When A Speaker Problem isn't a Speaker Problem

I need some sage advice from this group of savvy engineers. Over the last few months I have had problems with speakers. In Florida in February, it was a Turbosound iQ12 that lost all high frequencies. Blown horn, right? We had a spare. Put it on the pole, no problem. Took the Turbo sound to the shop the next week. They did their thing and found no problem… Weird.

So in April, a larger venue, I notice some intermittent "crackling" from one of our JBL VP7315/64DP that we use for larger venues, again on the right side. These things are huge and we use them seldom so I let the band leader know it needed to be check out before we use it again and left it at that.

So, now in May, we have a gig and I trot out the iQ12 having tested it at home and made sure that there are no issue. Before Soundcheck I notice distortion in the low frequencies. I'm running subs so I move the crossover up a bit and it disappears but when I get to soundcheck and the bass player starts, distortion on the low end. So we pull the Turbosound again and put up a different powered box and everything is fine. I take the Turbosound to the shop again and I just got off the phone with them… no trouble found. GRRRRRRRRRR!

So each time I had a problem, it was on the right side and each time the problem ( at least with the Turbosound) was to replace it with another box. My question is this, could this all have been a cable issue? I tend to think of cable failures as complete no signal, but, now I'm thinking the process of simply re-connecting the XLR may be what is solving the problem. Maybe the XLR has some corrosion or something? Does that seem feasible? I will get a chance to test my theory this weekend, but I wanted to test my logic here.

Again, first occurrence, loss of high frequencies, second occurrence, crackling in the high and mid-range on a 3 way speaker, third occurrence, distortion on low frequencies.

Hi JD! Oh man, what a struggle! I don't know, with stuff like that. If you can't reproduce the issue, then how can you solve it? You haven't even seen it occur the same way twice yourself.

I don't think it's a cable issue or it would have produced the same problem in the replacement box.

I think your first step is to find some way to reliably reproduce the issue. If you can't, or don't have time, then yeah, I think I would just lose confidence in the product and stop using it. And/or, the next time it happens, dedicate some time in that moment to troubleshoot the entire signal chain. You might also reach out to Turbosound to see if they have any ideas.

That's a tricky one!

Thanks for the reply Nathan. After talking to the repair tech that day and giving him more info on when it was happening this time (Lots of low frequency) he was able to reproduce the current issue. Turned out to be a loose dust cap on the woofer rattling around. I'm glad they were able to solve that, but I still suspect there's something going on, on the right channel. I hesitate to say it is the Turbosound at fault since I had issues on that same side with the JBL VP7315. Our next gig using our equipment is June 1 so I'm definitely going to change the xlr cable out on that side just to eliminate that as a possibility. Right is always output 16 so that is another common denominator. I have LR assigned to output 13 for one of my delays, so if the problem on the right occurs again, I may just use 13 and run mono to ensure it is not the actual output plug.

So basic troubleshooting 101 and we'll go step by step. Thanks again for the support!

A loose dust cap! Ok, well, nice to at least have some real answers.