Relocating power transformer in PS Audio GCPH


I just recently completed a project to relocate (or actually disable) the torodial power transformer in my PS Audio GCPH phono pre-amp.

I built a separate outboard power supply with a similar torodial transformer (so I could leave the stock one installed but disconnected) that has 132,000 mfd of capacitance. I run the V+ , V- and Gnd busses up to the GCPH and feed them through the chassis using an Amphenol connector, and run wiring from the connector to a molex style three pin that matches the connector on the original GCPH transformer. I removed the IEC AC connector (and associated circuit board) and mounted the Amphenol connector to a blind off plate that mounts in place of the IEC.

After the modification, the hum (60/120/240 Hz) noise component is completely gone. Much quieter on the 60 dB and 66 dB gain settings. I can also use more of the volume control than before.

This setup allows me to go back to stock if desired, as I did not disturb the position of the PS Audio power transformer (which is critical). But I doubt if I will go back beacuse the new noise performance is so much better.
dhl93449

Showing 1 response by m297904

I'd love to see pics too. Maybe another location for pics...
I have an Underwood modded GCPH and have no hum issues. Maybe the ERS around the PS section accomplishes some of the isolation that relocating the transformer accomplishes?
132,000uF!!!! That's a lot of capacitance for a little phono amp. BTW, I'm using it with a Bob's SUT, Denon 103R and Pass X0.2 pre.