Quote:
Originally Posted by PJL
When using screened audio cable I always thought only one end of the screening should be connected to earth?
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With single ended, both ends connected, otherwise there is no signal continuity. The problem is defeating hum loops and other interference. Now you can use ground lift resistors between the chassis safety ground and the analogue ground, often with a bypass cap to drain any HF energy to chassis (safety) ground. But signal interconnection in single ended can be a bit of a minefield. The bibles of this topic are "Grounding and Shielding, Circuits and Interference" by Ralph Morrison; I have both the 3rd and 5th editions; and Ott's book "Noise reduction techniques in Electronic Systems".
But with balanced cable, the guiding principle is to connect the shield directly to the chassis at each end, enshrined in an AES standard and championed by Neil Muncey in 1994.
Having said that, there is a more recent alternative view which connects only the signal source end of the cable shield in balanced systems (see for example Linear Audio, V10, pp25-36).
Ott, as previously mentioned, gave an excellent presentation given to the AES in 2008 covering both balanced and unbalanced cabling, hum, noise, RF susceptibility etc etc.
http://www.audiosystemsgroup.com/AES-RFI-SF08.pdf
Of course we have strayed off the topic of cable burn-in. Now some years ago I was keeping an open mind about this, and bought a kit of bits from Hagermann in the US for not a great amount, and built it into a box. I've done AB testing of identical cables of various constructions (BNC-BNC for SPDIF, balanced and unbalanced signal cable and speaker cables).
I am happy to report that I could discern absolutely no difference whatever between burnt in and virgin cables. The burn in device collects dust.