Click to enlargesome info to see if your amp has solid state sections or is all tube.

Lots of current amps say "all tube" unfortunately this is just not totally true.
The companies exclude effects like the reverb, effects loop, channel switching, even some  have a solid state preamp driving the input of the overdrive stage to avoid an extra tube - and they say "all tube"

 12AX7 (12AT7, 7025, 12AY7,5751 ETC)  tubes have two stages each I will count EACH stage  as  1/2 tube, both stages as "1 tube.    it takes 2 of the 1/2 tubes to make "one tube"

 If the amp has power tubes it has to have a phase inverter = 1 tube ALWAYS.   BE SURE TO ADD THIS ONE TUBE TO ALL AMPS

A Marshal preamp (tone control section) with ONE channel has three stages for just a clean channel = 1 & 1/2 tube

 the standard vintage Marshall has an extra volume (no distortion channel, just more bass on that volume) = 2 tubes.

 a fender tone control section = 1 tube. Optional

 that is 3 preamp tubes for a vintage Marshall NO EFFECTS, OR OVERDRIVE

 a Marshall like "overdrive" is at the least = 1/2 tube optional More commonly 1 tube

  double this if you amp has two complete channels (both with their own set of tone controls)

 a reverb at the cheapest = 1 tube a good quality (fender like) reverb = 2 tube Optional

a vibrato as used by marshall = 1 tube optional

an effects loop at the least = 1/2 tube a good effects loop with level controls = 1 tube optional

 AND the companies like to end up with an even count of tube halves. they do not like 1/2 tube hanging around, just not economical.

 Add them up, kind of hard to do, all the one tube and 1/2 tubes and see how many preamp tubes are NECESSARY to have an "all tube" amp with the effects your amp has.  If it doesn't add up, some stuff is solid state.  For Example, a Marshall 900 with 3 preamp tubes CAN'T have a tube reverb, overdrive, effects loop etc.

 See, kind of tricky and LOTS AND LOTS of amps are NOT all tube
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