Good low-noise triode

Not sure whether I have mentioned before, but Dutch designer Eli Duttman has recommended the use of the frame grid r.f.triode 6GK5 as a very good low noise tube for audio (seven pin miniature). It has a useful gain of about 60+ (depending on the anode current) and a quite high gm (members will recall that noise is inversely proportional to gm). It is apparently also fairly available and inexpensive. I got one that I intend testing and will probably buy a few for stock before it is too late. I will advise Mrs Valve (Johannesburg) to keep some stock.