There is one other difference. I'd discounted it until now. The older pickups had the ground wire of the coil soldered to the copper foil screen. The new pickups have the starts and ends of the coils go out via a 4 core screened cable. Only the screen is soldered to the copper. They're joined at the control cavity. I can't imagine that would make a difference, would it?
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
Magnets & Copper Wire: A Pickup Building Thread
- Thread starter Freekmagnet
- Start date
From first principles, series would have more resistance and more inductance. The resonant peak might be lower in frequency. Parallel would have less inductance but more capacitance. The dummy coil would act like a resistor to ground at low frequency but not so much at high frequency. Would you lose some bottom end?
While making new coils to the Kawai pickups I got an idea of an Alembic style single coil. Alembic makes stacked pickups with no magnet on the lower coil. Will I have a humcancelling pickup if I have one coil with magnet in it and another dummy coil with plastic core and wiring them in humbucking way? Does it matter if the coils are side by side instead of being stacked? I guess side by side will work just as fine as Alembic uses dummy coil in some of their pickup system.
Yes, if the dummy coil is approximately the same turns and geometry, wired reverse, and fairly nearby, then it will hum cancel. But, like Smart51 says, the sound won't be the same as a plain single coil, because of the added resistance and inductance to the circuit. A dummy coil isn't invisible.
Some pickup makers play around with the combination of the two coils to get a sound closer to the sound of a particular single coil. Larger wire or less turns, etc.
Yes, that's it. Adding a dummy coil will modify the sound somewhat, changing the shape of the EQ curve. You may like it, or you may not. They are easy to build and test.
This makes me curious whether a pickup + matched dummy coil can be made to sound the same as a Precision-style humbucker (or vice versa), if aperture widths of the sensing coils are the same, or are there characteristics inherent to the each that prevent this. (Assume the builder is using whatever types of magnets and wires that would help to make them sound identical.)
I'm also curious how "fairly nearby" a dummy coil has to be. A pair of Fender Jazz pickups will humbuck and are several inches from each other.
Old Alembics have dummy coil inside control cavity. I guess dummy coil does not need to be very close. Otherwise like said J-bass would not be humcancelling.
The wavelength of 60 hz (the main frequency you are trying to cancel with a dummy coil) is about 6 meters (or 18 feet); so, a few inches is not going to make much difference in phase shift between what the two coils pick up and they will cancel almost all of it. As you move them further appart, they might start to let some higher frequency noise pass through, so you shouldn't place them more than a few inches appart.
I guess that makes sense if they're wired in series. But wouldn't that also mean that if they're wired in parallel the leads could potentially be any length, as long as the leads from each coil to a common point are close to equivalent?
You can wire 2 single coil pickups - one neck other bridge positions - RWRP and make a humbucker.
I'm not sure what you mean, but there shouldn't be a difference whether the coils are in series or parallel.
60Hz as a sound wave is around 6m wavelength, but these are radio waves travelling at light speed, so roughly C/60 = 4996.54km. For 50Hz, that's 5995.85km. So the dummy coil's distance from the active coil is pretty much irrelevant.
Ohhhh you are right! What was I thinking???
@ardgedee I'm sorry, my answer was kind of completely wrong.
The principle was dead on though. Also worth mentioning, hum cancelling would be worst at half-wave distance when the dummy coil would be in phase with the active coil - if it were 2500km away!
Last edited:
One specific clarification: In Alembic Series 1 / Series 2 instruments, i.e. the ones with true single-coil pickup + a separate dummy humcanceller pickup, all 3 of the "pickups" immediately hit a high-input impedance opamp buffer before they interact with each other.
Feel free to correct me if this not the case, but I believe that if you're building a system with buffers like this, then the dummy pickup shouldn't affect the resistance/inductance of the single-coil pickups.
This is pretty above-and-beyond compared to almost all other basses out there, though, so for any basses that use dummy humcanceller pickups without these internal buffers, yes the resistance/inductance would be affected.
As to whether the buffers perfectly preserve the "plain single coil" sound - I'm sure Alembic would say yes
, but my best guess is that the answer is "There is a slight impact, but it's closer to true single-coil tone than without buffers."
Yep, you probably shouldn't put your dummy coil 2500 km away from your pickup. It might cause some undesired noise.
Latest posts
-
-
-
-
Curious what the percentage of bass players use rounds vs flats is.- Latest: UntitledProject
-
