Bassman Servicing

[darrellcheng]

maybe this amp's been sitting in your basement for 2 or 3 years untouched, maybe not but here goes:

Drifting more than 10% should be replaced, more than 20%, definately. Make sure to get the right wattage and ohmage. You should go ahead and check the ones in the filter cap pan and check the bias section as well as the phase inverter. This is where more work is being done, and it can get hot there. Also if there are blown caps (bulging, burst, blown) check the resistors in that circuit, they will very likely be cooked.

[dumbassbob]

I have three Bassman heads, two Silverface and a Blackface. If that amp were mine, I would do a complete recap on it including replacing the turd brown caps with orange drops or yellow mallorys, it will make a huge difference in the tone of the amp. I also would rewire the bias section to emulate the AA864 Bassman. I have done this on my SF tops, they sound damn good. Those snubber caps and all that other shit around the power tubes are making your amp sound like ass. Plus you would get rid of that "Bias-Balance" crap and be able to adjust the bias of the power tubes as needed.

I disagree about the death cap, if it shorts out in any way you will have 120v AC connected to the chassis of the amp. It's not an internet myth, Get Rid Of It. You can rewire the power cord using this diagram. Doing so eliminates the need for a ground switch, other than using it for a tie point.

About those dual caps, as was stated you can replace them with two separate caps and twist the ends together. Here is a page I did on my Bandmaster with pics where I did exactly that.

You can check the date codes on the pots to determine when the amp was built, here is how to do it.

This is a great amp, it has the potential to sound awesome, good luck!!

this is worth a second look