Stacks have 2 coils, both sense noise and string signal almost equally. The pickup produces almost equal string signal in each coil, and equal hum level in each coil. The coils are wired out of phase to cancel signals in common. Hum is a signal in common and so is the string signal. Both hum and signal get cancelled, but the signal gets cancelled a little bit less because the string is positioned on one end of the magnet so there is a little less signal sensed in the lower coil. The sonic output of the pickup is the difference between the level of string signal between the two coils.
Since the difference is small, manufacturers attempt to magnify the level of that difference by winding the coil with finer wire and many more turns. This increases Parasitic Coil Capacitance within the coil. Excessive capacitance is the arch enemy of good sound. Resistance of stacks is double and three times that of noisy single coils. This indicates a lot of turns of very fine wire.
More so than common stacks the two coils of a sidewinder produce signal in equal amounts, and hum in equal amounts. Because the coils in Sidewinders are the same distance from the strings the cancellation effect of string signal and hum signal is very efficient. In theory a Sidewinder should produce no sound but because of certain imperfections a little bit of string signal is present in the output. As with Stacks, coils with very fine wire and lot of turns are necessary to magnify the little bit of string signal to an acceptable level. The big trouble with doing that is the massive amount of Parasitic Coil Capacitance in all of those coil turns that results and which causes a great loss of articulation, transparency, dynamic response and frequency response.
Kinman’s P-90 Hx (above) double Magnetic Shield around the upper string sensing coil prevents magnetic coupling between the two coils. The P-90 Hx has 206 parts because that’s what it takes to produce a great sound and is priced at a few bucks more than these competitive look-alike but not sound-alike orphans (meaning not derived from the original).
Fralin noiseless P-90 look-alike has 14 parts. Even if magnetic shields could be fitted to Sidewinder pickups (left) they would sound just as bad because they are a terminally flawed design. Note the similarity to a side-by-side humbucker, there is a sonic similarity too but any sidewinder will never sound even as good as a humbucker.
Below is a 1960's Gibson sidewinder which was used only in their EB type basses because it sounded too horrible in guitar. Note the strong resemblance of Fralins noiseless P-90.
Resistance of Sidewinders is about three times that of noisy single coils. This indicates a lot of additional turns of very fine wire. In other words Sidewinders sound awful to anyone who appreciates fine sound character. Sidewinder P-90"s are look-alike pickups, and definitely not sound-alike. They sound nothing like a real P-90 what-so-ever.
Kinman's have a dedicated noise sensor, and a much different dedicated string sensor. There is negligible cross-talk (magnetic coupling) between the coils thanks to our patented Magnetic Shield and minimized Hum Sensors. The hum sensing coil, with it"s low Parasitic Coil Capacitance and high transparency factor, does only one job, the one it was designed to do, sense hum. It does not interfere with or produce string signal.
Kinman's DC resistance is often lower than noisy single coils.