Acoustic Pickups: An Introduction
There are many different ways to amplify an acoustic guitar, and each one has its own distinct character. They all produce a recognisable acoustic guitar tone, but finding the one that's right for you can be tricky. In this article, we'll look at the three main types - magnetic, piezo and microphone ? what they?re used for, and what they can do for you and your music!
- How They Work - Insulated copper wire is wrapped around a magnet, creating a magnetic field which is ?disturbed? by the vibration of a steel guitar string. This is identical to an electric guitar pickup.
- How They Sound - Warm and musical, with good string detail.
- Advantages - Sonic warmth, easy to control, and interacts well with effects.
- Disadvantages - Doesn?t capture the acoustic resonances inside the body itself.
- Best For... - Flatpicking (strumming)
- How They Work - The pickup is placed between the bridge saddle and the bridge itself, and vibrations from the string cause changes in pressure, changing the voltage of piezoelectric material.
- How They Sound - Very clear and direct, with purely ?string sound? rather than the resonances of the guitar?s body.
- Advantages - A very controllable sound with greatly minimised risk of feedback.
- Disadvantages - The sound can be a bit brittle, and is notorious for ?piezo quack,? a sharp overtone which most players dislike (but there are ways to combat it).
- Best For - Multiple styles.
- How They Work - Sound waves vibrate a diaphragm, which causes other components to vibrate. These vibrations are converted to an audio signal.
- How They Sound - Natural and realistic. A well-placed microphone will capture all the nuances of the guitar.
- Advantages - The most naturalistic sound reproduction possible.
- Disadvantages - There?s a risk of unwanted feedback, and the mic placement isn?t right your sound will suffer.
- Best For - Fingerpicking.
Combining Pickup Types
Many players find that they get the best results by combining different types of pickup, taking advantage of the particular strengths of each. For instance, many players like to use an internal microphone to capture the resonance and sonic depth of the guitar?s body, with a piezo system used to capture the detail and attack. Or, if the piezo sound is too up-front for that guitarists? particular musical goals, a magnetic pickup and a microphone will give you a very full, round, ?big,? natural sound with good detail.
Most players don?t blend piezo and magnetic pickups, because both methods are driven by the strings themselves, so you risk the possibility of clashing frequencies and all sorts of sonic weirdness. So in short, if you want to blend, you'll be using a microphone pickup blended with something else - the question you need to ask is 'why?'
If your style is more rhythmic, a piezo & mic combination will give you a great representation of your guitar?s attack. If it?s more detail-oriented, a magnetic & mic combination will be more representative of what happens to the string throughout the whole life of the note.
There are some piezo pickups (such as the K&K Sound Pure Mini) which are placed on the underside of the guitar top, giving it a much smoother voice than a regular under-saddle piezo. Seymour Duncan?s Mag Mic combines a hum-cancelling magnetic pickup with an omni-directional condenser mic in one unit.
Acoustic Guitar Preamps
The majority of pickups (and some mic systems too) come with a preamp to further shape the sound. Some offer control options such as multi-band EQ, whereas some simply offer a volume option, some take the shape of small panels on the side of your guitar, and some are even available as an external device that you plug your guitar into!
There?s no such thing as a typical or standard preamp, but there are some features that are more common than others.
There?s almost always a volume control, often with some kind of tone shaping. This can take the form of a simple ?tone? control, or perhaps individual knobs for different EQ options. You might also find a tuner built-in, often chromatic, meaning you can easily tune your guitar to alternative tunings.
Many preamps also include some kind of feedback-zapping button (more on this in a second). Some systems like the Fishman Aura even superimpose tonal images onto your tone, providing you with another level of realism!
If your guitar doesn?t have a preamp, that?s often a good sign that it?s a very transparent-sounding unit, and it?ll usually sound great plugged into any acoustic amplifier, DI / mixing desk or a preamp pedal.
There are many pedal-based units out there and they give you a lot of freedom because you can choose exactly what you?re filtering your guitar sound through. Fishman offers a number of different Aura models in stomp box form, and the D-Tar Mama Bear has more of a ?desktop? design. This unit digitally filters your guitar to neutralise the sound of the pickup, then lets you dial in one of 16 ?target instruments? from parlours to super-jumbos.
Installing Acoustic Pickups
When it comes to installing Electric Guitar Pickups, there's quite a lot of work involved; dismantling, soldering, wiring and so on. Luckily, it isn't necessarily the same for acoustics. Some pickups can even be installed without any modification whatsoever! Let's take a closer look:
- Expertise Required - Minimal.
- Amount of modification - Usually none. Most simply fit into the sound hole with no mods required
- How visible is it? - The pickup itself is invisible. Depending on the preamp, your guitar might end up with lights and knobs on the side.
- Expertise Required - Intermediate to advanced.
- Amount of modification - Requires some drilling, and you?ll need to cut a hole in the side of the guitar for some onboard pre-amps
- How visible is it? - It?ll be visible in the sound hole, but some are designed to integrate with your guitar?s look.
- Expertise Required - Intermediate to advanced.
- Amount of modification - Some models can be installed with no modification. Others require drilling etc.
- How visible is it? - The mic itself is invisible. Depending on the preamp, your guitar might end up with lights and knobs on the side.
Reducing feedback from acoustic pickups
Ah feedback, the common enemy of live musicians, public speakers and studio engineers alike. Feedback occurs when a microphone 'hears' itself through a speaker or output source, completing a sort of 'loop' in the sound - this causes the signal to increase in size, generating unattractive frequencies!
The same thing can occur with acoustic guitars - the pickup or mic system hears its own signal feeding back and creates a lot of unwanted noise. There are a few useful ways of preventing acoustic guitar feedback:
- Phase Switching - feedback is made worse by the fact that the phase (shape of the waveform) of the signal (in this case, your acoustic) going into the mic matches the one that's feeding back into it, causing that ugly loop we were talking about. A phase switcher inverts the phase of your acoustic so that it no longer matches the signal coming out of the speaker. This reduces the chance of the signals clashing and causing unwanted noise. Phase switches can be found in some acoustic preamps or acoustic pedals, such as the LR Baggs Para Acoustic DI Box.
- Soundhole Cover - this does exactly what is says on the tin. It's a simple piece of (usually) plastic or wood that sits over your guitar's soundhole, preventing the sound of your strings going into the body of the guitar. This can prevent any sound from looping back into the pickup system, but as you may have already guessed, it can change the way your guitar sounds, particularly if you're using a mic system!
- EQ Adjustment - sometimes the simplest solution is the best! In some cases, you can isolate feedback to a particular frequency - for example, a common issue with acoustics is feedback in the low-mid frequencies. This means a full-bodied, intrusive rumble coming out of your speakers - to combat this, try tweaking the EQ of your guitar. This can either be done on the guitar itself using the built-in preamp (if you have one) or on a mixer / sound-desk / EQ pedal. Reducing these frequencies can reduce the chance of boomy feedback!
Well there we have it, folks! The aim of this guide was to inform you of the different types of acoustic pickups available on the market today, and the advantages and disadvantages of each one!
Will you be performing live? Do you want a DIY project? Are you on a budget? Hopefully this article has answered all of your questions and taken you one step closer to finding the right acoustic pickup system for you!
While you're at it, why not check out the rest of our buyer's guides? You might just find something else you like!