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Old 10th July 2010, 07:21 PM   #1
phrarod is offline phrarod  United States
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Default dialectics and shield of an umbilical cord?

I'm finishing up my linestage which will have a separate PSU box. The crazy dac I made based on a Audio Note board that is tube output dual mono tube rectified with 3 separate supplies for the dac board. Recently I decided to try shielding its umbilical cord with some tin copper braid which I then grounded to chassis.

The result was the highs really came to life and things came into better focus. The drawback is notes and instruments lost their relaxed quality and roundness. It's a little more SS sounding. I'm trying to R&D before I build the ones for the linestage.

I have the braid flat again the umbilical and just for looks wrapped it in electrical tape. I've read about using air as a dialectic and I've had similar gains and losses when I put a ferrite on a power cord.

Am I going about it the wrong way? Should I be braiding the DC wires? Should I be looking for shielded wires from anyone? Should there be an air cushion between the braid and the umbilical?
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Old 10th July 2010, 07:25 PM   #2
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How long is the umbi cord?
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Old 10th July 2010, 07:29 PM   #3
phrarod is offline phrarod  United States
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1.5 ft
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Old 10th July 2010, 07:30 PM   #4
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You have the power supply enclosed in alum or steel?
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Old 10th July 2010, 07:32 PM   #5
phrarod is offline phrarod  United States
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Steel
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Old 10th July 2010, 07:43 PM   #6
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Well, ideally...a rather long umbi is good so you can palce the PS away from the unit. Better for eliminating chances of interference. Now as far as the umbi, I dont see as prob with braid. Did you try not grounding it?
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Old 10th July 2010, 08:16 PM   #7
phrarod is offline phrarod  United States
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I've played with length. It was originally 5ft in order to get the PSU away. The performance increased with every foot a shortened it. So either I'm not making it right or shorter DC lines is better.

I'm going to try and un-ground it and also see if I don't cover the whole length but have it grounded. Its really made the sound too hard. Weird something as seemingly small as that has such impact which is why I want to find the best recipe for the ones I make for the pre-amp.
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Old 10th July 2010, 09:29 PM   #8
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Also try a 100 ohm resistor or so, in series with the shield and ground it. Lowers the 'Q'.
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Old 10th July 2010, 10:40 PM   #9
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Well, you are certainly trying out many different parameters. Hell, if it was me by now I would have said SOUNDS GOOD! Efff it!
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