Fixed bias δεν σημαίνει ότι δεν θέλει ρύθμιση ή τουλάχιστον έλεγχο του bias, ίσα ίσα οι περισσότεροι fixed bias ενισχυτές έχουν τρίμμερ ή ποτενσιόμετρο για το λόγο αυτό.
Γεια,
απο το manual F-100.
Eχω αλλαξει δυο φορες σε boogie λαμπες και δεν πειραξα τιποτα.
Και επαιζε και παιζει σουπερ.
Well, there’s a short answer and a long answer to this question.
The short answer is that during my 12 years of repairing Fenders, one of the most frequent problems I saw was bias controls that were
either set wrong or that had wandered out of adjustment due to vibration. As any honest tech will tell you, there’s lot’s of easy money
to be made by sprinkling “holy water” on amplifiers ... uh, what I meant to say is “Your amp needed biasing.” See what I mean? What
customer is going to argue with that?
It only takes a moment and a volt meter: The Fender diagram shows how: “Adjust this trim pot for - 52 volts.” That’s it. Nothing more.
Now don’t be fooled into thinking that tubes “draw” more or less bias, they don’t. The way a bias supply is connected to a tube is akin
to a dead end road, it just trails off to nowhere without really completing a circuit. It’s a static voltage and regardless of what tube is in
the socket — or even if the tubes aren’t plugged in at all, it doesn’t change the bias voltage a bit.
So the end of the short answer is this: Since a bias supply needs to put out the right voltage and never vary, I wanted to build
amplifiers that were individually hard wired to the correct values and NEVER needed adjustment. And for 25 years, that’s how Mesa/
Boogies have been built.
Time to change tubes? Just plug our tubes into any one of our amps and you’re DONE. No tech needed. NO bills and no BS about
biasing. And most important: The bias is RIGHT because it can’t change!