Amplifying the Acoustics
articles from Acoustic Musician Magazine
Acoustic Musician #1
If you play venues larger than your living room you probably need more sound than your instrument can produce on its own. Even in practice situations its great fun to fill a room with the sweet spot sound of the instrument. For this you will need an amplifier. Yet for many acoustic musicians amplification seems frighteningly complicated. And whats worse is that players arent always completely sure why they need it, let alone how to do it.
A microphone in front of your instrument will be satisfactory in few performing situations, especially if you dont have access to a million dollar sound system and a professional sound engineer. Fortunately there are now a variety of pickups and internal microphones that do an excellent job of transforming the acoustic energy of a musical instrument into an electrical signal. This is the first step, next you need an amplifier/speaker to transform that signal back into sound. Now it gets tricky. Every instrument has its own quirks when its amplified, sometimes needing a little bass cut at, lets say 80 or 170HZ to remove a booming resonance or maybe a midrange boost because thats the sound you like.
Every instrument and performer is unique, and there are no generic settings on a PA or amp that work for everyone. I regularly hear from artists who are tired of doing shows where their guitar sounds like cardboard. You could be opening for James Taylor, playing through the same PA and yet your guitar ends up sounding like a ninteenth century dentists drill. The headliner usually has his or her own sound-tech who is familiar with the artist and their instrument. Yet most performers meet the sound-tech moments before their show, and without some form of amplifier all they can do is give them a cable and hope for good sound. Well yes, some engineers live for a challenge and a few can even make it happen... If you have your own amp then you have the ability to tailor the amplified sound to your instrument and taste.
So what makes an amplifier for acoustic instruments different from an electric guitar amp or a PA? First of all the sound has to be clean, clear and natural. This is in effect the exact opposite of what we ask from an electric guitar amp, and PAs often sacrifice "natural" for loud. Even if you want to alter the tone of your instrument with effects and EQ changes, you should start with a clear, natural sound, or the "acoustic-ness" of the instrument will be lost. Also you will need more tone control than most electric guitar amps or small PAs offer. Notch filters and graphic or parametric EQ are necessary to fight the bane of acoustic amplification; feedback. And finally the inputs of the amp have to accommodate the signal from your instrument by matching the impedance of the pick-ups; having enough gain without distortion; and also providing phantom power if necessary.
We can all appreciate the relationship of an amplifier to an electric guitar, the instrument and amplifier work as partners in creating musical tone. On the other hand an acoustic instrument amp may be required to faithfully amplify the natural sound of an acoustic guitar, interact with the guitar and pickup to create a unique musical tone, or function as a small PA for vocals and several instruments. Some amplifiers can handle all these functions but others may only be suited for one purpose.
What an amplifier is really doing is giving you control over your sound. Electric guitarists have considered their amp to be a necessary part of their sound for decades. How much control you have depends on how much you invest and are willing to carry around. It can range from a pocket sized graphic EQ to a state of the art audiophile quality amplifier. AM
Acoustic Musician / November 1997