AVS Forum banner
1 - 4 of 4 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hi! I have a Denon AVR-X1300W amplifier along with a pair of Klipsch bookshelf speakers and a Klipsch R-100SW subwoofer.

I just into a new house and upon setting up my system, I notice that my subwoofer is producing a low volume bass like sound (I suppose that's what humming is).
If the subwoofer is just plugged in (it uses a two prong plug) with no other cable attached, the hum is barely audible (you have to put your ear next to the sub to hear it.
If the LFE cable is then connected to the sub, the humming becomes louder. If the amplifier is then turned on, the humming becomes even louder. Turning the gain and low pass knobs up or down affects the humming, more gain - louder humming, more low filter - louder humming and vice versa.

I have searched all over the internet for solutions and have tried the following with no success:
I have tried a ground loop isolator on the LFE cable, no change.
I have disconnected or other sources from the amp except for the sub and speakers, no change.
I have tried different LFE cables, no change.
I have tried different electrical outlets around my house for both the sub and amp, also tried plugging them in on the same power strip, no change (amp uses three prong plug).
I also disconnected the ground cable from the electrical outlet where my amp is plugged in, no change.
Unplugged my fridge and switched off two transformers that power my garden lights just to be sure (they are not on the same electrical line), no change.
I don't have satellite TV or cable TV, just plain old aerial and that is only connected to my TV which in turn is only connected to the amp via an optical cable.

I was thinking of trying an AC cheater plug, but to my understanding, that's the same as disconnecting the ground cable from the outlet, which I tried already (correct me if I'm wrong).

Any help would be greatly appreciated, thank you!
 

·
Registered
Joined
·
979 Posts
It really sounds like the Sub amp is the culprit of the hum. I remember having that issue with a Klipsch sub on a bedroom system. I ended up removing the Klipsch sub.
 

·
Registered
Joined
·
3,554 Posts
Sounds like you have done your due diligence. Having removed the ac ground with no interconnection attached and it making no difference ,, sure points to the subs plate amp as the source unfortunately.
 

·
Registered
Joined
·
4,717 Posts
If the subwoofer is just plugged in (it uses a two prong plug) with no other cable attached, the hum is barely audible (you have to put your ear next to the sub to hear it.
If the LFE cable is then connected to the sub, the humming becomes louder. If the amplifier is then turned on, the humming becomes even louder. Turning the gain and low pass knobs up or down affects the humming, more gain - louder humming, more low filter - louder humming and vice versa.


I was thinking of trying an AC cheater plug, but to my understanding, that's the same as disconnecting the ground cable from the outlet, which I tried already (correct me if I'm wrong).

The cheater plug won't matter, as you have a 2 prong power cord that isn't grounded. Those only work on 3 prong (grounded) power cables.

You said it got louder when turned on, but that's with the LFE cable attached. Disconnect everything from the sub except power. Turn the amp on. If the hum is there, it's the amp. If it's louder with the LFE cable hooked up, then you're getting hum upstream (cable, receiver, ground loop, etc.)
 
1 - 4 of 4 Posts
Top