Question about shielded input wire
Moderators: pompeiisneaks, Colossal
Question about shielded input wire
On some pics I see a resistor connected directly to the preamp tube socket. Is this a 68k value ... and why is it sometimes not shown. I don't think I see one on Franchesca.
Re: Question about shielded input wire
The 68K resistor is used on the input (silver/gray) shielded wire to block radio signal interference. It may not be necessary on every amp and is therefore left off a schematic. I don't see one on her either.
Re: Question about shielded input wire
Correct me if I'm wrong, please.
My understanding is: the resistor into the tube's input capacitance forms a low pass filter that blocks very high frequencies (non-audio, way above guitar) that can cause other ultra-sonic problems (oscillation comes to mind). It may or may not be needed, depending upon other factors like layout and lead dress.
My understanding is: the resistor into the tube's input capacitance forms a low pass filter that blocks very high frequencies (non-audio, way above guitar) that can cause other ultra-sonic problems (oscillation comes to mind). It may or may not be needed, depending upon other factors like layout and lead dress.