Hello,

My father owns a few resturaunts and these use 70V commercial sound
systems for the background music. In one of his stores, the speakers
are making a crackling or popping sound all of a sudden. He asked me
to change 3 speakers (they were in quiet areas where it was most
noticeable so he thought that was all it was) and the problem is
still there, even in the new speakers. I started suspecting the 70V
amplifier. He had a spare one, though it was used and about as old,
so I installed that one to see if there was a difference. The
crackling was still present. Anyone have any ideas what to check
for?

So far, I have tried:
replacing a few speakers
tried a different, but not new, 70V amplifier
tried different wattage settings at the speakers
tried to adjust the volumes on both amp and source
balanced bass and treble

None of this seems to work. I do have an oscilloscope
and know how to use it, but have not had a chance to
bring that with me and look at the signals. Any suggestions?

Scott

"Scott McDonnell" wrote:

}Hello,
}
}...
}So far, I have tried:
}replacing a few speakers...amplifier...settings at the speakers
}...volumes on both amp and source...balanced bass and treble
}
}None of this seems to work.

Talk about the source...have you replaced it with a verified source,
like a portable cd player?

Stan.

Hi !

are these craks coming completely randomly ?

Isn't there fridge, a noise source some how ?

Can you swao the amp with another one from another restaurant, even on
closing days (if there any) just to give a try ?

Cheers

Georges

True american Zero wrote:
Hi !

are these craks coming completely randomly ?

Isn't there fridge, a noise source some how ?

Can you swao the amp with another one from another restaurant, even
on
closing days (if there any) just to give a try ?

Cheers

Georges

"Stan" wrote in message
...
: "Scott McDonnell" wrote:
:
: }Hello,
: }
: }...
: }So far, I have tried:
: }replacing a few speakers...amplifier...settings at the speakers
: }...volumes on both amp and source...balanced bass and treble
: }
: }None of this seems to work.
:
: Talk about the source...have you replaced it with a verified
source,
: like a portable cd player?
:
: Stan.

Stan,
Thanks for the reply!

No, I hadn't tried that yet. It is a digital satellite box tuned
with only
the music stations enabled. I did connect it to a portable video
monitor
with audio so I could switch stations. I noticed no distortion on
the
monitor, so I assumed it was not in the source. I may still try this
since
I am scratching my head on this. I still think it is the PA amp
going bad,
though. I see some on ebay going for about $20 right now, so I might
grab one of those and see.

When I get a chance, I will also try a new audio source as you
suggest.

Scott

Georges,
Thanks for the reply!

I believe they are random. They are normally quite far between,
but are very loud and annoying. It's more like a "pop" though,
but with a very short crackle sound after the pop. At first it
seemed as though the bass was too high because it seems to
occur when a high-energy sound is present, though I hear it
on rare occassions during lower energy periods. I suspected
a capacitor drying up in the PA amp, but haven't had a chance
to open it up yet. I am not even sure how a 70V PA Amp
works.

There are many noise sources, but those sources have
always been there and this problem only recently started to
occur. I suppose it's possible something has a failing motor
in it that could be casuing the noise, but it seems unlikely.

I am planning to buy a new PA amp from Ebay, since I
found a comparable one for ~$20.

Here's some other ideas I had thought to try:

Using a choke coil to kill the sudden change in current,
but this seems like a jury-rigging solution.

A power conditioner? An expensive solution, but would
be neccessary if it is caused by inductive loads on the
same circuit. I am not 100% sure about this, but I
believe it is standard practice to place large appliances
like those used in the resturaunt on seperate circuits.

Scott
"True american Zero" wrote in
message
news:030220050050314297%True_American_Zero@mickeyt hecat.org...
: Hi !
:
: are these craks coming completely randomly ?
:
: Isn't there fridge, a noise source some how ?
:
: Can you swao the amp with another one from another restaurant,
even on
: closing days (if there any) just to give a try ?
:
: Cheers
:
: Georges

In article , Scott McDonnell
writes
Georges,
Thanks for the reply!

I believe they are random. They are normally quite far between,
but are very loud and annoying. It's more like a "pop" though,
but with a very short crackle sound after the pop. At first it

In another post you say it's fed from a digital satellite receiver. A
dropout or error burst in the satellite signal will make exactly that
kind of noise. Could be the antenna/dish has moved or the cable is
getting water in it or something.

I'd try feeding it from another source for a few hours (days?) and see
if that fixes it.
--
Tim Mitchell

"Scott McDonnell" bravely wrote to "All" (03 Feb 05 22:24:19)
--- on the heady topic of " Clicks/pops in 70V commercial audio system"

SM From: "Scott McDonnell"
SM Xref: aeinews sci.electronics.repair:9366

SM Georges,
SM Thanks for the reply!

SM I believe they are random. They are normally quite far between,
SM but are very loud and annoying. It's more like a "pop" though,
SM but with a very short crackle sound after the pop. At first it
SM seemed as though the bass was too high because it seems to
SM occur when a high-energy sound is present, though I hear it
SM on rare occassions during lower energy periods. I suspected
SM a capacitor drying up in the PA amp, but haven't had a chance
SM to open it up yet. I am not even sure how a 70V PA Amp
SM works.

SM There are many noise sources, but those sources have
SM always been there and this problem only recently started to
SM occur. I suppose it's possible something has a failing motor
SM in it that could be casuing the noise, but it seems unlikely.

SM I am planning to buy a new PA amp from Ebay, since I
SM found a comparable one for ~$20.

SM Here's some other ideas I had thought to try:

SM Using a choke coil to kill the sudden change in current,
SM but this seems like a jury-rigging solution.

SM A power conditioner? An expensive solution, but would
SM be neccessary if it is caused by inductive loads on the
SM same circuit. I am not 100% sure about this, but I
SM believe it is standard practice to place large appliances
SM like those used in the resturaunt on seperate circuits.


Scott, I know some amps are very sensitive to fluorescent lights being
turned on (or off). Especially if they are run with a lot of gain that
is being unused. For example if the volume is turned way up to
compensate for a weak source. The lighting circuit wire path makes a
difference. You might try experimenting with removing the equipement
to a different location/circuit, etc. Play with the light switches to
find if one of them is responsible. Maybe try a line filter for the
amp and receiver. Borrow a power conditioner as last resort indeed.

A*s*i*m*o*v

.... Isn't Fourier and it's applications a bitch!

In article ,
Scott McDonnell wrote:
Hello,

My father owns a few resturaunts and these use 70V commercial sound
systems for the background music. In one of his stores, the speakers
are making a crackling or popping sound all of a sudden. He asked me
to change 3 speakers (they were in quiet areas where it was most
noticeable so he thought that was all it was) and the problem is
still there, even in the new speakers. I started suspecting the 70V
amplifier. He had a spare one, though it was used and about as old,
so I installed that one to see if there was a difference. The
crackling was still present. Anyone have any ideas what to check
for?

So far, I have tried:
replacing a few speakers
tried a different, but not new, 70V amplifier
tried different wattage settings at the speakers
tried to adjust the volumes on both amp and source
balanced bass and treble

None of this seems to work. I do have an oscilloscope
and know how to use it, but have not had a chance to
bring that with me and look at the signals. Any suggestions?

Using my theory of maximum inconvenience, it'll be a simple problem
in the hardest part of the system to fix. The wiring in the walls.

Is there a remote volume control panel? If it's on all the speakers,
it sounds like an intermittent on the input side of things. Or pickup
of radio transmitter. (Any highway patrolmen radioing in after they
finish lunch?. Somebody on the other side of the wall running real
estate deals on his cellphone)?

Mark Zenier Washington State resident

Scott McDonnell wrote:

Hello,

My father owns a few resturaunts and these use 70V commercial sound
systems for the background music. In one of his stores, the speakers
are making a crackling or popping sound all of a sudden. He asked me
to change 3 speakers (they were in quiet areas where it was most
noticeable so he thought that was all it was) and the problem is
still there, even in the new speakers. I started suspecting the 70V
amplifier. He had a spare one, though it was used and about as old,
so I installed that one to see if there was a difference. The
crackling was still present. Anyone have any ideas what to check
for?

So far, I have tried:
replacing a few speakers
tried a different, but not new, 70V amplifier
tried different wattage settings at the speakers
tried to adjust the volumes on both amp and source
balanced bass and treble

None of this seems to work. I do have an oscilloscope
and know how to use it, but have not had a chance to
bring that with me and look at the signals. Any suggestions?

Scott

First, what brand and model of unit are you using?
And i hope your not going to say radio shack.
It pays to get a high quality commercial unit.

The total number of all the taps must not exceed the amplifiers rated
outputs. Many non knowing people hang a 8 ohm speaker on to a 70 volt
line and wonder why the system went to hell. You can measure this system
load at the amp, but you need an impedance meter. A DVM will NOT do
this. Something like a TOA ZM 104 will. How many speakers?
what are there taps? do they ALL have line transformers on them?

Now, i have run into a situation like yours with a satellite receiver.
There was a grounding issue between the two units. The units needed
transformerisolation between them to float the audio grounds to solve
the problem.

Bob


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