Hi all,
As I understand the guitar cable line is like a capacitor, as long as the cable is, the high cable capacitance is, that's why long cable results high freq loss (capacitor in parallel to signal), solution for this is the buffer.
Buffer has low output resistance, how does it prevent the high freq loss? 😕
What is the considerations and triad off for selecting buffer's input & output resistor ?
As I understand the guitar cable line is like a capacitor, as long as the cable is, the high cable capacitance is, that's why long cable results high freq loss (capacitor in parallel to signal), solution for this is the buffer.
Buffer has low output resistance, how does it prevent the high freq loss? 😕
What is the considerations and triad off for selecting buffer's input & output resistor ?
If the buffer is "before" the cable
(that is between the pickup+pots and the cable)
then the buffer output resistance (which is low) defines the RC
instead of the pickup + potentiometers output R.
The corner frequency of the filter is 1 / (2 * pi * RC)
so the smaller the RC, the further up your corner frequency.
The buffer also has a high input resistance, thereby "isolating" the pickup.
_
In case you match series and terminating impedance to cable characteristic impedance, then you avoid capacitive loading rule and you can send signal to several hundred meters without problem.
Put the buffer with 75R output resistor at the transmitting end of cable. Use 75R cable (like coax). Insert 75R resistor across signal and ground at the receiving end of cable or on input of amplifier/mixer/what ever. Works every time 😉
Talking about impedance matching, guitar pickup resistance is about 10k.
Why in many guitar effects there is a big resistor (100k to 1M) in parallel in the input of the entry buffer?
Why in many guitar effects there is a big resistor (100k to 1M) in parallel in the input of the entry buffer?
I'm in no where into "live" gear, but mostly the reason to high input impedance is to provide as high load as possible for the equipment connected to it (to minimize Current need at the output). Two different worlds.....
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