Can someone explain, in dummy terms, what effect a 12AX7 has on the tonestack?

[RockStarNick]

I've heard that in a preamp design, there is a 1/2 cathode folower for the tonestack. (I'm aware that a 12AX7 has two halves, and each can operate independently.) And I'm well aware how different tubes (NOS vs new) can sound very different in the "Drive" section of the preamp (i.e., V1) Cuz I can hear the differences very clearly.

My Q is: What kind of effect does the type of tube have on tone, when half of it is used for the tonestack?

For example: V1 tube: each half is a gain stage. V2 tube: 1st half gain stage, 2nd half used for the EQ.

What kind of characteristics in a tube would work well for this position?
Since half of that tube is used as a gain stage, is that portion of the gain circuit more, or less, susceptible to microphonics?

[jamme61]

Even the same type and brand tube, can sound different from each other. a cool thing IMHO, that cost no money, is to swap around the tubes that are in your amps pre. So take V1 and put it in V2 and V2 in V1, you'll hear differences and will find something that sounds best to your ears. try to p/u some tubes to experiment with (it's doesn't have to be NOS, to much $) get a JJ, Chinese, Russian, 12ax7 and check out the lower output - 12at7,12au7, 5751. It's bets to figure out what you like, - your style , amp, guitar, fingers. IMHO

[RockStarNick]

Ah ha, that brings me to another question: Can a 5751 be used for a V2, in which half of it drives the tonestack?

Yeah, I've been doing alot of swapping lately. I've found that, to my ears, I'm really liking when I mix and match two different types of tubes. It's like they cancel out each other's bad things, and make up for what each other lacks, in a good way.

Example: All JJ's are kinda dull. But a Tungsol into a JJ, or vice versa, sounds kinda cool.

[jamme61]

It's cool doing this stuff but, sometimes I give myself a headache LOL. You can use any of those tubes listed, in any of the preamp positions. it's best to hear it for yourself, I have no idea how the 5751 will sound in your V2, maybe a little less volume, cleaner, a little more high end? I could be way off, give it a shot. It's all fun

[rockon1]

Ah ha, that brings me to another question: Can a 5751 be used for a V2, in which half of it drives the tonestack?

.

Yep,or a 12AY7,12AT7,or 12AU7 etc....Bob