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How to eliminate system hum?

I have the following
Rotel 1090 amp
Hovland Pre-amp
Sony 777 CD player
Shahinian Speakers
I have this irritating hum/hiss when I turn on the pre-amp. The sound comes from the speakers when the pre-amp is turned on. If the pre-amp is off and the amp is on, the system is totally silent. It seems as if the amplifier is ok. It seems to be doing its job and is amplifying the crappy signal it is receiving.
Thinking my home electric was poorly configured, I had my electrician install a panel and dedicated lines for my system. The problem is now worse!
I don't think the pre-amp is to blame as I had the same problem with my previous pre-amp. I also have a new cd player.
I have read about "floating" the system ground by using 3 to 2 prong adapters on all system power cords. Is that what I should try?
If anyone has any ideas, I'd be very appreciative. Having $20k worth of stuff that sounds bad is no fun!
holzhauer
holzhauer OP
201 posts
 
Thanks Judit. I now have 3 to 2 adapters on everything but the preamp and the hum is totally gone! Ah sweet music again!
I guess this is a fairly common problem. But in 22 years of stereo ownership, I haven't had it. I'm thinking the 380 watt/ channel Rotel exacerbated the problem as it amplifies the living day lights out of everything that comes its way.
foreverhifi
229 posts
 
YOu only need to float the ground on one of the components to break this hum problem Just try the 3/2 plug addaptor on 1 different component at a time until the hum goes away...no need to "unground" all the plugs with 3/2 addaptors. The fact that all the components are connected, and at least one is grounded, this will keep your system safe and grounded throughout. No problem...
sean
6,231 posts
 
Try reading this thread and see if it helps. There are GOBS of other similar threads in the archives also. Sean
>

Noise, Hum and AC Polarity
a1126lin
70 posts
 
hi this is probably a dumb question. what does it mean to float the ground and what's a 3/2 adaptor.
i have two system. when i use system 1( mark levinson 336/380s) no hum but system 2 nak pa7 nad nak ca 7, big time humming. all ancillary equipments are the same ( speaker , sources ...etc ) why is that?
holzhauer OP
201 posts
 
Sean:
I read your entire noise hum and polarity post. You receive an A+ in my grade book. I think you qualify for the honorary Phd in hi-fi. How long have you been doing this?
P.S. The owners manual for the CAT SL1 ultimate had a similar discourse. Just not as detailed. I bought a VOM today.

A1126lin: 3/2 adapter is a $0.39 hi-fi component at Ace hardware! The female end takes the 3 prongs from your power cord. The male end eliminates the ground and has only two prongs.
Floating refers to having only one of your components hard grounded to the outlet. The others have 3/2 adaptors and ground via the interconnects.
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