Actually they are not as bright as an 833A, they just pump out more heat.
The 4-250 and the 4-400 are very similar, the 4-400 has radiator fins on the plate, so it can dissipate more power. They are both tetrodes. The screen grid voltage is 800 volts max, which would allow triode connection at low (800 volts) voltages.
Operation as a tetrode can lead to nonlinearities, but it is also possible. Neither of these conditions is optimum for a good audio amp.
The 4-250 and the 4-400 are very similar, the 4-400 has radiator fins on the plate, so it can dissipate more power. They are both tetrodes. The screen grid voltage is 800 volts max, which would allow triode connection at low (800 volts) voltages.
Operation as a tetrode can lead to nonlinearities, but it is also possible. Neither of these conditions is optimum for a good audio amp.
You might be able to get away with fewer of the Hammond trannies than you'd think.
http://www.dogstar.dantimax.dk/tubestuf/dzindex.htm
"I found that the doubled-up output transformers really isn't necessary. Dogzilla works just fine with "just" a single Hammond 1650R. Just goes to show how conservatively rated these things are; I'm still getting well in excess of 200 watts out of a single transformer rated at 100 watts (albeit for hi-fi use), with no sign of overheating."
Granted that is for Guitar amp duty,but even in HiFi applications you can "push" them a fair bit.
http://www.dogstar.dantimax.dk/tubestuf/dzindex.htm
"I found that the doubled-up output transformers really isn't necessary. Dogzilla works just fine with "just" a single Hammond 1650R. Just goes to show how conservatively rated these things are; I'm still getting well in excess of 200 watts out of a single transformer rated at 100 watts (albeit for hi-fi use), with no sign of overheating."
Granted that is for Guitar amp duty,but even in HiFi applications you can "push" them a fair bit.
Well for a nice simple amp, how about a single-ended 6L6 with 12SN7 for a driver?
That would sound good, and be very easy to make.
That would sound good, and be very easy to make.
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