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Jl audio fathom f212v2 noise and hum

Just picked up a pair of these to replace the svs pb1000 i had prior. However after plugging these in to the same outlet (its a panamaz suge protected outlet) i’m experiencing two things i did not experience with the svs pair.  1) there is constant low level noise, like a very low white noise that is present when on, even if not connected to anything else. 2) a cyclical hum that seems to come on when my panasoni vt60 plasma is on. I beleive these are likey using the same circuit/ are wired though on different outlets.

Ive tried rca and balanced cables. No discernable difference there.  The subs are massive to move but next step is im goint to try them on dedicated circuits in a different room to see if that does anything.  Open to ideas here and hoping there is a solution. Thanks! 
esthlos13
rlb61
789 posts
 
It might be a ground loop hum ... too many components on the same outlet or circuit. 
photon46
1,082 posts
 
Are these brand new or used?
lalitk's avatar
lalitk
5,438 posts
 
@esthlos13,

I also own the 212v2, the low level noise you mentioned seems to be inherent with this model. The faint noise doesn’t bother me as it’s not audible from my listening position. 
esthlos13 OP
90 posts
 
Thanks for the responses. I’ve been researching ground loop hum. The hum when it came on was cyclical it was not constant which makes me wonder if it is being caused by something else in the house maybe a dimmer or microwave.  I’ve been very busy with work and have not had the time to do more testing but I have a test plan thought out which I will post when I have some time. The other odd thing, maybe it’s normal for jl, is there is a small pop on each when they are first plugged in. Once they are going they sound great and the white noise is basically inaudible. Didn’t hear the hum last time when I had the TV off which makes me wonder if it is the cable connection to the TiVo mini. I have read coax cable can be a culprit sometimes.  
gakman
52 posts
 
Hi esthios13,

A couple years back I bought a Classe CT-2300 power amplifier and found the amp made a rhythmic hum sound. The sound came from the amp not through the speakers, turned out that my 60" Panasonic Plasma television was introducing DC voltage into the AC main circuit, and the amp (on the same circuit) didn't like that.

Try using a extension cord from a outlet on a different circuit and see if that helps. I ended up running a dedicated circuit for my Classe amp and the problem was solved.

Good luck,
Gary
 
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