Recently, I was reading about a so-called zero capacitance guitar cable pitched to eliminate resonant frequency shifts when using higher impedance passive guitar pickups. The company claims their solution is not sleight of hand with a buffer to convert the AC signal to low impedance to make cable capacitance less of an issue.

So I was drinking my morning coffee and thunk about how this might work. My first guess is that series capacitance could reduce cable impedance to levels that would retain the pickup resonant frequency profile.

QED

But then I thought about how the AC signal voltage should increase. And then I thought about how the frequency dependent reactance would come into play. And that’s when my 40 year gap since I studied this stuff crept in.

So I wonder what would be the consequence of adding multiple capacitors in series with the low voltage (mV) AC signal arising from ferrous electric guitar strings vibrating in the magnetic field of the passive guitar pickups. How would the input voltage at the guitar amplifier be affected? I imagine it would be altered in a frequency-dependent way but am having trouble intuiting this. My calculations suggest low frequency signals will be attenuated to near zero by the very high reactance, but even at the high frequency range of an electric guitar (a few thousand hz though higher for lower voltage harmonics) the reactance is in the “kOhm” range, much greater than the resistance of the cable iteself.