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Condenser microphones have a very thin plastic diaphragm that is coated with metal (usually gold). The diaphragm vibrates very close to a metal back plate. An electric charge is applied between the diaphragm and the back plate, which makes electrical current flow in and out of the diaphragm as it moves closer to and farther from the back plate. This tiny current is amplified by an internal circuit. The whole shebang is powered either by a battery, or with phantom power from your mic preamp, or with an external power-supply box in the case of a vacuum-tube condenser mic. Condenser mics are more sensitive than dynamics and have a frequency response that is usually more extended on the high and low end. You can place them close to loud amps but the sound is usually better a foot or more away. More on that later in this article. Condenser mics with a diaphragm measuring 1 inch or more in diameter are referred to as “large-diaphragm” mics, and those with a smaller diameter (1/2" to 3 /4") are called “small-diaphragm” mics. Large-diaphragm condensers generally sound best close to a sound source and small-diaphragm condensers are more often used when the mic needs to be farther from the source, as is the case with drum overheads or distant mics for classical recording.

reasonable but non-injurious volume while you place your ear close enough to listen to each speaker individually. You may find that the speakers sound different due to age or damage. Once you have identified which speaker to use, locate its exact center. You may want to stick a small piece of tape on the grille cloth as a reference. Most engineers will start by placing a moving-coil dynamic mic about an inch from the grille cloth, pointing right at the amp near the center of the speaker. The sound is brightest at the center, and gets gradually darker and warmer as you move out towards the edge of the speaker. In the center of the speaker you will see a smaller circular cover that protects the voice coil within. I usually start by placing a Shure SM57 right at the edge of this smaller circle

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trusty SM57 I usually end up 3 or 4 inches away, at the edge of the voice coil. You will find that the SM57 gives you nice crispy highs, an aggressive and forward high midrange, and tight, clean lows without much extreme low bass. The Sennheiser MD421 is another very popular dynamic mic that will give you a noticeably extended and beefy low end with less crispiness on top. Figure 1 shows both mics positioned close to an amp; we discuss multiple-mic technique in detail below. You might also reach for the Sennheiser e609 (a remake of the classic MD 409) or the e906. Both of these mics were designed for guitar amps and have a similar sound to the MD421. If you have access to a ribbon mic like the Royer R101 or the Cascade Fat Head, you will find that these mics will give you a thick, warm sound, sometimes too dark but sometimes just right. Try every dynamic you have! Also try turning them at an angle instead of pointing right at the speaker. You will probably find that this lessens the highs and lows, giving a more compact and midrange-oriented sound. (See Figure 2.) Once you get the golden tone, why not take a few pictures of the placement and the settings of the knobs on the amp? That way you can duplicate your setup quickly next time.

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The amp The first thing you should do is sit with the amp facing right at your head while you adjust the volume and tone controls for the best sound. If the amp is not facing right at your head you will not hear all the highs and you might set up the amp sounding too bright. Also remember that the sound of the amp changes at different volume levels. Take some time to get things sounding great before you reach for your microphones. Any guitar amp will have one or more loudspeakers. Examine the amp carefully to determine exactly where the circular speakers are behind the protective grille cloth. If the amp has more than one speaker you should have the guitarist play at a
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where I find the sound has a good balance of highs and lows. The SM57 is a directional microphone with a cardioid polar pattern. All directional mics have some degree of proximity effect, which means they will give you stronger lows the closer you place them to the sound source. By moving closer and farther from the amp and closer and farther from the center of the speaker you will find a wide range of tones. Hit Record and move that mic around in search of tonal nirvana! You might end up anywhere from 1 to 12 inches from the amp depending on how much low end you want and close to or farther from the center depending on how much high end you want. With my

Condenser mics will usually sound more open and clear on guitar amps. You will see them placed right up near the grille, but most condensers are not designed to handle the high sound pressure here. You might find that the mic puts out too much signal and you have to turn your preamp gain all the way down. The signal might be distorting at the mic’s internal amplifier, or you might be slamming the sensitive diaphragm with too much raw awesomeness. However, at a distance of one foot or more these mics can really open up and sound fantastic, with a depth and realism that sounds different from the tight, dense midrange punch of a close dynamic. If you are recording clean, clear, sparkly sounds
Recording - July 2012

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