Effect of mic placement on guitar tone

[brubart]

What's a good place to mike an acoustic guitar?

I wanted to find out how the location of a microphone near a guitar affects the tone quality you hear in a recording or over a PA system. To make these tests scientific as well as subjective, I measured the spectrum of a guitar in several different mic locations.

The spectrum of a musical instrument is its output vs. frequency. It affects the tonal balance or timbre. It is the relative levels of the fundamental frequencies and harmonics, and can be measured with a real-time analyzer.

As an experiment, I measured the spectrum of a large-body guitar (Gibson Jumbo) in several different mic locations to find out what the differences were. I also compared the sound by recording the mic signals and listening to the playbacks at equal listening volumes. I repeated the tests with a small-body guitar.

Spectrum graphs and results are at http://www.bartlettmics.com/guitarmiking.pdf

Enjoy! It's enlightening to see the frequencies that are affected by various mic placements. The RTA plots might be helpful with EQ settings, too.

Bruce Bartlett

[captainate]

I hate to rain on your parade, that looks like it was hard work. But I feel like someone has to say it... so here goes:

1) There are way too many variables that go into these graphs - mic, pre, room, etc., so they are not all that useful.

2) Any engineer (even the greenest of hobby engineers) worth his beans will know to test different MIC (not mike) positions to know what they like.

Again, sorry for being a total jackass. For anybody who wants to use this as useful information (and what I teach people who want to learn about micing guitars), here is what I advise:

Assuming you have the time, take as many mics as you can get a hold of and try different positions, combinations, patterns (if using multi-pattern mics) and location within your room. The more one experiments with micing an instrument, the more one can understand the way the instrument produces different parts of it's "sound". But this is good advice for ANYTHING, really, and how any engineer can get better.

Your list is great as a set of guidelines, but all you need is your "quick summary" section to serve that purpose. Anybody who doesn't already know that probably wouldn't even understand the terminology or graphs that accompanied the text.

[Twig]

Originally Posted by brubart

What's a good place to mike an acoustic guitar?

I wanted to find out how the location of a microphone near a guitar affects the tone quality you hear in a recording or over a PA system. To make these tests scientific as well as subjective, I measured the spectrum of a guitar in several different mic locations.

The spectrum of a musical instrument is its output vs. frequency. It affects the tonal balance or timbre. It is the relative levels of the fundamental frequencies and harmonics, and can be measured with a real-time analyzer.

As an experiment, I measured the spectrum of a large-body guitar (Gibson Jumbo) in several different mic locations to find out what the differences were. I also compared the sound by recording the mic signals and listening to the playbacks at equal listening volumes. I repeated the tests with a small-body guitar.

Spectrum graphs and results are at http://www.bartlettmics.com/guitarmiking.pdf

Enjoy! It's enlightening to see the frequencies that are affected by various mic placements. The RTA plots might be helpful with EQ settings, too.

Bruce Bartlett

the above posting is correct. there are too many factors involved to say what is "correct" over what just sounds best for that application. a quick start.......try a med to large diaphragm condenser about a foot from guitar aimed at the meat of the body below the bridge......try a dynamic (sm57)a foot away from the 12th fret . maybe monitor this in phones to hear exactly what resonates well. try moving the mics closer and back them off.....try reversing both mics... this is a very good start up placement for most applications. read up on phasing. also try placing a mic over the players shoulder. this is sometimes very sweet.. hope this helps a bit. use your ears and trust em!

[brubart]

I agree. As the article said, "The purpose of these measurements is not to tell you how to mike your guitar -- that depends on your instrument and your personal taste in tonal balance. Each instrument is different, too. But hopefully these tests may shed some light on how mic placement affects the reproduced timbre of an acoustic guitar."

In recording acoustic guitars over 30 years, I have found the same general trends... bassy near the sound hole, midrange emphasis near the body, and tending to be "natural" or "well-balanced" several inches from the fingerboard/body joint. Here, "natural" means "similar to what a listener hears from the instrument a few feet out front".

The microphone (a flat-reponse omni lab measurement mic) and mic preamp used don't matter much in the spectrum plots, because the plots show only the difference between distant and close miking. Mic distance and location are the only variables, other than the studio acoustics, which were nearly anechoic.

As always, though, we need to use our ears. A natural timbre is not always what's needed for a particular song or mix. Thanks for your comments. -- Bruce

[ESL]

Thanks for posting this, Bruce. It was indeed enjoyable. Most guitar recordings I do involve an omni and I always try to confirm what I think I'm hearing with Spectrafoo. However, most of the time we end up ditching the omni...