Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: mresistor on October 08, 2018, 01:27:54 pm

Title: Ampeg B15S power tube substitution
Post by: mresistor on October 08, 2018, 01:27:54 pm

I have an Ampeg B15S here and the 7027A's are shot.  Is it OK to use Sovtek 6L6GC in this amp?

Title: Re: Ampeg B15S power tube substitution
Post by: davidwpack on October 08, 2018, 01:54:24 pm

I'd have to wire my Ampeg differently. Pins 1 and 4 are connected internally I think in a 7027.

Title: Re: Ampeg B15S power tube substitution
Post by: PRR on October 08, 2018, 07:40:03 pm

Check the actual factory wiring VERY carefully. The 7027 has some odd pins different than other octal pentodes. As said their is second G2 pin; there may be others.

Title: Re: Ampeg B15S power tube substitution
Post by: mresistor on October 09, 2018, 04:40:56 pm

thanks..  I ordered 7027A tubes for it .. but found out the OT is bad..   

Title: Re: Ampeg B15S power tube substitution
Post by: davidwpack on October 09, 2018, 05:48:07 pm

That sucks about the OT. I thought about wiring mine for 6L6 but I really like the sound of the 7027A's. I have 2 though so maybe I'll rewire one...or maybe 6550?... I don't know.

Title: Re: Ampeg B15S power tube substitution
Post by: sluckey on October 09, 2018, 06:48:52 pm

Quote from: davidwpack on October 09, 2018, 05:48:07 pm

I thought about wiring mine for 6L6 but I really like the sound of the 7027A's. I have 2 though so maybe I'll rewire one...or maybe 6550?... I don't know.

If it's wired as the schematic shows then you won't have to change any wiring. But you gotta verify that.

Title: Re: Ampeg B15S power tube substitution
Post by: davidwpack on October 09, 2018, 07:15:56 pm

It seems like it wasn't but it's been a while since I've pulled the chassis out. I'd have to look again. I remember something seemed weird with it.