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backround noise in speakers


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7 replies to this topic

#1 of 8 OFFLINE   Torsten Zurek

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Posted April 09 2003 - 05:12 AM

Hi there, i just bought a HK AVR 8000 and in the process of setting this thing up i did a lot of listening to little details. I experienced a strange happening. If i select an analog audio source on the receiver, there is a strange backround noise in the speakers. It's audible from all drivers and from every speaker. Turning up the volume will increase the volume of the noise. if i run music through it at very low volume, the noise actually is distinguishable next to the music. The noise sounds like the interference from a badly tuned radio station. Well i also reconnected my old receiver and i found out that it is doing the same thing.The noise is also there if i select an analog audio source which is not even connected. As soon as i switch to a digital source its gone.Is this normal? Are the speakers the problem or maybe the cables?
Oh,one more thing. When i select the DVD player , which is connected via coax, and its on but no source playing the noise is not there.When i push the play button it seems that suddenly the noise is turned on again. With the analog sources it is always there.And it is really noticeable. I really have no idea what might be the cause.Any help, hint, or advise is greatly appreciated.
TIA Zuck

#2 of 8 OFFLINE   Bill Kane

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Posted April 09 2003 - 11:20 AM

This HISSS is one of those *sigh* situations that could involve much tedious rebuilding of connections. Or, in the absence of major device failure, which is highly unlikely, just ONE connection might have failed at an RCA joint involving a cold solder fromn pulling and plugging repititions. This appears to be an electrical ground type problem, not to be mistaken for a ground loop HUMMM.

Start by considering what changed.

You don’t mention any HISSS problem in the past. Then you added a new AVR and introduced some change. Adding the old AVR replicates this change.

Was a surge protector in the chain before or is now. Do speaker wires now run alongside AC power cords. Was a cheater plug used prior and not now. Is the wall duplex’s ground-screw wire and neutral still solid.

Sometimes we have to pull the furniture out to expose the connection interfaces and proceed one connection wire at a time, hoping to isolate where the electrical fault is coming from.

Hope this might get you started, and I apologize if it sounds too basic…

G’luck

bill

#3 of 8 OFFLINE   Torsten Zurek

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Posted April 09 2003 - 12:13 PM

Hi Bill,
thanks for ur reply.
doesn't sound basic at all. i'm fairly new to that stuff.
I did not use a surge protector and i don't have one now.
The speaker wires are the same as before , but they are running from the back of my setup out to a max of about 17 feet.Naturally there are some ac power cords in the vicinity.do they really interfere ? Might the speaker cable be too long ? If its a single RCA how can i figure it out ? is it the connector on the cable itself? Then i would only have to check the different cables- right?
I'm going to work on that right now.
TIA
ZUCK

#4 of 8 OFFLINE   Bill Kane

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Posted April 09 2003 - 12:43 PM

Just keep the volume as low as possible so pulling and reattaching RCA plugs doesnt send large POP/BUZZES to the spkrs.

Grip RCA plugs as far forward as possible to avoid strain at the base where they may be soldered inside. Gently TWIST off and back on. If one IS loose there, this will be the time you discover it with a series of pop/hiss electrical sounds.

Your spkr wire length here is irrelevent. Just try to keep power cords away from spkr wires as best possible. Running alongside 4-6 feet may be all right, but any changes in your hiss might indicate otherwise.

#5 of 8 OFFLINE   Torsten Zurek

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Posted April 09 2003 - 01:02 PM

Hi Bill,
as a start i disconnected all RCA plugs and the coax plug , so only the speaker cables were attached.
Guess what - the hiss is still there. it sounds as if theres some sort of current flowing to the speakers which causes them to produce that sound. Any advice?
TIA
Zuck

#6 of 8 OFFLINE   Bill Kane

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Posted April 09 2003 - 01:14 PM

Z-

What kind of spkrs are you using? Are you wired "bare" or have neat banana plugs to keep spare copper strands from hanging out? Are you certain of the plus-to-plus minus-to-minus or red/black to red/black polarity for amp terminals to spkr terminals.

Is there a subwoofer in the chain?

Be VERY CAREFUL NOT TO SHORT BARE SPKR WIRE EVEN A STRAND ACROSS AMP TERMINALS; cud blow an amp.

Is the amp's 4-6-8 ohm switch on the rear set to match the rated impedence for your spkrs?

I dont think any of the above has direct bearing on your buzz, but gotta start somewhere.

#7 of 8 OFFLINE   Torsten Zurek

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Posted April 09 2003 - 04:29 PM

Hi Bill,
i got Bananas on the Avr and bare at the Speakers. My mains are Kenwood and the surrounds are jbl. I checked the connections and everything looks fine.All are 8 Ohm and the AVR is set for that. The sub had also been disconnected for the check - no effect what so ever. i unplugged the cable tv cable also and tried turning off other equipment on that outlet- no change.
????

ZUCK

#8 of 8 OFFLINE   Bill Kane

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Posted April 09 2003 - 05:33 PM

Sorry this hasn't been easy to trace.

Let's recap if this is the scenario:

A. The HISS which is master volume dependent arose after installing the new AVR. It wasnt there with the OLD receiver.
B. The HISS now reproduces with the OLD rcvr in a test.

Give B, you might deduce that the elecl problem is outside both rcvrs, perhaps a recently broken terminal on a main speaker that induces a short into the system, or internal speaker wiring failure.

But it's too easy to assume anything here. Only by swapping out a known/good rcvr with existing speakers, or known/good spkrs with the new 8000 amp can you further rule out what's causing the BUZZ.

Grasping at straws, you can also plug the rcvr into a different house CIRCUIT. Or borrow a wallplug tester ($10U.S. at a hardware store) that checks for proper ground and neutral/hot wiring for the receptacle.

By the way, halogen lamps around an AV system can be a big no-no. TrackLite dimmers, too.

Dont be discouraged...it's a mystery to solve...

bill