I'm considering installing a set of NOS Pope 6v6gt's (Phillip/Amperex Holland 1957-60) in my RV50. I was told these power amp tubes are the best NOS tubes for high plate voltages and hotter bias settings. They also get great reviews for their sound quality and character. It was suggested that Orange...

You're okay on preamp tubes. No bias required. I do however recommend buying a balanced triode tested tube for your V6 (phase inverter). You will hear an increased balance in the volume level of high and low frequencies vs just plopping any tube in. Learned from experience ;) As for the Sovtek 12ax7...

Could be a ground loop. I would have a different tech check out the amp, if you haven't already.

I bought my RV50 used and it is the best amp I've ever owned!

Just swapped out my preamp tubes in my rockerverb 50 for the first time. The swap was prompted by the reverb tube failing. I used Sovtek 12AX7lps for V1, V2, V3, & V6/ I replaced V4, & V5 with 12AT7 by J/J. Reverb is beautiful, Both channels are very noise free and sound good, albeit a wee tight sti...