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My first tube roll in a Primaluna Dialogue HP Integrated

First off, special thanks to tomy6--a fellow audiogoner who helped me identify, with specificity, the exact tube I was swapping in:  an Amperex 12AU7 tube made in the early to mid 70s; Great Britain Mullard factory. 

I swapped out stock Chinese sourced Primaluna 12AU7s--6 of them--from the preamp section. 

The process of rolling and twisting in a gentle swaying motion is really easy, yet there's an subtle art to it.  By the time I hit my 3rd or 4th tube, I got the hang of it.  In my mind's eye, I had a vignette of many folks who came before me, installing tubes.  I pictured repairmen with--what I think they had--a tube caddy, full of tubes separated by cardboard dividers like bottles of wine.  

I didn't bother to clean the somewhat oxidized-looking tube pins, which were much darker and tarnished than the 2016 Chinese Primaluna 12AU7s.  I rolled one set out, and dropped the other in. 

It was interesting to see the Amperex tubes flash up on startup.  I wondered if they were going to blow!  They flashed brightly and calmed almost as fast as they lit up.  My pessimism nearly expected the amp to signal that I had a bad tube or two.  Primaluna's autobiasing automatically kicks in and handled that--just like Mesa Boogie guitar amps.  

Things sounded just fine out of the box. I'd say no better or no worse than swapped tubes.  I've been running them now for 90 minutes.  The difference is real yet subtle. Here's what I think:

--The Amperex tubes have more top end attack.  I wouldn't call it bite. There's more detail on top....not much, but it's there. 
--The Amperex may be less warm.  The bass seems to be more defined but there's less of it. 
--The Primaluna's sounded a bit bloatier, which was kind of nice in some ways, yet in another it's making me thing and digest these differences. 
--While the soundstage of the Amperex seems to go back deeper than the Primaluna, it seems like I'm sitting a bit farther back from the performance.  I cannot tell which I prefer.

I haven't had a chance to really crank the volume and get them heated up and pumping.  

I have no strong takeways from this experiment yet and I certainly haven't decided which I prefer.  Next up is a set of 6 Ciftie military grade set of 12AU7s.  

Different indeed!  


jbhiller

Showing 6 responses by tablejockey

tablejockey
4,012 posts
 
"Next up is a set of 6 ciftie military grade set of 12AU7s."

I don't have an extensive collection of different NOS, but do hear the subtle refinements of the 2 preamp(innermost). The 2 other stages don't seem to be as sensitive to rolling. I ended up changing all of them, just for the sake of continuity. Mine are a row of 50'sRCA blackplates. Now and then I switch the 2 innermost with Raytheon and the Mazda(Cifte)

I have a shoebox full of old American tubes from years of guitar amp spares.

There does seem to be audible differences with generic new tubes and NOS. 6@$50+ is a little steep for the euro fancy glass, so the RCA I purchased for $5 each work.

Once you start playing with NOS, IMO the subtleties are even greater, and don't warrant the high cost. Or likely, my hearing is just aging like the rest of me.

The Power tubes are what can be the real wallet killer. I've seen a little price discount for the KT150, but $800 is just out of my league when it comes to lavish spending.

Regardless, enjoy the roll.
tablejockey
4,012 posts
 
"..and used to pull Baldwin brand tubes"

Jbhiller-if you're not already familiar:
http://www.audiotubes.com
Reasonable  pricing on tubes. Especially the cosmetically imperfect, otherwise fine RCA,GE brands.


tablejockey
4,012 posts
 
"the bottom 2 positions (nearest to the front) don't really benefit"

saki- do you mean to 2 INNERMOST positions?
its always been my understanding(per distributor/most of discussions) is first stage L/R channel of the preamp circuitry(the other 2 are do other technical stuff)that do make audible sonic difference(good or bad)

I find this to be the case. YMMV...its audio. 

If you do hear as stated, go with it.
tablejockey
4,012 posts
 
Has anyone tried the Brimar 12au7 in the 2 L/R slots? I understand it to be a nice tube. Impressions?

tablejockey
4,012 posts
 
saki70-
your insight is appreciated. Guess I will pass on those. I have a hard enough time really picking out the subtleties between the 4 brands I have on hand.

Presently rockin with a full rack of RCA glass:6L6G coke bottles and a row of blackplates. Clean and clear with plenty of energy of both ends to the spectrum.
I'll just leave well enough alone and contemplate new speakers sometime this year.

tablejockey
4,012 posts
 
aionlim-the authority on PL  is the distributor @ Upscale Audio.

Kevin also sells a  bazillion tubes, he can offer insight on the tube rolling thing.



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