Marcel's scratch build AC15 based clone

[DrNomis_44]

So everyone is on the same page I'll put it here that I've been using this amp build quite a lot. On guitar builds, on Bass builds, fiddling with effects, and everything else into a 2x12 vented cab loaded with a 16 ohm V30 and a 16 ohm G12H75....and it sounds great !!! It has more overall bottom end than maybe it should which I put down to the home made vented cab and I can adjust out using the bass and treble controls, but otherwise it is so easy to dial in sounds, the nice sounds, the sounds I want to hear.... it's great !!... Just sometimes I wish I had a real AC15 or AC30 to be able to do a worthwhile A/B comparison...

I hadn't noticed until today, but the amp has developed a low level 50Hz hum... not enough hum to stop using it for practice or testing or even gigging, but it would be or is too much for recording at lower volumes. High volumes it's no issue, low volumes it's a real pain... and the hum varies up and down with the master volume control but is not affected by the gain control, so it is getting into the amp via the 2nd pre-amp tube or adjacent circuitry. Yet another item to add to the list for when I decide to take the covers off and wire in the EF86...

Could very well be an earth-loop that's causing the hum, I was watching a video on youtube about a guy who was in the process of diagnosing a hum-noise issue in one of his Fender Tweed Bassmans, and he eventually traced the cause to the 6.3V AC heater supply going to the two 6L6 power valves and three 12AX7 preamp valves, his conclusion was that the heater-wiring between the two 6L6 power valves hadn't been done correctly at the Fender Factory as the amp was being manufactured, the Fender Bassman in question was an old early 50's vintage amp.


Incidentally, I wouldn't mind having a go at building a 50's Fender Tweed Bassman from a kit of parts, would be a fun project.