Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Lambertini on March 28, 2024, 05:06:16 pm

Title: Isolating RCA and speakers jacks on an AB763
Post by: Lambertini on March 28, 2024, 05:06:16 pm

Hi there!

I've started a new AB763 build from scratch, with a 2 points ground schema in mind, one for the power section, one for the preamp.

To strictly satisfy it, I'm considering using isolation washers to isolate the reverb IN/OUT, reverb pedal and vibrato pedal RCA jacks; as well as the speaker and ext speaker phone jacks. Then properly wires the ground lugs to the bus bar.

Does it make sense? Is it just useless? Or is it leading to any trouble?

Thank you!

Title: Re: Isolating RCA and speakers jacks on an AB763
Post by: pdf64 on March 28, 2024, 06:38:13 pm

I think it's pointless unless there's a single point 0V common connection to the chassis, or even more so if there's a hum break network between the circuit 0V common and the chassis.
(https://i.ibb.co/qysxQ1q/IMG-3304.jpg)

Title: Re: Isolating RCA and speakers jacks on an AB763
Post by: sluckey on March 28, 2024, 07:03:52 pm

None of the jacks on the original AB763 amps were isolated.

Title: Re: Isolating RCA and speakers jacks on an AB763
Post by: Lambertini on March 28, 2024, 07:28:56 pm

Not too sure if I will not do it or if I'll just forget it... ;)
Thank you!