Strange Valve: Experience anyone?

Not a lot of us still clunking around valve designs, but my horizons were broadened recently on DIY.Audio when encountering a D3a tube. It is a miniature (noval) pentode designed for wide band duty, with the almighty gm of 35mA/V (in triode mode:  41mA/V,  ? = 77). Boet, that should yield a really low noise pre-amp for the valve-inclined!

I intend to get a few from Mrs Valve; might be stopped in my tracks by the price, though.

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