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Swapping 5AR4 rectifier for 274B in a PrimaLuna Preamp

Long time lurker, first time poster.
I have recently acquired a PrimaLuna Dialogue Three preamp.  (not the new 'premium' preamp, the original Dialogue Three)  It's a fantastic unit and sounds incredible.  I've achieved some very nice results tube rolling some of the other components I own(ed).  I am contemplating switching the OEM 5AR4 rectifiers with a pair of mesh plate 274B's from Sophia Electric.  
http://www.sophiaelectric.com/pages/se/274b.htm   
While allegedly pin compatible, I understand the life of the rectifier might run short.  To quote Sophia Electric's site:
"The 274B is direct heating tube. The indirect heating 5AR4 may turn on slower, however, people who buy 274B is for its superior sonic performance. To fully utilize its benefits, it may require first stage capacitor (capacitor input) to be less than 10MFD, or would shorten the 274B life span (very much like smoking is bad for your health). It would not be a problem with common choke input. Please consult to your amplifier maker or refer to a tube manual.
The maximum current capability for Sophia Electric 274B mesh plate tube is 90ma, suitable for tube pre-amp. "   

I was hooked on the SE 274B when I saw that Woo Audio was offering the 274B as an upgrade to their WA6 headphone amplifier.   Further research turned up a couple of great reviews for the tube in other amplifier and preamp applications.

PrimaLuna / Upscale Audio have given great recommendations for the Phillips 5R4GYS in my preamp.  In all probability I'll find myself buying & trying both and selling whatever comes in 2nd place.  

I'm pretty new to the tube game, but learning fast. 
I would welcome the opinions of those with more experience and finely tuned ears.  


128x128t-bon3
t-bon3's avatar
t-bon3 OP
15 posts
 
I trust my ears.  I'm only on my second tube pre-amp, but I'm learning fast.

My first was a Chinese made "mid-grade" pre-amp that benefited immeasurably from being re-tubed with quality parts.  The rectifier tube upgrade made the most significant improvement.  That was a 5Z3P --> 274B swap.  

The starting point on the PrimaLuna Dialogue, my second tube pre-amp, was already pretty high - so one has to work that much harder to squeeze out a performance improvement.  Since Upscale is the US Importer (i believe) for PrimaLuna, I had to trust his tube recommendation based on his extensive professional experience with them.

Getting back to "trusting your ears" - I had a particular album, with particular tracks that just weren't right.  Swapping the tubes and playing the same track convinced me.  Sagging voltages and other electrical engineering topics are way over my head.  I stopped at "sounds better to me"  :-)   I wish I knew more about the science behind the sound.  

....what I really wish for was more time to sit back and RELAX with good music.
bradf's avatar
bradf
288 posts
 
Thank You, t-bon 3.
I really don't like to bother Kevin with theoretical questions unless I have intent or potential of purchasing the relevant  item. He's pretty busy trying to put food on the table. After all, he is a retailer, not the shell answer man. I usually try to make best of this forum, just like you did when I took the time to answer your questions.

Brad
aolmrd1241
759 posts
 
Just installed two of the Phillips 5R4GYS rectifier tubes into my PrimaLuna DiaLogue Premium preamp. With only a few hours of break in time.. I would consider these a must have tube for this preamp. Right off the bat, the increase in sound quality is huge. The impression of a more natural tone to instruments and voice is just plain awesome. The emotion and feel across the board is something to behold. And all this from a brand new,unused...non broken in pair. WOW!

The music now has meat on the bones and a true quiet elegance to the sound that was hugely lacking with the stock PL 5AR4 version. The review from Positive Feedback is spot on and true to this NOS tubes virtues... If you can...get a pair ASAP,before they are g-o-n-e. I am very happy I took the plunge. Hearing is believing.
aolmrd1241
759 posts
 
Installed six-matched NOS Mullard 12AU7 CV4003's into the PL Premium preamp. These NOS Mullard tubes in tandem with the Phillips 5R4GYS is just plain crazy good and outstanging in every way to the service of the music.. I no longer have a  PrimaLuna DiaLogue Premium pre amp...nope...no sir ree Bob!!! ...It is now a 'Super' Premium pre amp in every way that matters most to the music played through it.   ; ^)
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