In Reply to: RE: Well, if your preamp don't mind... posted by RPMac on March 28, 2021 at 15:32:47:
"Can't you get a capacitor close to crossover FQ and fine tune with the grid resistor value?"
That's what I do.
"What formula do you use to calculate crossover FQ?"
-3db point of the filter = 159155/(cap value in uf times resistance value)
"What can a 500 ohm output impedance preamp be comfortable with?"
Almost anything. The rule of thumb is 1:10 so it will drive 5k without trouble. Just don't forget about capacitance reactance at the high frequencies which is in parallel with the grid resistor value. That would include cable capacitance and the Miller capacitance of the tube being driven. Also the source needs to be able to supply the current that capacitance reactance will require.
Tre'
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Follow Ups
- RE: Well, if your preamp don't mind... - Tre' 16:24:21 03/28/21 (2)
- RE: Thanks a lot nt - RPMac 05:00:20 03/29/21 (0)
- Link to online calculator - Tre' 16:47:46 03/28/21 (0)