• All round pick-up
• Pick-up of room reverberation
• Low sensitivity to pop (explosive breath sounds)
• Low handling noise
• No up-close bass boost
• Extended low frequency
• Low cost

• Selective pick-up
• Rejection of room acoustics, background noise, leakage
• Better gain before feedback
• Coincident or near-coincident stereo miking

• A broad-angle pick-up of sources in front of mic
• Maximum rejection of sound approaching rear of mic

• Maximum difference between front and rear
• More isolation than a cardioid

• Maximum side rejection
• Maximum isolation, rejection of reverberation leakage, feedback and background noise

• Front and rear pick-up, with side sounds rejected (for across-table interviews or 2-part vocals)
• Maximum isolation of an orchestral section miked overhead, aiming down.
• Blumlein stereo miking (2 bidirectional mics crossed at 90 degrees)

• Most instruments - 80 Hz to 15 kHz
• Bass instruments - 40 Hz to 9 kHz
• Brass and voice - 80 Hz to 12 kHz
• Cymbals - 300 Hz to 15 or 20 kHz
• Orchestra or symphonic band - 40 Hz to 15 kHz

If possible use a mic with a frequency response that rolls off below the lowest fundamental frequency of the instrument to be recorded.

A frequency response curve is a graph of output level in dB at various frequencies. For a microphone, the output level at 1 kHz is placed at the 0 dB line on the graph, and the levels produced at other frequencies are so many dB above or below that reference level. The shape of the response curve usually indicates the tonal balance of the microphone pick-up at a specified distance from the sound source (probably around 2 or 3 feet).

A flat response mic tends to provide accurate natural reproduction at that distance. A mic with a rising high end or a 'presence peak' around 5 to 10 kHz emphasizes the higher harmonics giving a crisp, articulate sound.
Most uni- and bi- directional mics boost the bass when used within a few inches of the sound source (this is called a proximity effect) and it is often plotted on the response graph. The warmth created by the proximity effect adds a pleasing fullness to drums. In most recordings, however, this proximity effect lends an unnatural boomy or bass sound to the instrument or voice.
To minimize this effect, use a multiple-D or variable-D or switch in the bass roll-off on the mic (if any) - or roll off the excessive bass on the mixer's EQ. This will also reduce low-frequency leakage picked up by the mic.

Polarity

All mics should be of the same polarity. If 2 mics are wired in opposite polarity and combined to the same channel, low frequencies are attenuated or completely cancelled out. Check all mics are wired identically as follows:

1. Choose one mic as a polarity reference. Plug it in to the mixer. Talk into it from 3 inches and set the VU to peak around 0 VU.

2. Do the same with a 2nd mic and cable plugged into another input.

3. With both mics mixed to the same channel hold the mics together and talk into them again at 3 inches. If the meter reading is lower, the polarity of the second mic or cable is reversed. In which case, remove the connector shell from the second mics cable and reverse the connections to pins 2 & 3 (in one connector only). Use only that cable with that mic.

4. If you cannot remove the connector in the mic, reverse the connections to pins 2 and 3 for mics that are opposite in polarity to the reference. Check a few mics before doing this to make sure the reference itself isn't backwards.

Microphone characteristics.

Cables

After acquiring a mic, you may need to wire its 2 conductor shielded, balanced-line cable to a 3 pin audio connector :

1. Solder the shield to pin 1.
2. Solder the hot conductor to pin 2.
3. Solder the other conductor to pin 3.

If the mic output is 3 pin balanced, but the input to recorder or mix is an unbalanced jack:

1. Solder the hot conductor to the tip terminal of the phone plug
2. Solder both the shield and the other conductor to the long ground lug of the phone plug.