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Loud noise from amplifier

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Anonymous
June 18, 2004 11:58:29 PM

Archived from groups: rec.audio.tech (More info?)

Hi! I got a 5 channel surround amplifier with a problem in 2 of the
channels. The connections are split into front/surround on the left,
center in the middle and front/surround on the right. Whenever i
connect the source-rca and speaker to the two right hand channels i
get a loud noise just like the noise you get when connecting a guitar
to a amplifier sticking the jack-plug half way in. When disconnecting
the rca-plug there is no noise from the speaker. What can be wrong,
and how fix this?

More about : loud noise amplifier

Anonymous
June 19, 2004 9:18:05 AM

Archived from groups: rec.audio.tech (More info?)

Sounds like either a bad cable, or maybe a bad solder (ground) connection
where that input plugs in.

If the sound continued with no input plugged in, I was going to suggest a
problem with that amp channel.

Mark Z.

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Please reply only to Group. I regret this is necessary. Viruses and spam
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"Arne" <to498@yahoo.com> wrote in message
news:25f42a8b.0406181858.49d7f09b@posting.google.com...
> Hi! I got a 5 channel surround amplifier with a problem in 2 of the
> channels. The connections are split into front/surround on the left,
> center in the middle and front/surround on the right. Whenever i
> connect the source-rca and speaker to the two right hand channels i
> get a loud noise just like the noise you get when connecting a guitar
> to a amplifier sticking the jack-plug half way in. When disconnecting
> the rca-plug there is no noise from the speaker. What can be wrong,
> and how fix this?
Anonymous
June 19, 2004 4:26:52 PM

Archived from groups: rec.audio.tech (More info?)

Arne wrote:

> Hi! I got a 5 channel surround amplifier with a problem in 2 of the
> channels. The connections are split into front/surround on the left,
> center in the middle and front/surround on the right. Whenever i
> connect the source-rca and speaker to the two right hand channels i
> get a loud noise just like the noise you get when connecting a guitar
> to a amplifier sticking the jack-plug half way in. When disconnecting
> the rca-plug there is no noise from the speaker. What can be wrong,
> and how fix this?

This most probably indicates a a ground loop or the equivalent. The
obvious questions are why do you need to make the connections while both
sets of equipment are turned on? Is there any problem during use?

It is odd that you don't notice the problem with the left channel unless
you have never tried to plug the right side equipment into the left channel.

There are two things you can try which might help but won't remove the
root of the problem. If the plug for the right channel equipment is
two-prong, flip it over in the socket. This can remove significant AC
from the chassis. Second, take some wire and connect the chassis of the
offending equipment to the amp. This will prevent the "half-in"
condition while you use the rca connector.
Related resources
Anonymous
June 19, 2004 7:25:09 PM

Archived from groups: rec.audio.tech (More info?)

Robert Gault wrote:
> This most probably indicates a a ground loop or the equivalent. The
> obvious questions are why do you need to make the connections while both
> sets of equipment are turned on? Is there any problem during use?

I tested with the same cd-source and the same loudspeaker on alle the
channels. While amp turned off, plugging in the rca and speaker on the
first channel, turning on the amp would give clean crisp sound without
any hiss or hum. Turning off the amp and connect the source and speaker
to #2 channel and so on. On the #4 and #5 connection (located by itself
on the far right) an awful loud motor-like sound (music barely audible
in the background) and two loud pop-like sounds before silence when
turning off.

> There are two things you can try which might help but won't remove the
> root of the problem. If the plug for the right channel equipment is
> two-prong, flip it over in the socket. This can remove significant AC
> from the chassis. Second, take some wire and connect the chassis of the
> offending equipment to the amp. This will prevent the "half-in"
> condition while you use the rca connector.

Are listening to stereo music now using the #2 and #3 channel just now
and everything is all right..
Anonymous
June 19, 2004 7:25:10 PM

Archived from groups: rec.audio.tech (More info?)

Arne wrote:
> Robert Gault wrote:
>
>> This most probably indicates a a ground loop or the equivalent. The
>> obvious questions are why do you need to make the connections while
>> both sets of equipment are turned on? Is there any problem during use?
>
>
> I tested with the same cd-source and the same loudspeaker on alle the
> channels. While amp turned off, plugging in the rca and speaker on the
> first channel, turning on the amp would give clean crisp sound without
> any hiss or hum. Turning off the amp and connect the source and speaker
> to #2 channel and so on. On the #4 and #5 connection (located by itself
> on the far right) an awful loud motor-like sound (music barely audible
> in the background) and two loud pop-like sounds before silence when
> turning off.
>
>> There are two things you can try which might help but won't remove the
>> root of the problem. If the plug for the right channel equipment is
>> two-prong, flip it over in the socket. This can remove significant AC
>> from the chassis. Second, take some wire and connect the chassis of
>> the offending equipment to the amp. This will prevent the "half-in"
>> condition while you use the rca connector.
>
>
> Are listening to stereo music now using the #2 and #3 channel just now
> and everything is all right..

OK, that reads differently from the original message. You have a real
problem on the #4&5 inputs to the amp. Unless you have the schematics
for the amp, there may not be much you can do. At the very least, open
up the amp and look for any obvious damage on the #4&5 inputs/circuits.
Anonymous
June 22, 2004 2:31:01 AM

Archived from groups: rec.audio.tech (More info?)

Robert Gault wrote:
> OK, that reads differently from the original message. You have a real
> problem on the #4&5 inputs to the amp. Unless you have the schematics
> for the amp, there may not be much you can do. At the very least, open
> up the amp and look for any obvious damage on the #4&5 inputs/circuits.
>

And obvious damage it was.. The #4/5 rca had no ground because of a
small metal spade lever had slippeded out on the backside. Just push it
in, and everything was ok..
Anonymous
June 22, 2004 2:31:02 AM

Archived from groups: rec.audio.tech (More info?)

"Arne" <to498@yahoo.com> wrote in message news:1087849799.905247@gurney...
> Robert Gault wrote:
> > OK, that reads differently from the original message. You have a real
> > problem on the #4&5 inputs to the amp. Unless you have the schematics
> > for the amp, there may not be much you can do. At the very least, open
> > up the amp and look for any obvious damage on the #4&5 inputs/circuits.
> >
>
> And obvious damage it was.. The #4/5 rca had no ground because of a
> small metal spade lever had slippeded out on the backside. Just push it
> in, and everything was ok..

*ahem*
"Sounds like either a bad cable, or maybe a bad solder (ground) connection
where that input plugs in."

Nailed that one.

tee-hee.

mz
--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.
Anonymous
June 22, 2004 10:13:44 AM

Archived from groups: rec.audio.tech (More info?)

Mark D. Zacharias wrote:
> *ahem*
> "Sounds like either a bad cable, or maybe a bad solder (ground) connection
> where that input plugs in."
>
> Nailed that one.

Yes, I know. Thanks!

Nasty thing. it blew one of my speakers.. b&w tweeter.
Anonymous
June 22, 2004 10:13:45 AM

Archived from groups: rec.audio.tech (More info?)

BUMMER! I hate it when that happens.

mz

--
Please reply only to Group. I regret this is necessary. Viruses and spam
have rendered my regular e-mail address useless.


"Arne" <to498@yahoo.com> wrote in message news:1087877566.506276@gurney...
> Mark D. Zacharias wrote:
> > *ahem*
> > "Sounds like either a bad cable, or maybe a bad solder (ground)
connection
> > where that input plugs in."
> >
> > Nailed that one.
>
> Yes, I know. Thanks!
>
> Nasty thing. it blew one of my speakers.. b&w tweeter.
!