Posted by PakProtector [ 64.12.116.65 ] on December 03, 2005 at 16:27:25:
In Reply to: Re: The shunt capacitance of grid and anode chokes posted by Damir on December 03, 2005 at 14:50:33:
that any current interested in the 8k DCR is of a DC nature. I would suggest that it is not.
Yet the sonic benefits and power stage benefits to using a grid inductor, would sugget otherwise. So, for a given productin of grid charge, the inductor seems able to deal with it in a way that is less disruptive to the signal than simple Ohmic resistances. I have made some interesting measurements on an amp equipped with a well known multi-kHy grid choke that support this theory. AC grid current is treated resistively in the same way an equivalent resistive load would. So for a given omega*L the high L chokes begin to behave like resistors. In addition to this, the grid choke has substantial capacitance in parallel. So, use just enough L to get the job done is my current practice. Fortunately it is quite easy to custom specify coil production with Heyboer. those guys are brilliant! For me, it's indespensible. Can't make reasonable tube amps without them.
I will soon take delivery of some grid chokes specially wound for both balanced and minimized winding capacitance. The previous ones were simply balanced, and less attention paid to winding capacitance. They still smoked a few other devices I managed to acquire samples of. Even some allegedly well respected and well thought of designs.
I have a quote on amorphous C-cores in qty which makes them *VERY* attractive in comparison to laminated sheet steel. Hardly more than low qty M6 even. Just a question of absorbing that sort of volume....:)
cheers,
Douglas
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