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Old 30th November 2012, 06:52 PM   #30521
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Originally Posted by PMA View Post
Stereo input, RCA SE, 2 completely separated channels, 2 transformers, 2 power supplies.

You can see the amp at bottom right corner.
Lucky guy, if our livingroom looked like that it would be MY livingroom.
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Old 30th November 2012, 07:08 PM   #30522
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Would be nice, but it is a "room" of a guy who has been selling my power amplifiers
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Old 30th November 2012, 07:17 PM   #30523
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Stereo input, RCA SE, 2 completely separated channels, 2 transformers, 2 power supplies.

You can see the amp at bottom right corner.
Nice. Color me Jealous


With two rca's interconnection two chassis, if your source pushes 1 milliamp of current into the right core, how does the current get back to the pre?

If both ends of the rca's are tied to chassis, then half the current will return on the left channel IC braid.

For coax to properly shield magnetically, the cross section current through it must be zero. With two channels, this will only happen once the frequency is high enough that the lowest impedance path is the drive coax.

Personally, I'd patent an IC as a pair, where there is one overall cylindrical shield which serves as current return for both channels, and within I'd have two coax cables, one for each channel, where the braid of the smaller cables was tied at 1 end for electrostatic isolation interchannel.

But that's just me..

Luckily, posting it on a planetwide public forum doesn't mean anybody knows about it, right? So hey, maybe I will patent it...

jn
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Old 30th November 2012, 07:26 PM   #30524
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I can make you sure that the problem you mention is SOLVED in my amp. Sorry, I am not telling more now. I hope this decision of mine is quite understandable.
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Old 30th November 2012, 07:29 PM   #30525
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Quote:
Originally Posted by jneutron
Personally, I'd patent an IC as a pair, where there is one overall cylindrical shield which serves as current return for both channels, and within I'd have two coax cables, one for each channel, where the braid of the smaller cables was tied at 1 end for electrostatic isolation interchannel.
Would that work? The outer shield would not be concentric with the inner cores so magnetic shielding would still be incomplete, although perhaps better than two separate cables.

It's interesting to ponder that getting one signal from here to there is in principle soluble from DC to microwaves, but getting two signals from here to there (with a common reference) is easy for RF but hard for audio!

I haven't thought much about it, but could the solution be the careful placing of low value resistors to steer the return currents? The idea is that the resistors would be much smaller than line stage impedances, but significantly larger than cable shield resistance. Don't ask me for a diagram, as I am just thinking aloud and haven't got that far yet.
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Old 30th November 2012, 07:32 PM   #30526
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Two shielded boxes, one in another, do work.
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Old 30th November 2012, 07:36 PM   #30527
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For me, average is one star, quality would be 'napoleon'. Some people don't notice the difference. '-)
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Old 30th November 2012, 07:41 PM   #30528
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Would that work? The outer shield would not be concentric with the inner cores so magnetic shielding would still be incomplete, although perhaps better than two separate cables.
Very nice. (your statement and observation). While the net integral of the drive current is zero, due to lack of concentricity there will not be complete cancellation of any field generated by the IC current at audio frequencies (nor externally generated..but if you twist the coax pair, there will be a net zero integral to external influences which do not have extreme magnetic gradients). I neglected that as the currents are so low due to circuit impedance. As the drive frequency goes way past audio, the current on the shield would redistribute such that the current centroid of the shield is exactly in the same place as the drive in the IC.

What I was looking for was having only one path for the return current. That way, there is no loop of shield which can trap external magnetic fields, so no ground loop current. As a bonus, any current from external sources which will travel throught the shield will not be able to induce a voltage on the signal core runs because there is no magnetic field in the cylinder. The only voltage would be IR drop of the shield.

This would be a very good thing for two chassis which are each bonded to ground of course.

jn

Last edited by jneutron; 30th November 2012 at 07:51 PM.
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Old 30th November 2012, 08:00 PM   #30529
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For me, average is one star, quality would be 'napoleon'. Some people don't notice the difference. '-)
John, i was asking for technical description. Not a Guide Michelin or Zagat Restaurant rating. May-be i use a 'Napoleon' cable without knowing-it ?
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Old 30th November 2012, 08:04 PM   #30530
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Personally, I'd patent an IC as a pair, where there is one overall cylindrical shield which serves as current return for both channels, and within I'd have two coax cables, one for each channel, where the braid of the smaller cables was tied at 1 end for electrostatic isolation interchannel.
Like a cat6 network cable ?
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