SPAX7-A

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zodiac272 said:
yes, they are 12ax7 that simply tested very low for microphonics...

scott

Yep, they're good tubes. I have three of them in my Mark III right now; Mesa recommends them for V1 for obvious reasons, but in doing some home tube rolling, they ended up outperforming most of the other tubes I had on hand.
 
zodiac272 said:
yes, they are 12ax7 that simply tested very low for microphonics...

scott

I was always under the impression that they were just regular 12AX7's with just that little rubber band around it to keep it from vibrating. You could do better and cheaper with a Tung-Sol RI in V1.
 
swbo101 said:
zodiac272 said:
yes, they are 12ax7 that simply tested very low for microphonics...

scott

I was always under the impression that they were just regular 12AX7's with just that little rubber band around it to keep it from vibrating. You could do better and cheaper with a Tung-Sol RI in V1.


they are regular 12ax7's, but mesa tests all their tubes, and the best ones get the shrink wrap (rubber band) and are labeled SPax7


scott
 
I replaced all the 12ax7s in my MkIII w/ SPAX7 figuring they were just higher quality and it ruined the sound. Now I have to find time to go back and roll in the old tubes to see if one of the new ones is bad or if the old ones just sound better. I suspect I will at least keep an SPAX7 in the #1 position.
 
I agree. I believe the SPAX7's were screened for low microphonics and not screened for tone. From my experience, the SPA12ax7's sound no better, and in many cases sound worst than good 12ax7s. I've kept them in V1 in some amps, but replaced them with higher tonal quality tubes in many of my Mesas.
 

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