S&S BiPolar pickup details Jan 12, 2020 6:31:10 GMT -5
Post by antigua on Jan 12, 2020 6:31:10 GMT -5
I ordered a loaded pick guard of BiPolar pickups from www.bipolarpickups.com/ . I'm interested in trying some other wiring schemes that they don't allow for with their loaded pick guard, so I'm going to rewire it, but I have to document what's what in order to get the phases correct. I'm sharing this information here, and the info also gives some insight into how the pickups will probably sound too.
These Strat pickups have two coils per pickup, side by side. They were made by cutting neat looking orange colored Strat bobbins into two halve, winding little three pole pickups, and then combining them together on a third piece of fiber board that is shaped much line a base plate for Strats.
The pole piece stagger is nearly flat, but not quite. The pole pieces having reversed polarities on each side of the pickup, three north and three south, which isn't actually necessary since there are no "in between" positions. You only need reverse magnetic phase when any given string is sense by two pickups, but with the pre-wired pick guard, every string is sensed by one pickup at a time, in all five positions, so all that is required is reverse phase, but the reverse polarity could be ignored. Here's a video showing the different positions, I think the guy in the video is the one who thought it up
My plan is to change all the magnetic polarities to be the same, remove the hum cancelling and set up dual blade toggles to allow for almost any combination of coils. I don't know what they sound like other than what I've seen in demo videos.
White - start EAD
Black- finish EAD
Green - start GBE
Red - finish GBE
Pole pieces: 1100 Gauss, EAD north up, GBE south up
Bridge with combined combined (black white):
L: G-RB-W: 1606H G-RW-B: 1718H
C: G-RB-W: 86.98 G-RW-B: 88.98pF
Bridge pickup - low EAD strings (white to black):
Bridge pickup - high GBE strings (green to red):
Middle pickup - low EAD strings (white to black):
Middle pickup - high GBE strings (green to red):
Neck pickup - low EAD strings (white to black):
Neck pickup - high GBE strings (green to red):
Based on these measured values, these are very under-wound relative to a typical Strat pickup, about 1.7 henries. Normal Strat pickup achieve at least 2.4 henries with the usual ~8,000 turns. The capacitance of two of the coils combine is around 90pF, which is also typical of Strat pickup. The resonant peak wound be rather high, over 10kHz, and around 5kHz with 470pF added load.
The electrical values of the GBE side of the neck pickup have really low inductance and DC resistance compared to the others, and really high capacitance, which possibly suggests an internal short in the coil, but I'll try it out before seeing if it needs replacing or rewinding.
Usually when you add inductances together from two coils, the add together, but there is a second mutual inductance factor based on how the coil are geometrically aligned, so that their magnetic fields are near each other. If the magnet fields are in phase with eachother, the overall inductance goes up slightly. If they are out of phase, the inductance drops. Looking at the inductance of the bridge pickup's coils by themselves, and comparing that to the inductance of the two coils in series, it can be seen that the mutual inductance increases the overall inductance by 3.2% when wired in phase (G->RW->B), and drops by about the same amount when wired the out of phase (G->RB->W). Overall that bump up is not too impressive, since the magnetic connection between the coils is through the air, and not steel or iron.
Concluding thought: these are really well priced for what they are. $225 for some exotic split coil Strat pickups that can make sounds from a Strat that few people have ever heard before. I was a little disappointed that their pre-wired pick guard only offers five out of a potential 47 tones. Of course to get all 47 you have to do some exotic control, and guitarists tend to shy away from exotic controls. I think I can to with with two push-pulls and two blade selectors, though. The Eastern style blade switches are smaller and will fit nicely side by side, but the larger all metal American style ones probably wouldn't. I might do a demo video when it's all done. I don't love making videos, otherwise I'd have a Youtube channel by now, but in this case I think a video would be valuable. Conceptually, the wiring is like having two electric guitars connected to each other in series, with each controlling with three strings, with a master volume and tone.