Speaker return path

[john & Jake the dog]

Hi,
I'm wiring a solid state amp.
I am bringing the speaker return back to 0v at the caps.
Could anyone please tell me if it is ok/ advisable to earth the return to the chassis earth then on to 0v at the caps.
cheers

[Mike H]

Personally I would use 2 completely separate wires. Speaker earth back to 0V of the power supply caps, cos that's where the amp(s) gets its current from.

Then a separate wire from power supply 0V to chassis.

IMHO...

[Richard]

Hi John,

You may want to isolate circuit ground inside the case. I'd connect speaker ground back to cap, and case to mains earth, but if you isolate circuit ground and case earth (insulated phonos and speaker posts) you can then "lift" the ground to case connection by making it via 10R or 100R resistor if there's a hum problem.

Rich

[Mike H]

Yes there is that, alrighty then, 100R resistor from PSU 0V to chassis! And sure chassis deffo needs connecting to mains earth.

[john & Jake the dog]

hi, thanks,
the reason I ask is because I am using the same boards as these below and Exposure seem to tie the return (yellow) to the case earth then back to 0v at the caps.
I am using an Exposure transformer without an earth connection but the transformer is earthed in the pic below, but I think they always earthed the return even with an unearthed transformer.
There is a 0v pin next to the phono input but Exposure don't use it .


cheers