Does anyone know what could caused the problem and why it burned out my AER compact 60 (Acoustic Guitar Amp)?

Lately, I would take line out from Acoustic Guitar Amp AER and go directly to Full-Range Active Speaker, QSC K8.2 (B input and I would set to HI-Z. Because if I set line, signal is too low) with instrument/guitar cable. And that was working OK.

But last time:

  • everything was off (AER & QSC) - AER was 100% off, for QSC I'm 99% sure it was off, but there is a small chance that it was on, can't remember that for sure.
  • all volume levels were zero
  • AER & QSC were connected to different electrical outlet sockets.

So, when I tried line out from AER to QSC then something cracked while I plugged the cable in QSC. I tried to power on only AER later, but it was already burned out.

And electrical outlet socket where was QSC that socket didn't work after that incident. But QSC speaker was OK, still working fine.

Did my cable was bad? Or that electrical outlet sockets was faulty? Did I connect anything the wrong way? What would cause something like that?

AER repair service managed to repair my AER

-Replace 7 defective SMD/THT components

-realign transformer

-replace Cerafol (power stage insulation)

But now I have no more confidence to go line out or di out from AER to QSC, I can't let that happen to me again if it was my fault.

Any thoughts?

  • It might help to describe these devices in general terms (what category are they: audio interface? stage amplifier? etc.) Some people may not know your specific models but might have general advice that would apply.
    – Theodore
    Commented Oct 13, 2023 at 19:44
  • 1
    @Theodore sure, you right. Added.
    – Chris
    Commented Oct 13, 2023 at 20:45
  • Can you reach out to the repair service and ask them what they think happened? Commented Oct 14, 2023 at 2:36
  • @ToddWilcox Already did, but they can't say for sure why exactly this happened, only which parts were damaged. On other forum we have an assumption, that because both devices were plugged into two different sockets on the wall, and we think one was faulty, and when I connected AER with QSC power surge has occurred, and damage AER.
    – Chris
    Commented Oct 14, 2023 at 9:43
  • Have you had an electrician examine the sockets? Commented Oct 14, 2023 at 12:01

1 Answer 1



Here is an update about the situation, I found out the reason why this happened.

After AER service fixed my burned amp, I didn't want do line out to the active speaker again. So this time I use a Zoom H5 recorder powered on battery, to see what will happen when i do line out from amp to Zoom. Line out didn't work, it was only humming/buzzing all the time. AER off, line out still huming. So this line out was active all the time. And that explains why I burned out AER in the first place when I did line out from AER to active speaker. 

Problem was something to do with a missing ground on the amp. AER service overlooked this problem because they never had anything like this before. This probably happened over the years with my amp, there has probably been an insulation fault in the power amplifier which has led to a faulty voltage on the earth line, and they soldered a broken ground connection for fix.

So, because of a missing ground on the amp that happened to me.

AER service was very friendly and managed to repair the AER amp.

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