2. amps-preamps
  3. 1290296447

12ax7 12AU7 EL34 / KT 88/ 6550 upgrades for PL2

I acquired a used primaluna prologue two a month or so ago. This is my first experience with tube amp. Coming from rotel amplification I am just wowed with the tubes. The PL2 had upgraded tung sol 6550s. Nice sound. But I changed to new issue Electro Harmonix H EL34EH. Ran-in the tubes two days straight with music. Was simply blown away with soundstage and tone! Guitar riffs and blues sound gorgeous! Bass isn't too shabby either. Quite enjoyable.

Then found a little more improvement by switching 12ax7s from stock to Electro Harmonix ($10 bucks each).

The tried changing out 12AU7 with some old used tunsol 5963/12au7 (made in the USA) and was not happy. Changed back to stock.

Does anybody have any good experiences with upgrading the 12ax7/12au7 and power tubes on the PL2. I would appreciate the advise. Tube rolling is so much fun!

My speakers are quad 22L2, cd player oppo bdp 83se and analog source is MMF5 w/ MMshure ML140E.
rohitdev

Showing 2 responses by jwglista

jwglista
206 posts
 
I am currently using SED "winged" 6550Cs, along with NOS Pope 12ax7, and stock 12au7. The Popes are absolutely fantastic if you can find them. Mine were purchased from Upscale Audio. I do prefer the sound of the KT88 over the SED 6550s. Like another person said here, I find it to sound a bit flat and dynamically constrained, but it does sound extremely smooth. Just depends on what you're after.

I am looking to upgrade from my stock 12au7s. I was told by Kevin at Upscale that the 12au7s are just buffer tubes in the PL2, and that the 12ax7's should be upgraded first. I've already got that covered, so I'd like to go for some better 12au7s.
jwglista
206 posts
 
I've only tried the stock KT88s so far. I'd like to go for some Gold Lion KT88s eventually, but I've read that some people have reliability issues with them.

I'm not sure if the Popes are the same as the dutch amperex tubes. Adding the Popes added much more dimensionality to the sound, along with a smoother and more detailed presentation. A definite upgrade over the stock tubes, and it isn't subtle either.

What you've said about the 12au7's has me reconsidering upgrading those tubes. I was going to go for some NOS Radiotechnique 12AU7/6189, but not sure that it's going to be worth the money.
More to discover