Plugging In: Acoustic Guitar Pickups and Their Pros and Cons

I’ve been playing acoustic for a few years and I’m ready to start playing out. I want to put a pickup in my guitar (a Martin 000-15M) but I am a bit overwhelmed by all the different choices, and I don’t know what will work best. I play mostly solo or duo with a pick, but also play some solo fingerstyle. What is a good choice that will work with my guitar? —John Chen 

Amplifying acoustic guitars is a challenge, and many brilliant people have spent years working on solutions to do it well. There are loads of pickups available, and it can be hard to know which will best suit your needs. When recommending pickups to my clients, I start with a few questions to narrow down the choices: piezo or magnetic; active or passive; reversibility; and playing style/anticipated uses.

The first question is straightforward—piezo or magnetic? Piezo pickups are built of materials that transform vibration into an electrical signal. These are usually placed underneath the bridge saddle or stuck underneath the top. Since piezos directly sense the guitar’s wood, many players feel that they have a more accurate acoustic tone and character. However, this depends considerably on a well-executed installation. Poorly placed or badly installed piezos are notorious for uneven response, dead strings, and other maddening deficiencies. If you install a piezo system yourself, be aware that your results may not reflect the pickup’s fullest potential. Hiring a professional to install a piezo system is a good investment in performance and reliability.

Magnetic pickups for acoustics nearly always come in the form of a rectangular shell that clamps into the soundhole, just past the end of the fingerboard. Magnetic pickups only sense the strings, so they can sound a bit more similar to electric guitar pickups. Some players consider this an advantage—because magnetic pickups do not directly sense movement of the guitar’s top and air chamber, they can be more resistant to feedback than piezos. Their partial obstruction of the soundhole can also help with this. If you play with pedals or effects, a magnetic pickup may also interact with those in a more comfortable and familiar way. Fishman’s Rare Earth and L.R. Baggs’ M1 are two very popular magnetic systems, and come in both passive and active versions to suit player preference and budget.

Active systems are those that require onboard power, usually in the form of a 9-volt battery. Active piezo systems are the most common, for good reason—they tend to perform better and more consistently than passive systems. Piezo transducers require a high-impedance amp input to maintain their full frequency response, and many effects and amplifiers don’t have sufficiently high-impedance inputs to allow the pickups to sound their best. If the impedance is too low, the piezo will suffer from thin, scratchy response. Well-designed active piezo setups have a high-impedance preamp stage built in, which allows the pickup to perform consistently with a more robust signal across different kinds of inputs. 

The only real liability for the player is the occasional maintenance of changing the battery, along with the risk that the battery might die during a performance. Some guitars have battery compartments accessible from the outside, but most aftermarket systems assume the battery will be placed inside the guitar, requiring the player to loosen the strings in order to change it—hardly something that can happen between songs on a gig.

For players averse to the cost, weight, or maintenance of active systems, there are a few well-established passive piezo systems on the market. The most popular of these with my clients is the K&K Pure Mini. Though these pickups may be a bit more sensitive to the amp or input they are being plugged into, they offer a reliable and maintenance-free option that appeals to many. One downside: almost all the quality passive pickups on the market are meant to be wired directly to the output jack, with no volume or tone controls. If you want to adjust the level or tone of the instrument on-the-fly, an active system is the best choice. Finally, although good passive pickups can sound fine plugged directly into an amp or DI, they always perform better when matched with a high-quality external preamp.

As in any case where I am modifying a guitar, I consider reversibility and potential impact on value. Nearly every pickup on the market uses an output jack with an integrated endpin/strap button. Installing these involves drilling out the tapered endpin hole to a larger 1/2-inch hole. Generally, players are willing to commit to having this jack installed, as it is by far the most practical option. If you really prefer not to drill out the endpin hole, some magnetic pickups have long lead wires that trail out of the soundhole, with a 1/4-inch plug at the end. These can be a bit ungainly to store, but it is an option.

Beyond the endpin, there are other worthwhile considerations. Undersaddle pickups require drilling a small hole in the floor of the saddle slot in the bridge. This tiny hole presents no risk to the health or structure of the guitar—unless the tech drills through one of the braces by accident! (I’ve seen a few of these, even in factory guitars.) Once again, this is a strong argument for professional installation.

Body/top sensors are adhered directly to the underside of the guitar top, either with superglue or high-tech double-faced tape. These can be touchy to remove, with a risk of tearing away wood fibers, and a high likelihood of damaging or destroying the pickup itself, so this type of pickup is less reversible than the others.

Many piezo systems come with side-mounted preamps offering loads of functionality—EQ, onboard tuners, modeling, feedback filters, phase switching…the list goes on. However, all this comes at a big cost. They require the installer to cut a hole in the side of the guitar, which is a one-way street that understandably makes many players feel a bit queasy. It has been years since a client asked me to install such a system, since many good options now exist that don’t require such a drastic modification. However, if your needs include extended onboard controls, and the guitar is not a prized vintage model, it may be that a side-mounted preamp such as the Fishman Ellipse Aura would be appropriate.

Magnetic pickups typically clamp onto the top with a padded jaw on each side of their housing. Manufacturers do their best to make these jaws safe for the top, but I’ve seen plenty of cases where the top was scratched, dented, or otherwise damaged by magnetic pickups that were too loose, too tight, or otherwise incorrectly installed. Make sure the jaw pads are clean and undamaged, and use care in placing and tightening them.

The final and most important consideration is playing style and anticipated use. Players who record, or perform in quieter environments, may do well with a top-mounted sensor that conveys more nuance and acoustic character. My current favorite of these is the L.R. Baggs HiFi system. These pickups’ greater susceptibility to feedback is not likely to be a concern in such environments. More energetic players, or guitarists in ensemble settings, may opt for undersaddle pickups, which are less likely to sense the thumps and handling noise that can plague body sensors. Active undersaddle pickups also frequently have onboard volume and tone controls that allow for adjustments without needing any floor space for outboard gear.

It can be hard to weigh the pros and cons of each type of system. For players who want more versatility, there are hybrid systems such as the L.R. Baggs Anthem that combine multiple sources—magnetic and piezo, magnetic and microphone, or undersaddle piezo and top sensor. These multisource systems can perform well in a range of settings, allowing the player to adjust the system to emphasize the source that is best suited to each playing environment. More and more of my clients have been requesting systems with this kind of flexibility, and there are good choices available on the market. The only real liability with these is the added cost and more involved installation.

It can be dizzying to sort through all of these different considerations, when all we really want is to take our beloved acoustic and make it louder. However, a poor match between pickup, amp, and player can make the amplified experience pretty unsatisfying, so it’s worth spending time to understand the options. Your Martin is a nice guitar that can be a great amplified instrument, and it’s worth investing in a system that will make it perform its best.

This article originally appeared in the March/April 2025 issue of Acoustic Guitar magazine.