Mike,
I don’t think the 26 or thoriated filament tubes are quaking in their boots. I’m just looking for filament frugal tubes that sound good. I still use battery filaments/B+ so longer play before recharging colors my opinion. I need to get other ears to hear the 1J17B, but it sounds good to me.
In North America, there are sub-minature DHTs like 1D3, 5676, 6029, 6286 and the directly heated beam tetrodes like 1AG4, 512AX, 6088, 548DX, 6519, 6611, sound nice trioded. According to data books there are a few more but they are not easy to find like the above.
I’ve not found any sub-miniature Russian DHTs so that is why I’ve been looking at DH pentodes. The Russian tubes are just a little bit cheaper on average, even including shipping, which is why I’m looking there.
I would like to get a B7 preamp inside a box no larger then a thick paperback, including batteries for B+ and filaments, for no other reason then it sounds fun.
Matt
