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Prima Luna Prologue 3 rolled some tubes and...

My 2 channel system is pretty modest. The room upstairs is small and shaped entirely wrong. My budget is limited. I swap stuff regularly. A lot of it. When I coupled my Job 225 with a Prima Luna Prologue 3 something exciting happened. It was audio nirvana, a gorgeous balance of the Jobs lightning fast attack and high end sparkle coupled to the PL's laid back tube sound. My current speakers are LSA 1 Statements. The PL had new matched Gold Lions in it. As fate would have it, I bought a hand full of Amperex Bugle Boy 12ax7, 12au7 and some Telefunken 12ax7 tubes, along with some old equipment from an estate. I paid $200 for all of the equipment and the tubes. So my wee little brain thought, tube rolling? It might just work. Sure enough the tubes tested well and after about 5 minutes of warm up my jaw hit the floor. My oh my, what a change! After a day of swapping things around I settled on a pair of 12au7 Bugle Boys, a pair of 12ax7 Telefunkens and the Gold Lion GZ34s. The soundstage gained height, width and depth. The instruments and vocals had more air, but were also more focused in relationship to each other. Highs are clean and warm. Bass is solid and tight, but a tiny bit lean in the lower frequencies. My wife walked in and she asked what I had done to system.  In my mind, if I had spent $1k to get this much improvement it would have been a bargain.  So here are my questions...

1. How/why do tubes made in the 1950's (Amperex dated 1949 & 1950) sound better than my modern Gold Lions?

2. Is there a better combination out there?

3. Since swapped tubes make a huge difference what would happen if I swapped out capacitors, resistors etc?
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noromance's avatar
noromance
9,811 posts
 
Welcome to tubes. The difference is not subtle, is it? Combo looks good. Look at 5751 instead of 12AX7. Different theories on old tubes: simply better made with more attention to detail and tolerences (military spec), using materials that used processes not allowed today due to toxicity. Quality over profit maximization.
Yes, better passive components will bring benefits as long as you don’t change the voicing of the amp from the designer’s intentions.
tomcy6's avatar
tomcy6
2,597 posts
 

Amperex and Telefunken are considered top shelf tubes.  There may be a better combination out there but I couldn't tell you what they would be.  Some other PrimaLuna owners will probably chime in. 

If you're willing to spend some money, call Kevin Deal at Upscale Audio.  He is the PrimaLuna importer and has a large stock of NOS tubes.  He is very knowledgeable about both.  You can check out the Upscale Audio website to see what kind of prices we're talking about.

mechans
3,048 posts
 

I agree with trying 5751s.  I prefer the 5751 in most cases where the somewhat lower Mu is compatible with the other elements most people run. .  In your case I think it will work just fine.   I think your jaw may drop further with them, because I find them to have an even larger  and more imaging - soundstage.

The caveat is that 5751s produce about 70% Mu compared to a typical 12AX7. That means that they may not be sufficient to work with other parts of your system.  High gain  phono stages where the gain is critical,  such as in an MC stage.  

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