PA problem

[Secret Journey]

hey gang, I play at a church that has a decent sound system. (mackie 16 channel, two qsr power amps for mains and monitors, rack compressor equalizer etc etc.) It was installed about three years ago. The last two sundays there has been a problem.
Everything works fine for when they play a CD, or the pastor is speaking, but when we take the stage to play the right channel main goes out. and then does not come back on. There are only two vocal mics, one acoustic run direct, my bass run direct, and a drummer who isnt mic'd (and isnt loud).
I am baffled why this is happening. Any clues? Thank you in advance for any help.

[bigblondeafro87]

Are you playing when it goes out? Sometimes a combination of hot signals can cause the sound to drop out...

[Secret Journey]

yes we are playing when it goes out, but then it stays out. example.. we play right main goes dead, pastor comes up starts preaching, right main still out.
to me it sounds like a short of some kind, but I am not sure why it would affect only the right main.

[WayneP]

I’d say swap the speakers (connect the right one to the other amp channel). If the problem stays with the speaker, then it’s the problem. If not, then check the amp first. Swap the mains and monitor amps to see if the problem moves with the amp (i.e., the monitors would start having problems).

Regards,
Wayne A. Pflughaupt

[Stumbo]

Originally Posted by Secret Journey

Everything works fine for when they play a CD, or the pastor is speaking, but when we take the stage to play the right channel main goes out. and then does not come back on.

It sounds like one of amps fuses might be kicking in and then resets itself after you quit playing.

I suggest you get the group together early in the week and do a sound check.

Maybe run the CD player into each channel to test each one. Play it as loud as possible.

If everything is okay, maybe start with only one mic plugged in and keep adding to see if that will let you know something as the band plays.

Maybe switch the monitor and main amps.

+1 on the speaker switch thing.

Let us know how it goes.

[two fingers]

Originally Posted by WayneP

I’d say swap the speakers (connect the right one to the other amp channel). If the problem stays with the speaker, then it’s the problem. If not, then check the amp first. Swap the mains and monitor amps to see if the problem moves with the amp (i.e., the monitors would start having problems).

Regards,
Wayne A. Pflughaupt

This man has some PA experience, or is a scientist.

You have to narrow the problem down. Like Wayne said, swap the speakers first. If the problem switches sides, it's the speakers. If not, swap the speaker CABLES. Then the amps, then check the faders on your board, etc. By doing this in order, you can figure out what the problem is. While you're doing all of this, take this problem and turn it into a positive. As long as you are in swap mode, get some contact cleaner and clean EVERYTHING. The board, amp inputs, etc. Just make sure everything is TOTALLY dry before hooking back up and turning anything on. Good luck!

[modulusman]

Yeah you need to trouble shoot. If nothing mentioned above works then try removing the rack gear from the signal chain. It could be a bad patch cable also.

[davecanady]

With sound going out only after playing and them coming back on, it shouldn't be standard 2 wire cables. 3 wire are another issue. It sounds like a protection circuit. Your board and amp have overload protection. Your speakers may have overload protection as well.

Put some headphones on and listen to the board's main out mix. If the sound is still there when the speaker stops then move on to the amps.

Swap cables from the mixing board to the amps and see if the other speaker now goes out. If it does, its the amp. If not.....

Swap cables to the speakers. If the same speaker goes out, it's the speaker. If the other speaker goes out it could be a cable that is putting an odd load back into the amp. 3 wire Speakon being used? Check to see your 1 2 & 3 wires are correct.

[GregShadoan]

Could be as simple as an overheating amp. After three years, you may want to clean the amps. If they have been sitting somewhere for that long, without regular maintience, it might be a ton of dust on the intakes. Worth at look at. Trouble shooting is step one though.

[Zooberwerx]

....and track it down one step at a time. Nothing worse than an audio glitch where a self-proclaimed "engineer" changes 5 parameters (cables, cabs, amps, etc.) at one time, corrects the situation, but can't trace the root cause.

Riis

[Johnny Crab]

+1 Zoober.

WHEN you find the root cause, you CAN implement procedure(s) to prevent it(i.e. clean the amps of dust once per year, etc.).