2. amps-preamps
  3. 119835-68004

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.  


t-bon3

Showing 1 response by tablejockey

tablejockey
4,038 posts
 
"Regarding rectifier tubes, from what I’ve been able to piece together after significant research on the ‘net, is that the sonic differences between rectifiers is mostly caused by the “voltage drop” of each different tube model/design. This voltage drop is called “sag”. Apparently, under peek demands, some rectifiers will “sag” more than others, and this impacts how the rest of the amp performs with this brief drop in voltage from the rectifier tubes. From what I’ve found online, the 5AR4 / GZ34 family of tubes has the least amount of voltage drop, whereas the 5R4 family have the most (yet, many listeners prefer rectifiers with larger voltage drops"

This has NOTHING to do with listening to home audio. The"sag" is what is happening when your’re hearing an electric guitar amp being overdriven, producing the tones of some guitar gods.

More to discover