I have messed around quite a bit with SET-based amps using conventional tubes, so I thought it was time to try something new and mess with some giant brightly-glowing tubes I have always drooled over. I have been doing a lot of research and considering all sorts of different ideas, so I figured I would ask the most knowledgeable place on the Internet for any input they might have.
My eventual goal is to build a monster transmitting triode-based amp, using either an 833 or some huge Eimac tube like a 304TL (or a 450TL if I can find some). However, I managed to get a pair of brand new 100THs from a friend for 10 bucks, so I figured I'd try something with them first. As far as I have seen, the output stages for such amps are fairly simple (and I'm not looking at using any sort of feedback), pretty much just the tube, output transformer, and some sort of filament and bias supply. I have heard a lot of different opinions on drivers though, everything from "it won't really make much of a difference, use your favorite tube" to "you can only expect the output tube to truly sing if you have a very carefully designed drive stage". I have heard lots of recommendations for using thoriated tubes to drive other thoriated tubes, and I have also read about the 211-driven 211 amp. Does anyone have any experience with setups like this or any tips for what I can expect? I figured I would build a nice solid power supply that can do a range of (high) B+ voltages and plenty of filament current and then just sort of play around with a bunch of tubes. I have some 25Ts sitting around I thought might be a good start. I do have lots of experience with high voltage stuff (upwards of 700KV), so that is something I am comfortable messing around with.
My eventual goal is to build a monster transmitting triode-based amp, using either an 833 or some huge Eimac tube like a 304TL (or a 450TL if I can find some). However, I managed to get a pair of brand new 100THs from a friend for 10 bucks, so I figured I'd try something with them first. As far as I have seen, the output stages for such amps are fairly simple (and I'm not looking at using any sort of feedback), pretty much just the tube, output transformer, and some sort of filament and bias supply. I have heard a lot of different opinions on drivers though, everything from "it won't really make much of a difference, use your favorite tube" to "you can only expect the output tube to truly sing if you have a very carefully designed drive stage". I have heard lots of recommendations for using thoriated tubes to drive other thoriated tubes, and I have also read about the 211-driven 211 amp. Does anyone have any experience with setups like this or any tips for what I can expect? I figured I would build a nice solid power supply that can do a range of (high) B+ voltages and plenty of filament current and then just sort of play around with a bunch of tubes. I have some 25Ts sitting around I thought might be a good start. I do have lots of experience with high voltage stuff (upwards of 700KV), so that is something I am comfortable messing around with.
Not the easiest tube to work with. From the datasheet: High Rp - without feedback you will have a lousy damping factor. Needs to be driven in A2 - not very much grid current needed though. Take a look at TubeLab's "power drive", with that as a buffer you can use whatever favourite tube you like. Without a buffer (could of course be a CF is you suffer from sandofobia) you will need a good step down IT to get the drive you need.
On the upside you have a mu of 38 so you don't need that much voltage swing.
/Olof
On the upside you have a mu of 38 so you don't need that much voltage swing.
/Olof
I was already looking at using an interstage transformer to cut down on/eliminate caps in the audio path, and I have tons of space in the chassis I am making for extra power supplies for bias/whatever, so I figured if I could get away with a good SE drive stage if I picked a good transformer. Right now I'm browsing smaller thoriated triodes to see if any look like they will work well or can be had for a decent price. I'm hoping to find a decent one that I can either drive directly or with a more conventional tube if I have to.
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