I once designed a battery-powered directly-heated triode distortion pedal for guitar. It sounded really good in my opinion, but I don't spend so much of my free time doing electronics these days, so I never got around to making a few. It used a rare Russian valve which IIRC may have been used in MIG fighter jets.

This is all well and good, but where do I buy one? I guess Korg is keeping them all for themselves for the time being?

Someone here seems to think that vacuum tubes aren't being developed anymore and that is definitely not the truth. A friend of mine that is a valve enthusiast directed me to this site in reference to the miniaturization of vacuum tube devices. So along those lines, I am responsible to design sealed glass and ceramic electron, X-ray, and Neutron sources. We have our own glass blowing here at Thermo Fisher Scientific in Scotts Valley CA. I am able to design and build all sorts of stuff. Some of this is quote "miniature". And for example the micro-focus electron gun is a pentode designed to operate NIL to 10 KV and up to 2.5 mA of beam current. The device is normally welded to an X-ray envelope to traject a focused, or de-focused electron beam onto an anode,... say 45 KV to 150 KV. The electron gun is approx 0.7" long x 0.5" in diameter,... that's small, and it could be made smaller. We also make diode X-ray sources that are about 0.9" long x 0.45" in diameter and operate upwards of 50 KV. And to that end, there are X-ray tubes the size of a catheter that have been manufactured to run at 50 KV that are run up a human artery for in situ X-ray fluoroscopy...Anyway,... the point of this all being that there's no reason audio related tubes could not be developed to be miniature. Probably a matter of market needs and economics or the return on investment. That said,... anyone interested,... seriously interested,... well then contact me and I'll see if we can justify the R&D.

Frank Decent wrote:I'm digging these, big time. Sound great, and are cheap and light. It'll be interesting when they come up with a Nutube design for power tubes, rather than just preamp tubes.Cool, what have you heard them in? I checked out a NuTubescreamer video and I guess there's a Vox amp which claims "The MVX150H follows suit with Nutubes in its preamp and power amp sections."

I'm digging these, big time. Sound great, and are cheap and light. It'll be interesting when they come up with a Nutube design for power tubes, rather than just preamp tubes.

I've only heard it in the AC 50.