Ok, so I have finished my build of the EAR834p clone but have a hum problem and would like some help with resolving it from kind souls. I am not experienced. This is my first amp build. :) The hum is on both channels and increases with the volume. I have two inputs going trough a switch. One for MM, the other for MC routed trough a SUT. Hum is present from both inputs so it is not related to the SUT. I do have an aluminum plate between PSU and amp board. I have twisted all wires except for input and output. For output I have a shielded wire. I have followed this grounding scheme from LencoHeaven forum (picture below). This is what I have tried so far: If I do not have the turntable connected I still have hum (a little bit lower tough). If I remove ground on ICE I still have hum. I desoldered the input wire from board. Still hum, but lower. With three Brimar CV4004 tubes the hum is 50hz. If I change to JJ ECC83S (in particular the middle tube) hum is somewhat lower (around 4db) but now have I both a 50hz peak and a 100hz peak. If I increase the volume 50hz hum increases the most. If I touch the first tube (closest to input) hum increases. I have tried to change the wire from SUT to shielded also (but not to SUT). No difference. I have tried to move around the amp. Still hum. Hum changed a little with movement. Can you see any obvious ground loops? Could this be a transformer issue?

This is my EAR834p clone build. I followed Skunkies build guide on Youtube which was great! I did however implement the Thorsten and Roberts mods from the LencoHeaven forum and followed their grounding scheme. I also have a MM/MC switch on the back where the MC goes trough a pair of Lundahl LL1931 step ups transformers. This build do however have quite a loud hum that I have not been able to get rid of.