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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

Showing 2 responses by hifiman5

hifiman5's avatar
hifiman5
1,823 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!
hifiman5's avatar
hifiman5
1,823 posts
 
I am reclining in my listening room thoroughly enjoying The Rite of Spring due in no small measure to the Psvane 12AU7 Reference Vacuum tubes. I just recently purchased these new production tubes manufactured under tight tolerances in the Shuguang tube facility in China. The Psvanes replaced gold pin EH 12AU7s. The EHs were good sounding tubes in my heavily modified cj tube line stage. The Psvane's bring a whole new "sophistication" to all aspects of sound. Most notable is a complete lack of "glassiness" in the upper midrange and treble, a smoothness to the musical texture without any loss in detail. The soundstage is open and natural. Bass is powerful and tight. These tubes are very quiet, a characteristic missing in my trials with NOS Mullards. Yes, they were warm and "musical" but the several pairs I used were always noisy...losing their vacuum?

I purchased the matched pair with gold pins for $83 including shipping from Grant Fidelity located in Canada.
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