Live Sound Question

[Guitar Guy]

Not sure if there is a better thread for a general sound question or not, but here it goes:

A year ago, the right channel on my mixer stopped working. I sent it in for repair and the first time back out with it the speaker from that channel started making noise. Long story short, after a couple more concerts, the same channel went out again. I opened the mixer today and sure enough, the chipset for the R/L is fried. I will try to replace the OP-AMP and see if that alleviates the problem (no warranty anyway and $450 repair). If this doesn’t fix it, I’ll just buy something else.

Anyway, the question:

I have no idea which powered speaker is overloading the mixer. Both speakers function perfectly (to the ear) when plugged into another channel.

Not being super knowledgeable on the way resistance levels are tested, etc., how would I identify which speaker is the culprit without frying another board in the process?

[albee1952]

My thoughts(as a live sound pro for 30 years):
1-no powered speaker can overload any mixer. It simply doesn't work that way.
2-you are asking about a mixer, but you never mention what mixer it is(hint hint)
3-The word "channel" on a mixer usually refers to an input. Are you referring to an output or an input that fried?
4-what are your needs re a mixer? How many inputs and outputs? If your old mixer is an analog mixer, these days, you can probably get an amazing digital replacement that will be a giant step up

[Guitar Guy]

Thanks!

The mixer is an A and H QPac and the right main output is the one that keeps blowing.



I assumed my wording was off, but something is definitely over loading that op-amp over and over again and that channel is directly connected to my k12.

[zoff]

Have you tried putting the cable connector that is attached to your right output on your left output and the one on the left output on the right output? Without changing anything else.
This will tell you if the problem is in the mixer or external to the mixer.

[Guitar Guy]

Yes I did try that before I confirmed the chip was fried (pic above). But that output is done until repaired.

[zoff]

Originally Posted by Guitar Guy

Yes I did try that before I confirmed the chip was fried (pic above). But that output is done until repaired.

albee1952 gives very good advice.

If you repaired the mixer and then did what I mentioned above and the chip still fried than the problem is in the mixer.

[albee1952]

You maybe could re-route the main output to another set of physical outputs. Most digital mixers allow outputs to be re-assigned like that(I know its possible with Yamaha and Behringer digital mixers).

[Guitar Guy]

Originally Posted by zoff

albee1952 gives very good advice.

If you repaired the mixer and then did what I mentioned above and the chip still fried than the problem is in the mixer.

I agree with your line of thinking, however, another technician told me it is possible that if a speaker is on its way toward going bad, it can begin to overwhelm the connection while also staying functional.

Considering the entire pc board was replaced the first time it was repaired, I do lean slightly toward this being a speaker at the beginning phases of going bad.

I just wish I knew which one it was since it is something that happens over time and then the right output just gives up. Yes, I do think I can rout the audio differently but not having a r/l on a $1700 mixer, as well as the alt r/l for churches to stream from is a bit frustrating.

[albee1952]

I can see 1 scenario where the speaker might fry the output and that is if the speaker has phantom power on the input that the mixer is connected to Tough to think of anything else with so few details about the setup