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 Post subject: Mesa SP12AX7 tubes
PostPosted: Thu May 23, 2013 3:58 pm 
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Mark II

Joined: Mon Feb 23, 2009 7:09 pm
Posts: 75
Re-tubed my beloved F50 custom head today and ended up springing for the SP12AX7 tubes . I am wondering if there is actually any difference between them and the plain 12AX7 tube they offer ?

Anytime I see heat shrink wraps on preamp tubes, I tend to think that's the only difference.

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 Post subject: Re: Mesa SP12AX7 tubes
PostPosted: Thu May 23, 2013 4:18 pm 
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Dual Recto

Joined: Mon Jul 16, 2007 1:01 am
Posts: 2828
Location: SoCal
The SPAX7-A is cherry-picked from many others, tested and chosen for low-noise.
This is not necessarily the same thing as "best" tone.
Mesa only recommends them for V1.


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 Post subject: Re: Mesa SP12AX7 tubes
PostPosted: Thu May 23, 2013 4:26 pm 
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Mark II

Joined: Mon Feb 23, 2009 7:09 pm
Posts: 75
I figured it was a V1 tube, but it certainly does not hurt in 2, 3 &4. It's more a waste of money.

I use 7025's in place of 12AX7's in my vintage Marshalls and Fenders. Overkill maybe,.

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'64 Fender Concert Amp
'71 Fender Super Reverb
[2] '78 Marshall 2104 Combo's
Custom F50 head with matched 3/4 back 1x12
Custom F50 Combo
'87 Roland Cube 60 keyboard CK60
'88 Roland Cube 100 Keyboard CK100


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 Post subject: Re: Mesa SP12AX7 tubes
PostPosted: Thu Jun 27, 2013 2:34 am 
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Joined: Thu Oct 15, 2009 1:30 pm
Posts: 2534
Location: San Francisco Bay Area, CA
The SP12AX7 is low noise and low microphonics, but in my experience very low gain as well. Takes all the bite out of the amp :(

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 Post subject: Re: Mesa SP12AX7 tubes
PostPosted: Mon Jan 13, 2014 2:05 pm 
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Mark II

Joined: Mon Feb 23, 2009 7:09 pm
Posts: 75
It's been a while since I was last here, but I did re-tube the F50 with all Mesa SP12ax7's and the amp seems neutered to me.. It no longer has the bite and grind it had.

I'll leave the SP in V1, but am going back to the plain Mesa 12ax7 Russian 2 in it... I may do some tube rolling as well, but I cant see throwing NOS glass in a modern amp.

Will probably put an Electro Harmonix 12ax7EH in V2 and possibly some kind of long plate Sovtek 12ax7LPS ? in V4.
Am I wasting my time and money leaving the SP in the effects loop as being an analog kid I don't use the Parallel loop , see no reason to do the series mod if dont have the Effects level pot functioning, especially with my old BOSS stomp pedals.

_________________
'64 Fender Concert Amp
'71 Fender Super Reverb
[2] '78 Marshall 2104 Combo's
Custom F50 head with matched 3/4 back 1x12
Custom F50 Combo
'87 Roland Cube 60 keyboard CK60
'88 Roland Cube 100 Keyboard CK100


Top
 Profile  
 
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