Miking Acoustic Guitars

Note: Irony can be a wonderful thing. In the previous article, I mentioned that some of those beautiful old guitar amplifiers still hide in basements and closets throughout the world. Well, just as the last article was published, a friend of mine called me to tell me his 1957 Fender Tremolux guitar amplifier was for sale. Many years ago, I had told him that I would buy it if I could afford it. He called. The amp was for sale and I bought it. Yep. They’re still out there … lurking in dark corners, waiting for us to find them. And, by the way, I bought it for hundreds of dollars, not thousands. Sweet.

The last issue we discussed a few electric guitar / amp recording techniques. We’ll now move on to acoustic guitar recording techniques. First of all, the type of wood that the guitar is made of has a profound effect on the sound. For instance a spruce top with mahogany back and sides will inherently have a rounder, smoother, less aggressive sound than, for instance, a spruce top with rosewood back and sides. Rosewood is more dense and harder than mahogany. However, I have recorded really old Martin D18’s (mahogany back and sides) that sound every bit as bright as a newer rosewood guitar. I reckon this is due to an enormous break-in period (the more they’re played, the better they sound) and possibly the decades of dehydration and re-hydration are a factor as well. Though I play a D18, I also have a rosewood back and sides Beneteau. It’s brighter for gentle finger picking or for aggressive strumming when dense mid-range and high mid-range is required. The D18 is more pillowy sounding, bright on top, carved with a ‘smile’ in the mid range EQ and deep in the low end.

Generally my approach for miking an acoustic guitar is not that different from miking an electric guitar except that, in recording the acoustic, I mic the guitar instead of the amp.

If the acoustic guitar is the main focus of the recording, (I.e., the lead instrument), I use a stereo pair of omni directional, small diaphragm condenser mics or cardioid, if I’m avoiding reflections from above or behind the mics. I usually place them 12 to 18 inches in front of the headstock, 2 to 6 inches apart, pointing somewhere between the sound hole and where the neck joins the body, avoiding too much air from the sound hole and an excess of finger noise from the fretting hand and the attack of the pick.

To fill out the low mids I place a large diaphragm mic at or behind the bridge and below the bridge, miking the lower bout of the instrument again avoiding too much air from the sound hole which can produce a ‘woofy’ sound. Also beware of the pick’s attack on the strings which produces a ‘clicky’ transient that would have to be reduced because it can be louder than the sound you wish to record. If you have a variety of preamps, I’d suggest the more open sounding and less colored pre with the small diaphragm condensers and a tighter sounding, harmonically colored preamp on the large diaphragm mic. If I have to use compression for dynamic control, I use as little as I can get away with to achieve the signal level I need.

Another element to consider is an acoustic preamp and pickup system. I find the systems based on piezo pickups tend to have unusable high and high mid frequencies that must be eq’d out. Using a magnetic string pickup in conjunction with a piezo, blended in a desirable proportion, will have a much more useable tone for recording. I personally would never use the pickups by themselves, but rather prefer to mix that signal with a more natural sounding mic’d version. This type of hybrid mix can jump out of the mix at you when you need it to.

I should mention the strings themselves. More often than not, artists will arrive to record with dead or half dead strings AND no spares. Not only will the recording sound dull and lifeless but the dead strings can also cause tuning anomalies. Whenever possible, restring the day before the session or even two days (if you’re not playing a three hour set in between). When I restring for a session, I tune up and play the guitar for ten or fifteen minutes, not too aggressively, then, leave the guitar to settle over night. The day before the recording, I retune it and play it for another ten minutes or so, then leave it alone until the actual session. With this procedure, the strings’ high frequencies will be tamed down a little, they’ll hold their tuning better and last longer.

Please keep in mind that all these methods and techniques are not carved in stone. Beautiful results can be achieved using ribbon mics (another personal favorite) and even something as simple and inexpensive as a Shure SM57 placed in just the right place. There really are no rules.

In the past I’ve been stuck with acoustic and electric tracks, already recorded, that were flimsy at best. So, on occasion, I’ve re-amped the guitar tracks at really low volume through old electric guitar tube amps and speakers to create a more crisp version with gentle harmonic overtones introduced by the tube circuitry and cheap guitar amp’s speaker. Then, I mixed this signal with the original mic’d version. In fact, I’ve used this same technique on vocal, bass and drum tracks as well.

So, again, let’s strap on our best ears and above all, have fun.

Gerry Griffin is an independent songwriter, singer, harmonica player of note, and, yes, a guitar player. He owns a studio and will produce your album.

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