Ah, OK. In that case you are looking for a driver for PSE 4P1L to replace the 6e5p. I never liked the sound of 4P1L into 4P1L - seemed to accentuate some kind of edginess. 2P29L is OK and can be run at 15mA. Quite neutral, though the treble lacked sparkle for me. Probably better than 4P1L though. 01A is too low current unless you use one of Ale's circuits on his Bartola Valves site. 26 can be made to work but 7mA max. 10Y works but that's expensive and might not quite give you enough gain. You could also try a VT67, a 30 special with higher current heaters. OK but doesn't stand out.
I solved the whole thing with an op-amp stage into 46 into 300b which gave me better results. But that's a complete rebuild for you. If you want to use an op-amp first stage you can then use lower mu drivers, like maybe 71A which I haven't tried. But if you use an op-amp first stage or a step up transformer you can then look at outputs like 2a3 or 6C4C as well as 300b. See the thread on 300b SE with a DHT driver for all this stuff.
I solved the whole thing with an op-amp stage into 46 into 300b which gave me better results. But that's a complete rebuild for you. If you want to use an op-amp first stage you can then use lower mu drivers, like maybe 71A which I haven't tried. But if you use an op-amp first stage or a step up transformer you can then look at outputs like 2a3 or 6C4C as well as 300b. See the thread on 300b SE with a DHT driver for all this stuff.
That's just the output stage. Feel free to use whatever driver stage you fancy. There's no global NFB and 4P1Ls are easy to drive.
In my system I needed a mu of 12-15 in the driver stage. That's beyond most DHTs and I didn't want to use an indirectly heated driver, but that's just me. I moved the indirectly heated tube to the output so I could use an 01A on the input. Works for me. It's an unconventional way of doing it. You almost always see the DHT in the output.
In my system I needed a mu of 12-15 in the driver stage. That's beyond most DHTs and I didn't want to use an indirectly heated driver, but that's just me. I moved the indirectly heated tube to the output so I could use an 01A on the input. Works for me. It's an unconventional way of doing it. You almost always see the DHT in the output.
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