#12051 '68 replica with FX loop and PPI MV...in white!

[VelvetGeorge]

Just wanted to show off a recent build. This one was ordered in white, with an FX loop and PPI MV. It also included the new SoZo filter caps.

http://plexireplicas.com/amplifier-arch ... 000/12051/" onclick="window.open(this.href);return false;

Enjoy!

george

[neikeel]

Beautiful build George

A couple of questions:

I see you went with the older style dual 500k pot with the 220ks on the board rather than the 250k and 2M2 safeties - any particular reason.

You did not use bias resistors on the output valve sockets - have you found issues?

Interested to see your cathode wires in preamp have moved up towards the heaters, have you had problems being close to the grid wires?

I really like the way the effects loop is wired, I will be using that layout shortly

BTW where do you get those big ceramic 500pF caps from?

[VelvetGeorge]

Thanks Neil!

I went with the standard PPI MV as per the customer's request.

I can generally use only the 1.5k grid resistors going to the outside tubes in 100 watts. That keeps them stable if everything else is nicely wired and routed. And that's era correct.

I hadn't realized about the cathode wires. Good eye, it wasn't a conscience thing on my part.

I picked up 100 of those 500pf caps a while back, but I'm down to around 10 or so left. I'm not sure where I can find then again, which sucks because they sound great!

george

[Structo]

Very nice George!
You have very clean looking builds.

I was wondering about something as I am learning about Marshall amps.
Coming from more of a Fender background (yeah I know, but they have their place)

Anyway, I see that most of the builders here as well as you, bundle your power supply wires together.
I found on one amp that I built when I had my standby switch wires bundled with the other AC wires from the PT that I picked up some hum. It went away when I separated that SB wire from the rest. All I can think of is that it was picking up some 60Hz noise and feeding it into the B+.

So I was curious if you ever experience that with these amps?
Maybe it depends where in the circuit the standby switch is. On my amp it was after the rectifier diodes but before any of the B+ filter caps.

I see on most Marshall amps that the standby switch is before the diodes so maybe that is why it doesn't affect the wires because it is still AC.