Ampeg 7027A Power Tubes Replacement Blues

[Gtr_tech]

There is usually a schematic pasted inside so you can locate the bias setting resistor. You can install a pot if there is room to mount it, but its got to be somewhere it can't be accidentally bumped. Those original tubes were of really good quality and last a long time. In my experiance, they tend to fail suddenly and take other stuff with them. I always change the small electrolytics, especially the bias filters because there is a lot of heat in that chassis. Another tip is to change the screen resistors to 1K 3W wirewound in the older Ampegs. Its not an issue with the later MTI models.

I'll pad the screens a bit in the Ampegs as well. The JJ 6L's are a great durable output tube and work well in elevated plate voltage applications, but they'll last a lot longer if yer nice to the screens.