The Difficulties In Amplifying An Acoustic Guitar

Posted on by Dave Eichenberger


Acoustic guitars have always presented a problem when playing at higher volumes. Back in the day (as the kids say), if you wanted a louder acoustic guitar, you bought a bigger acoustic guitar. Bigger bodies = more volume, as there is more wood to vibrate and project the sound towards the listener. But what if you have to play a big club or theater with hundreds or thousands of people? Huh? HUH? You could get a guitar the size of the stage itself, but I bet you wouldn’t like how it sounded! This article will explain some of the difficulties that acoustic guitarists face when wanting just to be heard.

Back then, you didn’t have much choice…

The Man in Black lifts his guitar closer to the microphone.

The Man in Black lifts his guitar closer to the microphone.

Back when the only guitars available were acoustic guitars, players sat in the back of the band bangin’ out chords as hard as they could, competing with banjos, horns, pianos, and (in jazz) drums, and probably developing colossal picking-hand forearms in the process. Later on, the electric guitar became common and amplification allowed guitarists to play single notes that could actually being heard, something they couldn’t achieve before. Electric guitar playing split from acoustic, becoming its own thing. Acoustic guitarist still played bigger guitars, and they still bashed out chords from the back of the band. When playing in front of more people, the acoustic guitarist could step in front of a shared microphone in order for a brief solo to be heard. Soon acoustic guitarists graduated to using their own microphones, but this presented another problem. If the band got progressively louder (as some bands do*), the soundperson turned up the acoustic microphone, which soon picked up the sound of the monitors (if there were any) or the main PA. This resulted in howling feedback, and not of the Jimi kind. So there was always a balance between as loud as the band became, and boosting the acoustic guitarist’s microphone right before the point of feedback.
*All bands get louder.

There has to be a better way!

Sir Paul uses a microphone in the studio for great acoustic tone.

Sir Paul uses a microphone in the studio for great acoustic tone.

See, in the studio’s controlled environment, a great microphone or two is placed in front of an acoustic guitar. These sensitive microphones capture not only the sound of the instrument itself, but the sound of the instrument in the room – subtle reflections of the sound off of the walls, the floor and the performer’s body. Microphones like this are much too sensitive to be used at a live performance though, so pickups were developed. The problem is that while it solved most of the feedback problems, early acoustic  pickups didn’t really sound that great. They either stuck on the guitar’s top with some sort of tape or glue (!?!) and picked up the vibrations of the soundboard, or they were wedged into the soundhole and picked up the strings much like an electric guitar. Later designs utilized piezoelectric crystals under the bridge which sensed pressure and created an electrical charge. Check out Orpheo’s excellent description of how piezo* crystals work.

*I have heard many pronunciations of ‘piezo’: PIE-zo, pee-AY-zo, PEEZE-o, pizza-o’s. Even people in the industry pronounce it differently. I just say ‘under-saddle pickup’ so I can seem long-winded, and save myself the embarrassment. 

What sounded so bad about these pickups?

Despite Django's considerable talent, the pickup technology available during his time was less than ideal.

Despite Django’s considerable talent, the pickup technology available during his time was less than ideal.

No matter what technology is used, a bad acoustic pickup sounds, well …bad. It isn’t just the pickup either, it is the preamp too. Both soundhole and piezo pickups produce quiet signals when compared to their electric guitar cousins. They require a preamp to amplify the sound. The preamp takes the very quiet acoustic pickup sound and amplifies it so you can hear it. Truth is, an acoustic guitar being played in a room is one complex sound to get right. There are sound waves and their reflections flying all over a room when an acoustic is played, and a nice, thin, solid wood acoustic top brings out amazing overtones in an acoustic instrument that acoustic pickups just couldn’t capture. They either sounded thin, like the strings were stretched on a ukulele made of #2 plastic, or quacky- lacking in lows and low-mids. Even worse, many guitarists took those pickups and plugged them into an electric guitar amp. To get righteous acoustic tones, you’re gonna have to buy another amp.

Oh man! I spent all my money on the guitar!

I am sure you have heard acoustic guitars sound like this. Don't be that person that we are talking about.

I am sure you have heard acoustic guitars sound like this.

I think we’ve all heard great players with good guitars that have been reduced to a thin piece of cardboard by the time it reaches your ears. Sadly, a great acoustic amplified badly sounds as bad as a cheap acoustic amplified badly. Acoustic amps (like PA systems and keyboard amps) don’t emphasize the mids or cut the highs and lows as an electric amp does. The acoustic amp is full-range, and amplifies a much broader and clearer frequency range than your 5150 stack. For good live acoustic tone, you need a decent guitar + good pickup + good preamp + good acoustic amplifier or PA system to make it approach the sound that you hear in your cedar-walled ski lodge.

So what can I do?

The MagMic combines a microphone with a hum-cancelling magnetic pickup.

The MagMic combines a microphone with a hum-cancelling magnetic pickup.

The easiest is to get a modern soundhole pickup. The Seymour Duncan SA-6 MagMic is a hum-cancelling soundhole pickup that doesn’t just sense the strings, but also includes an omnidirectional microphone to pick up the vibrations of the instrument itself. This pickup includes a preamp, and can either be installed permanently or with no modifications to your instrument- you decide. It includes a volume knob and a blend knob for the internal microphone.


Available in 3 earthy colors, it takes longer to open the package than install.

Available in 3 earthy colors, it takes longer to open the package than install.

For another soundhole option, the Woody series by Seymour Duncan couldn’t be easier to install. It wedges in most soundholes with ease & makes it easy to switch between guitars too, as it takes just a few seconds to pop in. This pickup is passive though, so you will need to send the signal to either an outboard acoustic guitar preamp, an acoustic amp or a mixer channel with a preamp, or a device like the Mama Bear. The Mama Bear takes any acoustic signal and transforms it into many different acoustic guitar sounds for recording or live playing.

If you have an acoustic and you intend to perform with it, yet you don’t want to alter the looks of your guitar, the D-TAR Multi-Source combines an under-saddle piezo pickup with a condenser microphone in a stealthy, great sounding package. It contains a preamp with master volume and microphone volume knobs, and outputs a signal healthy enough to plug right into a PA or acoustic amp. Ban quacky CardboardTone forever, and look good doing it, I say.

How do you amplify your acoustic guitar? What is the best recorded acoustic guitar you have ever heard?

Written on July 18, 2014, by Dave Eichenberger

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  • Alderney Fred

    What ? You’re trying to tell me the Woody needs a preamp ? Not in my experience ! Don’t undersell it ! I use one in my Irish bouzouki, had to chafer the outer edges a bit to fit the sound hole, but I put it through a Roland MicroCube and it sounds brilliant……

    • kenji

      Would this work for nylon strings?

      • Alderney Fred

        No, because it is a magnetic pickup – only the covered strings would sound because of their wire component…..back to the drawing board…….I guess that’s why they’re trying to sell the new ones with added microphones.

      • SeymourDuncanBlog

        For Nylon strings, go with the Sadducer:

  • Patrick Durham

    I guess acoustic sounds are all in the ear of the beholder. I love those not-quite-acoustic/not-quite-electric sounds that Grant Lee Phillips and Chris Whitley played. In my first band, i put a cheap capsule pickup on my acoustic guitar and ran it through an amp and approximated the Jumpin Jack Flash tone. I only wish i still had that pickup and that amp.

  • Gary Wilson

    At the time of old days how guitarist hold that guitars at that position I tried it but I can’t play a guitar more then a 7 minutes.


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