Odds of blowing 3 receivers?

[Superprohero]

What are the odds of 3 receivers exhibiting similar conditions? What's going on is I built a new shop a couple years ago so it's all new 110 wiring. The one thing that has remained constant is all 3 receivers were hooked to a pair of Cerwin Vega 300 SE speakers. One speaker has a blown mid range speaker so I just deal with it. I have an old Kenwood KR A-5040 that I bought at the same time I bought the Vegas from Sears way back in the early 90's. The Kenwood Cerwin Vega combo has worked great all these years and never let me down but it's been a few years since it's all been hooked up. I installed these in my new workshop and after less than a couple weeks of use the Kenwood started kicking off and the display went out. Fuses were fine and couldn't get it to work so I assumed it saw it's better days. So I put the Kenwood in storage. A friend gave me an older Sony stereo just to have music in the shop. It also played great at 1st, but within roughly a week it started kicking off and the display stopped working too. Sooooo I figured since it was older like the Kenwood that it had seen it's better days so I trashed it. Now, I find a great deal on a very much like new Integra DTM 40.4 and like the others, hook it to the Cerwin Vegas. It sounded AMAZING, for about a week, then like the other victims, it started kicking off and on and the display went out!! Is it possible that there's something going on with these speakers that would cause 3 receivers to exhibit the same symptoms? Would incorrect speaker polarity cause this? Or should I look at something else? I even installed a new surge protector when I got the Integra to attempt to "protect" it. Any ideas what to look at? I really liked this Integra.

 

[KEW]

The obvious thing to rule out at his point is the receivers (unless you are cranking the speakers to insane levels).

Reversed polarity would not be the issue.
Most likely there is a short somewhere in your system. There are others who will follow who are better qualified to help you, but the first thing you should check is the connections to make sure there is not a stray wire between terminals. This would not be a strong short or the receivers would be more quick to shut down.
My younger brother had a very similar experience to yours and it wasn't until he was moving his system and while spooling the speaker cable around his forearm, he felt a sharp bump in the cable as it slid past his hand. Upon close inspection, the only thing that might have done it would be his cat digging a claw into the cable which actually cut and pushed a wire from the positive to the negative side. It was not a strong short and it was only when he (and friends) got plastered and cranked it that the receivers would die so I'd guess it was only when the voltage was high enough to arc across some oxidation or some minute gap between the wires that it would short.
In any case, give your wires a close inspection (and if it was like my brother's situation, you are better off feeling for the problem than looking for it!).
Good luck, and let us know what you find!

If nothing there, I think the problem must be internal to the speaker!

 

[Superprohero]

The obvious thing to rule out at his point is the receivers (unless you are cranking the speakers to insane levels).

Reversed polarity would not be the issue.
Most likely there is a short somewhere in your system. There are others who will follow who are better qualified to help you, but the first thing you should check is the connections to make sure there is not a stray wire between terminals. This would not be a strong short or the receivers would be more quick to shut down.
My younger brother had a very similar experience to yours and it wasn't until he was moving his system and while spooling the speaker cable around his forearm, he felt a sharp bump in the cable as it slid past his hand. Upon close inspection, the only thing that might have done it would be his cat digging a claw into the cable which actually cut and pushed a wire from the positive to the negative side. It was not a strong short and it was only when he (and friends) got plastered and cranked it that the receivers would die so I'd guess it was only when the voltage was high enough to arc across some oxidation or some minute gap between the wires that it would short.
In any case, give your wires a close inspection (and if it was like my brother's situation, you are better off feeling for the problem than looking for it!).
Good luck, and let us know what you find!

If nothing there, I think the problem must be internal to the speaker!

Thank You Kurt! I'll be checking all that out but I have a sneaking suspicion as you suggested that the wires may be it. Silly me used some of the old wires from who knows how long ago. Also I need to remove the woofers and check that wiring because I recently installed new orange foam surrounds and removed the woofers when I did so. Very hard lesson to learn. I don't have a clue where to get this Integra fixed but it sounded great.

 

[Verdinut]

In my opinion, the speakers seem to be at fault. Would you know a friend who knows a lot about speakers or some nearby audio repair shop for the possibility of testing them. I suspect that someone may have modified the crossover, or one of the drivers has an impedance curve digging down to a value nearing 2 ohms or less at some frequencies. It's also possible that you have a leaking capacitor in the crossover that has caused the failure of the receivers.

 

[Superprohero]

In my opinion, the speakers seem to be at fault. Would you know a friend who knows a lot about speakers or some nearby audio repair shop for the possibility of testing them. I suspect that someone may have modified the crossover, or one of the drivers has an impedance curve digging down to a value nearing 2 ohms or less at some frequencies. It's also possible that you have a leaking capacitor in the crossover that has caused the failure of the receivers.

Thank You Verdinut. I bought these speakers brand new from Sears around 1990 and they have never been modified. I have installed new orange foam surrounds twice now. As old as they are, a leaking cap could be a possibility. This isn't a big town so I'll have to do some asking around for someone experienced in audio repair.