Thanks to mass communication, one piece of news can quickly spread through the Internet and the media. Moreover, only one news agency is the source of information, while the rest simply copy and distribute further, reproduce the news. On news sites, you can see links to other informative articles with the same information. This is the principle of reverberation or echo, only in the field of mass communication.
The meaning of reverb
This term is found in physics and is associated with the section of acoustics. This is the effect of recoil and reflection of a sound wave from any obstacles, and its return to the source. This occurs in any natural acoustic environment - in a stadium, in a large hall, a room, and even a studio. The listener perceives with his ears not only the source of sound, but also its reflections from surfaces.
In physics, two types of reverberation are known: natural and artificial, when with the help of technology amplification and modulation of additional sound waves are created. The sound reflected by the walls graduallysubsides after the sound source stops sounding. People only hear echoes or reflections of sound of varying amplitude.
Artificial reflector
A reverb is a special device that increases the strength of the return of sound waves from walls or artificially creates such an effect in places where there is no natural acoustics. In the 70s, the tape reverb was popular. By design, it was somewhat reminiscent of a tape recorder of those times, with reels.
When the sound started to play, the reverb read it out with the recording heads and transferred it to the tape. The playback heads then read those sounds from the tape. The number of heads indicated how many times the reproduced sound would be repeated. Some models had up to ten of these heads and even more. The timbre of the acoustics of each signal with each head became quieter, which created the effect of a fading echo.
The high-quality reverb effect was achieved by the speed of the tape (about 38 centimeters per second) and the minimum distance between the playback heads.
A reverb is not a sound copier, it is an apparatus that is able to recreate the scale of a fading sound. Although, even in those days, tape recorders worked in two modes: they created an echo and distinctly repeated sounds.
Reverb Characteristics
Here are the main characteristics of the reverb and the standards it must meet:
- Reaction of impulses. When sound enters the recording headsbefore it exits, a short pulsation occurs. This interval between pulses should not exceed 0.05 seconds, otherwise the listener will perceive the echo as separate sounds repeating one after another. This is a sound defect.
- Reverb time. This is the time during which the voltage of the sound falls off after the main sound at the input stops. At the output, a small reverb reduces the sound strength to 60 dB from the first sound. The voltage should drop, as it happens in a natural acoustic environment. This effect can be adjusted independently by changing the reverb time and volume. Adjusts the decay rate of the signal or changes the ratio between the direct sound and the echo.
- Transmission ratio. The voltage amplitude of the incoming and outgoing sounds. In a large room, the amplitude peaks on the graph are arranged irregularly with an interval of up to 4 Hz and dips of 25 dB or more. Therefore, in order for a vocal reverb to be able to simulate acoustic echo in a large room well, the density and length of the frequency peaks must match these indicators.
What are the systems
Reverbs have several action systems:
- Tape. The playback sound is recorded on the tape.
- Spring. They are small in size, work on the principle of sound delay and mechanical vibrations of the spring.
- Digital reverb. The main sound is fed to the modulator of the transceiver, which delays the signal and creates an echo effect. Digital signal processing gives it a specificcoloration.
It is worth paying attention to the spring system, since such a device is cheaper, the design is not complicated, and you can make such a reverb with your own hands.
The principle of operation of the spring apparatus
The signal entering the device is amplified by a special device, converted and vibrates the moving element. A spring is attached to this moving element, which, depending on the length and coils, determines how long the incoming signal will reach the receiver, and how long the sound will be.
What standards need to be met
Let's consider what parameters you need to consider when making a reverb at home.
So, the frequency of repetition of peaks in the bandwidth range of 100 Hz should be no less than 15 and no more than 20. The average interval between signals is 0.025 seconds. Operating frequency range from 150 to 3000 Hz. Sound vibration time at lower frequencies - no more than 4 seconds, at upper frequencies - no more than 2 seconds.
Increasing the echo time at low frequencies distorts the clarity of the sound. In a spring reverb, the time at high frequencies is quite short, no more than 2 seconds, but the lower the frequency, the longer the time becomes, reaching 8 seconds. Therefore, we need to install a damper in our reverb, which will reduce the time of signals at low frequencies.
How to calculate the length and coils of a spring
A spring is a mechanical filter that allows low-frequency sounds to pass through. Can be usedsteel wire or piano string with a diameter of 0.2-0.4 mm. Coiling is done on a lathe so that the turns are of the same diameter. The delay line frequency is 3-4 kHz, and the diameter is calculated by the formula: average wire diameter=required cutoff frequency equals the winding diameter. The number of turns depends on the audio delay time.
Converter and verification of calculations
Instead of a converter, you can use a magnetized rotor or a coil with a magnetic core. The coil is attached to the wall of the reverb with a piece of wire. Being between two magnets, the transducer, under the influence of a sound wave, oscillates the coil and the spring. It is necessary that the wire passes through the converter. One of its ends inside the converter clings to the main wire, using a hook method, and the other end, 30 millimeters long, is a holder. If a larger diameter wire is used, then the cross section of the turns should correspond proportionally to the diameter of the wire itself, measured in cubic millimeters. The receiver on the other end does the opposite.
Not everyone can accurately calculate and make everything at home, because the check of the delay time is performed by special equipment. Not everyone has it. But with a little logic, ingenuity and quick wit, the reverb is no longer just a dream.
In artisanal conditions, we set up the device as follows: turn on the sound generator, measure the output data with a voltmeter. We slowly change the frequency of the generator until we determine the interval of peaks andfrequency dips.
Modern reverbs
Let's briefly discuss the best reverbs that are considered the best in today's ranking.
First place Bricasti Desing M7 is a fine digital device of the highest quality. Former Lexicon engineers have teamed up to create the best in algorithmic sound reverb. Even though it's expensive, it's still far less expensive than comparable top-of-the-line reverbs, according to studio recording professionals. Digital format - 24 bit/192 kHz, on a dual-core DSP platform. Fully consistent with studio requests.
Fender '63 Reverb is in second place. Replica of the legendary 1963 reverb. Fender developers have tried to completely recreate the device according to its parameters. Phenol electronic parts were replaced with printed circuit boards, 6K6 lamps were replaced with 6V6. First-class engineers have invested all their many years of experience in its creation, so the device is in demand by many world musicians. Reverbs are also used to enhance the sound of musical instruments equipped with an acoustic output, such as electronic guitars.
