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Of Mics and Men

We have taken a look of some of the most commonly used permanent/internal solutions for amplifying classical guitars. Let’s flip to the opposite end of the spectrum and discuss the king of external amplification: the microphone.

I’m just going to go ahead and say it: mics are a much more cost-effective and tonally accurate way to amplify. If you were to spend $100 on a pickup or on a condenser microphone, you’d be getting a much more natural and just plain better sound with the latter. The downsides? Microphones are not as “plug and play” as an internal pickup, as they need to be setup carefully for best results; they are also susceptible to feedback and external/ambient noise (such as wind). In my experience, the tonal advantages largely outweigh these drawbacks, especially considering that many of these problems can be obviated through technical means (proper placement and EQ).

A Few Technical Definitions

The three main kinds of microphones that concern us as classical guitarists are dynamic, ribbon, and condenser microphones. Dynamics are the most common—the Shure SM58 and SM57 are perhaps the most widely used backline microphones in venues around the world. Dynamic mics don’t need to be powered, and are rugged, cheap, and reliable. However, most of these mics lack top-end definition and a flat enough response to be the first choice for our application.

Ribbon mics are interesting—they have a very warm, smooth kind of detail in the top end. From a practical standpoint, ribbon mics are fragile and require gobs of clean gain from a dedicated preamp—the front-of-house mixing board might not be enough. The Beyerdynamic M160 is an excellent ribbon mic for live use, if you can feed it enough clean gain.

Condenser microphones are not as sturdy as dynamics (don’t use them to hammer nails, or to fight your way out of that biker bar where you tried to play Recuerdos), and for the most part require Phantom Power from the board or (better) your preamp. However, these are small prices to pay in return of the sonic goodness and detail they provide. Condenser are also among the smallest microphones—an element that can provide crucial for placement. My favorite microphone at the time is the amazing Line Audio CM-3.

Do You Notice a Pattern?

I’m going to be speaking broadly about a very technical and detailed field here—I refer you to the Microphone University on Danish maker DPA’s website if you want more (and more accurate) definitions.

The pattern with which a microphone captures sound is crucially important for live amplification. The two most useful and common patterns are called cardioid and omnidirectional. Cardioid microphones get their name from the heart-shaped pickup pattern—they reject sound coming directly behind the microphone. This is extremely helpful in fighting feedback on an amplified stage. Because of their directionality, cardioid microphones exhibit a bass boost when placed close to the sound source—this is called proximity effect and can be easily countered with some sensitive EQ (such as a high-pass filter set at 80Hz for a guitar tuned to E).

Omni mics, as the name suggests, pick up sound from all directions. They offer the least colored and accurate response of all microphones, with no proximity effect or off-axis coloration. However, the fact that they pick up all sounds can be a problem when playing live. Because of this caveat, I suggest using omnis only when you need light amplification in an otherwise quiet setting, such as a large recital hall or church. You can use them in less ideal situations, but it might take some experience.

Placement is Key

Positioning the microphone is perhaps the most critical element in achieving a truthful and solid sound. One solution that I have been using for about a year now is to mount the microphone directly onto the guitar with a harness such as Exploraudio’s H-Clamp. You’ll have to deal with an extremely close placement (resulting in proximity effect with cardioid mics, which you can and should counter with EQ), but once the mic is positioned you won’t have to worry about the sound changing as you go through the music (you WILL move during a concert, believe me). Close micing also helps rejecting feedback, as the microphone will be “hearing” the guitar much louder than the surrounding environment. I like to position the mic to be somewhat centered in the lower bout, close to the widest point of the soundboard. You could use a low microphone stand to obtain a similar effect, just be careful of not bumping your guitar into it if you’re micing close.

Since I switched to microphone-only amplification I feel like my live sound has improved immensely. I perform amplified in less than ideal situations (such as coffeehouses, open-air festivals, and all sorts of background music gigs), yet I can tell my amplified tone is truthful to the source—especially in terms of dynamics and tone-color nuances. One last word of advice: if you’re going to embrace microphones, you should forget about monitoring. Your guitar will provide enough sound. Keeping the stage volume low is the best way to avoid feedback problems.

Next we’ll talk about preamps, EQs, and removable pickups.

One Response leave one →
  1. 2012 November 4
    Tim permalink

    I have the DPA 4099G. It is a stellar but expensive little gizmo. I am not too familiar with EQ and settings and all things amplified sound. Your comment above:

    “cardioid microphones exhibit a bass boost when placed close to the sound source—this is called proximity effect and can be easily countered with some sensitive EQ (such as a high-pass filter set at 80Hz for a guitar tuned to E).”

    seems to be the solution to the feedback problem I have at almost all venues I play. The issue I have is knowing where to look on a PA to execute that effect. I almost never have a sound engineer, and have to keep the gain very low to avoid the proximity effect, which can mean the guitar is not as loud as I would like it to be. When you say the “high pass filter” is that an additional piece of equipment, a master setting on the board or a level on that mics channel?

    I am a new subscriber to this blog and I love it. Thanks in advance for your help!

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