Subwoofer has got me down!

[dave.lemper2]

I'm now on my 4th subwoofer for my 2.1 MUSIC system in about a year. A simple setup of a Yamaha A-S501(2 ch.integrated amp), a Pioneer PL 55X TT; and depending on my mood either 2 psb MK50II or a pair of B&W DM310s...but if I'm real lucky I have a smaller sub to make my smaller speakers come alive and improve the overall sound quality...but like I mentioned I'm on my 4th sub! The first 3(Polk, Velodyne, & Mirage)all went similar routes...sounded good, develop vol.increasing hum, and die. I figured just a run of bad luck with Craigslist vintage audio gear.
So last night I purchase my 4th, a nice Def Tech. A nice guy auditions it for me...sounded really good and I could not detect any hum. Spoke at great length with him about my hum concerns. He offered possible reasons and said he's had no hum issues with this sub. I believed him and he took $30 less than his asking...so I took her home & plugged her in....
...To the surge protector that my other components are plugged into and an immediate disturbing LOUD pop followed by the dreaded hum. I unplugged the surge there by the amp & TT and plugged sub directly into outlet with same results...nothing was plugged into sub like LFE cable. With ext chord I proceeded to plug her into other outlets in my apartment all creating initial loud pop followed by hum of varying volumes. Would assume it was sub but just heard it with no hum and also prev. 3 all developing same issue although not from the gate like this DefTech. Researched and ground loop isolation doesn't seem applicable because no ground prong on sub power cable and hums w/o being connected to amp. Im guessing maybe bad outlets or wiring in apartment...I'm really clueless...
Any info on possible causes/solutions would be greatly appreciated!!
-Bummed out in Colorado

 

[americanaudiophile]

SInce the sub hums with no input and doesn't have a ground connection perhaps it needs one.
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
If you are in a private home I would try to find a good electrician. Your wiring may have some issues. You can try an AC outlet tester that might tell you if they aren't wired correctly.
https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0

 

[dave.lemper2]

SInce the sub hums with no input and doesn't have a ground connection perhaps it needs one.
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
If you are in a private home I would try to find a good electrician. Your wiring may have some issues. You can try an AC outlet tester that might tell you if they aren't wired correctly.
https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0

 

[dave.lemper2]

SInce the sub hums with no input and doesn't have a ground connection perhaps it needs one.
http://web.mit.edu/~jhawk/tmp/p/EST016_Ground_Loops_handout.pdf
If you are in a private home I would try to find a good electrician. Your wiring may have some issues. You can try an AC outlet tester that might tell you if they aren't wired correctly.
https://www.amazon.com/Electrical-Receptacle-Outlet-Ground-Tester/dp/B0012DHVQ0

Americanaudiophile,

Thank you for your insightful reply and the informative suggested reading.

I purchased an ac outlet ground tester and tested all the outlets in my apartment. It would appear the outlets are wired properly.

My next step is to purchase the ebtech hum x. From what i can gather with my limited insight, this appears to be different from other ground loop isolaters in that you plug a power cord directly in to it, which plugs directly in to an outlet. Others seem to connect via a signal cable between 2 components, which doesn't seem applicable.

If the hum x doesnt help, i will try a power conditioner. If neither control the subwoofer hum, i will cut my losses and start saving for quality tower speakers with good bass response!