IIRC, the web site states pentode operation with dissimilar screen and plate voltages, so, that sounds like sweep tubes would be involved.
Or, it could be that somewhat more output could be had by running the plates at some higher voltage while the screens are kept in spec, or maybe they can be driven into AB2 push-pull. All of this is rank speculation, however. I have a bunch of 6BQ5 class tubes, but I've never used them.
To get enough extra power to make any meaningful difference, it just seems like a different tube would be needed. Given the number of incandescent 6BQ6's we've seen over the years, I'm thinking that might be a clue .....
I would probably go for 6146B and then 6BQ6/6DQ6. There is also some small euro tube - part number escapes me - that is pretty compact and has a top cap - likely a sweep for portable televisions - might even have a nine pin base. I have some in the warehouse of junk - haven't paid much attention to them ....
Win W5JAG
Or, it could be that somewhat more output could be had by running the plates at some higher voltage while the screens are kept in spec, or maybe they can be driven into AB2 push-pull. All of this is rank speculation, however. I have a bunch of 6BQ5 class tubes, but I've never used them.
To get enough extra power to make any meaningful difference, it just seems like a different tube would be needed. Given the number of incandescent 6BQ6's we've seen over the years, I'm thinking that might be a clue .....
I would probably go for 6146B and then 6BQ6/6DQ6. There is also some small euro tube - part number escapes me - that is pretty compact and has a top cap - likely a sweep for portable televisions - might even have a nine pin base. I have some in the warehouse of junk - haven't paid much attention to them ....
Win W5JAG
reaper, I think what you might be referring to is George's testing with JJ EL84s. As I understand it, these tubes are actually built to 7189 specs and can withstand quite a bit more plate voltage than 6BQ5s and other EL84s. Most regular 6BQ5s would glow brightly at the voltages a real 7189 takes in stride. They can also produce more power. I suspect George got his JJs from Stan at ESRC just like I did after reading George's results. Now I just have to order the iron to finish my SPP.
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