Balanced phase inverter tube?

[Little Pigbacon]

I've read a lot of conflicting things about phase inverter tubes. This is the dual triode that generates the negative waveform for half the tubes in a push-pull amp. Basically I'm hearing three things:

1) You want a tube that's been tested for a close match between the two sides, i.e., a tube that is "balanced".

2) You don't gain anything with a balanced tube in the phase inverter spot, so you'd might as well save a couple of bucks and get a regular, unbalanced tube.

3) A balanced tube actually sounds worse, so use a regular, unbalanced tube.

What do you think?

 

[Scott_F]

Balanced phase inverter tube?

Grab a tube and pop it in there an listen. Tubes that are noisy in V1 or V2 end up in a PI spot much of the time.

I don't place a lot in balancing the PI. Even when you buy matched power tubes, they are never exactly the same. Never in my experience. So why bother on the PI? That's my two cents.

You get to the point where you start chasing your tail. I want amps that work well with new production tubes and don't require uber matching of the PT's. I think a tiny bit of mismatch sounds good.

 

[JeffB]

Re: Balanced phase inverter tube?

Don't know. Have not tested it. Like anything tube related- lots of a-holes/opinions.

 

[jeremy]

Re: Balanced phase inverter tube?

ive used balanced pi tubes and also just thrown in whatever and havent noticed much difference

 

[Gone_Shootin]

Re: Balanced phase inverter tube?

I prefer an unbalanced PI tube in a guitar amp. The difference is subtle, though.

 

[Hank-]

Re: Balanced phase inverter tube?

You will need to try it out to know for sure for the amp in question and for your preference

Buy a cheap higain+balanced tube & another one of same brand that is just high gain(i assume they allow both options on some online sites). If you prefer the balanced one in the PI spot then get those next time around.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

I have a balanced and an unbalanced 12AX7-EH coming.

 

[Rex_Rocker]

Re: Balanced phase inverter tube?

It's only a couple of extra bucks for a tube with balanced triodes, so I don't see why not.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

I'm more concerned about the theory behind the why/why-not than about the $2. What if you order a regular tube but just happen to get an untested tube that's closely balanced?

 

[jeremy]

Re: Balanced phase inverter tube?

in a perfect world i think it matters but in the real world where there is a 10% tolerance or more i dont know how much benefit there is. in my old deluxe i tried two tubes that tested similar other than one was closely balanced and the other wasnt. i cant recall the exact numbers since it was a while ago but there wasnt enough difference for me to really care.

 

[MetalManiac]

Re: Balanced phase inverter tube?

Phase inverter gets a lot of stress. I've read it's best ot replace it well b4 the rest of your tube compliment.

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

Phase inverter gets a lot of stress. I've read it's best ot replace it well b4 the rest of your tube compliment.

I'm hearing from a lot of people that it should be changed along with the power tubes.

 

[MetalManiac]

Re: Balanced phase inverter tube?

I'm hearing from a lot of people that it should be changed along with the power tubes.

That makes sense. From what I understand with modern amps with the tube sockets on the circuitboard, with modern production tubes, it's a best bet to replace them one a year , assuming you play the amp regularly. If one of them Power tubes gives up the ghost , you have a real mess on your hands with one of those amps.

 

[Gone_Shootin]

Re: Balanced phase inverter tube?

I'm hearing from a lot of people that it should be changed along with the power tubes.

Huh? I never have

 

[zzmoore]

Re: Balanced phase inverter tube?

Grab a tube and pop it in there an listen. Tubes that are noisy in V1 or V2 end up in a PI spot much of the time.

I don't place a lot in balancing the PI. Even when you buy matched power tubes, they are never exactly the same. Never in my experience. So why bother on the PI? That's my two cents.

You get to the point where you start chasing your tail. I want amps that work well with new production tubes and don't require uber matching of the PT's. I think a tiny bit of mismatch sounds good.

I think this is pretty much the essence of it.
Certainly nothing "wrong" with buying a matched tube. As said above.....give it a try and see what you hear.
A matched PI is probably not high on the list of Import where most builders are concerned.
good luck

 

[Myaccount876]

Re: Balanced phase inverter tube?

I usually don't give the phase inverter much thought. As long as it works and retains at least some clean headroom, then good enough. That position is more about functionality than tonality and current production tubes are fine IMO.

 

[Nostalgic Distortion]

Re: Balanced phase inverter tube?

Grab a tube and pop it in there an listen. Tubes that are noisy in V1 or V2 end up in a PI spot much of the time.

I don't place a lot in balancing the PI. Even when you buy matched power tubes, they are never exactly the same. Never in my experience. So why bother on the PI? That's my two cents.

You get to the point where you start chasing your tail. I want amps that work well with new production tubes and don't require uber matching of the PT's. I think a tiny bit of mismatch sounds good.

Here here!!!

 

[Gone_Shootin]

Re: Balanced phase inverter tube?

I usually don't give the phase inverter much thought. As long as it works and retains at least some clean headroom, then good enough. That position is more about functionality than tonality and current production tubes are fine IMO.

I used to think that way, until I tried a JJ. Then my ears perked up and said, "This, I like this!"

 

[Little Pigbacon]

Re: Balanced phase inverter tube?

I didn't order any JJ preamp tubes. But there's always next week.

 

[ken361]

Re: Balanced phase inverter tube?

Sovtek LPS are good PI tubes