Acoustic equipment

Mistakes in speaker connection

Having studied in detail the passport of the console (mixing console), which is already an exception to the rule, and making sure that the jack input in the console also has two wires, many people do not hesitate to plug there their source with a stereo signal. And having connected all this to the network together with the amplifier, they realize with horror that they were cheated with the speakers, vocals and instruments went far away, and there is no bottom at all. In fact, the symmetrical input should be fed with a symmetrical signal, which has nothing to do with a stereo signal. At a symmetrical input, the useful signal is added and the interfering signal is subtracted out of phase. The stereo signal in this case is subtracted, and at the output of the console we have an antiphase resultant component. In order to still spin in this techno-linguo-equilibrium, you need to feed the left and right outputs of the source to different inputs of the console, using mono jacks, and divide the panorama in different directions (if there are no stereo inputs in the console).

It is undesirable to use loudspeakers from different manufacturers in one installation

Recently, it has become fashionable to use active subwoofers and satellites. If you use products of the same manufacturer, there should be no problems, if you follow the rules of switching. But if, for example, subwoofers from different manufacturers, then due to different circuitry solutions may be a phase shift of one box, relative to the other. In more expensive models to match one active subwoofer (subwoofer, editor’s note) with another in phase characteristics, there are either phase rotation switches (0 – 180 °) or smooth phase shift controller. When low-frequency, active boxes are out of phase, the low-frequency energy is mutually destructive. Also if you use in your installation active low-frequency loudspeakers and active satellites, different manufacturers and different configurations, when adjusting them you need to use special expensive devices and it is desirable that it was done by a specialist in this field, not your good friend, who once repaired your TV set.

Avoiding Power Loss

With proper switching, amplifiers are placed next to loudspeakers, minimizing losses in speaker cables.

Failure of HF speakers

As a rule, the weakest link in the path – signal source – mixing console – amplifier – loudspeakers – is mainly the amplifier itself and the high-frequency speakers of the loudspeakers.

If the “…. casing of the tape recorder does not shield it from electromagnetic fields” the following may happen: ” …. long speaker wires connected to the loudspeakers emit into space up to 50 mV of high-frequency signal, which is 10 times higher than the sensitivity of the magnetic head of the tape recorder; and “…if conditions are created under which the induced signal is in phase, self-excitation of the tape recorder-amplifier system occurs. This event “…usually occurs outside the audible range and has full amplitude at a particular frequency, and usually results in the failure of high-frequency loudspeakers or a poorly protected amplifier.

Another variant of events development is when the tape recorder itself, not knowing how to work on a long line from the headphone output without load, enters the state of self-excitation with the same consequences…. with the absence of skills of work on the reflected sound (loudspeaker systems are often located with the rear part to the “DJ”) it is possible to raise the HF tens of times above the nominal level, and goodbye to the “squeakers”.

About Amplifiers

A professional amplifier differs from a household amplifier in that it is designed to work in extreme mode with minimal intermodulation distortion. Despite all sorts of circuit protections, sometimes converting the signal at overloads into an unrecognizable form, amplifiers are not always so protected.

As you know, almost any professional amplifier circuitry has a low impedance resistor that decouples the circuit ground from the chassis ground. In case of illiterate switching, conditions arise in which a decent current flows through this resistor, leading to both the failure of the power amplifier and the notorious “squeakers”…” (“squeakers” – high-frequency dynamic heads – editor’s note).

Subwoofer failure

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“… if you consider that you got an honest amplifier, and the specified power is measured under load at sine, then the peak values at overload will be at least 1.4 times more. Since, in modern music, the low-frequency signal has an almost constant time factor, it turns out that the low-frequency box works at long-term overload, unlike satellites that have a level-varying time factor. Coil dynamic head “subwoofer” in such an operation will turn into ashes.

Audio equipment rental in Kiev

Remember that

1. Seven out of ten consumers, after the purchase of expensive equipment, first include it in the socket, and then read the instructions, why all the same went smoke. This is our reality, which has to reckon with the Russian manufacturer.

2. When buying acoustic systems you should be guided by the volume of the sounding room, not the amount of money allocated for this.

How to choose acoustics

Do not be deceived by passport data about reproduction of low frequencies from 30-40 Hz by available models of speakers (speakers – acoustic systems, editor’s note). Only those low notes, which are reproduced without “roll-off”, really participate in the formation of the sound picture. Everything that is reproduced with a “slump” of at least 4-5 dB is masked by the “upper bass” (80-160 Hz), so the perceived range starts “below” from 50-80 Hz for most speakers.

Most domestic speakers sound normal in a room with capital walls, upholstered furniture, carpet and sufficiently dense curtains on the windows. Non-capital walls, plasterboard false walls and ceilings, large furniture (cabinets, etc.) absorb low frequencies. In these conditions, any normal speakers require a subwoofer that is properly matched to them and the room.

How to install

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Good sound is impossible in a room without sound absorption. For household speakers normal listening room area: 12-30 m2 (approximate).

The correct placement of speakers is at equal distances from the symmetry axis of the room. The acoustic environment for the left and right speakers should be equal. For example, if the right side has a window covered with drapes and the left side has a bare wall, the sound stage will shift to the left due to reflections from the wall.

If you place the speaker in the middle between the floor and the ceiling, for example at a height of 140 cm with a ceiling of 280 cm, the bass frequencies will not be reproduced. The reason for this is a certain system of standing waves in the room. In order to get a good soundstage, the speakers should be at least 60-70 cm away from the rear wall. You should not move them closer to the side walls than 20 cm. When the speakers are 1-1.5 m away from the rear wall, you get an excellent spatial picture, but may lack low frequencies. The closer the listener is to the opposite wall from the speakers, the greater the impact of the lowest frequencies, the excess of which is often more harmful to the music than the lack.

If the distance between the speakers is less than 2 meters, the sound will be “squeezed” and “flat”. If it is more than 3.5 meters, there will be a gap in the soundstage.

When placing the listener and the speakers in the corners of an equilateral triangle, it becomes possible to localize sound sources in all directions. For example, when listening to a competently recorded movie soundtrack, sounds from the sides and rear can be localized without connecting a surround processor and without rear amplifiers and speakers.

Nevertheless, in a home theater, rear channels are useful because the above-mentioned speaker and listener positioning is often not respected.