The B-15R comes setup to use 6L6 or EL34 tubes. All you have to do is put whichever tube in and then flip a switch on the back that sets the bias.
I've read numerous times that the EL34 and 7027A are sort of interchangeable. I.e. they are, as long as the tube socket is wired "correctly" to accomodate either tube.
I emailed Ampeg Tech Support to ask if I can use 7027A tubes and their response was:
| It is not recommended to use anything other than 6L6 or EL34 tubes in this amp. While the 7027A operationally matches the 6L6GC tube, there are some tubes that are tied together on the 7027A that could cause issues with the B-15R. |
I assume where they said "there are some tubes that are tied together" they meant "there as some PINS that are tied together".
So, can anybody tell me what would be required to do to a B-15R to allow me to use 7027A tubes?
Why, you ask? Because I have a matched set of old Magnavox 7027A tubes that I was saving to use in my early 70s V4. I sold the V4. And I'd like to try some "higher quality" tubes in the 15R than what came in it stock - without spending more money on tubes.
Alternatively, if anybody wants to trade a good quad of matched, vintage EL34s for my set of 7027As, let me know.