other companies already offer a wide range of gates
-- some under $100 per channel.  These less expensive units use cheap external
power supplies (ie. wall warts) so it might behoove you to connect them 
to devices that already have good signal grounds.  Of course, these 
companies also offer more expensive units.  I just love my extremely 
versatile Dbx 172 "Supergate" :)  

PEACE OUT :)
MARK