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
horchai
62 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.
rohitdev OP
18 posts
 
Horchai - Thank you. The Shuguang Treasure KT88-Zs look gorgeous! Are they the black treasures you have? There are pictures of them at tubestore.com. At ~ $480 for a matched quad they are quite expensive for my standards. Are they worth the sound? Other than being incredibly liquid are they transparent? how do the mids, treble and bass sound?
rwwear
2,692 posts
 
http://www.ehx.com/
rohitdev OP
18 posts
 
Ok Rwwear. Stop with the links already. My thread is for hifi amps and not guitar pedals.
maxmad
182 posts
 
I would get NOS GEC KT88, thats what I did and stop rolling after.

You want punch and musicality at the same time, KT88 are your choice, other than that, EL34 Tesla's are my second one.

Tried:

6550 TUNG SOLS BLACK SMOOTH PLATES, very expensive and I would choose GEC KT88 anytime instead, but they do sound very good and build to last.

EL34 NOS TESLA ( NOT JJ ) - Very good value, recommended.

6550 NOS SYLVANIA - Nothing special, nice sounding.

To me, driving and input tubes make as much difference as the output.

Tried:

12AU7 - Telefunkens Smooth plated, Brimars long plated square getters, Tung Sols Black coated glass and Mullards from the 50's, which I end up with.

12AX7 - Tungsram, Tungsols and CV4004 Mullards, which I ended up with to.

The other one I would recommend is E83CC NOS Tesla, simply one of the best sounding up there. They are identical to E83CC Telefunkens, which are such expensive that these Tesla's are just an bargain. Dont miss up with other E83CC they try to sell, cos only Teles and Teslas are the ones to get, but be carefull with your source choice, cos fakes are there.
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