In article , Nick Gorham
wrote:
Arfa Daily wrote:


Perhaps someone who purports to know the difference could enlighten
me, as I really am interested in knowing.

Arfa



Well, I don't purport to KNOW if there is a difference, but one thing
comes to mind. Once the makers start to use a cathode, which is
effectivly a rigid cylinder, then the grid to cathode spaceing can be
much reduced. Ending up in the 50's with the very high gm frame grid
valves like the e810f and d3a. The DH valves, because of its "floppy"
fillament needed to keep the first grid out of the way.

This would also presumably affect the inter-electrode capacitance values,
etc.

At least you have suggested an plausible hypothesis for some difference in
performance.

I wonder if this is in part the cause of the difference.

Alas, this pre-supposes that there *is* an audible difference when the
devices are used in a well-designed amplifier. So far, all we have on that
is Andy's assertions which failed to back up with any plausible explanation
or reliable evidence.

TBH It seems to me to be daft to try and suggest someone who wishes to
start experimenting with building their own amp should begin with such
arkane and evidence-free matters, involving parts that have not been made
for decades. However this is for the OP and others to decide, each for
themselves.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html