LM3886 very quiet

[pacificblue]

Do you mean something like that below.

Yes, those are the capacitors.

As for the star ground you need to find a compromise. One thing you want to achieve is that all ground connections have the shortest possible path to the star point which you achieve by following Andrew's advice. The other thing is that you want different currents to share as short a common path as possible which you achieve by keeping the star point next to the smoothing caps.

 

[MJL21193]

Thanks for your suggestions. I tried using an to220 insulation kit a had lying around. But is still get the hum. The only way I could get it to stop was to cut to ground cable from the regulator to the preamp.

Look at ALL of the ground paths, including the input and output jack grounds (these are often overlooked) and make sure they are not forming a loop with another ground point. For example: main supply ground to chassis and input ground to chassis creates a loop. In this case, the chassis is grounded in 2 places at different potentials = bad hum results (usually).
Do some reading on the subject. There's tons of info out there, some of it is even correct .
Here: Aiken Amplification

 

[x51]

Thanks,
There were two grounds going to the preamp one from the output and the other from the regulator. I removed the one from the regulator and now the hum is gone. Thank you.