Simple Gating Transistor

[nirvanas silence]

I have built a synth using SPST switches.  The problem is that each note is slightly audible since the SPST bleed some signal which is expected.  Instead of grounding each signal when not in use, what is a simple schematic I can use that is basically a gate.  Anything below a certain point is just cut entirely.  I don't care if it adds some slight clipping, I just need a simple and quick schematic.  Thanks guys!

[smoguzbenjamin]

Well a noise gate is basically a buffer with a envelope detector. But for an effective noise gate you'll need an optocoupler and a few opamps. Craig Anderton's EPFM noisegate is pretty simple, why don't you try that?

[petemoore]

I had some semi cool gated sounds with FF and maybe some other stuff.
 Octaves do that pretty good sometimes.
 Problem is, most of the time there's 'too much' crackly 'between signal and signal gate..

[Tim Escobedo]

Correct me if I'm wrong. I'm assuming the SPST switches are the "keys"?  

If your output is unfiltered square wave, maybe you could use a comparator of some type.

If the oscillator(s) constantly run and the SPST switches simply key the oscillators to the output, there may be lots of capacitive coupling going on. Layout is important. So is good power supply decoupling.

If it's a more traditional analog type synth, things are a lot more complicated. You could try asking the SDIY list. You'll have to be much more specific, though.