#1
I have a few questions about noise gates. I'm currently using the noise gate in the line 6 m5 with the decay at zero and the threshold at 30%. My signal goes through a Maxon od(boost only) to the m5 to an AMT preamp to the sound card.

Whenever I turn the boost on and finish a lick(and roll the volume down) there is woshh sound which lasts for about 2 seconds and fades. Increasing the decay makes longer. What causes it?Is it because the m5 doesn't react fast enough?

I was also thinking of getting an ISP decimator (not the G string) but I noticed it has no decay knob. How does the decay work in it and will it cure my noise issues?

Thank you
#3
There is tc delay after them but it doesn't produce any noise. Each pedal is being powered by an isolated output. I get no noise at all when using the amt by itself, but engaging the boost makes the noise apperent (which is expected) . My issue is the wosh sound the m5 does after turing the volume down. The guitar is a jeff loomis signature and the electronics compartment is shielded so are the cables.
#4
Often the back panel is shielded, but not the cavity. Are you sure?

Cables are always shielded, it's the nature of coaxial cable - but that doesn't prevent them from being noisy. Try different cables.

What power supply? Not all bricks are isolated.

Here's some helpful info:
http://www.beavisaudio.com/techpages/PoweringPedals/index.htm
Skip down to the part about Line 6 stuff.

Try inserting this between your Maxon and PSU, see if it improves:
http://www.beavisaudio.com/projects/Huminator/index.htm
A 100nF instead of the 47nF would work well too.