Opposite of noise gate?

[MACHINE MEDIA]

>You need two noise gates... Put your drum machine into the external key of the 
>first, and put a constant tone into the input of the first... (In the UK an easy
>way to get a constant tone is to leave your 'phone off the hook).
> 
>Then put the output of the first gate into the key input of the second, and the 
>real signal into the audio input of the second gate...
> 
> Voila! An inverse noise gate... Modular logic wins again...

I don't see how this would work.  In the first gate you replaced the key 
input with a dial tone, and then used the output as a key for the other gate.
Despite a few possible minute changes in envelope, this would be the same 
as just using one gate with one key input.  What you describe would not 
replace a ducker.

PEACE OUT :)
MARK