PH16 Hum pcb loop.

I have been battling a hum in my PH16 for years. I’ve tried everything and the hum is always there. I even went so far as to eliminate the power supply and wire in a solid state power supply and it was still there. So I’ve been poking around
On the board and I noticed with the J3 jumper out I still get continuity between the nodes and all ground points on the board. Seems like there’s a a loop on the pcb. I’m tempted to get a new board and start from scratch. Any thoughts?

I just noticed on an online picture that a newer version of the board has a j4 jumper to ground. Does that mean my version has issues that needed changing?

You might do better emailing Roy directly. He's said many times that he can't check this forum that often and he's the guy that can answer your questions.

info@tubes4hifi.com

Have you tried nylon standoffs for mounting the PCB?

Tried this fix? I used 2-wire (1 red & 1-white) double shielded wire (like what's used for microphones) for input and output wires to fix my problem and now it's dead quiet. Wire both input connectors ground tabs to shield and then ground shield to either R or L board ground, not both. Do the same for output wires. Make sure your Phono connectors are the type that isolate ground from chassis (double check with meter when wires are disconnected), otherwise above fix is not going to work. Like vtshopdog suggests use non-metallic standoffs. Triple check all grounds to make sure you only have a one-way path to prevent ground loops.

FearOfMusic if your PH16 is several years old, maybe it wasn't wired with shielded cable, or is missing a ground somewhere.
LevConZ, yes, all preamps I've sold the past 3-4 years uses that great Canare two wire plus shield mini-microphone cable.

I built mine in 2013. Tubes4hifi is who can help you best FearOfMusic. Best of luck!