BFDR popping sound when STBY switched off and a few small issues...

[PeaveyBandit]

Black face deluxe reverb has a few issues I'm trying to eliminate. I found one problem I was having with the amp popping and squeeling which was elimiated when I removed the V1 preamp tube for CH1 but it happens when I wiggle any tube in that socket. I'm not retensioning it though. I just pulled the 12ax7 and going to replace the 1" socket and tube when they come in. This could somehow play into the problem I'm asking about so I wanted to explain.

Main issue I'm asking about is when I switch the amp on it seems fine right now except for more hum in the overall sound than I'd like to hear. And when I turn the stdby switch off I get a distinct quick and instant pop or snap in the sound. Nothing you'd really worry about except I know this amp has some issues and this might tie in.

I ordered this as a brand new BFDR clone from an amp builder that sells on Ebay and got great ratings on Harmony Central as his auction pointed me to. Unfortunately his workmanship has a lot to be desired. It's a mojo kit based amp with upgraded parts like all mercury trannys, JJ tubes which I'm beginning to loathe with a passion (another story) and it has nice sprague caps and mallory tone caps, carbon film resistors and some okay but pretty sloppy lead dress through out.

I think I'm still fighting a few issues and Lord knows I've been through every solder joint and connection of the whole amp and corrected at least 20-30 little items. I cannot see how this amp still has problems but any instinct and experience some of you gurus out there can pass on to a newbie I'd appreciate.

By the way the only way Ibe capable of checking or setting bias is a crude way with a scope and signal generator and just slightly eliminating the crossover. I dont have the other tools like most of you do. I also have an excellent multimeter and basic tools.

Thanks again for any ideas,
PB

[Enzo]

Replacing the socket will probably work, but did you try just resoldering the connections on the socket that is in there?

Pops when switching off the standby are quite common and not what I would label a "problem."

Isolate the hum, does it go away when all the controls are at zero? Or do ANY controls affect the hum, either in amount or in tone? Are the power tubes a matched set, or just four of a kind? Mismatched power tubes hum.

In my view, the crossover method of bias setting does not produce the best results.

Add a bias probe to your tool kit, or learn to use the shunt method with your meter. If this is a recent build, is there by any chance a 1 ohm resistotr in the lead from cathode to ground at the power tubes? Use that.

[stokes]

I agree,the crossover method is not the way to go.The shunt method is my favorite,it shows what current is being drawn across the side of the OT rather than across a supposedly 1 ohm resistor.Just connect the red lead of your ammeter to the CT of the OT and your black to the plate of your tube,more accurate than the 1ohm resistor.

[Amp Kat]

I like the shunt method also but for someone not used to it can be quite dangerous and a challenge as one slip and it could 1.) fry your meter and your output transformer and create a shock hazard. The best solution would be to purchase a bias-rite and then you can be safe and accurate and much easier. I've seen this problem in many Fenders and it's usually a ground issue. Tighten all the grounds good and don't rule out tubes especially Sovtek WXT's. If you can hit the amp and create the problem it's not fixed. I've seen it happen with almost all Fender twin reissues and of course it's worse with the volume cranked up as the emmisions are higher at that point. Check the cap grounds under the hood good too.