Playing an acoustic guitar offers a uniquely intimate experience, where the instrument’s natural resonance envelops you in sound. This personal connection is a major part of the acoustic guitar’s charm. However, this beautiful, subtle sound often struggles to project beyond a small group. Whether you’re facing a larger venue, the ambient noise of a coffee shop, or the challenge of playing alongside louder instruments, amplification becomes essential to make your acoustic guitar heard. Understanding the world of Acoustic Guitar Amplification can seem complex, but it’s crucial for any performing acoustic guitarist. Let’s break down the key components of an acoustic amplification system: pickups, preamps/DIs, and amplifiers/PA systems, to help you navigate your options and achieve the best possible amplified sound.
The Starting Point: Guitar Pickups
The first step in acoustic guitar amplification is converting the guitar’s acoustic vibrations into an electrical signal. This conversion is achieved using either a microphone or a pickup. While microphones excel in controlled, quiet environments, they become problematic in louder settings or when other instruments are present, as they tend to capture unwanted ambient sounds and are prone to feedback. For most performance situations, guitar pickups offer a more practical solution. They allow for greater mobility on stage, provide higher volume levels before feedback occurs, and effectively isolate your guitar’s sound from other instruments on stage. Therefore, this article will primarily focus on amplification systems built around pickups. The market offers a vast array of pickups, but they can be broadly categorized into several main types:
Magnetic Soundhole Pickups: These pickups operate on the same principle as electric guitar pickups, utilizing magnetic fields to detect string vibrations. Typically, they are designed to mount directly into the guitar’s soundhole, often clamping onto the guitar top for secure installation. Some models are easily removable, offering flexibility for players who want to use them on multiple guitars. Magnetic pickups are favored by musicians who need to play at higher volumes due to their enhanced resistance to feedback. They are known for producing a warm, full tone, albeit with a somewhat “electric” character, which can be desirable for various musical styles. Popular examples of magnetic soundhole pickups include the Sunrise S-2, Fishman Rare Earth, Krivo Djangobucker, L.R. Baggs M80, and DiMarzio Black Angel.
Fishman Rare Earth pickup installed in an acoustic guitar soundhole
Undersaddle Transducers (USTs): USTs are extremely thin, piezo-electric strips that are positioned within the saddle slot, directly beneath the guitar’s saddle. They are the most prevalent type of pickup found in factory-installed acoustic-electric guitars. The popularity of USTs stems from their effective balance of feedback resistance and reasonably natural acoustic tone reproduction. However, they can sometimes produce a harsh, artificial sound, often described as “quack,” particularly when the guitar is played aggressively. USTs are easy to install and are virtually invisible, maintaining the aesthetic of the acoustic guitar. Common examples of USTs include the Fishman Acoustic Matrix and the L.R. Baggs Element.
Soundboard Transducers (SBTs): SBTs are sensor-based pickups that are typically attached to the guitar’s bridge plate inside the instrument. They function by detecting the vibrations and resonances of the guitar’s soundboard. SBTs are often lauded for capturing a more “woody” and natural acoustic tone compared to USTs, as they respond to the complex vibrations of the guitar’s top. However, in high-volume performance settings, SBTs can be more susceptible to feedback compared to USTs or magnetic pickups because they are more sensitive to the guitar body’s resonance. Examples of SBTs include the Trance Audio Amulet M, the K&K Pure Mini, and the DiMarzio Black Angel Piezo (which is a different model from the magnetic Black Angel).
Internal Microphones: Internal mics are positioned inside the guitar body to capture a more natural and airy sound, similar to using an external microphone. They offer better feedback rejection than external mics, as they are less exposed to ambient sound and stage noise. However, the sound quality may not be as pristine as a high-quality microphone placed externally. While some internal mics are designed for standalone use, such as the MiniFlex 2Mic Model 1, they are more often used in conjunction with another type of pickup in dual-source systems to blend the mic’s natural tone with the pickup’s feedback resistance.
Dual-Source Systems: To capture the complex and nuanced sound of an acoustic guitar more comprehensively, and to offer greater versatility in different performance situations, dual-source systems combine two or more different types of pickups. These systems aim to harness the strengths of each pickup type, often blending the natural tone of a microphone or SBT with the feedback resistance and directness of a UST or magnetic pickup. Popular dual-source systems include the L.R. Baggs Anthem (UST and internal mic), the Fishman Ellipse Blend (UST and internal mic), and the Fishman Rare Earth Mic Blend (magnetic pickup and mic). For adventurous players, creating a custom dual-source system by combining different pickups from various manufacturers is also an option, allowing for tailored sound and performance characteristics.
When choosing acoustic guitar amplification, it’s important to consider the specific instrument you play. For instance, magnetic pickups are not compatible with nylon-string guitars, although USTs, SBTs, and internal mics can be used. Resonator guitars, with their unique saddle construction, often require specialized pickups. Guitars with wider string spacing or unconventional soundhole shapes may also limit pickup choices.
Preamps, DIs, and Essential Effects
For optimal acoustic guitar amplification, a preamp or DI (direct input) box is often essential. A DI box, in its simplest form, is a passive device containing a transformer that converts the high-impedance signal from a passive pickup into a low-impedance signal that is compatible with mixing consoles. A DI accepts a standard 1/4-inch instrument cable and provides an XLR output, which is the standard input for professional audio mixers. Using a DI improves the signal quality by ensuring proper impedance matching, minimizing signal loss, and allowing for long cable runs without compromising tone. Examples of simple, passive DIs include the Whirlwind IMP 2, Radial ProDI, and Radial JDI. Active DIs, such as the Radial J48 or Samson MDA1, require power and may include additional features like signal boosting or buffering.
A preamp’s primary function is to boost the guitar’s signal level. Preamps, whether integrated into the guitar or used as outboard gear, typically offer volume and tone controls for shaping the amplified sound. Many outboard preamps also include an XLR output, effectively functioning as a DI as well. In practice, the distinction between an “active DI” and a preamp is often blurred, with marketing considerations sometimes playing a larger role in categorization than technical differences.
A DI or preamp is crucial for achieving the best sound when connecting an acoustic guitar to a PA system mixer. Many guitarists also prefer using a preamp even when plugging into a dedicated acoustic guitar amplifier, as it offers greater control over the guitar’s signal. Some preamps provide advanced routing capabilities, allowing you to send your guitar signal simultaneously to a PA system and a stage amplifier. (Fig. 3) A comprehensive preamp can serve as a central hub for your acoustic signal chain, offering features like mute switches, notch filters for feedback suppression, and more sophisticated EQ options than typically found on amplifiers or mixers. Some preamps also incorporate effects, tuners, and other valuable tools.
Popular outboard preamps for acoustic guitar include the Fishman Platinum Pro EQ, L.R. Baggs Venue, and Grace Alix. For players seeking an all-in-one solution, pedalboard-style preamps like the Tech 21 Acoustic Fly Rig, which includes reverb, chorus, compression, and a tuner, or the Boss VE-8 Acoustic Singer, which adds vocal processing with harmony and pitch correction, offer comprehensive functionality. Furthermore, preamp/DIs like the Fishman Aura Spectrum DI or Audio Sprocket ToneDexter utilize modeling technology to enhance the natural sound of your guitar.
Amplifiers and PA Systems for Acoustic Guitar
The choice of amplification and speaker system significantly determines the final sound that your audience hears. The two main options are dedicated acoustic guitar amplifiers and PA (Public Address) systems, although some products effectively bridge the gap between these categories.
Combo amplifiers, which combine an amplifier and speaker(s) in a single cabinet, are a convenient and portable option. Compact amps like the Fishman Loudbox Mini or Henriksen The Bud provide sufficient volume for smaller venues and are easy to transport. Many acoustic amplifiers also include a DI output, allowing you to connect to a PA system in larger venues (Fig. 2). Alternatively, using a preamp with routing capabilities enables you to send a signal to both your stage amplifier and the PA. This setup allows the amplifier to function as a stage monitor, while the PA system projects the sound to the audience.
PA systems typically consist of a mixing console with multiple inputs and larger separate speakers placed in front of the stage. PA systems are designed for projecting sound to larger audiences and often include monitor speakers directed back at the performers. PA systems generally offer higher volume capabilities and better projection than combo amplifiers. Portable PA systems, consisting of a compact mixer like the Mackie ProFXv2 or Allen & Heath ZEDi-10FX paired with powered speakers such as the QSC K10.2 or JBL EON610, offer a balance of portability and power.
“Personal PA Systems,” such as the Bose L1 Model II, Fishman SA330x, or L.R. Baggs Synapse, represent a hybrid approach, blending features of both amplifiers and PA systems. These systems are designed to project sound to a large audience like a PA, but are positioned behind the performer like a traditional amplifier, allowing the musician to hear the same sound the audience hears. (Fig. 1)
Fishman Rare Earth pickup installed in an acoustic guitar soundhole
Dialing In Your Ideal Amplified Acoustic Sound
Once you’ve assembled your amplification gear, mastering its effective use is the next crucial step. Feedback is a common challenge for amplified acoustic guitarists, often occurring even at moderate volume levels. Optimizing amplifier placement is the initial step in managing feedback. Positioning your stage amp on the floor, slightly to the side, allows your body to act as a sound barrier between the amp and your guitar (typically to your left for a right-handed player). When using a PA system with wedge monitors, ensure the monitors are not aimed directly at your guitar. PA speakers should ideally be positioned well in front of you. Soundhole covers, often called “feedback busters,” can also be effective in reducing feedback by minimizing resonance within the guitar body.
Many amplifiers and preamps include a notch filter to combat feedback. To use a notch filter, gradually increase the volume until feedback begins, then slowly adjust the notch filter knob until the feedback diminishes. Remember that feedback frequencies can change depending on your position relative to the amplifier or speakers. Moving around while playing may reveal different feedback hotspots to avoid. Feedback can also be note-specific, so thoroughly check different bass notes during soundcheck.
A soundhole feedback buster can be a simple yet effective tool to control feedback.
With feedback managed, the next focus is EQ (equalization) to achieve a desirable tone. Ideally, aim for a good basic sound with EQ controls set flat. This allows you to use the EQ to adapt to different room acoustics and volume levels rather than compensating for inherent tonal issues in your gear. Acoustic guitars often have resonant frequencies in the lower midrange, which can become problematic at higher volumes. Reducing bass frequencies (60–120 Hz) or low mids (200–400 Hz) can help eliminate muddiness and boominess. When using magnetic pickups, reducing upper mids (around 1 kHz) can minimize the “electric” sound. For piezo pickups, especially USTs, cutting frequencies around 1 kHz and 5–7 kHz can reduce harshness and “quack.” Preamps with parametric EQ controls offer precise frequency adjustments, while basic bass, treble, and mid controls offer less flexibility.
Volume levels also influence perceived tone. At lower volumes, our ears are less sensitive to bass and high frequencies. To compensate, you can make your guitar sound fuller at low volumes by reducing mids and/or boosting bass and treble. At higher volumes, reducing bass and treble and slightly increasing mids may be preferable. In a band context, consider how your guitar sound blends with other instruments. A significant midrange cut can help your guitar stand out in a dense mix.
Generally, it’s more effective to cut frequencies than to boost them. Cutting provides more headroom and reduces the risk of overloading your signal chain. For example, if your guitar sounds too dark, try cutting bass or lower mids instead of boosting treble. The specific response will depend on the EQ characteristics of your equipment. Another effective EQ technique, particularly with parametric EQ, is to start by boosting frequencies to identify unpleasant resonances, then cutting those frequencies.
It’s important to note that some EQ suggestions may seem contradictory. Achieving a balanced amplified acoustic sound is a dynamic process, requiring adjustments based on volume, tone, and feedback considerations, especially at higher volumes. Experimenting and learning how different frequency adjustments affect your sound will empower you to trust your ears and respond effectively to various performance situations. The more you use your gear, the better you will understand its nuances and how to quickly dial in a great sound, allowing you to focus on your music.
Close up of acoustic guitar battery compartment
Active vs. Passive Pickups: Choosing the Right Type
A key decision when selecting an aftermarket pickup is whether to choose an “active” or “passive” system. Active pickup systems incorporate an onboard preamp within the guitar, powered by a battery. The preamp may be discreetly integrated into the endpin jack or mounted on the guitar’s side, often accompanied by volume and tone controls. Some side-mounted systems even include a built-in tuner. Active systems offer several advantages: fingertip control over volume and tone, and the preamp buffers and optimizes the raw pickup signal, ensuring consistent sound quality across different amplification systems. The majority of modern pickups are active, and virtually all factory-installed systems are active.
Passive systems are simpler, lacking onboard electronics or batteries, which appeals to some players. However, the tone of passive pickups can be more sensitive to the input impedance of the connected equipment. An external preamp can provide a consistent interface and address potential impedance mismatch issues. External preamps may also offer higher quality components and more advanced features than typical onboard preamps.
Factory-Installed vs. Aftermarket Pickups: Convenience or Customization?
Amplified acoustic guitars are so common that most manufacturers offer models pre-equipped with pickup systems. Some guitars are even exclusively available with built-in pickups, often featuring control panels integrated into the guitar’s side. Certain manufacturers, like Taylor, Takamine, and Maton, exclusively use their proprietary pickup systems in their guitars. Alternatively, you can add an aftermarket pickup to an existing acoustic guitar. Installing an aftermarket pickup allows you to choose your preferred guitar and then select a pickup separately, offering customization and the ability to experiment with different pickup types. Conversely, purchasing a guitar with a factory-installed pickup provides a ready-to-play, integrated system designed to work harmoniously, allowing you to evaluate the complete amplified sound before purchase.
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