Using big power tubes as buffer?

[dave123]

Hey dudes,

is there any reason why not to use big power tubes in buffer application except the cost? could a GM70 for example be used in a tube buffer?

 

[DF96]

Reasons why not:
cost, size, energy consumption, damage to load if parasitic oscillation takes place.

Reasons to do it:
just to be different?

 

[bigwill]

Probably more microphony too. Not necessarily a Gm advantage over smaller valves either. Basically it's mostly if not entirely pointless!

 

[kevinkr]

GM70s also have comparatively short service lives at the operating currents and voltages where they perform best. (In my power amps they're done at around 1200 hours of use)

Smaller DHTs like the 45 and triode connected DHP 4P1L can be quite good and are practical for a line stage or buffer application.