We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be but they
were usable. Over the past two years they have gotten more noisey. We
set up a test today. All cables were open ended, that is unterminated
on the other side. We set each input individually so that the VU meter
read 0VU noise level. Then doing one input at a time we plugged a mic
in. The noise level dropped to -6 on all inputs when checked
individually. It was an improvement but certainly still not too good.
Next we started out with open ended cables again, established our 0VU
noise reference and then shorted all three terminals on the XLR
connector together with a piece of foil. I repeated this with all the
remaining cables and the results were the same. The noise completely
disappeared and the line was clean. I next disconnected the line at
both ends and checked each conductor to ground for high resistance. I
read infinity from each conductor to the sheild as well as to building
ground. Next we took one mic and boosted it to line level at the far
end. We ran this line level signal through one of the underground
cables to a line level input on the mixer. The noise level is now way
below the signal level and the signal was squeaky clean. So now we
know that we can definitely retrofit the job and get it to work this
way, but this whole thing really puzzles me. Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas. But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated. Lenny Stein, Barlen Electronics.

In article . com,
wrote:
Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas.

Probably poor balance at either or both ends.

But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated.

I'd have started out with star quad cable.

--
*On the other hand, you have different fingers*

Dave Plowman London SW
To e-mail, change noise into sound.

wrote:
We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be but they
were usable. Over the past two years they have gotten more noisey. We
set up a test today. All cables were open ended, that is unterminated
on the other side. We set each input individually so that the VU meter
read 0VU noise level. Then doing one input at a time we plugged a mic
in. The noise level dropped to -6 on all inputs when checked
individually. It was an improvement but certainly still not too good.
Next we started out with open ended cables again, established our 0VU
noise reference and then shorted all three terminals on the XLR
connector together with a piece of foil. I repeated this with all the
remaining cables and the results were the same. The noise completely
disappeared and the line was clean. I next disconnected the line at
both ends and checked each conductor to ground for high resistance. I
read infinity from each conductor to the sheild as well as to building
ground. Next we took one mic and boosted it to line level at the far
end. We ran this line level signal through one of the underground
cables to a line level input on the mixer. The noise level is now way
below the signal level and the signal was squeaky clean. So now we
know that we can definitely retrofit the job and get it to work this
way, but this whole thing really puzzles me. Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas. But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated. Lenny Stein, Barlen Electronics.


Of what use is an unterminated cable? You say you're getting noise, but
that it goes away when you terminate the cable. If I understand you
correctly, that's not unusual. A cable without something connected *on
both ends* is kind of useless and will act like an antenna...unless of
course, it's intended to be an antenna.

Other issues with underground conduit may be at play here as well. Is
the conduit environmentally sealed at both ends? Mice just love to play
in those things. Water gets in....

jak

" wrote:

We ran 5 microphone cables

Balanced and low impedance ? Individual screened cables ?

What equipment (make and model) are the mics plugged in to ?

Graham

" wrote:

We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be

When tested in exactly what way ?


but they were usable. Over the past two years they have gotten more noisey. We

set up a test today. All cables were open ended, that is unterminated
on the other side.

What's the point of that ? You should fit a 200 ohm resistor between the 2
signal conductors to simulate a microphone's source impedance.


We set each input individually so that the VU meter
read 0VU noise level.

You cranked up the mic gain with open circuit inputs ? What were you trying to
achieve ?


Then doing one input at a time we plugged a mic in.

Use a 200 ohm resistor !

The noise level dropped to -6 on all inputs when checked individually.

I'm sorry but your test seems utterly bizarre. As an audio pro for 35 years I
can't believe the stuff you're saying. You don't come over as remotely
competent never mind professional at all. Your tests are absurd in the extreme.
Whatever are you thinking of ?


Graham

" hath
wroth:

Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas.

Yep. If you look at the "noise" on a scope, it probably will look
like an AM broadcast transmitter modulation envelope. Also, the
unterminated end point will pickup some 60Hz hum. If the "noise" is
on/off keyed, you're near a Navy submarine communications transmitter.

The increase in "noise" level might be due to water incursion,
corosion, or dissimilar metals electrolysis.

Running a microphone into an unterminated load is silly. They weren't
made to operate like that, they turn the cable into an antenna, and
you'll never see it in real life. Install a termination and
re-measure.

It's also rather odd measuring the "noise" level with the microphone
active. I suspect you're measuring either the background audio noise
pickup of the microphone (i.e. road noise), or the added noise of the
mic pre-amplifier.

What you've done is described the symptoms, without also supplying
much information as to what you have to work with (type of cable,
connectors, end points, proximity to sources of "noise", depth of
burial, type of microphone, etc. It's rather difficult to guess(tm)
the cause without such details.

Also, the term "noise" is subject to much creative interpretation. It
could easily be mic audio background pickup, ingres, transformer
action, rectification, or RF. If you have a suitable audio spectrum
analyzer *AND* an oscilloscope, you may want to take a photo of both
and post it somewhere. The frequency and waveforms of this "noise"
will offer considerable information as to determining its cause and
source. That will supply much more info than a Vu meter.

I'll bet on road noise from the live microphone.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

wrote in message
ups.com...
We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be but they
were usable. Over the past two years they have gotten more noisey. We
set up a test today. All cables were open ended, that is unterminated
on the other side. We set each input individually so that the VU meter
read 0VU noise level. Then doing one input at a time we plugged a mic
in. The noise level dropped to -6 on all inputs when checked
individually. It was an improvement but certainly still not too good.
Next we started out with open ended cables again, established our 0VU
noise reference and then shorted all three terminals on the XLR
connector together with a piece of foil. I repeated this with all the
remaining cables and the results were the same. The noise completely
disappeared and the line was clean. I next disconnected the line at
both ends and checked each conductor to ground for high resistance. I
read infinity from each conductor to the sheild as well as to building
ground. Next we took one mic and boosted it to line level at the far
end. We ran this line level signal through one of the underground
cables to a line level input on the mixer. The noise level is now way
below the signal level and the signal was squeaky clean. So now we
know that we can definitely retrofit the job and get it to work this
way, but this whole thing really puzzles me. Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas. But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated. Lenny Stein, Barlen Electronics.

First thing to try is to unground the shield at one end. Reason is that
ground is not ground between remote points and you could have a ground loop
current that is inducing noise.

Charles wrote:

First thing to try is to unground the shield at one end. Reason is that
ground is not ground between remote points and you could have a ground loop
current that is inducing noise.

Not on a balanced circuit.

Graham

On Oct 19, 9:15 pm, Eeyore
wrote:
Charles wrote:
First thing to try is to unground the shield at one end. Reason is that
ground is not ground between remote points and you could have a ground loop
current that is inducing noise.

Not on a balanced circuit.

Graham

__________________________________________


175 ft cable runs , underground routes , grounding each end ,
microphone level signals , no line termination , no signal
conditioning . noise level measurement's on open lines ..

Whole thing reads like a TV repair man , mending a radar set....

G ..

Graham wrote:

Eeyore wrote:
Charles wrote:
First thing to try is to unground the shield at one end. Reason is that
ground is not ground between remote points and you could have a ground loop
current that is inducing noise.

Not on a balanced circuit.

__________________________________________

175 ft cable runs , underground routes , grounding each end ,
microphone level signals , no line termination , no signal
conditioning . noise level measurement's on open lines ..

Whole thing reads like a TV repair man , mending a radar set....

There are certainly some issues that need addressing wrt 'technique' there !


Graham

On Oct 19, 11:37 pm, Meat Plow wrote:
On Fri, 19 Oct 2007 10:59:24 -0700, wrote:
They seem to acting like antennas.

BINGO!

I thought that I would provide just a little more information for
those of you who seem to think that I'm totally incompetent. The mixer
is a Shure M67. The cable is two conductor AWG. 18 with a tight
braided tinned copper sheild. Its Mil spec instrument cable which I've
used on microphone jobs before. In fact we've done longer runs without
incident. There are 5 XLR female jacks mounted on an aluminum plate.
The 5 sheilds are connected to their respective jacks but are not tied
together, nor are they earth grounded at this end. The open cable test
was just to compare all the lines to each other and thats all. The
microphone plugged into one line with all the others turned down
should have balanced that line and ideally been noise free. I think
that I know the difference between ambient room noise and buzz and
hum. This isn't my first barbecue. All I was asking was for opinions
as to why a balanced line terminated with a low Z microphone might be
noisey. If you feel that you must insult me further to speculate as to
the cause of this please don't bother to respond. Thanks, Lenny Stein,
Barlen Electronics.

What you should do, is first make sure that the wire is a high quality
shielded type. What can happen is that if the pipes are of PVC and not of a
metal with magnetic shielding properties, it will not offer external
shielding against electromagnetic fields from electrical distribution
wiring. The longer your cable run, the more it is susceptible it is to pick
up other radiated signals, or noise.

What I do with long microphone runs, is put pre-amps in line at the sending
end. I then send the audio at line level down the cables rather than at mic
level. Line level is normaly +4 dB with professional equipment. The mic
level is normaly at -50 to -60 dB.

At the receiving end, which I assume in your case is an audio board, you can
then have the inputs set to line level. With this method, if there is any
noise pickup, then it is extremely severe.


--

JANA
_____


wrote in message
ups.com...
We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be but they
were usable. Over the past two years they have gotten more noisey. We
set up a test today. All cables were open ended, that is unterminated
on the other side. We set each input individually so that the VU meter
read 0VU noise level. Then doing one input at a time we plugged a mic
in. The noise level dropped to -6 on all inputs when checked
individually. It was an improvement but certainly still not too good.
Next we started out with open ended cables again, established our 0VU
noise reference and then shorted all three terminals on the XLR
connector together with a piece of foil. I repeated this with all the
remaining cables and the results were the same. The noise completely
disappeared and the line was clean. I next disconnected the line at
both ends and checked each conductor to ground for high resistance. I
read infinity from each conductor to the sheild as well as to building
ground. Next we took one mic and boosted it to line level at the far
end. We ran this line level signal through one of the underground
cables to a line level input on the mixer. The noise level is now way
below the signal level and the signal was squeaky clean. So now we
know that we can definitely retrofit the job and get it to work this
way, but this whole thing really puzzles me. Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas. But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated. Lenny Stein, Barlen Electronics.

In article . com,
wrote:
I thought that I would provide just a little more information for
those of you who seem to think that I'm totally incompetent. The mixer
is a Shure M67. The cable is two conductor AWG. 18 with a tight
braided tinned copper sheild.

I can't understand why you're using that. I've not used ordinary pair
balanced mic cable for over 30 years. Star quad is so much better. It can
change an unusable mic circuit into a satisfactory one - the difference is
that great.

--
*Do infants enjoy infancy as much as adults enjoy adultery? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
JANA wrote:
What you should do, is first make sure that the wire is a high quality
shielded type. What can happen is that if the pipes are of PVC and not
of a metal with magnetic shielding properties, it will not offer
external shielding against electromagnetic fields from electrical
distribution wiring. The longer your cable run, the more it is
susceptible it is to pick up other radiated signals, or noise.

What I do with long microphone runs, is put pre-amps in line at the
sending end. I then send the audio at line level down the cables
rather than at mic level. Line level is normaly +4 dB with professional
equipment. The mic level is normaly at -50 to -60 dB.

I really can't understand why you guys haven't discovered star quad cable.
With a deal of experience of TV work it's unusual to need to raise the mic
level when using star quad - even with cable runs of a mile or so. And a
mic to line amp capable of handling anything any mic can throw at it
without being able to adjust the preset gain is a rare and expensive
beast.

--
*Reality? Is that where the pizza delivery guy comes from?

Dave Plowman London SW
To e-mail, change noise into sound.

JANA wrote:

What you should do, is first make sure that the wire is a high quality
shielded type. What can happen is that if the pipes are of PVC and not of a
metal with magnetic shielding properties

The screens on such cables are made of copper. Their action has NOTHING to do
with magnetic shielding.

Graham

JANA wrote:

What I do with long microphone runs, is put pre-amps in line at the sending
end. I then send the audio at line level down the cables rather than at mic
level. Line level is normaly +4 dB with professional equipment. The mic
level is normaly at -50 to -60 dB.

What the guy has done is entirely normalpractice in profesional audio. That's
NOT a problem.

Heck, I've actually run UNBALANCED mic signals 60 metres without trouble.
Obviously that needed some care with the grounding arrangements.

Graham

"Dave Plowman (News)" wrote:

wrote:

I thought that I would provide just a little more information for
those of you who seem to think that I'm totally incompetent. The mixer
is a Shure M67. The cable is two conductor AWG. 18 with a tight
braided tinned copper sheild.

I can't understand why you're using that. I've not used ordinary pair
balanced mic cable for over 30 years. Star quad is so much better. It can
change an unusable mic circuit into a satisfactory one - the difference is
that great.

Star Quad should only really be needed in areas of high interfering field
strength, where the extra rejection it offers comes in handy.

Graham

In article ,
Eeyore wrote:
I can't understand why you're using that. I've not used ordinary pair
balanced mic cable for over 30 years. Star quad is so much better. It
can change an unusable mic circuit into a satisfactory one - the
difference is that great.

Star Quad should only really be needed in areas of high interfering field
strength, where the extra rejection it offers comes in handy.

Well the OP has problems. Unless you can do tests to make sure ordinary
cable is ok just use star quad. The difference in price is tiny compared
to the cost of replacing 'ordinary' if it gives problems. Rather the same
as using ordinary UHF aerial cable - most now don't but prefer CT100 etc.

--
*Yes, I am an agent of Satan, but my duties are largely ceremonial

Dave Plowman London SW
To e-mail, change noise into sound.

" hath
wroth:

I think
that I know the difference between ambient room noise and buzz and
hum.

Ok, I'll bite. You're measuring "noise" with a Vu meter. Got an
audio spectrum analyzer in your war chest? If so, use it and tell us
what you see. Is it hum, buzz, crackle, AM radio station, submarine
communications, power supply switching noise, or alien signals from
the overhead flying saucer?

This isn't my first barbecue.

True. However, the way I recognize experience is by the numbers. You
didn't supply any. How many dB was the "noise" increase? What
frequencies was the "noise"? What manner of equipment was used?

All I was asking was for opinions
as to why a balanced line terminated with a low Z microphone might be
noisey.

There's some question as to whether terminated at one end with a
microphone constitutes proper termination. In my never humble
opinion, both ends need to be terminated to prevent the coax from
turning into an antenna, transformer, or linear capacitor. What
manner of "noise" you're seeing will also help isolate the cause and
mechanism.

If you feel that you must insult me further to speculate as to
the cause of this please don't bother to respond.

Sometimes, insults and haranguing are the only effective way to get
people to disclose sufficient information to supply an intelligent
answer. My asking for additional information does not constitute an
insult, although I can see how it might be construed as such.

Thanks, Lenny Stein,
Barlen Electronics.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

" hath
wroth:

All I was asking was for opinions
as to why a balanced line terminated with a low Z microphone might be
noisey.

There's some question as to whether terminated at one end with a
microphone constitutes proper termination. In my never humble
opinion, both ends need to be terminated to prevent the coax from
turning into an antenna, transformer, or linear capacitor.

The correct method is to 'terminate' the line with 200 ohms at the microphone
end (don't use an actual microphone) and the 'termination' at the other end is
provided by the input impedance of the microphone amplifier. Since it's not
operating as a transmission line, the characteristic impedance of the cable is
not relevant (it would be about 100 ohms FWIW).

Graham

On Oct 20, 6:42 pm, Jeff Liebermann wrote:
" hath
wroth:

I think
that I know the difference between ambient room noise and buzz and
hum.

Ok, I'll bite. You're measuring "noise" with a Vu meter. Got an
audio spectrum analyzer in your war chest? If so, use it and tell us
what you see. Is it hum, buzz, crackle, AM radio station, submarine
communications, power supply switching noise, or alien signals from
the overhead flying saucer?

This isn't my first barbecue.

True. However, the way I recognize experience is by the numbers. You
didn't supply any. How many dB was the "noise" increase? What
frequencies was the "noise"? What manner of equipment was used?

All I was asking was for opinions
as to why a balanced line terminated with a low Z microphone might be
noisey.

There's some question as to whether terminated at one end with a
microphone constitutes proper termination. In my never humble
opinion, both ends need to be terminated to prevent the coax from
turning into an antenna, transformer, or linear capacitor. What
manner of "noise" you're seeing will also help isolate the cause and
mechanism.

If you feel that you must insult me further to speculate as to
the cause of this please don't bother to respond.

Sometimes, insults and haranguing are the only effective way to get
people to disclose sufficient information to supply an intelligent
answer. My asking for additional information does not constitute an
insult, although I can see how it might be construed as such.

Thanks, Lenny Stein,
Barlen Electronics.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


_________________________________


The cable is two conductor AWG. 18 with a tight
braided tinned copper sheild. Its Mil spec instrument cable which
I've
used on microphone jobs before.


Er , Instrument cable , 20 mA dc loop , with 5 mA residual ? , that
sort of instrument.... ?
I dont think open cct noise and micro phonics are part of the cable's
initial design requirement's.
Are the conductors are in parallel ??

Ground termination, balanced to balanced, is not the screen left
disconnected at the source (mic) end ? and terminated to the 'case'
of the mixer, , (unless there are high radio frequency levels , which
case you need a small 'rf' capacitor) .in this case , the outer
shells must go somewhere , is the alloy plate floating ?


The mixer has floating 'balanced' inputs , ie no centre tap , with no
mention of a screen winding , ... this may not give you much 'common
mode' (cross talk) protection , if your managing to induce large
signals over the transformer's ..

Reading the mixer application note's, I would say its not being used
as intended, in contrast, the line out is well specified, with 100 mA
(dc signalling) saturation and is protected with series suppression
chokes , where as the inputs are not provided with any 'environmental'
protection , 'same room' type of installation , not across the yard ?

http://www.shure.com/stellent/groups...pro_m67_ug.pdf

On a more serious note , Are you not bridging the buildings earthling
arrangements , and endangering the users from a near lightning ground
strike ?

G ..

Graham wrote:

Ground termination, balanced to balanced, is not the screen left
disconnected at the source (mic) end ?

No, it's connected to pin 1 of the XLR connector which connects through to the metallic body of the mic.



and terminated to the 'case'
of the mixer, , (unless there are high radio frequency levels , which
case you need a small 'rf' capacitor) .in this case , the outer
shells must go somewhere , is the alloy plate floating ?

The connector shells may or may not be connected along with the screen/shield to pin1 of the XLR
(microphone) connector.


The mixer has floating 'balanced' inputs , ie no centre tap , with no
mention of a screen winding , ... this may not give you much 'common
mode' (cross talk) protection , if your managing to induce large
signals over the transformer's ..

Common mode rejection is usually quite adequate.


On a more serious note , Are you not bridging the buildings earthling
arrangements , and endangering the users from a near lightning ground
strike ?

For heaven's sake ! Are you serious ?

Graham

On Oct 20, 8:38 pm, Eeyore
wrote:
Graham wrote:
Ground termination, balanced to balanced, is not the screen left
disconnected at the source (mic) end ?

No, it's connected to pin 1 of the XLR connector which connects through to the metallic body of the mic.

and terminated to the 'case'
of the mixer, , (unless there are high radio frequency levels , which
case you need a small 'rf' capacitor) .in this case , the outer
shells must go somewhere , is the alloy plate floating ?

The connector shells may or may not be connected along with the screen/shield to pin1 of the XLR
(microphone) connector.

The mixer has floating 'balanced' inputs , ie no centre tap , with no
mention of a screen winding , ... this may not give you much 'common
mode' (cross talk) protection , if your managing to induce large
signals over the transformer's ..

Common mode rejection is usually quite adequate.

On a more serious note , Are you not bridging the buildings earthling
arrangements , and endangering the users from a near lightning ground
strike ?

For heaven's sake ! Are you serious ?

Graham

Sure am ...

Just think about it ... the concept of earth bonding ..

All the metalwork, electrical systems and service supplies are
communally bonded to the building electrical supply point and may be
also be linked to a ground spike. So during any short, spark or
other miss fortune the potentials within the buildings earth planes
remain uniform, not saying they don't or wont rise , but uniformly ..
faraday cage style.

You have established a insulated link to a second buildings earth
system , some 175 feet long ..

The average lightning 'strike' has a rise time of 250,000 Amps/micro
second, so any parasitic inductance and or series resistance , when
subjected to such a 'stimulus' will produce extreme voltages , (reason
for flat tape conductors - less inductance)

As the second building will de similarly configured, the possibility
exists for a 'pd' to exist between the microphones and there
immediate surrounding , generated by purely ground resistance and/or
parasitic inductance ...

this may the cause of the noise in the first place ?

Sorry If I'm stating the obvious ..But, 'hay I'm not holding them !

On Oct 19, 10:59 am, "
wrote:
We ran 5 microphone cables about 175 feet through PVC pipe underground
between two buildings. Shortly after the job was completed we tested
the lines. They weren't as quiet as I had hoped they would be but they
were usable. Over the past two years they have gotten more noisey. We
set up a test today. All cables were open ended, that is unterminated
on the other side. We set each input individually so that the VU meter
read 0VU noise level. Then doing one input at a time we plugged a mic
in. The noise level dropped to -6 on all inputs when checked
individually. It was an improvement but certainly still not too good.
Next we started out with open ended cables again, established our 0VU
noise reference and then shorted all three terminals on the XLR
connector together with a piece of foil. I repeated this with all the
remaining cables and the results were the same. The noise completely
disappeared and the line was clean. I next disconnected the line at
both ends and checked each conductor to ground for high resistance. I
read infinity from each conductor to the sheild as well as to building
ground. Next we took one mic and boosted it to line level at the far
end. We ran this line level signal through one of the underground
cables to a line level input on the mixer. The noise level is now way
below the signal level and the signal was squeaky clean. So now we
know that we can definitely retrofit the job and get it to work this
way, but this whole thing really puzzles me. Does anyone have any
ideas as to why we are getting all this low level noise on these
cables? They seem to acting like antennas. But when grounded they are
clean. Also since addional equipment is now going to be an added
expense to my customer, and one which they will not apreciate, any
ideas as to what I might try to remedy the situation other than pre
amplifying my mics before they go through the underground cables would
be nost sincerely appreciated. Lenny Stein, Barlen Electronics.

gugle is u r friend u sad pathetic loser ******.

On Oct 19, 9:23 pm, "
wrote:
On Oct 19, 11:37 pm, Meat Plow wrote:

On Fri, 19 Oct 2007 10:59:24 -0700, wrote:
They seem to acting like antennas.

BINGO!

I thought that I would provide just a little more information for
those of you who seem to think that I'm totally incompetent. The mixer
is a Shure M67. The cable is two conductor AWG. 18 with a tight
braided tinned copper sheild. Its Mil spec instrument cable which I've
used on microphone jobs before. In fact we've done longer runs without
incident. There are 5 XLR female jacks mounted on an aluminum plate.
The 5 sheilds are connected to their respective jacks but are not tied
together, nor are they earth grounded at this end. The open cable test
was just to compare all the lines to each other and thats all. The
microphone plugged into one line with all the others turned down
should have balanced that line and ideally been noise free. I think
that I know the difference between ambient room noise and buzz and
hum. This isn't my first barbecue. All I was asking was for opinions
as to why a balanced line terminated with a low Z microphone might be
noisey. If you feel that you must insult me further to speculate as to
the cause of this please don't bother to respond. Thanks, Lenny Stein,
Barlen Electronics.

u get a life u social rejected loser