ToneQuest

First and most important. There are four different functions that different tubes perform.

Preamp tube - Typically these are from the 12AX7 family, which includes the following:

ECC83- for the Marshall sort of sound

7025 - for the Fender 60’s and 70’s sound

5751 - for blues and less aggressive attack

Preamp tubes are the most critical, least expensive, most overlooked tubes in your amp. The preamp tube in the first gain stage (usually V1 and / or V2) sets the tone and initial gain structure of the amplifier

Each half of the preamp tube works separately in the circuit even though it the same tube. It is good to have both halfs matched.

Best buy is in this group (In decreasing order)

1) JJ/Tesla 12AX7S

2) GE 12AX7WA

3) Ei EC83/12AX7

http://www.guitaramplifierblueprinting.com/12ax7.html

Rectifier tube

The rectifier basically converts the AC line current coming into your amplifier to the DC voltages that are needed. The power limits of your amp's transformer limit the choices that can be made!

GZ34 = 5AR4 GZ32 = 5U4 = 5V4GA GZ31 = 5U4GB GZ30 = 5Y3GT

Driver tube

The driver tube can be consider the interface between the preamp section and the power amp section

Power tube

Power tubes drive the speaker transformer and must be impedence match to it and the speakers.

Biasing - These are the tubes that are biased. (Although several amp manufacturer preset the bias and market it as "Self biasing or Cathode Biased) all thee tubes can be self-baised, that is preset to run with a certain voltage.

Class A verses Class A/B1 - Again more marketing stuff, all these tubes can be setup to be Class A or Class A/B.

Several different styles and power outputs for each power tube grouping.

6V6 Group - Fender Princeton sound

EL-84 Group - Mesa Boogie Dual Caliper sound

6L6 Group - US Rock and Roll via Fender

5881 Group (Confused with a 6L6, because it was designed as a military replacement, but not as a copy)

GEC KT-66 - Beano sound, Marshall bluesbreaker sound, No longer made by GEC - currently cheap copies

EL-34 Group - Classic English Marshall sound

KT-88 Group - Big round sound

6550 Group - Thickest and most powerful tube currently being used for guitar amps - Classic US Marshall sound

I use several different Sims. Pod 2.3, J-Station, RP2000 and Sans.

I like each for different reasons and have use one to drive the other. (Pod into the RP2000)