Take a breath of fresh air on a country morning.
That’s the sensation you get from a well-amplified acoustic ensemble.
Guitar, upright bass, mandolin, dulcimer, banjo – all produce a sweet, airy sound that can be captured with the right approach.
Acoustic music heard over a sound reinforcement system is all about beauty and naturalness, not hype.
Listen to a number of well-recorded CDs of old-time country, bluegrass and acoustic jazz. In most cases you’ll hear no effects except some corrective EQ and maybe just a little reverb.
Let’s look at some ways to capture that delicate sound and prevent feedback.
Picking It Up
An acoustic instrument can be picked up in four ways: with a microphone on a stand; with a contact mic; with a pickup fed into a preamp or DI box; and with a distant large-diaphragm condenser mic (LDC).
A good mic choice for acoustic instruments are small-diaphragm cardioid condenser models. The cardioid pattern reduces feedback, while the condenser transducer captures a detailed, accurate sound, in which you can hear each string within a strummed chord. Of course, the venerable Shure SM57, a dynamic unidirectional (cardioid) does a good job too, especially when feedback is a problem.
Some musicians might prefer a contact mic, which is a miniature clip-on condenser type like a lavalier (Figure 1). The advantages are consistent sound from gig to gig, an uncluttered stage, and freedom of movement. The musician is not tied to a single position near a stand-mounted mic.
Figure 1: A contact mic on a fiddle. (click to enlarge)
Other musicians might prefer a piezo or magnetic pickup. Sensitive only to string vibrations, it has more gain before feedback than a mic, and total isolation. However, this produces an “electric” rather than “acoustic” sound, missing the resonance of the instrument’s body and air chamber.
Some EQ can help – try a narrow cut at 1.2 to 1.5 kHz, along with some high-frequency roll-off. Pickups also prevent phase cancellations between two mics deployed for a singing guitarist.