More than anyone ever wanted to know about Fender Bassman Amps

[Barry Schaede <barrys@xxxxxxxxxxxxxxxxxxxxxxx>]

The tweed 4-10 Bassman is an entirely different amp than the 50 watt 
silver face Bassman heads.  The 4-10 Bassmans have pressence and middle 
controls that the heads lack.  The 4-10 Bassman uses a 2 ohm output 
transformer that is interleaved and wound on a paper core.  The silver 
face Bassmans use a 4 ohm output transformer wound on a plastic bobbin.  
The 2 types of transformers sound dramaticaly different to  most ears.  
The tweed Bassman uses a tube rectifier that is unable to supply full 
current at peak demand and creates a sound in the output tubes known as 
sag. A much sought after phenomenon.  The newer Bassman uses solid state 
diodes to rectify the current which results in a cleaner less distorted 
sound.  The phase inverter circuit of the silver face Bassman uses a 
12AT7 tube instead of the 7025 or 12AX7 used in the tweed version.  The 
Output tubes of the siverface are 6L6GC's instead of the 5881's founds in 
the original Bassman.  5881's are a higher performance military grade of 
the 6L6 tube.  They use gold in the internal conductors instead of the 
original silver used for the 6L6's and as a result have less output and 
lack the fidelity of the 5881's.  Yes you could put 5881's into the newer 
Bassman but it still wouldn't sound the same as the 4-10.  The silver 
face Bassman is probabaly a head.  That is it lacks the built in speakers 
of the Tweed combo.  This presents the problem of finding a cabinet that 
matches the impedance of the output transformer (8 ohms) and sounds 
good.  What you'll probabaly find is 2-12 closed back cabinets.  Not in 
my opinion a good sound for harmonica.  You could try the Peavey 4-10 
open back cabinet but you'd be running at a 100% impedance mismatch.  Not 
a terrible thing to do but not the best thing to do.  Oh one last thing 
the silver face Bassman has a deep and bright switch that the older 
version lacks.  I've never been able to get a tone I like out of the 
newer Bassmans.  Not so much because they're bad amps but more because 
they're more suited to guitar.  Try the amp and if YOU like the sound buy 
it.  After all if Lee Oskar can play through a solid state Roland bass 
amp and be happy anything's possible.  FJM