Please ensure Javascript is enabled for purposes of website accessibility Jump to content

Tube F.A.Q.


Q: What is the difference in power rating between tube and solid-state power amplifiers?

A: Tube power outputs can peak 200 to 400% above solid-state, so a 50watt tube power amp can output a volume equivalent to a 100-200w solid-state amplifier output.


Q: What are the common Preamp tubes?

A: The 12AX7 (ECC83 is the European term, or the military term of 7025) is the most common preamp tube for driving the Gain and EQ sections of the amplifier, as well as driving the signal into the power amps.


The following tubes have a lower power rating and can be used in the preamp section or other amplifier functions such as the reverb tank drivers, inverters, etc.


12AT7 (ECC81, 6201): 60% power of the 12AX7

12AU7 (ECC82, 5963): 19% power of the 12AX7

12AY7 (6072): 45% power of the 12AX7


Q: What are the common power amplifier tubes?


6L6 (5881/KT66): Commonly used in American amplifiers such as Fender, Mesa, Peavey. Typically has more low-end emphasis.

EL34 (6CA7/KT77): Commonly used in British amplifiers such as Marshall. Typically has more midrange emphasis.

EL84 (6BQ5): Commonly used in Vox , Gibson, Matchless, and Bad Cat amplifiers

6550 (KT88): Commonly used in VHT, Ampeg SVTs, and Leslie Speakers cabinets. Typically has more power output than the other tubes listed here.


Q: What other power amp tubes are compatible with the Spider Valve?

A: Line 6 stresses using 6L6 (5881/KT66) power amp tubes only. Other power amp tubes such as 6550's can draw too much power and damage your amp and void your warranty.


Q: How long should I let tubes "cook" after biasing before I measure again?

A: The standard cooking time is 3-6 hours after an initial bias (regardless of the tube age).


  • Create New...