This came up in a tube rolling thread but I think it is more appropriate here.
I think the 807 is the equal of any other pentode within its power range, no reason why they shouldn’t be. After all, they are pretty much a 6l6 tube with the anode connection moved to the top so it can handle more voltage in pentode mode. Plus, they were manufactured to a high standard for more demanding RF use.. Apparently the Brits had a hard time making a good one.
http://www.r-type.org/addtext/add029.htm You’ll see a lot of tubes made like the ones this article calls a goat. That’s not a compliment like it is nowadays lol. It also implies that the vt60 is “better” than other British 807 but is scarce on the details as to why. Presumably it is more of an issue when being pushed hard for transmitting purposes.
I think there are 3 main reasons they are still pretty cheap:
1) They were made by the bazillions for years for radio use.
2) Guitarists don’t use them. A lot of the grail pentode tubes got their reputation for their overdrive characteristics and the ability to handle being thrashed.
3) Home audio amp manufacturers stay away from tubes with top caps. Few people grew up listening to them in things like McIntosh, Leak, Quad, Scott, Fischer, etc. so never developed an audiophile reputation. It also means that stocks have not been depleted over the years by replacements for those amps.
If you like the sound of 6l6 tubes and don’t need the power you can get from the likes of el34, kt88, 6550, etc. I think the 807 is an excellent option. Besides the price there is also a large variety to choose from. Like any other tube I have yet to hear 2 tubes of the same type from different manufacturers that sounds the same. These are tubes in the same “family” I can think of off the top of my head:
6l6, 1619, 6l6g, 6l6gb, 1625, 807, 6bg6, 5881, 5b/25*m, 6ar6, vt60, kt66, and probably more. The 6l6gc, 7581a, and 7027a are all higher power versions in the same family. Lots of tubes and lots of different manufacturers both old and new. 807 and metal 6l6 are probably the best deals going right now.
Someone guessed that the problems the British military was having probably won’t be an issue for audio use. I agreed and posted:
Yeah, I assume AF duty in triode mode for single digit output power won’t reveal whatever problems the military was having. Can’t imagine tubes being rejected because they were too warm or didn’t have the midrange presence they wanted lol. The problems could be around emissive capabilities, mechanical construction, microphonics, manufacturing difficulty, vacuum quality or something else that could also affect audio quality though. I quite like my brown base Mullard 807 so <shrug>. The kt8c seems support the idea that they are “ace” for audio frequencies but useless above 15mhz. The good old 807 could go out to 60mhz no problem.
http://www.r-type.org/exhib/aab0080.htm
