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What is causing my speaker hum?

My speakers, Joseph Audio RM22si's, hum (unwanted noise) when the receiver is on. It was the same with my old Infinity speakers. It's there when the receiver (Denon 70Watt x 5 channel receiver) is on, but it's much louder when I'm playing a CD and then pause the CD (using a Toshiba DV333 DVD/CD player). I am using the digital out from the player into the receiver (and therefore using the D/A built into the receiver).

Is this just bad amplification? Could it possibly be bad grounding, and if so is that something I can fix? I don't think it's the CD player, because I'm using the digital out, and when that is paused there should be zero signal sent, yes?

One other very weird side note. Usually it is just white/pink style noise, but one time I heard a song playing. I'm not schizophrenic, there was actually a song playing silently in the noise, different from the one on my CD. Could that be the receiver's tuner leaking out or something coming through the power lines?

One thing I'm trying to figure out is if I buy an amplifier and plug the receiver into that, if my problems will go away, or if you guys think the problem is upstream from the amp.

Thanks,
Matt.
matt8268
ljgj
955 posts
 
If it is by a cable tv cable it could be that. Also the digital cable from the CD player to the receiver could be the problem. Does it hum when you have the rca cables from the CD to the receiver plugged in instead of the digital?
kublakhan
718 posts
 
It doesn't know the words?
AAAAhhhhhhhhh. i'm not back - i just couldn't help that one and i'm wired on 2 triple espressos.
while i'm here though...WHAT'S AAAAAAAAP, fREaKS!?
audiopath
92 posts
 
I suspect that it is a ground loop caused by your cable television. If your Denon receiver is connected to a VCR or TV, then it is usually the cause of the hum. To find out for sure, disconnect and unplug everything from your receiver...all inputs and outputs including speaker wires. Start by connecting the speaker wires to the outputs of the receiver and turn it on. Does it hum? If so, then it is a problem with the receiver. If not turn it off and connect one item and listen for the hum. Repeat until you hear the hum return. It will take a while, but you should find it.
inscrutable
313 posts
 
Yes the most likely cause is the cable tv. you can correct this with 75 > 300 > 75 ohm adaptors. if it is ground loop in the ac, i would hesitate to go to cheater plugs, which floats (eliminates) the grounding of your equipment - this is not safe. try reading the article on ground loop hum on the smr forums. or search any number of boards for such a thread - there have been many. good luck!
lornecherry
135 posts
 
damm Kublah ... that was actually quite funny. Seriously, I suspect cable TV, ground loop, or power cords too close to interconnects or speaker wire. You might also have one bad interconnect (that cross talk you complianed about). And it may not be just one of these, rather a combination of all/some of the above(that was case with me). Well, at least you don't have tube noise to worry about!

I like Inscrutable's suggetions for you, as I doubt you're about to invest in a $1200 PS 300 power conditioner a this point. But $75 -$100 for a dedicated power outlet would be a nice start along with what Inscrutable has suggested. --Lorne
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