There comes a time in many acoustic guitar players lives when you’re ready to take your songs to the masses, but figuring out how to take your guitar’s sound and translate it to the stage is no easy task. The sheer wealth of options when it comes to pickups, preamps, DI boxes and amplifiers can be overwhelming. In this guide, we’ll break down the how and why of acoustic amplification, whether you’re hitting your local open mic or taking your show on the road.
To amplify an acoustic instrument, we need to convert its acoustic sound into an electrical signal, using either a traditional microphone setup (which can be prone to feedback and inconsistent sound at high volumes) or a pickup. Pickups can take myriad forms, but the most common are magnetic, undersaddle transducers, soundboard transducers, internal microphones, or some sort of blend between multiple systems, usually with an onboard pickup to control the sound.
Magnetic pickups are the most basic pickup available. These work in a similar way to electric guitar pickups, and usually clamp onto the soundhole of your acoustic guitar. Fishman Rare Earth and LR Baggs M1 and M80 systems are the best examples of these, and they produce a fat, warm but somewhat electric sound that sounds best in a full band mix. An added bonus of these pickups is that they can be easily removed and swapped between guitars.
Undersaddle transducers, or ‘piezo’ pickups, are by far the most prevalent acoustic pickups. These pickups use a thin metal sensor between the bottom of the saddle and the saddle slot, to sense vibration from the bridge of the guitar. They have great feedback resistance, a well-balanced tone and are invisible once installed. The LR Baggs Element VTC and Fishman Matrix Infinity systems are the most popular of these systems, but there are dozens of brands that work in a similar way. Piezo pickups benefit from careful EQing on your amplifier or preamp to remove their natural ‘quack’ and ‘honk’.
Soundboard transducers (or SBT’s) are small, passive sensors (usually attached to the underside of your guitar’s bridge), which sense the movement of the soundboard. These are the most natural sounding of all pickups, with accurate translation of the guitar’s tone and a dry, woody tone. These pickups tend to work best in intimate settings, such as solo concerts, small ensembles and low volume settings. At louder volumes, soundboard transducers can be more prone to feedback and low-end rumble because of their sensitivity. The K&K Pure Mini is by far the most popular SBT pickup in the world, and is a wonderful sounding, non-invasive pickup that works especially well on lighter-braced guitars. JourneyTek’s EP001K is a similar pickup that is more suited to heavier or larger guitars, because of the greater area of it’s sensors, and the James May Ultra Tonic pickup adds feedback resistance to the traditional SBT, making it more usable at high volumes.
Internal microphones are just that – a small, carefully tuned microphone within your guitar that unsurprisingly gives an airier, ‘mic-ey’ sound. While they are often blended with other pickups to lend some roomy sound to a direct tone, mics like the LR Baggs Lyric can be a great choice for intimate settings or recording sessions.
Blending pickups can be a way of getting varied and dynamic sounds, and the LR Baggs Anthem or Anthem SL is a wonderful all-in-one unit, mixing an undersaddle pickup and internal mic with an onboard preamp. Maton and Cole Clark also use multiple-source pickup systems, and their plugged-in tone is second to none.
DIs and Preamps
From your guitar, the next part of the signal path is the preamp or DI box. A DI box converts your guitar’s signal to a high-impedance signal that is expected by the mixer or PA system. This ensures a strong, clean and consistent tone, and will often have handy features such as phase reversal, ground lift switches and EQ. At its most basic, a preamp increases the volume and strength of your guitar’s signal, but most units will also have EQ and tone-shaping controls, as well as handy features such as effects, boosts, ground lifts and a DI.
A DI or preamp is essential for getting the best sound when plugging a guitar into the mixer of a PA system, and many guitarists prefer to use a preamp even when plugging into an amplifier. Some preamps can also route your guitar to multiple locations. There are myriad options available, from the basic but very usable NUX Stageman and LR Baggs Para DI, to the fully featured LR Baggs Venue, Fishman Platinum Pro and Radial PZ-PRO. The LR Baggs Voiceprint also deserves a mention, because of it’s incredibly smart iPhone App that allows you to create ‘Impulse Responses’ of your favourite acoustic sounds and blend them with your signal.
Amps and PA Systems
The final link between your guitar and your audience is the amplifier or PA system. The most popular for most acoustic guitarists are Combo Amps; a small and compact combined preamp and speaker cabinet. Small amplifiers like the Acus 6T, the Fishman Loudbox Mini or the Fender Acoustic Jr are great for smaller gigs, while the Fender Acoustic 100 is a great creative tool with onboard effects and looper. Battery-powered amplifiers like the Fender Acoustic Jr Go and Fishman Loudbox Mini Charge are perfect for outdoor and busking gigs. Most of these smaller amps will have an XLR out, which can be used as an onboard DI to send your carefully crafted tone to a larger PA system. Of course, you can also go directly from your DI or pickup into the mixer of your PA system.
Tweaking Your Sound
Once you have chosen your equipment, its’s time to apply EQ to find your preferred sound. A notch filter on your amp or preamp is useful to dial out a problem frequency. To adjust the notch filter, turn up the volume until feedback starts and then turn the notch filter knob until the feedback goes away. If you play in a band, you also need to consider the overall sound of the group, and where your guitar sits within it. Midrange often ends up overwhelmed in a mix with other loud instruments, so a deep midrange-cut may help your guitar stand out.
It is often better to cut frequencies instead of boosting. Cutting instead of boosting can provide more headroom and avoid overdriving parts of your signal chain. For example, if your guitar sound is too dark or is lacking presence, you might cut the bass or lower mids instead of boosting the treble.
The biggest issue most amplified acoustic guitarists face is feedback, a frustrating squealing even in surprisingly low-volume situations. The first step to attacking feedback issues is amplifier placement. A good spot for a stage amp is often on the floor, off to the side, so that your body is between the amp and the guitar. When working with a PA system with a monitor, make sure the monitors are not facing back directly into your guitar. PA speakers should be far out in front of you. Some guitarists find that a “feedback buster”—a device that plugs up your soundhole—helps to reduce feedback.
Dialing in a good sound with an amplified acoustic guitar is a delicate balancing act, and carefully choosing the right equipment and EQ for your situation will be instrumental in getting a great sound. For more information, contact any of our friendly staff at firstname.lastname@example.org
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