Shielded cable for internal amp wireing: where do I connect the shield? - diyAudio
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Old 5th March 2003, 01:43 PM   #1
Bricolo is offline Bricolo  France
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Default Shielded cable for internal amp wireing: where do I connect the shield?

I'm using shielded cable in my gainclone, for the input and output signal (should I use shielded cable for the supply rails, too?)

But I don't know where to connect the shield
To analog ground?
To chassis (earth)
Not connected?
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Old 5th March 2003, 02:47 PM   #2
SY is offline SY  United States
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Connect the shield to analog ground at one end only. The last is very important to avoid ground loops.

Shielding of power supply leads is pointless, since they're already at AC ground.
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Old 5th March 2003, 03:46 PM   #3
sam9 is offline sam9  United States
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In addition, AC power wires can be twisted tightly together to possible radiated interaction with the audio signal.
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Old 5th March 2003, 05:19 PM   #4
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Default were the shield go?

Hi Bricolo!

Don' t use shielded cable at the output...you can find problems of stability!

Use only at the input!

Salut!

Jorge
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Old 5th March 2003, 06:01 PM   #5
Bricolo is offline Bricolo  France
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Default Re: were the shield go?

Quote:
Originally posted by Tube_Dude
Hi Bricolo!

Don' t use shielded cable at the output...you can find problems of stability!

Use only at the input!

Salut!

Jorge

I use ofc speaker cable, shielded

what's the problem with this? since it's the same as the one used between the amp and the speakers
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Old 5th March 2003, 06:24 PM   #6
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Default To bricolo!

The problem is capacitance at the output....power amps with lots of feedback as yours (after all is a power op amp) don't like to see to much capacitance at the output

Have you wonder why you don't see shielded cables as speaker cables outhere??

Au revoir!

Jorge
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Old 5th March 2003, 06:41 PM   #7
Bricolo is offline Bricolo  France
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Default Re: To bricolo!

Quote:
Originally posted by Tube_Dude
The problem is capacitance at the output....power amps with lots of feedback as yours (after all is a power op amp) don't like to see to much capacitance at the output

Have you wonder why you don't see shielded cables as speaker cables outhere??

Au revoir!

Jorge

mine is shielded (monacor ofc)
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Old 5th March 2003, 06:47 PM   #8
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Default to Bricolo!

A shielded cable....is a shielded cable!!!

Monacor...or other trad mark!

Cheers

Jorge
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Old 25th June 2003, 01:40 PM   #9
Bricolo is offline Bricolo  France
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I'm on the way to put my gainclone in it's final chassis, and to rewire everything


since the only "quality" wire I have is this shielded ofc cable, and thant the chassis is aluminium

is there any advantage in using shielded cable INSIDE the metal chassis?
Connecting every shield to star ground will add a mess in the chassis.

If shielding is nonsence in the chassis, what would be better:

use the cable as if, and leave the shield unconnected
remove the shield?
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Old 26th June 2003, 01:30 AM   #10
sam9 is offline sam9  United States
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I. Why shielded cable if everthing is inside a grounded enclosure?

Even if you have a gounded metal enclosure there may be value to shielded input: A- protection from noise on the poer lines AC or DC, however a few inches (=2.54cm) will oftem resolve that problem, B- crosstalk from the output of the other channel (monblocks eliminate this).



II. Self's book shows a diagram where one end of the shield is connected to the outer ring of the RCA connector and the other end of the shield joins up withe the ground from the NFB return and both then go to the star point. However, the same diagram also shows a direct connection betweenthe outer ring of the RCA connector to chassis earth but the star point NOT connected to the chassis earth. As much as I admit that Self knows more than me, this looks odd. Certainly there is no room for a loop but not connecting the star point to the chassis ground (except indirectly back through the shield anf the outer RCA ring seems like there might be a safety issue.
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