[Boatanchors] various rectifiers

[Troglodite at aol.com]

In a message dated 7/6/2006 2:24:16 PM Central Standard Time,  
mikea at mikea.ath.cx writes:

> I'll risk asking a question that may start some controversy,  because
> I genuinely am interested in the answer as the owner of a Fender  
> Bassman and some old tube-type stereo amps. 

> How would  going from tube rectifiers to SS rectifiers change the tome
> of an amp?  It's all DC at the filter output, isn't it?
 
Mike,
 
You'll get all kinds of answers on this, some informed, some snake oil. :-)  
Generally, there's not too much snake oil in this group, but you never know.  
Anyway, here's mine:
 
The Fender Bassman with the four 10" speakers is one of those classic  
designs like the DC-3 airplane. It is nearly perfect just as it stands. If you  want 
different sounds, buy another amp, don't mess with a classic. Put in new  
output tubes, change the electrolytics and wax/paper capacitors if necessary,  
but don't change the basic circuitry.
 
If you put in silicon diodes, the voltage will go up just enough to stress  
the output tubes. The sound will be "harder" due to the lack of voltage droop 
in  the vacuum rectifier. The electrolytic capacitors will be under more 
stress.  (These tend to dry out in the Fender amps due to their "upside down"  
construction with the heat from the tubes heating the chassis.)
 
In other words, "If it ain't broke, don't fix it."
 
Doug Moore