In mine, I started out with the original Chinese Peavey one. I then tried some N.O.S. GE and RCA ax7's, and even a Groove Tubes one of unknown pedigree. For some reason that original Chinese one sounded best. Still does in fact!![]()
I had two Peavey T-Maxx bass amps and really loved them both. I had to let them go because they were killing my back. But I used the first one (which sounded the best) for like 4 years with an SWR Goliath SR. 6X10 1000 watt cab. Truly, truly awesome sound. I did exactly what you did, Fran; Tried a Groove Tube 12AX7 in place of the original Chinese 12AX7 and I found out exactly what you did. The Chinese tube sounded a whole lot better. I wound up selling both T-Maxx amps and buying two GK 1001-RB's and I still have them. When I sold those T-Maxx amps, I took out the Chinese 12AX7 and replaced it with a Groove Tube 12AX7. I kept the Chinese tube in case I might need it someday. )-(
