The Watering Hole

Custom Shop
2 posts
This article will begin to address some basic concepts of tube loadlines - or how to bias a tube.   The focus, here, will be in the triode, which is seen in pretty much every preamp out there, with some notable exceptions (Matchless DC30, VOX AC15, etc).  The rules/principles, applied to the triode, are fundamentally applicable to the Pentode and Tetrode – used in the power amps.  
As much of the amplifier voicing comes, fundamentally, from the preamp, I thought it more important to start there.   After this series of articles, we’ll begin to focus our attention on more “mundane” aspects of electronics – voltage, current, resistance, capacitance and inductance and the rules that govern those elements.   Without a solid understanding of these principles, a lot of what has been explained heretofore, won’t make a lot of sense.    But, since I started the topic of tube bias, I figured I might as well finish it.
Loadlines are the fundamental method used to bias a tube.   They’re relatively simple to construct, and understand
Nice work Dar  8-).

I do feel that the standard "beware high voltage can kill" disclaimer ought to come into play at this point. I doubt we have anyone here who doesn't know this (or they wouldn't be here reading this) but, you never know who lurks.

Stupidly enough, more people are hurt/killed in "MY" industry (Air Conditioning) by low voltage 24 and 48 VDC control curcuits. this is mainly because these curcuits run at stupid high amperages (600-1000A).

Beware guys, this stuff doesn't just hurt if you get it wrong!!!