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previous: Randy Jamz I have been using and do occasional... -- 10/9/2000 10:43 PM

Re: zener diode part #

10/10/2000 2:00 AM
nuke	Re: zener diode part # Randy, as has been pointed out, you can't beat ohm's law. If you have a 4x 6L6GC (like a SF Twin) that's sitting at 525 volts at idle, and you like to knock 40-50 volts off of that, what are you going to do? The idle current is going to be 4x 40ma just for the 6L6GC's. That's 160 ma, so you'd need a 250 ohm resistor to drop 40 volts. That produces 6.4 watts of heat. Now Randy, go ask your old Canadian guru what happens when you stick a 250 ohm resistor in series with the power supply. I'll give you a hint, it increases the source impedance by 250 ohms. Now, take that amp and put a signal through it, and crank it up so it puts out 60 watts, then you'll see what I mean by "sounds like ass." If you pull out a pencil and paper and work out what happens when the amp is under load, you'll quickly discover that there's too much sag, the amp can't make power and your 250 ohm resistor will quickly go up in smoke. (exercise left up to the reader, but here's a hint E=IR ) The zener on the other hand, will not result in appreciably increased power supply Z, will offer a constant voltage drop, less power expended as heat, and if properly heat-sinked (bolted to the chassis or other suitable chunk of metal), probably never fail. FWIW, you are well on your way to whistling dixie out your butthole, cause you've made repeated showings with your pants down on technical matters.

10/10/2000 2:00 AM

nuke

Re: zener diode part #

Randy,

as has been pointed out, you can't beat ohm's law.

If you have a 4x 6L6GC (like a SF Twin) that's sitting at 525 volts at idle, and you like to knock 40-50 volts off of that, what are you going to do?

The idle current is going to be 4x 40ma just for the 6L6GC's. That's 160 ma, so you'd need a 250 ohm resistor to drop 40 volts. That produces 6.4 watts of heat.

Now Randy, go ask your old Canadian guru what happens when you stick a 250 ohm resistor in series with the power supply.

I'll give you a hint, it increases the source impedance by 250 ohms.

Now, take that amp and put a signal through it, and crank it up so it puts out 60 watts, then you'll see what I mean by "sounds like ass."

If you pull out a pencil and paper and work out what happens when the amp is under load, you'll quickly discover that there's too much sag, the amp can't make power and your 250 ohm resistor will quickly go up in smoke. (exercise left up to the reader, but here's a hint E=IR )

The zener on the other hand, will not result in appreciably increased power supply Z, will offer a constant voltage drop, less power expended as heat, and if properly heat-sinked (bolted to the chassis or other suitable chunk of metal), probably never fail.

FWIW, you are well on your way to whistling dixie out your butthole, cause you've made repeated showings with your pants down on technical matters.

Replies:

Randy Jamz au contraire, mes amie. My 'Canadia... -- 10/10/2000 10:54 PM