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Problem with sub amp?

I have Tyler Acoustic PD80s with the built in subs/amps. A couple weeks ago after shutting the system down, the subs in the right speaker started humming. I powered up the McIntosh, the hum stopped, I powered down the Mc and 5 seconds later the speaker started humming again. I run single wire to the lower terminals on the speaker then jump from the upper terminals to the high level input on the PDs amp. When the subs hum I can not detect any noise comming from the mids or horns. The problem happens probably 50% of the time. My fear is leaving for work having forgotten to kill the power, that low hum would drive my dog completely insane after 8-10 hours. I suspect it is a problem with the sub amps... any ideas on how to narrow it down?

Thanks
nuguy

Showing 2 responses by nuguy

nuguy OP
195 posts
 
OK, the problem is in the speaker. I unhooked the speaker from the amp and the hum continues. Here is what's happening... I have the sub amp off (red light on), I can push on either midrange driver, the amp turns on (green light on) and the hum starts, the mudrange speakers vibrate as well. I can put slight pressure on either mid with my finger and the hum quits. It's like the mids are acting as microphones and creating a feedback loop. I can even start the hum by yelling into the mids.

This may sound strange but, here's another example, I can close a door in the house and create enough of an air pressure to move the mids and create enough voltage to trigger the amp. I know this shouldn't happen, but it does. I assume the amp is at fault. Has anybody had a similar experience?
nuguy OP
195 posts
 
Thanks for the replies. The amps are class D, and it's not your typical inherent noise. There is definately a problem. I have not measured the hum, but I am guessing it is achieving 85-90 db. Not enough to do damage to the drivers, but like I said it could drive my dog insane if I ever forgot to switch off the power before leaving for the day.

I did call Ty and of course he will help, although he has never came across this issue. He wants to start with a new amp. I will have to eat the shipping to return the old amp, but I'm sure Ziggy (the dog) will be appreciative.

Thanks again
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