Double triode, Will it catch on ...

[Jon Snell]

I came across this double triode, aparently, according to KORG in Japan it will replace the ECC83 or 12AX7.
They work well with a 12 volt anode supply. NuTube by KORG.pdf
Not sure myself. What do you all think I wonder.

[Greg Robinson]

They're manufactured by Noritake in their now otherwise defunct VFD (vacuum fluorescent display) factory. They're pretty sub-obtimal as amplifiers of course (microphonics being a particular issue; note the mounting requirements in the datasheet), being they're designed to be displays. You can also use any old VFD as a triode anyway, pretty sure you could harvest them from ewaste cheaper than you could buy a nutube (EDIT: even factoring in failed ones and paying yourself a wage).

[loudthud]

This has been discussed at length. This is one thread: https://music-electronics-forum.com/...tubes-is-today

Nelson Pass designed a HiFi preamp around one documented here: https://www.diyaudio.com/community/t...triode.313612/

Problems are: They cost a hundred bucks and there are plenty of bad ones. A high number are microphonic. Checkout Nelson's circuit, he surrounded them with JFETs.

[Mick Bailey]

My own view is that they're a bit of a gimmick - like having a window in an otherwise solid state pedal to show it has a real triode. The price is the killer.

[drewl]

Is that similar to what they're using in those Vox "Baby Beatle" amps?

[Jon Snell]

"Checkout Nelson's circuit, he surrounded them with JFETs."
That schematic was taken from the data sheet. See page 4 attached

[Helmholtz]

It seems the device needs to be driven from a low impedance source, probably because it has low input impedance due to positive grid bias (grid current).

Also to achieve a meager gain of 5, to load needs to be very high - hence the second source follower.

Note that the max. plate dissipation is only 1.7mW, so plate current is restricted to ľA's.

In other words, the performance is significantly worse than that of a simple Jfet gain stage.
As the device is not operated like an ordinary triode, it won't "sound" like an ordinary triode.

[Mick Bailey]

There's a headphone amplifier kit that uses Jfets to drive the device and a pair of opamps to drive the headphones. The triodes seem to be almost redundant in this application and add extra noise.

[g1]

It's been quite a few years now that they've been around. They didn't catch on.
I expected to see them in Korg keyboards with some kind of marketing about 'warming up' the sound, not sure if that ever happened.