Larrchild wrote on Thu, 25 March 2010 22:17 |
Ryan, didn't Tubby or Scientist build some leviathan tube amp? Maybe it was another dubster but I think you posted pix. |
Larrchild wrote on Thu, 25 March 2010 14:28 |
The tough part with these amps is that the plate load is pretty hi-z so an output transformer that passes full HF is tough due to size and high-ratio. |
Larrchild wrote on Tue, 30 March 2010 16:43 |
Svetlana once took a 4CX250 external anode tetrode (forced-air all-metal transmitting tube) tube die and built it as a triode with a desired load of about 700 ohms. Dunno if it's still around, but that had promise. (if you put it in another room to overcome the blower!) |
Jim Williams wrote on Tue, 30 March 2010 17:38 |
For those interested in mondo power tube amp design, Electro Harmonix has released the new KT120 power tube. 60 watts each and you can do some severe damage with those. Maybe I'll replace the GE6550's in my 1966 Deluxe Reverb with a pair of those. It could win the mighty small amp award. Great for small clubs when no one suspects the little amp as the offender. |
Larrchild wrote on Tue, 30 March 2010 14:56 |
In his circuits with rows of tv tubes or KT-88's, the load is reasonable as you say, but with 4 transmitting tubes, it's still pretty high. (9500 ohms) I'm saying transmitting tubes like 813's operating at higher voltages seem to want a fairly hi-Z load. Looks like a pair of 813's in AB1 want 19 k load resistance @2500 vdc. http://faculty.frostburg.edu/phys/latta/ee/wing813amp/813dat asheet1.jpg |
Jim Williams wrote on Tue, 30 March 2010 17:38 |
It could win the mighty small amp award. |
RMoore wrote on Tue, 30 March 2010 10:04 |
Apparently there is the possibility of arcing with these 813's if there is a failure mode.. |
bruno putzeys wrote on Thu, 01 April 2010 04:06 | ||||
Ah right. I should've done my homework there (I only looked at the posted pic which showed 8 smaller tubes). 9500 is high.
I'm afraid I'll always win that one. |