My Pro Junior to 5f2a-ish conversion project has come together quickly over the past week (being on annual leave helped there). I started her up tonight and plugged in, and it's a buzzy beast. As I haven't used a kit and it's different to a 'normal' 5f2a in a number of ways (i.e. SS rectifier, tag strips instead of board, choke, one input), the layout is also different but I have tried to follow convention where possible. Actually it sounds great, if you can ignore the buzz - which isn't really possible as it's a rather loud buzz which gets louder as volume increases. With volume on zero, the buzz is not there and the amp is fairly quiet, just a very mild hum - at zero, it's quieter than the Pro Junior was! I've been reading @robrob 's troubleshooting guide and he refers to an example where he tracked down a buzz: "Since the volume and tone controls affected the noise I knew it was entering the amp before the control--somewhere between the guitar and the volume pot". So I guess that is where I should focus too -- before the volume control. I'm aware that noise related to grounding issues is common. In my case though, with the buzz being volume dependent, can I rule out bad grounding or poor grounds design as the cause?