Can someone explain humbuckers to me?

[JT Foster]

I know this is a stupid question, but I’ve been playing Bass for about nine years; and I still don’t fully understand the concept of humbuckers. When I think of humbuckers; I think of MM still style, exposed coil, fat pickups that sound huge and metallic.

I recently learned that the CAP pickups in my old SR300 are actually humbuckers. I always thought soapbars were their own type of pickup, but apparently that is referring to shape and not the actual build. Someone also told me that my Bart MK1’s are reverse PJ, and that really threw me for a loop.

Now that I know that you can have different styles of pickups in different shapes, I’m curious as to WHY the MM pickups are so large? Do the bigger coils give it a bigger sound? I also noticed these huge coils in smaller pickups too, like the ones in the Yamaha TRBX, G&L L2000, and Wal basses.

Also, do the exposed coils sound different from the covered pickups? I noticed some newer Ibanez SR’s have small, exposed coils on the soapbars. Does this give it a different sound?

Just been curious about this.

 

[LoveThatBass]

A plastic cover has no affect. A Nickel cover has small effect as it contains metal.
Any style pickup can be made single coil or humbucking beit a P style, J or soapbar. The way humbuckers work is to have 2 separate equally wound single coils wired opposite polarity from one another. In doing this they both produce the audio signal as each side the string vibration effects the magnetic field producing current going out that is turned into audio by the amp but being reverse wound of the other the noise gets cancelled out As 2 coils are producing that noise signal but in equal but opposite polarity thus bucking hum and that is where the term humbucker started

 

[dwizum]

Broadly speaking you can think of pickups as having two characteristics: output level and tone. Pickup builders make decisions about how they build the pickup to impact those factors.

Output is a function of the strength of the magnetic field that the string and coil are in, and the number of turns of wire in the coil. Generally speaking, bigger magnets are more powerful. If you see a pickup with big magnet poles (exposed or not), you can expect it to be a little more powerful than a similar pickup with smaller poles. Similarly, switching the type of magnet makes a difference - switch from alnico to ceramic and the output will increase since you made the field stronger. Adding turns of wire also increases output, though things get weird pretty quick, since adding lots of turns makes the coil bigger, which means it's not as close to the magnet and the effect diminishes.

Tone is a function of the electrical properties of the pickup and the conductive things nearby the pickup. As you add turns of wire, you make the coil bigger, and the impedance increases. That causes a shift in tone. Similarly, if the magnets are conductive, or you use conductive materials in the pickup (like: a steel blade), they can interfere with the signal at certain frequency ranges and cause a change in tone. Coils also have some capacitance, which changes the tone. Capacitance is mostly a function of how the coil is wound (loose or tight) and the overall shape and design of the coil.

Pickup format has an impact on tone and output level too. A single coil (like a Jazz pickup) is pretty simple. A humbucker, by definition, will have an even number of coils. The position and electrical relationship between the coils has a huge impact on the tone produced. A humbucker with two coils placed end to end (like a split coil Jazz or a split coil P) will have a more single-coil-like tone, since each string is only sensed once. A "traditional" humbucker with two coils next to each other, such that each string is sensed twice, will have a different tone - there will be some frequencies lost when the signal of the two coils is combined, since they're sensing the string movement slightly out of phase with each other (since they can't physically occupy the same spot under the string). That's what most people think when they think "soapbar."

And, humbucker coils need to be wired together in order to function - they can be wired in series or parallel. A series configuration tends to make the output higher and more mid-heavy. A parallel configuration tends to result in a lower output and a mid-scooped tone.

Put all that together and it nicely explains what you're seeing in the pickups you're talking about. The MM pickups have a "huge and metallic" sound because they have big poles and big coils, and they're wired in parallel. That's a straightforward recipe for strong output and a scooped tone, which can sound metallic as you're describing - it's the typical recognizable stringray tone.

And of course there are a lot of other factors involved in why one bass sounds different than another - active EQ vs passive controls, string choice, pickup location, etc.

 

[JrMare]

Great explanation, thanks.

 

[spatters]

There's another factor to "humbucker sound" that people haven't mentioned:

Do the two coils both sense all the strings (MM, MFD, soapbars), or does each string only have one coil sensing it (like a P-bass)?
And...if both coils are sensing all the strings, how far apart are they?

When the string is being sensed in two different locations, this means that the two signals out of each half of the pickup aren't exactly the same, and the sound changes. A Jazz Bass provides the extreme case. With both volumes at maximum, each J pickup forms one half of a humbucker...but several inches apart, instead of a fraction of an inch!

As the two halves of a humbucker move apart, the result tends to result in an audible mid scoop, forming both the recognizable Stingray tone and the recognizable Jazz Bass tone. (It's a lot more complicated than that: see below for a simulation! But the audible result tends to be some degree of mid scoop.) In contrast, when the two halves of a humbucker are close together, as in a soapbar (think Thunderbird), they don't produce an audible mid scoop.

You can play with pickup positions and see the frequency response changes I'm talking about here:
Guitar Pickup Response Demonstration
Remember that you're not hearing anything above 5KHz out of a bass cabinet, and the meat of the response will be under 2.5KHz. As you'll notice, once two pickups start moving apart, a big dip in the frequency response starts moving down the spectrum and into the audible range.

 

[JrMare]

Há outro fator no "som do humbucker" que as pessoas não mencionaram:

As duas bobinas detectam todas as cordas (MM, MFD, barras de sabão) ou cada corda tem apenas uma bobina que a detecta (como um P-bass)?
E... se ambas as bobinas estão detectando todas as cordas, a que distância elas estão?

Quando a corda está sendo detectada em dois locais diferentes, isso significa que os dois sinais de cada metade do captador não são exatamente os mesmos e o som muda. Um Jazz Bass fornece o caso extremo. Com ambos os volumes no máximo, cada captador J forma metade de um humbucker... mas com vários centímetros de distância, em vez de uma fração de polegada!

À medida que as duas metades de um humbucker se afastam, o resultado tende a resultar em um mid scoop audível, formando tanto o tom Stingray reconhecível quanto o tom Jazz Bass reconhecível. (É muito mais complicado do que isso: veja abaixo uma simulação! Mas o resultado audível tende a ser algum grau de furo médio.) Em contraste, quando as duas metades de um humbucker estão próximas, como em uma barra de sabão (pense em Thunderbird ), eles não produzem um furo médio audível.

Você pode brincar com as posições de captação e ver as mudanças de resposta de frequência das quais estou falando aqui:
Demonstração de resposta do captador de guitarra
Lembre-se de que você não está ouvindo nada acima de 5KHz de um gabinete de graves, e a carne da resposta será inferior a 2,5KHz. Como você notará, quando dois captadores começam a se afastar, uma grande queda na resposta de frequência começa a se mover para baixo no espectro e para a faixa audível.

e se este tiver quatro bobinas e as bobinas combinadas em série, ponte e braço separados, mas trabalhando em série, terá os mesmos resultados?

 

[JrMare]

and if this has four coils and the coils combined in series, bridge and neck separate, but working in series, will it have the same results?

 

[spatters]

and if this has four coils and the coils combined in series, bridge and neck separate, but working in series, will it have the same results?

Yes, if I understand you correctly.
Pickup position changes your tone independently of series/parallel.
Changing pickup positions will cause the filtering you see in the simulation I linked.
Changing from series to parallel will cause weaker output but much more treble.