Go to http://aikenamps.com/ and click on the "Tech Info" link. Start with the "Basic" topics.
"A cheerful heart is good medicine."
Cathode Bias, a cathode resistor is used. Grid voltage is kept at ground potential with a high value resistor.
Joe
If there is referrence to an analogy it must be in the topic itself. Look up analogy to find out what it means. :shock: Here's another analogy: Bias is like the idle of a car. Imagine driving and having to stop your car every time you hit a red light and then having to start it again when the light turns green. You wouldn't be getting anywhere fast. Bias is like idling in that there is current so that when a signal flows through the "car" can continue on without interruption. In otherwords the tube doesn't have to keep "warming up" to operation speed. If there were no bias it would be like a very high threshold gate but much slower. So, your sound would come out of the amp in swells instead of the continuous sound that we've grown so accustomed to. :P
Analogy is the comparison of two pairs which have the same relationship. The key is to ascertain the relationship between the first so you can choose the correct second pair. Part to whole, opposites, results of are types of relationships you should find.
When you're dealing with electrical current or water, remember: If you keep putting in either water or electric it has to come out someplace. Let's look at the water analogy: you have a hose with just a dribble of water coming out. Half the water is leaking out of the back of the faucet, and the other half comes out of the faucet output. Now try it again with a good controller. The nozzle on your garden hose is good; just a little water leaks out of the trigger on the nozzle. Where does the rest of the water go? Same as with a electrial circut, a good circut will send almost all of the input current to the output.
It could also be call hydralic analogy, bathtube analogy, water analogy.
The bias of a tube amp is referring to the idle current of the tube. To help set the bias current, the grid voltage is adjusted (which is a negative voltage), which in turn sets the current. You are adjusting the voltage of the grid which in turn controls the degree to which the output tubes overlap in conduction.
Joe
