Using skills of professional audio exciter

Author: 　 From: 　 DateTime: 2021-11-16　 Hits: 5413　 【Font: T  T 】

Audio exciter is actually a kind of harmonic generator, which uses people's psychoacoustic characteristics to modify and beautify the sound signal.

1、 Related acoustic principles

（1） What is the pitch?

We should know that the sound of nature is not composed of a single frequency. Most of it is a compound sound, and the pitch refers to the component with the lowest frequency in the compound sound. Pitch is like the foundation of a house. If there is not enough pitch in a tone, the whole tone will change. Therefore, it is very important for our sound engineers to adjust the pitch part of the sound.

（2） What are harmonics?

Harmonics are called sub tones in physics, harmonics in electroacoustics and overtones in music. We know that the sounds emitted by all things in nature are various, with different timbres and complex waveforms. In addition to the waveform of the basic frequency (pitch), this complex waveform also has a series of resonant frequencies, that is, the so-called overtone, which has a certain doubling relationship with the tonic tone, Moreover, overtones can also be divided into even overtones and odd overtones: 2, 4, 6, 8... Are even overtones, 3, 5, 7, 9... Are odd overtones. If the base audio rate is 50Hz, the second overtone is 1oohz and the third overtone is 150Hz.

（3） Function of harmonics

I know what is harmonic (overtone). What's the use of overtone? We take the piano as an example: the lowest frequency of the piano is about 30Hz and the highest audio rate is about 4000Hz, while the piano has more than a dozen overtones, and its high frequency can reach about 20000hz. These overtones can be divided into low-frequency overtones, intermediate frequency overtones and high-frequency overtones. If the low-frequency overtone is moderate, the timbre will be thick and plump; If the overtone is moderate, the timbre will be round, natural and harmonious; If the high-frequency overtone is moderate, the timbre will be bright, clear, analytical and penetrating. Therefore, a sound not only has the most basic pitch, but also has corresponding overtones, and these overtones are very important to the timbre. For example, various musical instruments with different playing methods can produce overtones with different quantities and strengths, so different musical instruments will also have different timbres.

2、 Application of exciter

The design purpose of the exciter is to recover the harmonic components lost in the audio signal, effectively expand the high-frequency bandwidth and improve the signal-to-noise ratio, so as to improve the clarity and expressiveness of sound restoration. Moreover, the level of these harmonics is very low and has little effect on the level of the signal. Because the exciter has the above advantages, using it to process the signal can improve the sound quality. The specific applications are as follows:

（1） Increase the loudness of the sound: Although the exciter only adds about 0.5dB harmonic component to the sound, it actually sounds that the volume seems to have increased by about 10dB. Using people's psychoacoustic characteristics, we can give better play to the sound system and appropriately reduce the acoustic feedback of the microphone.

（2） Increase the penetration of sound: the use of exciter can improve the clarity, intelligibility and expressiveness of sound. Generally speaking, it feels that it increases the penetration of sound! Moreover, it makes the sound more pleasant and pleasant. On the basis of increasing the loudness of the sound, it can effectively reduce auditory fatigue.

（3） Increase the sense of space and three-dimensional of sound: the use of exciter can improve the positioning and sense of hierarchy of sound, and improve the sound quality of replayed sound. Because it can well increase the overtone in the sound, and the exciter with low-frequency expansion function can well improve the sound quality of bass, the frequency range, dynamic range and loudness of the sound have been significantly improved after using the exciter. In general, the feeling is to increase the sense of space and three-dimensional of the sound!

（4） Improve the timbre of analog tape reproduction: the sound signal of analog tape will lose a lot of high-frequency harmonic components in the process of transmission and recording. At this time, we can use the exciter to compensate the high-frequency harmonic of the signal and create a certain high-frequency component again, which can better improve the sound quality.

3、 Using skills of exciter

（1） Determination of incentive object: what sound source should we use the exciter to deal with? We should have a clear concept, whether to deal with music alone or human voice alone? Or both? Generally speaking, the effect of exciter on human voice processing is more obvious; The effect of single music processing is also obvious; But when dealing with the mixture of music and human voice, the effect is relatively less obvious.

（2） Connection of exciter: the connection of exciter is basically connected in series in the signal channel to be excited in the sound system like equalizer and other peripheral equipment. When exciting different targets, the connection methods of the exciter are also different. For example, in a mixer, the 1-2 group is human voice. If the human voice is to be excited, the exciter should be connected to the 1-2 group channel of the mixer by using the plug-in / plug-out interface; If the band of 3-4 group also needs to be excited, an exciter shall also be added to connect to the 3-4 group in the mixing console by using the plug-in / plug-out interface; If comprehensive processing is required, an exciter can be connected in series in the main channel of the mixer. Of course, the exciter can also send signals from aux like the effector, and then return to the mixer. In this way, it can adjust which channels need to be excited and how much power needs to be processed. In fact, it is more flexible. In short, the specific connection of the exciter should be used flexibly according to the situation!

（3） . adjustment method of actuator:

At present, there are not too many audio actuators used in the sound system, mainly because the engineers do not pay enough attention to the actuators. In addition, there are not many high-quality actuators in the industry in recent years, so now I think the actuators are a little "marginalized". At present, the more famous actuators in the industry include Aphex, BBE, and blockbuster. They have their own characteristics, but the general functions, principles and parameters are basically the same. I won't introduce a certain actuator in detail here, but briefly talk about the overall aspects:

Introduction to exciter function keys:

1. In / out with or without actuator effect selection: this key is mainly used for effect comparison during adjustment.

2. Tune exciter signal fundamental frequency adjustment: mainly used to select the frequency to be excited.

3. Mix (mixed) harmonic output control: mainly used to control the excitation intensity.

4. High / normal: high is applicable to excitation processing for single sound source such as human voice and musical instrument; Normal is suitable for stimulating music with a wide range such as overall music.

The above four function keys are called the auditory exciter part, which is mainly used to adjust the high-frequency harmonics and sound penetration.

5. Overhang: This is mainly used to adjust the bass length.

6. Girth (low volume): Bass intensity adjustment.

The above two function keys are unique to the exciter with low-frequency expansion function, and can adjust the bass tone.

Adjustment method of actuator:

1. Put in / out in "in": at this time, the corresponding indicator light is on, so that the actuator can enter the working state.

2. Tune at 12 o'clock: this knob shall be flexibly adjusted according to the needs of excitation frequency.

3. Put high / normal in the required position: put it in normal for comprehensive treatment and high for other treatment.

4. Mix (harmonic quantity) and girth (low volume): both are placed at the minimum position at the beginning of adjustment.

5. Raise the mix until you hear the edging sound (the sound becomes brighter): pay attention to it. This sound is not particularly obvious.

6. Tune to improve the timbre or penetration of the sound: pay attention to distinguish the timbre. When adjusting, you can use music and microphone to adjust in turn. Generally, it is adjusted to the 11-14 o'clock position similar to the clock.

7. Repeat the adjustment of mix until the harmonic effect is satisfactory: it is generally adjusted to the 13-15 o'clock position similar to the clock.

8. Raise overthang until its indicator light flashes: generally, it is adjusted to the 11-14 o'clock position similar to the clock. The bass time is too short, there is no fullness, and it is easy to be turbid if it is too long. Be careful to adjust it.

9. Raise the girth and adjust overthang until the bass effect is satisfactory: it is generally adjusted to the 10-13 o'clock position similar to the clock.

During the adjustment process, you can use in / out to compare the sound effect with and without excitation, and adjust it repeatedly until the treble is bright and clear, the bass is plump and elastic, and the soft and hard strength is appropriate. Of course, there are all kinds of actuators now, and their functions and adjustment methods are different. We can adjust each audio equipment only by learning, watching and listening more.

Problems needing attention when using exciter

1. When connecting the exciter in the sound system, we must pay attention to the flow direction of the signal. If we are going to use an exciter to comprehensively process music and human voice in a mixer, we can connect an exciter in series behind the main channel output signal of the mixer; If only the 3-4 marshalling in the mixing console is processed, the 3-4 marshalling: plug-in / plug-out interface shall be used to connect an exciter. In this way, the 3-4 marshalling will be sent out through the main channel signal of the mixing console after excitation processing; Of course, if the sound of group 3-4 is not sent through the main channel of the mixer, but directly through its own separate signal output port of group 3-4, we don't need to connect the exciter with the insertion / insertion method. We can directly connect an exciter after the output signal of group 3-4. It seems simple. If the connection is wrong, the whole effect will change. Of course, to fully understand the connection and use of the exciter, we also need to study it ourselves.

2. If there is level selection on the rear panel of the exciter, generally + 4 and - 10dB or + 4 and - 20dB, we must select it at + 4dB to ensure the matching of signal level.

3. When using in / out to compare the sound effects with and without excitation, many sound engineers can't distinguish the subtle difference of sound, because the sound released from the speaker can rarely directly radiate to the sound engineer's ears. At this time, it is difficult to accurately distinguish the sound effects with and without excitation. In fact, there is a simple way: if we connect the output signal of the left channel of the exciter to the channel 1 of the mixer, but note that the volume pusher of this channel should be turned off. Then we can wear headphones to monitor the sound of channel 1 alone. At this time, we have a high ability to distinguish the sound effect with or without excitation, then take off the headphones to adjust the right channel of the exciter, and then distinguish the effect from the on-site speaker. In this way, the combination of the two will soon bring up a perfect effect.

4. In the music based sound system, for example, in the disco ballroom, the exciter can be used for large-scale adjustment. The bass volume and bass time can be adjusted to satisfaction at will, and the middle and high tones can also be adjusted greatly to achieve strong penetration. Because of the turbulent flow of people, strong sound absorption and large background noise in these places, it is very necessary to use the exciter for adjustment.

5. In the sound system dominated by human voice, for example, in the singing stage, be careful when using the exciter to adjust. The bass volume and bass time should be adjusted repeatedly. Too many bass affect the clarity of human voice, too few bass, and the sound is too thin and plump, so adjust it until it is appropriate. In fact, the adjustment of midrange and treble should be flexibly adjusted according to different voices. Because the pitch frequencies of male singers and female singers are different, the harmonics (overtones) that need to be processed by the exciter will be different. Therefore, pay attention to the differences in this regard during adjustment.

6. Some sound fields have too many smooth reflection areas, so the treble reflection is very strong and the sound quality is very noisy. At this time, if the exciter is added to increase the "penetration", it will undoubtedly make things worse, and the treble will become more harsh and noisy. Therefore, a good sound field is very important, and the exciter can not be used in any place.

Having said so much, I don't know if it will help you, but we can find that although the popular use of digital processors is a development trend, few digital processors now have incentive functions, most of them are: equalization, voltage limit, frequency division, delay and inverse equality. Therefore, I think the high-quality audio exciter can not be replaced for a long time, and the smart use of the exciter can increase 10dB loudness, which can also reduce the number of audio equipment and save the project cost!