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mesa sp12ax7


 
10/22/1999 4:59 AM
kevin
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mesa sp12ax7
does anyone know the story on the sp12ax7 from mesa? is it  
"non-microphonic" because of the rubber strip wrapped around it or is it internaly different from standard 12ax7's???(it does work great in high gain stages)
 
10/22/1999 6:36 AM
Bruce
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My guess it's like every other cheap 12AX7 but prescreened for microphonics before the end user gets a hold of it.  
Bruce
 
10/22/1999 1:50 PM
MJ Harnish
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That's my understanding of it as well, as described by MB. I've read somewhere that they are extensively prescreened and then the band (which looks like thick shrinkwrap tubing to me) is added to further enhance resistance to microphonics. I would be willing to bet that as far as manufacturer goes, they are just whatever cheap flavor of the month MB is selling at the time (which for the longest time were the chinese tubes but I'm not sure anymore).  
 
MJ
 
10/22/1999 2:19 PM
Mark Buckingham
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It's kind of funny, but when I first got my DC-2 (1993), it came with two of these tubes in it. (First two preamp sockets).  
 
They were really microphonic. Mesa even sent me two more, which were just as bad.  
 
I replaced them with standard sovteks, and the problem went away.  
 
Very Strange.
 
10/22/1999 3:25 PM
Jim S.
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I have four Mesa Chinese SP12AX7s that I bought some years back. I found them to be no less microphonic than 50% of the unweeded white-box Chinese 12AX7s I've bought from Mojo. But I've never been that crazy about how any of those Chinese 12AX7s sound. They lack bass and can be a bit edgy sounding.  
 
BTW, I'm considering buying a bunch of the JJ (formerly Tesla) frame-grid ECC83's. I have two now - one is dead quiet and the other is slightly microphonic. I like the way the sound. Are these tubes generally free from microphonics in your experience?
 
10/24/1999 3:24 PM
John S.
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BTW, I'm considering buying a bunch of the JJ (formerly Tesla) frame-grid ECC83's. I have two now - one is dead quiet and the other is slightly microphonic. I like the way the sound. Are these tubes generally free from microphonics in your experience?  
 
Funny because...I liked the way Mesa's Chinese 12AX7's sound,and actually I have a Mesa SP12AX7 in this position of my Tremoverb head(bit darker and warmer sounding)...I also own the JJ Tesla ECC 83 tubes,and also some new Sovtek LPS tubes.The LPS tube sounded best in the TVerb's # 2 position...The Tesla tube sounded harsher and even a little gainier to me,so these are sitting and waiting on a better amp to put these in..Right now I don't care for the Tesla preamp tube...  
 
It is a proven fact that Mesa matches tubes and the tone of tubes to their amps.I myself have found this out with all of the different tubes that I have tryed in my amps...John.
 
10/27/1999 1:13 PM
Ken Gilbert
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quote:
"BTW, I'm considering buying a bunch of the JJ (formerly Tesla) frame-grid ECC83's. "
 
 
John, are you sure they're FRAME grid ECC83's?  
 
That would be surprising.  
 
KG  
 
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