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Thread: 12ax7 vs. 12at7

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    Toneologist Dirtyking's Avatar
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    Default 12ax7 vs. 12at7

    Whats the big difference between 12ax7's and 12at7's. Especially in the V1 spot.
    I'll have a Gibson Flying V straight into a Mesa, hold the BS please!!!!!

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    Default Re: 12ax7 vs. 12at7

    12at7 has 60% of the gain a 12ax7 can provide.
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    Default Re: 12ax7 vs. 12at7

    Here's a link I just found that explains the difference with different pre-amp tubes. http://thetubestore.com/gainfactor.html

    It says in there that the power amp section works harder if you use a lower gain tube I wonder if it actually makes overdriven tones easier to achieve.
    Last edited by greendy123; 05-13-2006 at 10:08 AM.
    Fender MIM Strat 59 trembucker bridge/Super II neck
    Edwards 56' Goldtop 2 x SD P90-1s
    Marshall JCM 900 MKIV 2100 slx
    Marshall JCM 900 1936 Celestion GT-75/Vintage 30 cab,
    Fender Frontman 15g
    Cry Baby
    Boss DS-2
    Boss CE-3
    Danelectro Wasabi

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    Default Re: 12ax7 vs. 12at7

    A 12AX7 has a gain factor of 100
    A A12AT7 only has a gain factor of 70..
    Amps: 66 Fender BF Pro Reverb Combo,1973 50 Watt Marshall Head,Marshall 4x12 A/V Cab,Vox ToneLab LE,Vox VTH Valvetronix 120 Head,Vox AD 2x12 Cab,Roland Cube 20X

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    Default Re: 12ax7 vs. 12at7

    For some reason, 12AT7 has never been a very popular tube in the first stage either with manufacturers or with swappers. I have a box of them here of various Euro/US brands and none of them sound very good in V1. 5751 or 12AY7 (or even 12AU7) work better for me...

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    Tone Member Faraday's Avatar
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    Default Re: 12ax7 vs. 12at7

    Quote Originally Posted by ES350
    For some reason, 12AT7 has never been a very popular tube in the first stage either with manufacturers or with swappers. I have a box of them here of various Euro/US brands and none of them sound very good in V1. 5751 or 12AY7 (or even 12AU7) work better for me...
    I use the 12au7 in most slots because it makes the power tube distortion more noticable.

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    Default Re: 12ax7 vs. 12at7

    Quote Originally Posted by ES350
    For some reason, 12AT7 has never been a very popular tube in the first stage either with manufacturers or with swappers. I have a box of them here of various Euro/US brands and none of them sound very good in V1. 5751 or 12AY7 (or even 12AU7) work better for me...
    That's because a 12AT7 is used more as a functional tube and not as a tube in a tonal spot in amps...It's "normally" a phase inverter tube or used to drive reverb or the vibrato circuits in Fender amps...
    Amps: 66 Fender BF Pro Reverb Combo,1973 50 Watt Marshall Head,Marshall 4x12 A/V Cab,Vox ToneLab LE,Vox VTH Valvetronix 120 Head,Vox AD 2x12 Cab,Roland Cube 20X

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    Toneologist Dirtyking's Avatar
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    Default Re: 12ax7 vs. 12at7

    Awesome link bro.

    I'm still a little confused if there would be any problems switching my 12at7 with a 12ax7. Like frying the circuits or ?. My head has 5 preamp tubes, all Ruby's with the 1st being a 12at7 and the others being 12ax7's.

    "Edit...I'm sorry the 12at7 is actually a Phillip's tube"
    Last edited by Dirtyking; 05-13-2006 at 11:54 AM.
    I'll have a Gibson Flying V straight into a Mesa, hold the BS please!!!!!

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    Default Re: 12ax7 vs. 12at7

    Quote Originally Posted by STRATDELUXER97
    That's because a 12AT7 is used more as a functional tube and not as a tube in a tonal spot in amps...It's "normally" a phase inverter tube or used to drive reverb or the vibrato circuits in Fender amps...
    Wow I may be looking at my preamp backwards. My head has Reverb so the 12at7 may be in line for that.

    Hmmmmm. Is there a common direction that preamp tubes run. Like from left to right or ?
    I'll have a Gibson Flying V straight into a Mesa, hold the BS please!!!!!

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    Administrator Scott_F's Avatar
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    Default Re: 12ax7 vs. 12at7

    The preamp tube closest to the power tubes is normally the phase inverter. I'm betting the 12AT7 in question is your PI. I will often put a 12AY7 into a slot that might normally call for a 12AX7 to achieve more cleanheadroom, lower gain front end basically.


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    Default Re: 12ax7 vs. 12at7

    Pretty much the only way you'll screw up with the "common" preamp tubes is to put an EF86 somewhere designed for the 12A@7 style tube.


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    Stratoblaster Tone Meister STRATDELUXER97's Avatar
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    Default Re: 12ax7 vs. 12at7

    A 5751 tube is another choice also with a gain factor like the 12AT7....It's been stated that SRV used these tubes for more clean headroom?
    Amps: 66 Fender BF Pro Reverb Combo,1973 50 Watt Marshall Head,Marshall 4x12 A/V Cab,Vox ToneLab LE,Vox VTH Valvetronix 120 Head,Vox AD 2x12 Cab,Roland Cube 20X

    Guitars: Several Stratocasters,2 Fender Telecasters,Gibson SG Standard,Tokai Love Rock Les Paul,Dean Acoustic.

    Pickups: SD SSL2,SSL5,Twangbanger,Antiquity Surfers,59N,Seth Lover N/B,Dimarzio Fred,Dimarzio VPAF N,Fender Fat 50s,Fralin SP43 Bridge,Brobucker,Antiquity Texas Hot.

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