The Single-Mic Technique For Music Reinforcement
by Bruce Bartlett, Crown International
What goes around, comes around. In the 1920's through the 1940's, PA systems for music used a single microphone. Band members gathered closely around this single mic and balanced themselves by moving toward or away from the microphone. Radio broadcasts and recordings used one mic as well.
This old-fashioned technique is making a comeback. Many new bluegrass and folk bands are trying the one-mic method with surprisingly good results. They use a single modern microphone: typically a large diaphragm cardioid condenser. It picks up the sound with amazing clarity, and usually with very good gain-before-feedback. Of course, the technique may not provide enough volume in some venues.
How can a single mic work so well? As theory says, the fewer the number of open microphone, the better the gain-before-feedback. Also, a single mic picks up all the instruments and vocals with a coherent, focused sound. There are no phase cancellations between multiple mics to color the tone or smear the transients.
Want to try the single-mic method? Install the microphone on a stand, ideally in a shock mount. Use a boom if you need more room for instruments. Place the mic at about chin height and 12 to 18 inches away from the performers. The mic stand goes in the middle of two or three musicians.
If the band is larger, every two people might use their own single microphone. In a typical bluegrass or folk group, you'll see a fiddle, guitar, banjo, mandolin, singers and maybe a dulcimer or bass. It's possible to get a good balance of all these elements through careful mic placement.
Raise the mic stand to make the vocals louder relative to the instruments, or vice versa. You might aim the mic slightly left or right of center to adjust the balance between performers. Some bands prefer to run the mic through a high-quality mic preamp, then they give the preamp's line-level signal to the FOH engineer.
Feedback can be a problem with floor monitors, so this method generally omits them. Performers tend to hear each other just fine anyway because they are close together and don't use guitar amps. However, lead acoustic-guitar players often need a monitor to hear themselves. It's a good idea to start with no EQ, then tweak a graphic equalizer to notch out feedback frequencies.
One obvious advantage of the single-mic technique is that the stage looks cleaner. Gone is the forest of mic stands, booms and cables. Instead you have a low-tech, old-fashioned look that fits in well with the music.
Setup is much quicker, too. Just place the mic, plug it in and you're done. The band determines the mix, rather than the sound mixer, who might not be familiar with the music. Of course, musicians are happier with this arrangement than sound mixers!
Frank Lee and Rayna Gellert were an old-time duo who used the single-mic method. "I've often been disappointed with the PA sound that we've gotten on tour from sound mixers," says Frank. "Some of them don't know our style of music, so the mix is wrong or the instruments sound unnatural. But when we use one mic, the audience hears how we really sound. This technique is a natural for small bluegrass bands. As each musician takes a solo, he or she walks up close to the mic, just like in the old days." Some bluegrassers currently using a single microphone are Del McCoury and Doyle Lawson & Quicksilver.
With the single-mic method, you do give up fine control of the mix balance, EQ and effects. The technique works best for small acoustic groups that have a good live balance.
Also, the sound may be a little thin because you're not hearing the usual close-mic proximity effect. Some bass boost can help with this. Another disadvantage is that the method is unfamiliar to house engineers. As Frank Lee says, "About nine out of ten sound mixers are reluctant to use this technique. They don't like to give up control, or they don't think it can work. I have to convince them. Some engineers (understandably) don't want to re-EQ the room to work with our mic. "But some sound mixers are open to the idea. They are surprised at how loud it is, and how balanced and natural it sounds. And during our set, they can relax and take a break!"
As they say, "Air is the best mixer." The single mic captures a balanced blend of of all the instruments and vocals at one point. Give it a try, and you might be delighted with the purity and simplicity of this technique.