I don’t supply pickups, not can I recommend which to by – there are simply too many on the market for me to try them all. However if you buy a pickup I will be happy to fit it for you, and I can offer some advice to help you decide what type of system will suit you best. Regardless of manufacturer, pickups fall into four basic types: magnetic, contact, undersaddle and blend. The sound you get from a pickup depends almost entirely on which type it is, not who made it.
Do you really need a pickup?
The first thing to think about is the difference between a pickup and a microphone. A microphone capture sound – vibrations in the air. A pickup doesn’t capture sound, it picks up vibrations directly from the strings or wood of the instrument. With a stringed instrument like a guitar sound is produced in two ways: high frequencies radiate directly from the soundboard, but low frequencies are amplified by the air inside the guitar and radiate from the soundhole (for the science geeks it’s a system known as a Helmholtz resonator). This means that any pickup that takes vibrations directly from the wood or strings doesn’t get those low frequencies, the raw sound from the pickup is always too bright and tinny and needs tone control or equalization in the amplification system to make it sound anything like a guitar. So for studio recording or for classical recital type performances, by far the best solution is to forget about pickups and use a stand microphone in front of the guitar to capture the true acoustic sound of your instrument. But in many live performance situations playing to a microphone is completely impractical, so a pickup becomes a necessary evil.
Types of pickup:
Magnetic. From the sound quality point of view magnetic pickups are the least realistic option, but they do have some other advantages. They pick up vibrations directly from the strings, like an electric guitar. With some of the cheaper ones you may have to change to nickel wound strings to get an even balance across the strings, although the better ones use rare earth magnets, which respond much better to bronze strings. The advantages of magnetic pickups are that they usually just clip on across the soundhole, so can be removed or transferred between instruments very easily); they can be plugged straight into an ordinary guitar amplifier, without a preamp; and they are less prone to feedback than any other pickup – if you play acoustic in a loud electric band a magnetic pickup might be a good choice.
Undersaddle pickups consist of a piezo transducer fitted between the saddle and the wood of the bridge. To make room for them without raising the action, and to allow the cable to run inside the guitar, the bridge and saddle have to be modified, so they need to be fitted by a competent person. The raw sound they produce is very bright and percussive (often referred to as ‘the piezo quack’) but it can normally be equalized to sound quite reasonable, and they are reasonably immune to feedback. Undersaddle pickups are usually the cheapest to buy, but that saving is often cancelled out by the extra work involved in fitting them.
Contact pickups use the same piezo technology as undersaddle pickups, but instead of being mounted in the bridge they are stuck to the underside of the soundboard. This gives them a warmer sound, closer to the acoustic sound of the instrument, but it also makes them more vulnerable to feedback. The sound they produce is very dependent on exactly where they are attached to the soundboard, and a bit of experimentation is needed to find just the right spot.
Blend systems sit at the top of the price range and give by far the most natural sound. They employ either a contact or undersaddle transducer to pick up the high frequencies, combined with an internal microphone to pick up the low frequencies from the air within the guitar. The microphone does bring feedback problems, but you can adjust the balance between the two elements, reducing the microphone output in high feedback environments or even using only the transducer if necessary.
Apart from magnetic pickups, acoustic guitar pickups can’t be plugged straight into an ordinary guitar amplifier or mixing desk, they need a pre-amplifier. The pre-amp might be built into a dedicated acoustic amplifier, or take the form of a stomp box. These are OK providing you keep the cable as short as possible to minimize noise, but a much better solution is to have the pre-amp built into the guitar. These days most manufacturers sell their pickups as systems consisting of transducer, pre-amp and output socket. The pre-amp is more critical to the sound than the transducer, so having decided on which basic type of pickup you want, concentrate on the spec. of the preamp when you compare manufacturers. Internal pre-amps generally come in one of three forms: the simplest is the combined end-pin jack preamp – the electronics are built into a jack socket which replaces the strap button (the bottom of the guitar has to be drilled to accommodate it). These are simple and unobtrusive, but they have no controls, so you are left at the mercy of the sound engineer. Next come the soundhole adjusters. These have the preamp on a small circuit board that mounts under the soundboard at the edge of the hole, with volume and usually simple tone controls that you can adjust by slipping a finger past the strings. A bit fiddly, but very unobtrusive, and the guitar doesn’t need permanent modification. Finally there are the the side mounted pre-amps. These are mounted in a hole in the top rib of the guitar. They usually have much more sophisticated controls including a multi-band equalizer and often a built in tuner, and are very easy to adjust, even mid-song. The down side is that a hole has to be cut in the side of the guitar to accommodate them, so they become a permanent fixture.