hiss and hum problems

[xr7segfault]

I recently purchased a set of KG3.5s, used in conjunction with my harman/kardon AVR45 receiver. If I'm within a foot or two of either speaker, I can hear both a hum (120hz, I think) and a hiss. I tried disconnecting everything except the speakers, same thing. The noise is the same in all modes, changes very little with volume settings, and is unaffected by balance, bass/treble, mute, etc. I tried different outlets and speaker/power cord positions, no change.

I know it's pretty far from being audiophile-level equipment, but I thought that only Wal*Mart-level equipment puts out that kind of noise nowadays. Heck, my 20-year-old Pioneer Centrex minisystem didn't hum!

Is the noise a byproduct of having such sensitive speakers, and something I have to live with, or is it indicative of a problem with the receiver? Call me cynical, but I have this funny feeling that if I took it to a service center, they would keep it for about 4 weeks and return it to me with a few extra ground wires inside, a choke on the power cord, and the same problem. I haven't had the best experiences with getting these kinds of things fixed!

[Ray Garrison]

Just to state the obvious and get it out of the way... speakers don't produce hum and hiss, electronics do. As you noted, you now have VERY sensitive speakers, so any low level grundge that you might not have noticed before will be much more audible than it would be over lesser speakers. The better the speakers, and the more sensitive they are, the more the quality of the electronics will be a factor.

Having said that... the hiss you might not be able to do much about. It's an intrinsic characteristic of the (probably) preamp section of the receiver. Make sure all your interconnect connections are tight and clean - RFI noise can squeegy itself into the system through any less than adequate ground connections. Also, you might try putting shorting plugs or caps on any unused inputs (that is, if you have an AUX1 and AUX2 input with nothing connected, if they are not really well isolated inside the receiver noise can enter that way.) Check out this link: http://needledoctor.fastcart.com/showitem.cfm?catnum=14&parentcatnum=0&itemnum=495

The hum may be fixable. If the receiver's power cord is terminated with a three prong plug, get a cheater plug (three to two adapter) and see if that helps. Try reversing the way the plug is plugged into the outlet - one way round may produce less hiss than the other way. You can also try something like one of the Monster Cable power strips (or other brand) that are supposed to provide some degree of isolation from power line noise contamination. Also try getting a long, heavy, shielded extension cord from Home Depot or a hardware store, and try plugging the receiver into different outlets around the room. Hum may be better or worse from different outlets.

Good luck!

Ray

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Music is art

Audio is engineering

[boa12]

xr, the hiss may really go down when you switch the receiver to stereo/2-channel mode.

if so, then that's those loud dsp on your receiver being reproduced by those loud speakers.

for the hum, could be a grounding problem. try a search on this board for ground or hum.

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Klipsch KLF-30 (front), KLF-C7, Cornwall I (rear)

Velodyne HGS-18 sub woofer

Monsterbass 400 sub interconnect & Monster S-12 cable

Sony STR-DE935 a/v receiver

Sony DVP-C650D cd/dvd player

Sony Trinitron 27" stereo tv

Toshiba hi-fi stereo vcr

Technics dual cassette deck

Technics direct drive turntable

Scientific Atlanta Explorer 2000 digital cable box

2nd room:

Klipsch RF-3 (front), RC-3, cheap little Technics (rear)

Kenwood KR-9600 AM/FM stereo receiver (vintage '75)

Teac PD-D1200 5-disk cd player

Sega Genesis game player

Sub: None yet

rock on!