What do you guys think about having a 12ax7 balanced for the phase inverter (v3) position. I was going to order some new tubes and the guy suggested this to me. I tried getting some info on it and its really a double edged sword, some swear by it and others say its just a way to get a few extra dollars out of you. I know that no amp manufactures use them. Whether its just to save money on tubes or they think a balanced triod is bullshit I dont know. What do you guys think?
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BALANCED 12AX7?
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Re: BALANCED 12AX7?
Yea, Bob also told me to get one. Then I talked to a guy at the tube store and he told me its all bullshit. I also heard that the first company to come out with the whole balanced triode was Groove Tube, and we all know what a rip off they are. I haven 3 heads, 2 are running 9th gen Chinese and 1 is running JJ's. None of them have a PI. I put one in and never noticed any difference.
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Re: BALANCED 12AX7?
You'll only really get the effect if the value of the resistors in the phase inverter are matched too... and vintage amps (and many newer commercial amps) use 5-20% tolerance parts. If it makes you feel better go ahead, but I wouldn't stress about it. It's more of a 'hi/fi' thing anyways - and a guitar amp is far FAR from hi fidelity.
Just my 2 cents.
Pete
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Re: BALANCED 12AX7?
[ QUOTE ]
*****I haven 3 heads, 2 are running 9th gen Chinese and 1 is running JJ's. None of them have a PI.*****
Unless your heads are single ended amps (like a Fender Champ), then they absolutly DO have a PI.
[/ QUOTE ] What are you talking about? I know for a fact that I didnt put a balanced tube in.
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Re: BALANCED 12AX7?
thebisch, paul ment that he didn't put a balanced tube in his PI tube spot. alot of people just call them "PI tubes" sometimes, even though it's just a regular tube, just inverting a 180 phase.
if i'm ordering a set, and it comes with it, then sure. why not? i have one in my boogie from JJ right now. just for piece of mind i guess.
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Re: BALANCED 12AX7?
[ QUOTE ]
thebisch, paul ment that he didn't put a balanced tube in his PI tube spot. alot of people just call them "PI tubes" sometimes, even though it's just a regular tube, just inverting a 180 pha
if i'm ordering a set, and it comes with it, then sure. why not? i have one in my boogie from JJ right now. just for piece of mind i guess.
[/ QUOTE ] Yea,but do you notice any difference in the tone?
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Re: BALANCED 12AX7?
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I haven 3 heads, 2 are running 9th gen Chinese and 1 is running JJ's. None of them have a PI.
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All tube amps except for small single ended amps like a Gibson GA5 or Fender Champ have a phase inverter.
And as for the balanced issue, I challenge anyone to find a tonal difference. If you can than your ears are better than mine or anyone else that I know. [img]/images/graemlins/scratchhead.gif[/img] I think it's just a way of milking a few extra bucks for a tube.
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Re: BALANCED 12AX7?
You don't need a balanced PI tube, but for a couple bucks it isn't going to hurt. Most of the common amps use a long tailed phase inverter circuit which is self balancing. The circuit is also deliberately skewed to help make up for the imbalance in the output transformer winding.
Jerry
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