"If you use any number of stompbox effects, you may have already asked yourself, 'Why does my guitar tone sound dead when it reaches my amp, and what can I do about it?'" says Paul Shedden, president and head of sales at Mission Engineering.
With amplified sound, the story begins with the start of the signal chain: The guitar’s pickups. When, say, the A string is struck, the string vibrations are converted by the pickups into an electrical wave frequency of 440hz. The amplifier increases this signal level through several stages of amplification, until the tiny pickup voltage is increased sufficiently to drive a speaker. But along its journey, higher frequencies are affected by the interaction of the two individual copper wires inside your guitar cable and the way they, in turn, interact with the pickups. During this interaction, higher frequencies are lost in a similar way to running the guitar signal though a "low pass filter"—a type of EQ that just cuts the top frequencies.
The farther the signal travels, the more high frequencies are lost, eventually resulting in dull and lifeless tone. This is where a buffer comes in. A buffer is basically an amplifier that operates at unity gain. Most guitar pedal buffers use an op-amp chip to implement it, but it could be any suitable amplifier circuit. The guitar pickups are only connected to the input of the buffer’s amplifier circuit, but the output signal from the buffer is essentially only connected to the power supply.
In practice, this isolates the buffer’s input signal from anything connected to the output—i.e. your effects pedals. So the normal interaction of the guitar cable with your pickups—which causes the low-pass filter effect and the loss of higher frequencies—is limited to the length of cable between your