Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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  #11   Report Post  
Old March 11th 14, 12:00 AM posted to rec.radio.shortwave,sci.electronics.repair
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Default Highly Shielded Audio Cable

On 3/10/2014 7:11 AM, Phil Allison wrote:
"Ralph Dope"

I need a cable (ideally about 20ft), stereo 3.5mm male/male, highly
shielded to connect my audio source to a transmitter across a room. This
cable passes many sources of interference, so the shielding is critical.



** I have a sense of "deja vu" about this question ?

Is the signal stereo or mono ?

A 20 foot long 3.5mm two core cable is not gonna be easy to find at all let
alone with different qualities.

BTW:

Do you REALLY have a problem or are you just imagining one ?

How about some details ?

The solution may NOT be what you have guessed it to be.



.... Phil




Hack a long HDMI cable.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

  #12   Report Post  
Old March 11th 14, 01:32 PM posted to rec.radio.shortwave,sci.electronics.repair
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Default Highly Shielded Audio Cable

On 03/10/2014 09:56 AM, Cydrome Leader wrote:
In sci.electronics.repair Ralph D. wrote:
Hi,

I need a cable (ideally about 20ft), stereo 3.5mm male/male, highly shielded
to connect my audio source to a transmitter across a room. This cable passes
many sources of interference, so the shielding is critical.


get some electrical conduit.


There should not be a lot of RF in the radio room, compared to near the
antennas. Do all the other stations use EMT for audio? It really isn't
necessary. You can probably use unshielded twisted pair if you know what
you're doing. The Phone Company doesn't use shielded cable for baseband
audio.
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Old March 11th 14, 03:28 PM posted to sci.electronics.repair
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Default Highly Shielded Audio Cable

On Sunday, March 9, 2014 11:30:08 PM UTC-4, Ralph D. wrote:
Hi,



I need a cable (ideally about 20ft), stereo 3.5mm male/male, highly shielded
to connect my audio source to a transmitter across a room. This cable passes
many sources of interference, so the shielding is critical.

I would prefer to get it from Amazon so as to get it quick with Prime
(incredibly narrow window of free-time during a currently very busy
schedule) but would be OK with ordering from one of the Ham sites if
turnaround time is very good. I could not get a good search parameter on
Amazon that didn't turn up thousands of hits that I just don't have time to
sift through right now.

Any good cable with known good isolation would be good. I have ferrite
chokes I can use, but would prefer a cable of suitable quality that did not
need them (current cable is getting interference even with them as this is
not just run-of-the-mill 60cycle stuff).


Hmm, What kind of interference are you seeing? (can you turn things off and make it go away?) To get rid of electro-static pick-up (display screeens flourescent lights...) get a cable with both braid and a almuinized mylar sheild.
(Driving the cable with a low impedance source should help too.)

60 Hz, magnetic interference is darn hard to shield against (In my limited experience.) Your best bet there is to keep a good distance between transfomeres and the cable.

George H.

Any good suggestions would be appreciated.





Thanks!


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Old March 12th 14, 04:02 AM posted to sci.electronics.repair
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Default Highly Shielded Audio Cable

On Tue, 11 Mar 2014, wrote:

On Sunday, March 9, 2014 11:30:08 PM UTC-4, Ralph D. wrote:
Hi,



I need a cable (ideally about 20ft), stereo 3.5mm male/male, highly shielded
to connect my audio source to a transmitter across a room. This cable passes
many sources of interference, so the shielding is critical.

I would prefer to get it from Amazon so as to get it quick with Prime
(incredibly narrow window of free-time during a currently very busy
schedule) but would be OK with ordering from one of the Ham sites if
turnaround time is very good. I could not get a good search parameter on
Amazon that didn't turn up thousands of hits that I just don't have time to
sift through right now.

Any good cable with known good isolation would be good. I have ferrite
chokes I can use, but would prefer a cable of suitable quality that did not
need them (current cable is getting interference even with them as this is
not just run-of-the-mill 60cycle stuff).


Hmm, What kind of interference are you seeing? (can you turn things off
and make it go away?) To get rid of electro-static pick-up (display
screeens flourescent lights...) get a cable with both braid and a
almuinized mylar sheild. (Driving the cable with a low impedance source
should help too.)

That's the question most of us missed. I could have sworn he said "rf
interference", but when I looked back after posting, realized he hadn't
indicated any specific bit of interference.

Michael

60 Hz, magnetic interference is darn hard to shield against (In my limited experience.) Your best bet there is to keep a good distance between transfomeres and the cable.

George H.

Any good suggestions would be appreciated.





Thanks!



  #15   Report Post  
Old March 12th 14, 03:58 PM posted to sci.electronics.repair
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Default Highly Shielded Audio Cable

On Tue, 11 Mar 2014 20:02:49 -0700, Michael Black wrote:

...snip...


That's the question most of us missed. I could have sworn he said "rf
interference", but when I looked back after posting, realized he hadn't
indicated any specific bit of interference.

...snip....


I assumed stuff like nearby motor drivers, or worse, from those new solid
state ballasts. The cheap ones can get VERY energetic. and coupling
magnetic into audio is not an easy item to stop.

People are so used to 'shielding' with electrostatic shields and lowering
the impedance to reduce high impedance interference, that they are
completely caught off guard when confronted with low impedance noise
sources, like magnetic field. May have noticed that lowering the impedance
makes little difference.

Sometimes, high impedance noise gets 'converted' somewhere to a low
impedance source which is really mindboggling, since you recognize the
noise and expect it to be coming from high impedance.

Best way,...balanced pair, shielded. And I MEAN balanced over the WHOLE
spectrum! DC to GHz, 10GHz if you can do it. That includes termination
circuitry, Tx/Rx, and high quality cabling with very symmetrical conductor
placement and spacings within that cable. That is, if you're goal is 120
dBV, or better 140dBV, down noise floors you had better pay attention to
everything.






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Old March 12th 14, 04:07 PM posted to sci.electronics.repair
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Default Highly Shielded Audio Cable

On 03/12/2014 07:58 AM, RobertMacy wrote:
On Tue, 11 Mar 2014 20:02:49 -0700, Michael Black wrote:

...snip...

That's the question most of us missed. I could have sworn he said "rf
interference", but when I looked back after posting, realized he
hadn't indicated any specific bit of interference.

...snip....


I assumed stuff like nearby motor drivers, or worse, from those new
solid state ballasts. The cheap ones can get VERY energetic. and
coupling magnetic into audio is not an easy item to stop.

People are so used to 'shielding' with electrostatic shields and
lowering the impedance to reduce high impedance interference, that they
are completely caught off guard when confronted with low impedance noise
sources, like magnetic field. May have noticed that lowering the
impedance makes little difference.

Sometimes, high impedance noise gets 'converted' somewhere to a low
impedance source which is really mindboggling, since you recognize the
noise and expect it to be coming from high impedance.

Best way,...balanced pair, shielded. And I MEAN balanced over the WHOLE
spectrum! DC to GHz, 10GHz if you can do it. That includes termination
circuitry, Tx/Rx, and high quality cabling with very symmetrical
conductor placement and spacings within that cable. That is, if you're
goal is 120 dBV, or better 140dBV, down noise floors you had better pay
attention to everything.


These are pretty darn close to what you need, as long as they are true
balanced. This will put a face on it, any way.

http://www.markertek.com/CATV-Headen...ver-CAT5.xhtml
  #17   Report Post  
Old March 12th 14, 04:10 PM posted to sci.electronics.repair
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Posts: 3,833
Default Highly Shielded Audio Cable

"RobertMacy" wrote in message news[email protected]

Best way,...balanced pair, shielded. And I MEAN balanced over
the WHOLE spectrum! DC to GHz, 10GHz if you can do it. That
includes termination circuitry, Tx/Rx, and high quality cabling
with very symmetrical conductor placement and spacings within
that cable. That is, if you're goal is 120 dBV, or better 140dBV,
down noise floors you had better pay attention to everything.


It's unfortunate that the OP seems limited to 3.5mm connections. There are AR
cables (Master Series) that have a separate shield, grounded at the receiving
end, with identical wires (not the shield) carrying the signal. There is also
a ferrite choke. I use these in my system.

http://www.amazon.com/Acoustic-Resea...+master+series

They used to be fairly cheap, but have gotten pricey again. (Of course, the
price is still rather lower than "audiophile" cables with the same features.)



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Old March 12th 14, 04:22 PM posted to sci.electronics.repair
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Posts: 449
Default Highly Shielded Audio Cable

On 03/12/2014 07:58 AM, RobertMacy wrote:
On Tue, 11 Mar 2014 20:02:49 -0700, Michael Black wrote:

...snip...

That's the question most of us missed. I could have sworn he said "rf
interference", but when I looked back after posting, realized he
hadn't indicated any specific bit of interference.

...snip....


I assumed stuff like nearby motor drivers, or worse, from those new
solid state ballasts. The cheap ones can get VERY energetic. and
coupling magnetic into audio is not an easy item to stop.

People are so used to 'shielding' with electrostatic shields and
lowering the impedance to reduce high impedance interference, that they
are completely caught off guard when confronted with low impedance noise
sources, like magnetic field. May have noticed that lowering the
impedance makes little difference.

Sometimes, high impedance noise gets 'converted' somewhere to a low
impedance source which is really mindboggling, since you recognize the
noise and expect it to be coming from high impedance.

Best way,...balanced pair, shielded. And I MEAN balanced over the WHOLE
spectrum! DC to GHz, 10GHz if you can do it. That includes termination
circuitry, Tx/Rx, and high quality cabling with very symmetrical
conductor placement and spacings within that cable. That is, if you're
goal is 120 dBV, or better 140dBV, down noise floors you had better pay
attention to everything.





http://muxlab.com/wp-content/uploads...i-Fi_Balun.pdf
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Old March 12th 14, 04:28 PM posted to sci.electronics.repair
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Posts: 449
Default Highly Shielded Audio Cable

On 03/12/2014 08:10 AM, William Sommerwerck wrote:
"RobertMacy" wrote in message news[email protected]

Best way,...balanced pair, shielded. And I MEAN balanced over
the WHOLE spectrum! DC to GHz, 10GHz if you can do it. That
includes termination circuitry, Tx/Rx, and high quality cabling
with very symmetrical conductor placement and spacings within
that cable. That is, if you're goal is 120 dBV, or better 140dBV,
down noise floors you had better pay attention to everything.


It's unfortunate that the OP seems limited to 3.5mm connections. There
are AR cables (Master Series) that have a separate shield, grounded at
the receiving end, with identical wires (not the shield) carrying the
signal. There is also a ferrite choke. I use these in my system.

http://www.amazon.com/Acoustic-Resea...+master+series


They used to be fairly cheap, but have gotten pricey again. (Of course,
the price is still rather lower than "audiophile" cables with the same
features.)

That is pure audio snake oil. If you are dealing with induced magnetic
fields (hum) you need a competent differential input and balanced lines.
The copper part of the phone company is not shielded. Even the part that
carries high fidelity audio for industry is not shielded.

Big clunky interfaces like that are usually very reactive and do affect
the sound...badly. Try Hosa brand. Spend the difference on better speakers.

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Old March 12th 14, 05:31 PM posted to sci.electronics.repair
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Posts: 3,833
Default Highly Shielded Audio Cable

"dave" wrote in message
news
That is pure audio snake oil.


My point was that the AR cables had features designed for good shielding. I
never directly claimed that they sounded better. Indeed, my experience has
been that expensive cables don't sound better than the cheap ones that come
"in the box".



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