Is there a trick to getting the SQ channel gates to operate on toms without clicking?
Engaging the filter with suitable frequency settings will allow you to have a lower threshold which I find helps.
Ah, because by the time the gate opens the signal is already too large? Which filter type do you use?
Lengthening the attack time to 80us seemed to help a bit, but obv don’t want to lose the attack.
It is common to hear an audible click when the attack time is set to the fastest time possible. I’ve found this to be true with many different console manufacturers, not just Allen and Heath. As you discovered, setting a slightly slower attack time will generally get rid of the click. You might have to play around to find the fastest time that doesn’t cause a click however.
It depends on what else is bleeding into the mic. Find a prominent frequency from the instrument that will trigger the gate to open as you want and then experiment with High/Low/Band Pass and tweak until it works.
No two setups are the same unfortunately.