DIY sheilded B+ cable

[duderduderini]

Hi guys
Supposing i needed to shield some of my B+ cabling near my phono section how would anyone suggest this is attempted. I have done some experiments with pulling the cables out of some shielded signal wiring and then threading the electical cabling through that. One other way I thought is to wrap the length once braided then maybe cover that with foil and heatshrink it.
Any other ways?
Thanks
Nick

 

[Chris Jennings]

Hi.

Have you tried RF coax, this can be purchased with silver plated inner and screen with working voltages over 1.2kV. Something like RG316U.

HTH

Chris

 

[kevinkr]

Hi guys
Supposing i needed to shield some of my B+ cabling near my phono section how would anyone suggest this is attempted. I have done some experiments with pulling the cables out of some shielded signal wiring and then threading the electical cabling through that. One other way I thought is to wrap the length once braided then maybe cover that with foil and heatshrink it.
Any other ways?
Thanks
Nick

There shouldn't be enough noise on the B+ near your phono section for this to be an issue?

 

[Poindexter]

That's what I thought.  It's a low-impedence DC line; it's not making any noise, it's not picking up any noise, where's the problem?

P

 

[koolatron]

Perhaps he is not so much interested in shielding the B+ and phono circuitry from one another as simply avoiding induced RF around this sensitive circuitry.

 

[duderduderini]

You got it Koolatron

Hey and thanks for the replys.
I had prototyped my preamp and got it working and hum free. When I decided to build it nicely I used a pre built chassis which is made of steel (not wood and aluminium) and I also decided for reasons of H-K potential to seperate the 6sL7 srpp stage into an upper and lower tube (each tube serves both left and right channel duties) Because of this the connections between the K of the upper tube (and the connection twixt the anode of the lower tube and grid of upper tube) are now seperated (whereas in the proto, srpp was performed all on the one 6sl7)..
Anyway i have residual hum which I have largely eliminated through having to rerun all the grounds (again different from my proto) but seeing the wires between the 6sl7's are now long in comparison, I wonder if any hum can emanate from those(They are just pvc coated mains single core copper).
Sheilding these wires may have no effect I agree but i thought i would try it
Thanks