Electronic music - pickups: Difference between revisions
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'''Electromagnetic pickups''', a.k.a. '''magnetic pickups''', means | |||
* a coil, | |||
* close to a permanent magnet (practically often around, it's useful positioning), | |||
* with both oriented and positioned so that a nearby conductor moving in that field affects the field in a way that makes it into the coils | |||
In the case of a guitar, the vibrations of the string becomes the signal, pretty directly. | In the case of a guitar, the vibrations of the string becomes the signal on the coil, pretty directly. | ||
This is why such guitar pickups only work with metal strings, | |||
and do not pick up anything acoustic ''at all'' so the rest of the guitar's design barely matters to the sound. | |||
'''Single coil or humbucker''' | |||
Coils are by nature an antenna, so are good at picking up any electromagnetism happening nearby, | |||
the strongest of which is usually the 50Hz / 60Hz power hum. | the strongest of which is usually the 50Hz / 60Hz power hum. | ||
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The simplest pickup is a '''single-coil''' pickup, which don't address this at all. | |||
two such coils, | |||
hooked up in opposite polarity, | |||
and one with its magnets flipped. | People then thought up '''humbuckers'', a setup that takes | ||
* two such coils, | |||
* hooked up in opposite polarity, | |||
* and one with its magnets flipped. | |||
You can work this out on paper if you want, but practically, due to being hooked up opposite, | |||
anything that both parts of the pickup pick up the same amount ends up being subtracted from that other near-copy. | |||
It's far from perfect, not least because of the varying position, but it's pretty decent for things that further away and low frequency - and mains hum is that. | |||
The movement from the nearby string, on the other end, will end up being picked up opposite (due to the flipped magnetics in the pickup) so that subtraction ends up being addition again. | |||
{{comment|Technically, you can connect humbuckers either in series or in parallel, | {{comment|Technically, you can connect humbuckers either in series or in parallel, | ||
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There is | Single coils tend to be brighter (and used in surf, guitar, sixties sounds), humbuckers tend to be bassier. | ||
And then there are distinct designs of each. | |||
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'''Individual pole or rail''' | |||
There is a distinction between | |||
* having individual poles under the strings | * having individual poles under the strings | ||
: closer poles | : closer poles mean you have more control of focusing the magnetics on the string, meaning somewhat stronger output | ||
: and when poles are screws, you can | : and when poles are screws, you can position it closer, per string | ||
:: ...and you may care to do that to change the relative volume of each string) | |||
* rail pickups, which have one long conductor do the same thing | * rail pickups, which have one long conductor do the same thing | ||
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:: and allow bending strings without volume loss | :: and allow bending strings without volume loss | ||
--> | |||
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There are a bunch more design choices that tend to | There are a bunch more design choices that tend to | ||
focus a little more on warmer sounds, or cleaner sounds, | focus a little more on warmer sounds, or cleaner sounds, | ||
There are a lot more specific designs, like | There are a lot more specific designs, like | ||
You can also individually wind poles | You can also individually wind poles | ||
--> | --> | ||
'''Passive or active?''' | |||
<!-- | <!-- | ||
Active pickups (a.k.a. hot pickups?) are any that are powered, whatever the style {{verify}} | Active pickups (a.k.a. hot pickups?) are any that are powered, whatever the style {{verify}} | ||
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Pickups give enough signal that they do not need to be powered, | Pickups give enough signal that they do not need to be powered, | ||
yet amplifying that signal closer to the source avoids some loss and noise issues, | yet amplifying that signal closer to the source avoids some loss and noise issues, | ||
and that | and that motivation is also why active pickups are usually humbuckers. | ||
--> | --> | ||
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(And no, you can't tap a single coil to do humbucking) | (And no, you can't tap a single coil to do humbucking) | ||
--> | --> | ||
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Yes but no. | Yes but no. | ||
Yes in that the physics of the guitar body matters ''much'' less than it does in | Yes in that the physics of the guitar body matters ''much'' less than it does in acoustic guitars. | ||
No in that there are still differences. | No in that there are still differences. | ||
Construction matters | '''Construction matters''' | ||
There are a lot of small 'because physics' notes to be made here | There are a lot of small 'because physics' notes to be made here. | ||
: A soft wood will bend, bending notes along. | |||
A lot of them matter more when it's poorly made and less when it's well made. | |||
This is part of why why there are no awesome $20 guitars - but also why the high end doesn't vary so much. | |||
The neck should to be a solid wood because of string tension, and arguably even weather. | |||
: A soft wood will bend, bending notes along. Bending can be a cool effect itself, but almost uncontrollable this way. | |||
: It's workable in theory, but it is more practical to design a guitar with a harder wood, and bend yourself. | : It's workable in theory, but it is more practical to design a guitar with a harder wood, and bend yourself. | ||
The bridge probably shouldn't be soft either. How solid the neck-body connection | The bridge probably shouldn't be soft either. | ||
How solid the neck-body connection also effect how long a tone is sustained. | |||
At the same time, there ''is'' a price at which it's all intentional design focus, | At the same time, there ''is'' a price at which it's all intentional design focus, | ||
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'''Pickups aren't created equally.''' | |||
Let's not forget the tone circuit, which are often RC lowpass filters, sometimes highpass style. | Let's not forget the tone circuit, which are often RC lowpass filters, sometimes highpass style. | ||
These are filters. Filters make a These make a large difference. By design. | |||
Also, a pickup and passive tone circuit will become a larger circuit that interacts. | |||
Guitar tone can vary for just this reason. | |||
If you like the result, it doesn't matter much whether that was accident or highly intention design. | |||
On the other hand, tonewood is ''mostly'' nonsense.. | |||
Yes, choice of woods is ''absolutely'' a thing in ''acoustic'' instruments, because of the resonance on the body and cavity of the guitar, | |||
neither of which are noticeably on the body of the electric guitar - only anything that makes it into the strings will be heard, | |||
which means the pickup is the largest factor. | |||
There are some footnotes to this (like the already mentioned sustain), but they are mostly quite subtle. | |||
''DIY'' | '''DIY pickups''' | ||
You ''can'' wind your own pickups. There's a bunch of math involved, | You ''can'' wind your own pickups. | ||
There's a bunch of math involved, | |||
and while a lot of pickups are enough like each other that you can have a goal, | and while a lot of pickups are enough like each other that you can have a goal, | ||
that's also roughly why it may not be worth the work. | that's also roughly why it may not be worth the work. | ||
Revision as of 13:44, 2 August 2023
Piezo elements
A piezo element (often in disc form, sometimes in others like a guitar pickup's rectangular pellets) responds to bending/stress on its surface with voltage.
This makes them useful to sense vibration, impact (they are common in electronic drumkits), and in theory bending.
You can also use them as actuators, but only for very small movement - small sounds, small actuators in microscopy, maybe some haptic feedback.
(They are seen in some vandal proof buttons, because there can be a serious amount of hard material in between button and piezo. But they are not the only or often even best way to do that.)
There are also piezo based kinetic switches - e.g. battery-less RF buttons that operate from the energy you put in.
On piezo polarisation
Electromagnetic pickups
Electromagnetic pickups, a.k.a. magnetic pickups, means
- a coil,
- close to a permanent magnet (practically often around, it's useful positioning),
- with both oriented and positioned so that a nearby conductor moving in that field affects the field in a way that makes it into the coils
In the case of a guitar, the vibrations of the string becomes the signal on the coil, pretty directly.
This is why such guitar pickups only work with metal strings, and do not pick up anything acoustic at all so the rest of the guitar's design barely matters to the sound.
Single coil or humbucker
Coils are by nature an antenna, so are good at picking up any electromagnetism happening nearby,
the strongest of which is usually the 50Hz / 60Hz power hum.
And this hum can be made worse by certain effects, including distortion, fuzz, compressors .
The simplest pickup is a single-coil pickup, which don't address this at all.
People then thought up 'humbuckers, a setup that takes
- two such coils,
- hooked up in opposite polarity,
- and one with its magnets flipped.
You can work this out on paper if you want, but practically, due to being hooked up opposite, anything that both parts of the pickup pick up the same amount ends up being subtracted from that other near-copy.
It's far from perfect, not least because of the varying position, but it's pretty decent for things that further away and low frequency - and mains hum is that.
The movement from the nearby string, on the other end, will end up being picked up opposite (due to the flipped magnetics in the pickup) so that subtraction ends up being addition again.
Technically, you can connect humbuckers either in series or in parallel,
but series is more typical due to the output signal (and the effect(verify)) being a little stronger.
Single coils tend to be brighter (and used in surf, guitar, sixties sounds), humbuckers tend to be bassier.
And then there are distinct designs of each.
Passive or active?
Sustainers
A guitar sustainer is an electromagnetic pickup coil, plus amplifier and driver coil.
The net effect is that it amplifies the electromagnetics it picks up (relatively low frequencies, due to its design),
which on a guitar means forcedly resonating the tone currently being played.
These are often separate products.
Some guitars have sustainers built in (this is often custom), which will often look like regular pickups, and could even be used as a pickup when not active, should you want to.
These are often used for spacey sounds or other genre-specific things, because while it's good at controlling slow volume swells, tremolo, and some other expressiveness that you cannot easily do on guitars (and are more commonly associated with other instruments, like violins - which is e.g. where the e-bow gets its name), long sustains don't combine too well with strumming or fast playing.
The E-bow is one brand of hand-held sustainer, aimed to work on one string, to add expressiveness to phrasing. It has a groove to rest on one string (that you're not playing) to help align and pivot is to modulate the effect, the other to indicate where it picks up and excites.
Its designer found that if you reverse the driver coil, it dampens the fundamental frequency and amplifies overtones/harmonics a bit more. This is presumably all that the harmonics switch does.