Type 6L6 GC can handle higher voltages, output more power and have lower transconductance than the other 6L6 variants. I would be careful about using a GB in place of a GC - it will depend on the design of the amplifier. You need to ask the manufacturer to be sure. My McIntosh MC240 is a GC design with 430V on the plates and -50V control-grid, which would be enough to shorten the lifespan of a GB significantly.
Looking at a Tung-Sol 6L6 GB datasheet I happen to have, max plate is 360V for push pull apps which would be no where near enough to be used in my amp, for example.
What amp is it you have?
Arthur
Looking at a Tung-Sol 6L6 GB datasheet I happen to have, max plate is 360V for push pull apps which would be no where near enough to be used in my amp, for example.
What amp is it you have?
Arthur