Two 3-500b's should loaf along at 1200 watts (with the amps rated input of 100 watts.)
It amazes me that so many don't understand 2x 1200 will make no difference on the other end. I wouldn't drive that amp with a watt over 80 (that's just me.) There's just no point!
I admit to knowing less than any member of this site. But I do know driving 2 3-500b's with 400 watts or 200 for that matter doesn't prove the tubes are 100%. Or even 60% for that matter. That's what a tube tester is for. Back to my point on output (for those who don't know or don't care.)
4x your current output will give you one (1) s-unit gain on the other end.
2400 watts will do one thing and one thing only. And that's show 2400 watts (on your meter) as opposed to 1200.
BBI like most golden screwdrivers use technical terminology to make those who (like myself) aren't able to work on equipment for lack of knowledge and ability, in order to convince them he knows what he's doing. IMO he's little more than a golden screwdriver.
When I see someone post one of his clips then have people with true knowledge critique his "work", it just brings to light BBI is exactly what I claim him to be. A golden screwdriver period end of story. Even if he's not a golden screwdriver he's little more than a tinkerer of radio gear. There's nothing wrong with being a tinkerer as long as you're tinkering on your own equipment and not charging others to do so on there items. Who was the teacher he stopped his recording for in order to answer the phone call? I have a feeling it might have been that snake radio customs guy? He's a technician in his own mind and only in his own mind. The world according to BBI. It's sad to see such a terrific piece of equipment in the hands of a total hack!
Unbelievable! And sad at the same time. I truly believe whomever purchases that amplifier will have nothing but problem after problem after problem with it.