Newbee: LM3875TF P2P

[Arty]

Fuse blows if transformer secondary shorts to primary (transformer fails).
If no connection, fuse will not blow and you have the mains at the amplifier output.

absolute correct.
and to deal with any hummm associated with this connection one can use a pair of really high current diodes in anti-paralell bypassed by a high power resistor.
you keep the safety functionality, and you don't have -as mutch- possible interference.

 

[bendio]

again the new schematic... I'd be really glad if someone could tell me whether it correct to have c1-3 one per rail or whether it should be two per rail.
I'm also still not sure if I got the grounding right (leaving aside Arty's suggestion for the moment).

The cap in the feedback network and input ground should go to the quiet signal ground. The decoupling caps, power supply ground, and ground pin on the LM38xx should go to the power ground. The power ground and quiet signal ground should both be low impedance (as wide as possible --> ground planes/pours) and connect at one spot only: the ground connection at the output connector.
Tom

-> As far as I can see, the lm3875 does not have a ground pin...?!