Can a blonde bandmaster (6g7-a) handle 6ca7 power tubes?

What would I need to change if so?

Pins 1 and 8 need to be tied together.

You might want to consider that they draw twice as much filament current and more plate current than 5881s. The extra filament current is substantial... 1.5 amps more than 5881s. Two 6CA7s draw as much filament current as four 6L6s! If it's a clone have at it but I'd think twice about risking the PT in a vintage amp.

So is the stock power tranny not capable of handling these tubes?

Pins 1 and 8 need to be tied together.

Yep. The 6CA7 is basically a beam tetrode version of the EL34. It biases like a 34. Heater current draw is higher than a 6L6.

Basically, if you set up the amp for EL34s, you'll be fine.

You'll also be able to run KT77s.

Just like the old Philips 7581A was the butt kicker of the 6L6 family, the old Philips 6CA7 was the big bruiser of the "EL34" with beam former family.

Didn't EVH run the Philips 6CA7s in his Plexi?

I once heard a Hiwatt 100 with Philips 6CA7s, it was earbleed loud and clean, very articulate. Not what one expects from Brit amps.

You might want to consider that they draw twice as much filament current and more plate current than 5881s. The extra filament current is substantial... 1.5 amps more than 5881s. Two 6CA7s draw as much filament current as four 6L6s! If it's a clone have at it but I'd think twice about risking the PT in a vintage amp.

I agree with this. If it's vintage please don't do it. Just sell the amp and get one with 6ca7's if that's what you want. Just throwing this idea out there.

So is the stock power tranny not capable of handling these tubes?

I wouldn't push it. It will do it for a while. If you do the conversion play it for a while (5-10 minutes) and grab the power transformer. If you can't hang on to it you probably don't want to run it.

A long time (and many brain cells) ago, I did this conversion to my '66 SR. You could cook eggs on the PT. I promptly put the 6L6's back in.:lol:

I wouldn't push it. It will do it for a while. If you do the conversion play it for a while (5-10 minutes) and grab the power transformer. If you can't hang on to it you probably don't want to run it.

Your ability to "hang onto it" happens pretty much around 50 °C. I'd think one of these trannies would be good up to at least 70 °C.

Well I decided to keep the 5881s, but, I learned I have one of the models that came with the 125A6A OT and the 125P19A PT. they're both dated 1963 and it is for sure the 6G7A circuit. Has the presence knob etc

Weird