Well, I do like these! It's really hard not to like a 12B4, so when Bill asked me to make one for him, of course! These amps have a naturally sweet and detailed sound that's hard to beat, and it's easy on the tranny selection at least in terms of bulk size! You can use almost anything and get an acceptable amplifier, but careful screening and selection of used trannys gives better results. In fact you are hard pressed to find good trannys in the impedance range needed without breaking the bank, so used pulls are the natural selection.

If you don't need to drive a full range speaker, and just need a tweeter amp for a horn or any good tweeter, you can use trannys at 24K. This one uses a tranny of 14K, and I think I would not go any lower. With the 14K tranny, this amp has a little more bite to it than previous versions and a little more power as well. So when you really crank on it, it bottoms out at the high Vp end rather than at the high Ip end of the curves. Because triodes are hard to fully turn off, it gives the sense of a lot more headroom than my previous efforts.

Operated within its normal range, like all small amps is best of course, and within its range this is about as sweet as it gets. Darling type amps sound warm after listening to this, almost muddy until you get readjusted.

Sound staging is another big plus for this amp, with sharp imaging a very good depth. No wonder I like them!
Thanks Bill, for letting me build another. Someday I will add one of these to my personal stash.

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I use solid oak almost exclusively now.
As you can see, these amps can be made even smaller than this one!

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