So it is, like most LS100's, actually an ELS100 as the inside tag says. He made the switch from the 6550 early on since there was some issue with heat from the tube, so well I guess I'm better off, but as you probably know, us bass players tend to like the 6550. I got to play with it a bit yesterday although mostly with guitar since I had to rehearse some stuff. Needless to say, it kills, I'm actually overly impressed by it and it easily fits into the running for best tube amp I've ever heard for both guitar and bass. Here is some info on the gain stages I found online:
"TWO GAIN STAGES.
The normal preamp gain structure of a Fender, Marshall, or Vox amp is
stages. The difference between Fender and the English designs, is the
use a first gain stage feeding a volume control, which then drives a
tube. Following are the Tone Controls, with no additional gain into the
Driver. This design allows the player to turn the volume up to the point
where the second gain stage starts to distort. This is all but
with a fender, because the Tone Controls AND the Volume Control throw
so much gain before the second gain stage is met, it's nearly impossible
get the Fender into high gear.
THREE GAIN STAGES
But if you add another Gain Stage to a Fender after the Tone Recovery
plenty of drive can be provided into the Inverter/Driver tube. With
one Gain Stage added after the tone controls (Post-EQ), you have a
A total of three gain stages.
THREE GAIN STAGES WITH MASTER VOLUME
Add one gain stage in front of the Tone Controls (Pre-EQ) and you have
the Marshall Master Volume design. A total of three gain stages, all
in front of the EQ, and none behind...
I'm going to divide all designs into two major classes: Pre-EQ and
design. To identify these different topographies, we'll use a notation
3+0 for the Marshall above. Some different amps would then be:
Vox Top Boost 1+1
Nash, Clean 1+1
Trainwreck Rocket 1+1
Trainwreck Express 1+2
Nash, Dirty 1+2
Marshall MV Low Inptut 2+0
Marshall MV Lee Jackson 2+1
Marshall MV Hi Input 3+0
Marshall MV Frank Levi 3+0
Marshall MV Soldano 4+0
Thunderfunk 100ELS 4+1
FOUR GAIN STAGES
Add to gain stages in front and you have a Thunderfunk, or
Soldano Marshall amp for a total fo four gain stages (Pre-EQ).
The more gain stages you add, the smoother, the more
compressed the tone. The four gain stage designs have an
instant Allman Brothers tone. The three gain stage designs
have a rougher more aggressive texture to them. I was
working for a guy named Eddie, and he thought the three
gain stage, Post EQ design had too much gain. He preferred
the Thunderfunk, which is actually, at four gain stages, the
higher gain design, but sounds smoother.
FIVE GAIN STAGES
The Soldano amp has Five Gain Stage Pre-EQ, but the
FX loop is part of it. If you remove the FX gain stage
you're back to four distortion stages."
Two 6 spring units:
I will be updating with more info when I have time since I can't find another resource for this amp out there. Please chime in with any info you have about these amps. Thanks.