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Microphones, as we know, are where the sound enters into the electronic realm of our control. Some basic guidelines for mic placement are in order to minimize problems right where they may start. Items to consider:
- Generally the mic should be as close to the sound source as reasonably possible. The further the mic is away, the more other unwanted sounds you will have to contend with. A far mic may also not be able to bring the level (gain) of the desired sound source (singer, instrument etc.) up to the desired level without risking or causing feedback. The clarity of the sound will also be a factor.
- A singer using a mic that is further away may tend to sound distant and/or locking vocal clarity even if you are able to achieve the desired gain without feedback.
- If there are several microphones in use concurrently, a mic that is further away from the source can also induce what is known as phase cancellation. This is a rather in-depth concept. To briefly summarize, phase cancellation occurs when a second mic picks up the same sound at a different time and the sum of the two sounds are sent to the sound reinforcement system (miser, amp, speakers) just enough out of phase that the sound cancels itself out at certain brief instances. A general rule in mic placement is: the distance from one mic to the next live mic should be at least 3 times the distance between the mic and the sound source. For hand held vocal mics, this is seldom a problem. If one singer is holding the mic 2" away, the closest mic must at least 6" away. However, if several vocalists are sharing a mic and they are each 8" away, the next must be a minimum of 24" away (assuming the same type of mic). If the next closest mic is a more sensitive podium mic, a greater distance will be advisable.
- So, where should the microphone be relative to the sound source? For vocals, as close as possible without picking up an objectionable amount of percussive sounds like "P". This may vary a bit depending on the type of mic used. For our favorite vocal mic, the Shure model SM58, the mic can be 1"-2" away from a singer. In the case of a high quality podium mic, 8-10 inches away may be normal.
- Using microphones to enhance instruments is becoming necessary to be able to balance a variety of instruments. For optimum sound reproduction an instrument mic should be used although a standard vocal mic such as the aforementioned SM58 may get by although an instrument mic will sound noticeable better. Some sound technicians will claim that a microphone should be used in front of a guitar amp. However, a "direct box" can be placed either between the instrument and the amp or, in come cases, between the amp and the instrument speaker. Picking up between the instrument and amp eliminates sound alterations effected by the amplifier while a mic or direct box between amp and speaker replicate the amp's sound.
- Clip-on lapel mics are for speaking and not generally recommended for singers. However, a high quality lapel mic can bed used. For musical theatre a wireless lapel mic may be the only reasonable option. Note that mid to low quality lapel mics will not produce good musical sound. The "rule of thumb" for placement of a lapel mic is to spread your hand with the thumb and little finger extended as far as possible. This distance is how far the lapel mic should be from the speakers' lips when the head is in the normal speaking position.
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