Question about AC and hum in regards to my Twin Reverb build

[shepdog]

I have just started building a blackface Twin Reverb and after having wired up the mains, I decided to move the bias pot to the empty ground switch hole on the back because I've already got bias test points back there. Anyway, this has cut down on the amount of space between the heater wiring and mains. I am wondering about any possible negative effects of running my mains to the fuse and switch in parellel, and possibly cable tied, to the heater wiring and along side the bias pot. I've attached a photo so you can get an idea of what I am talking about.

[Firestorm]

It would be better to twist the heater wires tighter than you have them, and I would strip the outer insulation on the power cord so you can twist the hot and neutral wires too. The safety ground should be near the point where power enters the amp anyway.

[Structo]

I agree.

Move the ground wire to a solder lug and dedicated screw and lock nut near where the power wire comes in.

Due to the way they used to wire the AC, convenience outlet, ground switch, it took a lot of room and moved the AC wiring further than ideal from the corner.

There is some thought when you have a hard wired AC entrance like you have to make the ground wire longer than the hot and neutral wires so in case the power cable is yanked out of the chassis that even if the hot or neutral wire is pulled free, the ground wire will remain connected, protecting the end user electrocution.

You may or may not feel like redoing your heater wiring as you have it all soldered up at this point.
But, having a tighter twist pattern will help cancel out 60Hz hum especially on the power tubes, also retaining phase of those wires helps as well.
In other words you want the same wire to go to pin 2 on each tube and the same with pin 7.

Also, the wires that leave the rectifier board which are now carrying DC, should be kept away from AC wires to reduce hum.

I also notice some wires (reverb transformer?) coming through a chassis hole. You should install a rubber grommet to keep the wires from chaffing.

Looks like a fun project!

Hope this helps!

[shepdog]

Thanks for the replies. I have uncovered the power cord and connected the ground to a power transformer mounting bolt with a strong crimped and soldered lug. The heater wiring was slightly neater before I started yanking it around to wire up the other pins of the power tubes. I do plan to keep the heater lines as they are now, as I have run out of that wiring. I will rewire if they give me reason to. I've got some grommets in the mail now. The wires that are hanging out around the rectifier board are just twisted about to keep them out of the way. Also, where is a good place to ground the filter caps?

Heres an updated photo

[Structo]

You know, there are probably as many grounding schemes as there are amplifiers but I like the school of thought that Dumble used.

But with the Fender amps that use the dog house on top of the chassis I'm not sure you need to change from the Fender method.
Just follow the layout and schematic.