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ND13
ND13 Posts: 7,601
edited October 2005 in 2 Channel Audio
Someone tell me if I understand this correctly.

I can swap out 12AT7s and 12AU7s for 12AX7s, but can't sub 12AX7s for those, right??? Something to do with voltage being higher in the X variant, correct?? The Ts have the lowest of the three. so it can be used as a replacement for either the U or X, but those can't be put in where a T is called for, right??

12AT7= 12AU7 or 12AX7
12AU7= 12AX7
12AX7= 12AX7

Make sense???
"SOME PEOPLE CALL ME MAURICE,
CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
Post edited by ND13 on
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  • ND13
    ND13 Posts: 7,601
    edited October 2005
    Surely someone knows if this is right or wrong or close...
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • beardog03
    beardog03 Posts: 5,550
    edited October 2005
    I fear that`s a question for Russman, bro...

    Sorry, I can`t help ya..
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited October 2005
    Check the specs of the tubes in question on this data sheet lookup database. I've never subbed the tubes you listed. That is not to say they cannot be subbed, though.
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  • RuSsMaN
    RuSsMaN Posts: 17,987
    edited October 2005
    He has a quad of something other than AX, that he wants permission to put in his MLP.

    What he needs to do, is quit dicking around, and use what he has, or pony up for a quad of AX that he wants (or thinks he wants). Noel, using what the circuit was designed for is ALWAYS the best option.

    Going DOWN in gain factor is usually ok, going up - proceed at your own risk.
    Check your lips at the door woman. Shake your hips like battleships. Yeah, all the white girls trip when I sing at Sunday service.
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  • ND13
    ND13 Posts: 7,601
    edited October 2005
    No, I don't have a quad of something else. I have a quad of something else available to me on the cheap if I want them, though ;) And the question had arisin in a conversation with friend of mine who wanted to know the answer for himself.
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • organ
    organ Posts: 4,969
    edited October 2005
    Noel,
    I did a research on this at audioasylum after reading your post and it's not a good idea to sub U7 for an X7. The U7 only has 1/10 the gain of an X7. It will also change the voltage/current flow in the circuit. The only tube people sub for X7's are 5751.
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  • ND13
    ND13 Posts: 7,601
    edited October 2005
    Thanks, won't need these anyways, just ran across a quad of smooth plate, diamond bottom Teles :D
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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  • BlueMDPicker
    BlueMDPicker Posts: 7,569
    edited October 2005
    Noel,

    Since Gary Dodd is accessible, have you asked what tube(s) he used during his prototyping of the preamp? NOS tubes are a lot of fun to roll through a signal path. But, I've found, many "boutique" designers build their circuit on the characteristics of current production tubes.

    The only Tele smooth plate I've had experience with (12AU7) was in my MiniMax pre. It was too "bright" for my tastes. Some have speculated this "brightness" in modern circuits can be attributed to a conscious design philosophy of the tube aimed at overcoming some of the "darker" tonal characteristics of contemporary circuitry of that era.

    Mike
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  • ND13
    ND13 Posts: 7,601
    edited October 2005
    Mine aren't bright at all, so far. I would date them around the late 50s-early 60s era. alot of the lettering is worn off, but the important parts are still legible, like 12AX7, made in West Germany, and of course the diamond on the bottom of the tube is the dead giveaway of what you have. I have a much better looking matched pair of the same that I need to find another pair to go with. I have a feeling those might just get a little salty to acquire.
    "SOME PEOPLE CALL ME MAURICE,
    CAUSE I SPEAK OF THE POMPITIOUS OF LOVE"
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