Re: [Harp-L] Preamp tubes

["Ralf K. Buschner" <r_buschner@xxxxxxxxxxx>]

Hi Mike,

> Is this a bad tube, or is it because one has a D
> getter instead of a halo getter?

the form of the getter carrier hasn't to do anything with the sound of the 
tube. The only purpose of the getter halo or D or A structure is, to carry 
the getter pill, which is heated up from an induction heater and then is 
vaporized and ends on the inside of the glass tube. So the getter is only a 
kind of mechanical support for the pill, before it's vaporized, and you can't 
i.e. say, that a D getter sounds brighter or better than a halo getter.

The intrinsic (not sure about the translation) sound concerning parts of the 
tube are far below, you can see the grey plates, and inside them is the 
actual structure - in the middle is a thin tube, that's the cathode, and 
around that are different structures of grids - two long steel pins with lots 
of very thin wire around. On some tubes you can see it from the bottom of the 
tube.
Each of these inner parts (cathode, grids, plate) has a capacitance to each 
other. These capacitances are - together with the different components of the 
particular stage of the amp - the most important reason of the different 
sound properties, because the tubes of the different manufacturers have 
different inner capcitances. 

Huh...had to use my dictionary this time. :-)

cu,
Ralf