Foo - electronics problem - arcing in audio system

Hey all, I thought I'd throw this out to Foo in the hope that some bright spark is lurking here...

We've got an audio system chaining from source through to preamp, then audio actuators on to voltage controlled amps, then to power amps.

The problem is in the steps from audio actuators to the power amps. When you switch channels on (via controls in the listening rooms), the relay contacts in the actuators close and since the power amp is always on it's pulling down the current.

Thus arcing occurs in the actuator and this results in an almighty 'pop' at the speaker end. It's really quite unacceptable.

(did that make much sense?)

What are some possible ways of dealing with this? There doesn't seem to be any way of controlling any "ramping up" of voltage in any of the amps, and the power amp is not controllable (i.e. must always be on).

Change out the channels switch to a fader? Fade from A--->B--->C instead of a hard switchover?
Hey all, I thought I'd throw this out to Foo in the hope that some bright spark is lurking here...

We've got an audio system chaining from source through to preamp, then audio actuators on to voltage controlled amps, then to power amps.

The problem is in the steps from audio actuators to the power amps. When you switch channels on (via controls in the listening rooms), the relay contacts in the actuators close and since the power amp is always on it's pulling down the current.

Thus arcing occurs in the actuator and this results in an almighty 'pop' at the speaker end. It's really quite unacceptable.

(did that make much sense?)

What are some possible ways of dealing with this? There doesn't seem to be any way of controlling any "ramping up" of voltage in any of the amps, and the power amp is not controllable (i.e. must always be on).

The point of the actuator is to control channel switching from control panels in the rooms. Unfortunately there is no inherent fade or ramping ability in the devices.

The arcing occurs because the power amp is always on. So as soon as the contact closes it yanks the power from the actuator which causes the arcing.

We even tried a time delay by giving power to the intervening voltage-control amp after the actuator switches, but no dice.

A capacitor will dampen the arc. Calculate what value you need to as to not filter any of the audio signal. This would be based upon the impedance of the circuit along with the inductance of the wires.

^ yeah, a capacitor is the best thing we've thought of so far. If no other ideas come to mind I think we'll have a stab at sticking a capacitor in each circuit. It just may be the brilliantly simple solution we need.

the relays are normally supposed to provide a delay that prevents power surges from being heard as a pop through the speakers. Capacitors are normally used to filter 60 cycle hum out of the power supply. are you sure you're using correctly sized relays and the correct relay circuit?

MacGuyver it with three tic tacs, (one orange, two wintergreen, duh) the tang off your belt buckle, a gum wrapper and a strip of duct tape. The duct tape is not entirely necessary, but lends authenticity.

the relays are normally supposed to provide a delay that prevents power surges from being heard as a pop through the speakers. Capacitors are normally used to filter 60 cycle hum out of the power supply. are you sure you're using correctly sized relays and the correct relay circuit?
We have no control over the relays - they're just the bits inside the actuators that we're using. They're supposed to be used with the same brand power amp (presumably that would eliminate the problem), but their power amp is a POS.

There's no hum. We had good fun sorting out the myriad grounding issues, but that's clean now.

We'll try some capacitors I reckon.

That or the MacGyver solution :lol: