Integrated vs External Acoustic Guitar Preamps

What built-in acoustic preamps offer

Acoustic-electric guitars often ship with a preamp built into the body, typically powered by a 9V battery. These onboard systems combine a pickup (often a piezo) with a small preamp circuit and control panel. The controls vary by model, but common options include volume, a tone or EQ knob, and sometimes a phase switch and tuner.

For example, many Martin acoustic-electric models use Fishman or LR Baggs systems. The Martin electronics guide lists the Fishman Sonitone with volume and tone controls, the Fishman MX with volume and tone that can scoop the midrange, and the Fishman MX-T with a built-in tuner and phase switch. The Martin E1 adds a phase switch and a chromatic tuner that mutes output while engaged. The LR Baggs Anthem offers volume, a blend control between pickup and microphone, a mic level adjust, and a phase inversion switch.

Built-in systems are designed to match the guitar's pickup and body, and they are factory-installed, so you don't need extra gear. For practice, recording at home, or plugging into a mixer or acoustic amp at a gig, a good built-in preamp is often all you need.

• Volume control adjusts overall output level.
• Tone or EQ control shapes the frequency response.
• Phase switch helps reduce feedback and enhance bass at low volume.
• Built-in tuners mute the output for silent tuning.
• Blend controls mix a condenser mic signal with the undersaddle pickup for a more natural tone.

What external preamps add

External preamps are separate devices, usually floor pedals or rack units, that sit between your guitar and the amplifier or PA system. They accept the raw signal from a pickup and provide additional gain staging, EQ, and often a direct (DI) output for connecting to a mixer. Some also include effects like reverb or notch filters to tame feedback.

The main advantage of an external preamp is control. While built-in systems typically offer one or two EQ knobs, external units often give you graphic or parametric EQ with more bands, so you can dial in specific frequencies. They may also include a high-pass filter, a phase reversal switch, and a tuner that can be placed on a pedalboard.

An external preamp also lets you maintain a consistent tone across different guitars. If you play several acoustics, you can run them all through the same external unit, instead of relying on each guitar's onboard preamp. This is useful in a studio or when you need to match a house PA system.

Tone shaping: built-in versus external

The tone your audience hears starts with the guitar's natural voice. As the Martin wood guide explains, the top, back, and sides affect volume, sustain, and tonal balance. Denser woods like rosewood produce more overtones, while mahogany offers a focused midrange. The body shape also matters: a dreadnought gives a boomy bass, while a concert body has a softer, more balanced tone. Your preamp does not change that natural tone entirely; it shapes the electrical signal after the pickup captures it.

Built-in preamps usually have just one or two tone controls, which is enough to compensate for a bright top or to reduce excessive bass at a gig. The Fishman Sonitone's tone control, for instance, only cuts treble, while the Fishman MX can scoop the midrange for a more modern sound. These limited controls keep operation simple and reduce the risk of tweaking yourself into a bad tone. For a closer look at the typical controls you might encounter, see our guide on acoustic guitar preamp controls.

External preamps give you more precise control. With multiple EQ bands, you can notch out a specific frequency that causes feedback or highlight the low end for fingerstyle passages. A 3-band EQ is common, and some units go further. When you need surgery on the sound, an external unit is the tool. But with more control comes a longer setup time and the need to learn how each band affects the sound.

Live use: convenience and control

On stage, built-in preamps offer the greatest convenience. You plug your guitar cable into the jack, set the volume once, and rely on the sound engineer. Most built-in systems have a tuner that mutes the output, so you can tune silently between songs. The phase switch helps with feedback without having to adjust the EQ. This is why many performing singer-songwriters prefer a solid acoustic-electric with a reliable onboard preamp, as covered in our acoustic-electric guitar guide.

External preamps are useful when you need direct control during a set. If you switch between a rhythm tone and a lead tone, you can program presets or step on the EQ. You can also place a pedalboard on the floor with the preamp, a tuner, and an effect pedal, keeping your acoustic setup flexible. However, that adds gear to carry and power to manage, which is worth considering if you travel light.

Feedback is a common issue with acoustic-electric instruments on loud stages. Built-in phase switches reduce feedback, as noted in the Martin electronics guide. External preamps often have more sophisticated feedback suppression, such as notch filters that target the frequency of the howl. If your gigs are loud or you monitor with in-ears, an external unit can be a safety net.

Regardless of which route you choose, keep the battery in good condition. A fresh 9V battery is essential for both built-in preamps and most external pedals. If your guitar's battery dies, you have no output. See our guide on replacing the battery in an acoustic-electric for a step-by-step process.

Matching the preamp to your guitar

The right preamp depends on the guitar you're using and the music you play. A small-bodied guitar, like a concert or parlor model, has a softer tone and less bass. A built-in preamp with a simple tone control can add presence without making the sound harsh. The Martin body type guide notes that concert guitars have a clear, crisp treble with delicate bass, so you might want a preamp that lets you cut some treble or boost the low end slightly.

For a dreadnought or jumbo that is naturally boomy, a built-in tone control that cuts bass can be useful. Many onboard systems, including the Fishman MX, offer a scooped setting that reduces midrange, which can help the guitar sit in a mix. If you play with lots of dynamics, a built-in blend control like the Fishman Aura VT Blend lets you mix in a microphone simulation for a more natural tone, as described in the Martin electronics guide.

If your guitar does not have a preamp installed, you can add an external one. This is common for players who want to upgrade an older acoustic or a plain acoustic-electric with a lower-quality pickup. In that case, an external preamp is the only option unless you install a replacement system, which is a more involved project. If you're considering upgrading, read about acoustic guitar pickup types to understand the options.

What to pick for your use

The table below summarizes a sensible approach for common scenarios. If you prioritize convenience and play mostly at home or in small venues, a built-in preamp is hard to beat. If you tour with a complex pedalboard or need precise EQ for recording, an external preamp gives you the tools.

What to pick for your use

Questions

Can I use an external preamp with a guitar that has a built-in preamp?

Yes, you can connect the built-in preamp's output to an external preamp. Many players do this to add extra EQ or a DI output. Keep in mind that the built-in preamp will color the signal before it reaches the external unit, so you may want to keep its tone control flat.

Does an external preamp improve the sound quality of a cheap pickup?

An external preamp can give you more control over the sound, but it cannot fix a poorly made pickup. The pickup itself determines the fundamental character of the amplified tone. If you're starting with a low-quality undersaddle piezo, you might hear a bigger improvement from upgrading the pickup or using a microphone.

Should I get a preamp with a built-in tuner?

Having a tuner in the preamp, whether built-in or external, is very convenient for live playing because it mutes the output while you tune. Built-in systems like the Fishman MX-T include a tuner that mutes the signal, which is a great feature if you don't want to carry a separate tuner pedal.

Are built-in preamps repairable if they break?

Many built-in preamp systems can be replaced, but it's often easier to swap the entire preamp unit inside the guitar. If your preamp fails, you might consider using an external preamp as a temporary or permanent solution. Check with the guitar manufacturer or a qualified repair shop for options.

Does the battery type matter for built-in vs external preamps?

Most built-in preamps and many external pedals use a 9V battery. Some external units can be powered by an AC adapter or a pedalboard power supply. If you play long gigs, you might prefer an external unit that accepts a power adapter to avoid battery changes. For built-in systems, keep a spare battery in your case.