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
rar1's avatar
rar1
1,811 posts
 
Correct ... new production EH tubes made in Russia.

Rich
rohitdev OP
18 posts
 
Rich,
Thank you for confirming

Hifiman,
Thanks for the Herbiefeet idea. I will definitely look into that.

can anybody else share their experience with PL2 tuberolling?

has anybody tried the sovtek 12ax7 lps?
grinnell
1,132 posts
 
I use mullards for the 12ax and rca cleartops for the 12au tubes and new sensor mullard EL34's for the output tubes.
horchai
67 posts
 
i've a prima luna prologue 2 using shuguang black treasure kt88z (grade B tubes), sylvania 5751 3 mica black plate and rca clear top. Speakers are proac response d1.

sylvanias and rca clear tops sound more linear and transparent which mix well with the smooth and extremely liquid sounding black treasure kt88z.

Previously i was using sed c wing kt88. It's dynamic with razor sharp focus and pin point imaging but can be quite fatiguing when paired up with the sylvanias and clear tops.

I didnt like sed 6550C or sovtek kt88. Not enough oomph rather flat. They didnt draw out the emotion as much as the sed c wing kt88 or the black treasures.

Other tubes i've tried are full music 12ax7 and create audio 12ax7/12au7.

NOS preamp tubes still sound much better than modern tubes.

My humble opinions....
horchai
67 posts
 
oh yes, herbie labs ultra sonic rx tube rings for the preamp tubes. much much more extension from the top to the bottom. strongly recommended.

for my case, it didnt kill the "airy sound" of the tubes.
More to discover