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Please explain the single-mic technique of sound reinforcement (5 questions and replies)
What are the preferred mics for the single-mic technique of sound reinforcement? I have seen two mics used about five feet apart center stage at larger festivals.
The Crown CM-700 cardioid condenser would work well for this application because it has low noise and very little off-axis coloration.
I really enjoyed your article on the single microphone technique, as we have seen quite a number of groups, mainly bluegrass, using this technique and we have had really good success with it in smaller, more intimate settings. Single-mic technique article
However, at our most recent show the single mic technique proved not quite as ideal. The venue was a family concert series in an outdoor park, amphitheater type setting with an audience of approx. 2000 - 2500, who chose to talk through the vast majority of the band's performance. The sound system itself has more than enough power for the venue as we have used the same system for blues, pop, jazz, etc. in the same setting. The 4-piece bluegrass band brought their own main microphone and wanted an additional mic for the acoustic guitar and had a mic strapped to the stand up bass. The group did an excellent job at working the mic during their performance, most of the time huddling within a foot of the mic.
Reply: As your situation shows, it's hard to determine during the sound check (if any) whether the single mic will work, because the audience noise can be such a factor.
Be sure the floor monitors are off. They are usually the main source of feedback.
Compared to a cardioid mic, a supercardioid or hypercardioid mic would tend to have less feedback, but they also have tighter polar patterns - requiring all the band members to stay in front of the mic, which is difficult or impossible. So you might use two mics about 5 feet apart so that the band members can get a little closer to the mics. They would have to re-learn their mic technique, though. You might try a bidirectional mic with its side nulls aiming at the left and right house speakers.
We are a three-piece acoustic band: one guitar, fiddle or dobro, mandolin and two vocals. We own a 100-watt
acoustic combo amp with an open back. We want to try feeding it with a single condenser mic. Do we have a chance with this technique in a small room without feedback problems?
Try out this system and see if it has enough gain before feedback in your venue. If not, use a 1/3rd octave graphic EQ to turn down frequencies that feed back. The graphic equalizer connects between your mixer output
and power amp input, if that is possible with your equipment. Maybe your mixer-amp has a graphic equalizer built in.
I play in a bluegrass gospel group. What is the best way to EQ or set the sound for a single mic set up? The problem we have is getting the mic and the house sound loud enough without getting feedback. Could you please give me some tips on how to start from square 1 to set the EQ and get the mic as hot as possible as well as the house level?
Reply: With the single-mic technique, it is difficult to get enough volume without feedback because the microphone is far from the performers. If your group has more than two or three people, you might want to use a second microphone (one mic on every two or three people) so that the performers can get closer to the mics. Also, do not use monitor speakers. Either listen to each other live on stage, or use in-ear monitors.
SETTING GAIN STAGING
1. Ask the band to stop playing. Keep turning up the power-amp volume just until you start to hear feedback ringing at a single frequency. The band should plug their ears or wear ear plugs to avoid ear damage from feedback.
Some bands use an automatic feedback suppressor such as made by Sabine or Shure.
Good luck; it's a challenge to make this technique work.
I have a question about using single microphones for a bluegrass band. I first saw it done effectively with Allison Krauss about five years ago; they each stood about 8 feet from it, and stepped a couple of feet closer to solo. Excellent sound! When, soon after, I saw Del McCoury using this system, I was under the impression that they stood closer, and that the balance was a bit less regular. . . but still quite fine.
I now find myself playing bass in a six-piece bluegrass band. One member has a cardioid condenser mike, which sounds very good in a relaxed stage configuration. But as the evening progresses, the solo instrumentalists or lead vocalists "crowd" the mike, standing maybe a foot away, and blocking its pickup of instruments behind the soloist. So, many other instruments fall from the mix, and we can't really hear each other, except with floor monitors. No amount of microphone choreography seems to solve the problem.
How far from the mike should all musicians stand? How close should soloists appoach?
Reply: A six-piece band probably would need to use two microphones (three musicians on each mic). That way, nobody gets blocked, and more people can get close to their mic. Follow the 3-to-1 rule: the mics should be spaced apart at least 3 times the mic-to-source distance. Six-foot spacing is typical.
You need to stand as close to the mics as physically possible without crowding each other. That way, the mic picks up a loud signal, so the sound mixer doesn't have to turn up the mic so much and cause feedback.
The soloist should stand in front of the mic about a foot away. It really helps to practice while listening to the PA. Run the mics through a PA system with the speakers aimed at the musicians. Practice moving in and out while listening to the balance. Pretty soon you'll know by ear where to stand.
With the 1-mic or 2-mic technique, it's hard to get enough gain-before-feedback in noisy venues because the performers are much farther from the mics than in a multi-mic setup. Some performers have to omit the stage monitors (to prevent feedback) and just listen to each other live on stage.
One bluegrass/old-time band, Uncle Earl, uses the 2-mic technique augmented by spot mics. They use the two large condenser mics for the vocals and fiddle, and use clip-on mics or pickups for the instruments that need it.