Phase inverter/driver tube question

[TSE]

Hi, I play a 6505+ half stack using Groove Tubes and I've been getting some mixed messages about which tube is best for the driver stage. Some guys say the 12AX7C is best because it is linear and close to full 12AX7 spec and other people are saying go with the 12AX7M, Mullard copy because it reaches full 12AX7 spec and it is ballanced or matched or something. Does it really matter, also how does the tube in the driver stage affect the overall sound? Right now I have a 12AX7C in there, would it be better sonically and functionally to use the 12AX7M?

Thanks alot for any help.

 

[jeremy]

Re: Phase inverter/driver tube question

the pi has minimal effect on tone itself but the way it works with the other parts of an amp effect the tone.

personally i would go with the 12ax7M for the pi. its a stronger more rugged tube that will hold up better in the harsh environment of the phase inverter.

basically the pi takes the signal from the preamp and bumps it up and splits it into two signals 180 degrees out of phase that go to the push pull output section. a stronger tube will push the output section more.

 

[Sludgenutz]

Re: Phase inverter/driver tube question

I would respectfully disagree with jeremy's first statement, that the PI is not important to tone. My Sunn will take any PI tube and sound the same. OTOH, my Mesa is far pickier. Different brands sound different...even at this last stage of the preamp circuit. It all depends on the circuit, I suppose. YMMV.

FWIW, I just spend the extra $3 for balanced output sections...because in the course of year of money making...I can afford it this small amount. 12AX7's are dual triodes, meaning there are two independent triode sections enclosed within the single glass envelope in which they are encased. These two sections can actually amplify very differently...so tube sellers sell "matched triodes" for a few dollars more each.

There are no universal standards by which tube sellers test their tubes, and one must trust the seller in this respect. It also of note, that the guitar greats who created the finest tones in the history of amplified guitar music, never knew what a phase inverter tube was, or could have possibly cared about phase inverter matching.

I am tortured by info overload, so I like balanced outputs on the phase inverter tube.

 

[Dr.Mavashi]

Re: Phase inverter/driver tube question

the pi has minimal effect on tone itself but the way it works with the other parts of an amp effect the tone.

personally i would go with the 12ax7M for the pi. its a stronger more rugged tube that will hold up better in the harsh environment of the phase inverter.

basically the pi takes the signal from the preamp and bumps it up and splits it into two signals 180 degrees out of phase that go to the push pull output section. a stronger tube will push the output section more.

So what type of playing do you think Balanced tube in PI is needed for more than others?

 

[kmcguitars]

Re: Phase inverter/driver tube question

So what type of playing do you think Balanced tube in PI is needed for more than others?

Hi-Fi Stereo Audiophiles types. I don't consider my guitar amp to be Hi-Fi. IMO tube amplification is at the bottom of the food chain when It comes to Hi- Fi circuitry.:cool2:

 

[jeremy]

Re: Phase inverter/driver tube question

I would respectfully disagree with jeremy's first statement, that the PI is not important to tone. My Sunn will take any PI tube and sound the same. OTOH, my Mesa is far pickier. Different brands sound different...even at this last stage of the preamp circuit. It all depends on the circuit, I suppose.

the phase inverter is actually part of the power section even though it uses what are typically preamp tubes.

like i said, the pi itself doesnt do much for tone but the way it interacts with the rest of the amp does. mesa amps are typically designed to have a very clean power section where the preamp does most of the work, so it makes sense that different pi tubes will effect the overall sound of the amp since different tubes have different output characteristics.

 

[Gr8Scott]

Re: Phase inverter/driver tube question

I'm like Jeremy in the respect that I primarily go for a good strong design. I also look for something hot because I want to push my output section a bit more. It doesn't have much of an effect on tone, but it does effect it slightly in terms of the amount of distortion I get out of the power tubes.