Bad Channel on Amp

The front left tweeter (high frequencies) of my coaxial (2-way) speaker will cut out intermittently when I have the volume up high. The mid and low frequencies (i.e. woofer) still will work on that speaker when the issue occurs. I found that if I quickly increase the volume on my head unit, the problem will go away and the high frequencies/tweeter work again.

The problem only occurs for that particular speaker. I eliminated the head unit as the cause because I purchased/upgraded to a new Alpine and the problem is still there. I inspected the speaker and wiring and they seem fine.

I suspect the left front channel of my 4 channel amp is going bad. I read online that it may be a relay issue inside the amp or a transistor or capacitor issue. Does anyone have any ideas what may be causing the problem? If so, how can I fix the problem?

Connect your front left speaker to the front right channel of the amplifier, and connect the front right speaker to the left channel of the amplifier. Do not move the rca cables. Change nothing else. Let us know if the problem stays on the same speaker or if it moves to the other side.

I'll try that when I get home today. I'll post the results.

Ok, I finally swapped the speaker wires of the LF channel (channel 1) and RF channel (channel 2) on my 4 channel amp. It took a while for the issue to come back, but I was able to confirm that the LF speaker is still having the issue. Therefore, this eliminates the amp as the culprit.

I should mention that I incorrectly stated the issue in my original post. The mid and low frequencies (i.e. woofer) would stop working in the LF speaker, leaving only the high frequencies (i.e. tweeter) working whenever the issue occurred (i.e. playing at relatively high volume). It would only occur intermittently.

At this point, I have ruled out the HU because I replaced it and the amp by switching the speaker wires of the LF and RF channels. The only other possibilities are bad RCA wires or a bad speaker. So I think I have a bad speaker. Any thoughts?

It is not the RCA cable. Possible culprits are passive crossover (if one exists) wire between said crossover and the woofer, or the woofer.
If there are crossovers involved, and you can not find the problem, try moving the crossover from door to door and see if it follows or stays in the same door. If there is not an external crossover, chances are it is the speaker. What brand and model?

I don't have an external crossover for the speaker. It is an Infinity Reference 2-way (coaxial) speaker. I suspect it's the woofer. It's time I upgrade them anyway. The speaker is about 10 years old. I got good use out of it.

I don't want to spend much on a set of new speakers because I don't plan to keep my car for a long time. I definitely don't want to go with components because I don't want to cut a hole in the door panel in case I sell the car. I'm thinking of buying a set of Alpine SPR-60 (Type R 2-way) speakers. I found them on Amazon for about $100.

Thanks for your troubleshooting help!