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How to choose and use the conference room microphone

In Electronic Infomation Category: H | on April 14,2011

Meeting room

general requirements of sound bright, clear, loudness should be moderate. In the layout of the venue, the speaker can not audition to the site. Therefore, in order to achieve the live sound when the bright, clear sound (loudness, but not just the howling of the requirements), microphone choice and LM2578AN datasheet and placement will have a certain knowledge.

1 microphone choice

Due to the different microphones of different sound sources have different effects, so the choice before the microphone Microphone must better understand the technical characteristics, performance, strengths and LM2578AN price and weaknesses and LM2578AN suppliers and the application of occasions. Microphone when used in addition to considering the sensitivity of the microphone, the output impedance of the mixer input impedance matching and other electro-acoustic indicators, need to be considered in a conference room microphone directivity, frequency response characteristics and the shape of the microphone and so on.

To point to in terms of super-cardioid pickup for more distance, heart-shaped for most cases, non-directional pickup is not suitable for language, as prone to feedback. In addition, speakers at the conference room but also according to the layout, to choose the right point to characteristics of the microphone.

1) centralized or semi-centralized layout of the PA system, microphone directivity should be heart-shaped or heart-shaped super.

2) a distributed sound system layout, the general should choose the heart-shaped microphone, if the microphone far away from the PA speakers, and hall reverberation time not too long, non-directional microphone can choose.

3) when the sound source is very close to the microphone, you can use technical indicators to eliminate effects of recent talk about heart-shaped microphone near.

Frequency characteristics for the microphone, the technical indicators are often slightly lower static and transient characteristics of a good microphone, slightly higher than the static and transient characteristics of technical indicators of poor microphone better. In addition, from low to high frequency response characteristics of uniform and smooth than a microphone, then briefly highlighted the band is good, because some are prone to highlight the whistle part.

In addition, sound blunt mouth is often too close to the microphone was too serious. Of course, you can use e-correction (of voice circuits in) to compensation, which the mouth is too low for the audio did not affect the sound, but restricted movement before and after, the distance between the microphone caller must remain constant, otherwise there will be low-frequency components change, and direct and reverberant sound (in sound state of "active" in the sound field) will change the ratio between.

In 6 000-9 000Hz peak between the large number of microphones, with a hissing sound will become dental heavier accent. Of course, also be adjusted electronically, but have to pay to bring dead at the peak price. Therefore, generally no need to use the conference room of high-quality microphone, the microphone has a smooth response on it.

To the internal structure of the microphone types, the general meeting room use before moving coil microphone PA. In recent years, with the conference table to increase, widening, and now the majority choice condenser gooseneck microphone. Thus, when the conference table is wide, and will not be pushed to the edge of the table and the speaker can not pick up sound. In addition, the condenser microphone of the microphone head is relatively small, and will not cover the speakers face is one of the reasons is selected.

In summary, in addition to special requirements, meeting rooms generally recommended to choose wide frequency response, frequency response transfer characteristic uniform, smooth, distortion small gooseneck cardioid condenser microphone.

2 microphones placed

Microphone placed in the conference room table display and microphone are generally divided into two kinds of display rack.

Microphone placed on the desktop, we should pay attention to the speaker and microphone center of the mouth angle and distance, the best microphone in the center axis aligned to the speakers mouth, then the output of the frequency response characteristics of the microphone good; mouth farther off-center axis, the worse the frequency response characteristics, the more serious treble damages, and the microphones output voltage will be reduced. Generally heart-shaped microphone, mouth and the central axis within the angle of 450 is appropriate.

Conference room to talk, to improve speech intelligibility, the microphone away from the mouth to 20-30cm is appropriate, too close, then the easy low-frequency jet accents, clarity of sound, far too many pick up the microphone and reflected sound and reverberation sound, easily lead to whistle. At this point, if you push too small mixer, then the loudness below standard, the audience could not hear the content of the speech, pushing too big and easy to whistle. Therefore, when the microphone is placed in the speakers speech accurately estimate the distance is crucial.

When people talk over the microphone to be placed, should be greater than the distance between the microphone and the microphone from the sound source 3 times (that is, to satisfy the principle of 3:1), when added to reduce the signal interference generated by the phase.

When a person talks, need to pick two or more microphones (for example, do report), to two or more microphones as close as possible, and keep each microphone to the sound source (mouth talker ) equal to the distance as far as possible, so that the signal generated when the sum of the phase interference. At this point, with particular attention to the microphone to the same phase. The two microphones, for example, if two microphones do not pick a big volume of the microphone, then the two microphone reverse, this time, the need to adjust the phase of a microphone, in general, the problem lies in the microphone online, as long as the wiring will be adjusted over a microphone can be.

Microphone stand placed, because a lot of the microphone stand is a tripod, so the installation of the microphone, the focus of the microphone to make a projection of a branch fell on the feet, the other, the activities of the microphone pole not installed pits too long, so microphone stand outside the center of gravity out of the dumping.

3 microphone audition

Because of the special nature of the conference room, in most cases not possible to audition speakers in person at the venue (such as leadership speech), so just press the volume of normal good can be, as far as possible so that the first sentence of the speaker reached if the volume is moderate (moderate size without howling sound), but also leave enough margin adjustment. However, if the microphone a lot, the mixing members need between the mixer and microphone repeatedly stressed that the test is cumbersome and inefficient. I have a little trick here is to gracefully after the microphone, microphone mixer all the faders on the lowest, the gain adjustment knob at the minimum, and then transferred to normal use of the appropriate amplifier position, the main mixer pushed to 0dB at the output, a mic and then push the corresponding fader to the road at the most high (usually the mixer is 10 ~ 12 dB), and then slowly adjust the mixer to the mic gain knob, * sound and carefully until you hear a slight whistling when the knob back soon retire 3 dB, then back to the way fader at 0dB. In this way, the mic can only ensure there is sufficient volume of the speaker loudness of the performance, but also not cause howling, the sound when the speaker is small, there are sufficient margin (13 dB) for adjustment. The same treatment to the other microphone. After this adjustment, while supporting the microphone will not open caused more howling.

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