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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
hifiman5's avatar
hifiman5
1,832 posts
 
I do not have experience with your gear, but have found Electro-Harmonix 12AU7s to work very well in my heavily modified conrad johnson PV12L. Previous to them, I had been using NOS tubes which had a warmer timbre but they became noisy quickly. At $90/pair it was too much $ for the sound. The EH tubes have a more linear sound across the frequency spectrum and like the Energizer bunny just go on and on. I was much more successful tuning my system with Herbie's tenderfeet than with endlessly rolling tubes.

Enjoy!
rar1's avatar
rar1
1,800 posts
 
I have owned the PL2 & PL5 for 5 years.

After experimenting with SED Winged C KT 88s & 6550s for the power tubes and NOS Mullard & Sylvania 12AX7 & 12AU7 for preamp tubes, I settled on Electro Harmonix EL34s & 6CA7s for the power tubes and Electro Harmonix for the preamp tubes.

I found that I got the sound I liked best with the EH's. The speakers are Totem Mites & Opera Plateas.

Rich
rohitdev OP
18 posts
 
Thank you Hifiman & Rich.

Pardon my ignorance but by EH for the
12ax7
12AU7
EL34s
6CA7s
you guys mean the electro harmonics made in russia tubes? correct? Not NOS USA or Europe.
rar1's avatar
rar1
1,800 posts
 
Correct ... new production EH tubes made in Russia.

Rich
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