Don't know why, but I keep having "thoughts" about using these monsters in a single ended amp.
I know Darren had one, and at Owston Nick admitted a fancy for them as well.
My question is, what is likely to be the minimum HT to get them working well in an audio amp and what spec of output transformer would likely be required.
I'm hoping that something like 1 - 1.5KV would be enough.
This is (to me) the ultimate "once in a lifetime" amp.
The only thing necessary for the triumph of evil is for good men to do nothing.
Ye, as you say, the 100th has prompted a certain desire towards the 833. I think something like 1500v @ 150ma, grid at -20v, with a direct coupled A2 driver and a 7k5 transformer could be expected to produce something in the order of 75W.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
I have to admit to having a pair of 833's, a pair of hammond 1642SE's and four 5v 10 amp smps waiting in the wings to keep me quiet when the gm70's are finished. I plan to use the 1.1Kv 250ma PSU's i have bult for the GM70 PP amp.
The big question is how to drive them, I must admit Tube lab's powerdrive looks good. Phillip at bluebell hinted he is working on some 4:1 SE interstages with hammond for a KT88 or 300b driver but i have not been able to get any more than that from him than that.
It will make some sound, not that much, but then again you probably dont need that much.
James, my musing was thinking about using the same sort of driver as I did for the 100Th, if anything the 833 would be a easier load, less grid current as the 100Th was sitting with the grid at +20, the 833 would be about -20v. Its similar to the power drive, just using high gm beam pentodes with a active load (another pentode).
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
James wrote:I have to admit to having a pair of 833's, a pair of hammond 1642SE's and four 5v 10 amp smps waiting in the wings to keep me quiet when the gm70's are finished. I plan to use the 1.1Kv 250ma PSU's i have bult for the GM70 PP amp.
Fabulous James! First GM70 PP and now 833 (SE presumably?). What else would you like to admit to .
Talking of A2 drivers, I'm thinking about options to drive GM70 in A2. An obvious candidate is 10Y/801A but I don't know too many more suitable valves. Any suggestions?
