"Greg Mayman" wrote to "Mike Ross" (03 Dec 02  09:24:00)
 --- on the topic of "TRAFFIC LIGHT"

 -=> Mike Ross said to Thom Kouwenhoven
 -=> about "TRAFFIC LIGHT" on 11-30-02  10:44.....

 TK> Isn't 50 ohms a bit low for the driving tubes ?

 MR> Those were special low plate impedance tubes designed to specifically
 MR> operate with the 12 volts from a car battery. The 12AL8 was one. By

 GM> My data book shows the recommended load for a single 12AL8 in
 GM> class A as 800 ohms.
 GM> A pair of them in push-pull class AB or B
 GM> wouldn't be very much different from that figure.

In Push-Pull the plate resistance is 4 times less than the plate to
plate value. IOW 2 times the voltage = 4 times more power. Does this
make sense? Hey, I might be helping prove your point...


 GM> I'm pretty sure that the 50 ohm CT speakers were used only with
 GM> transistor output stages.

You could well be right...

 Mike
 ****

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