Tube adaptor safety

[Neuronal]

I just bought one of the Garage1217 6sn7 to 12au7 adapters for my Foreplay III. They work great, but I'm worries about the exposed pads on the bottom of the PCB coming into contact with my baseplate, and so I use them slightly pulled out. This seems pretty janky to me, so I'm wondering whether people have ideas about how to safely insulate the bottom of the PCB to allow me to fully push the adapter into the 12au7 socket? Would electrical tape suffice?

[Deke609]

Maybe make a silicone rubber disk to go between adapter and chassis? I think 1/16" sheet for gasket making is widely available -- e.g., Amazon.  You could cut a circle the size of the adapter and cut/punch holes for the pins.

cheers, Derek

[Neuronal]

Thanks for the great suggestion! I have a related question - if I retrofit the preamp for octal sockets, I will need to change the heater resistors (to support 2x 6sn7 + 1 x 12au7 - I need to go down, according to old posts by PB to .166 Ohms from about .4 in the extended FPIII). I'm just using the adaptor for now without changing that resistor - is that ok? I'm mostly using the adaptor to test whether I like the change, and then will switch to a proper octal socket if I do, but I'm worried now that using the adaptor without changing the resistor will blow something up.

Thanks for any insight into this!

[Paul Birkeland]

You would want to also make the change in the heater supply if you're going to run those tubes all that long.