How powerful should the audio amplifier be?

                       How powerful should the audio amplifier be?

In a sound system, using a power amplifier properly is not as simple as you think. It is really necessary to discuss it.

1. What power amplifier should be used?

     Generally, before choosing a power amplifier, the first problem you encounter is how much output power to choose. This is not only related to the effect and stability that a sound system can achieve, but also the cost of the system. As we all know, there are many ways to express the output power of a power amplifier, including rated output power, musical power, and peak power. They can differ by several times, and some can differ by ten times. Moreover, these output power values are inversely proportional to the load impedance. That is, the smaller the load impedance, the greater the output power of the same power amplifier. Theoretically, the impedance is reduced by half and the output power is doubled. Now let's define the rated output power of the amplifier. The so-called rated output power means that under a certain load impedance (usually 82) and a certain harmonic distortion (according to the manufacturer's 0.1% or 0.3%, etc.), a sine wave signal is fed into the input end, and the output On the terminal load, the maximum power obtained can be obtained by using the formula P=U2/R. What I want to remind everyone here is that although defining the rated output power of a power amplifier is a very strict matter, some manufacturers are still not so strict in their promotion. Some use the rated power at small load as the nominal value, and some even use music power or peak power. It is suspected of misleading the public. This depends on our judgment using the knowledge and experience we have.

    Secondly, how to choose a power amplifier in a hall? In practical applications, we generally do not directly choose a power amplifier with 400W output or 800W output. Because of the size of the amplifier output, whether the sound is loud enough in the hall is really not the same thing we care about. In terms of the power output of the system's power amplifier, in terms of type, some push full-range main channel speakers, some push-pull imaging speakers, some push stage return speakers, and some push subwoofer speakers. The quantity and effect are different. It is very large, and it is also related to the sensitivity of the speaker being pushed. In addition, it is also closely related to the acoustic environment of the hall. We can use a formula to quantify the impact of so many factors on the sound pressure level (usually said that the sound is not loud): W=10 (LP-LS+20Igr) /10LP: Test point (speaker radiation distance) requirements sound pressure level in dB;

    LS: Speaker sensitivity dB, given by the speaker parameters;

    r: the distance m from the speaker to the test point, also called the speaker radiation distance W: the driving power required by a single speaker. We can use this as a basis to reasonably determine the electrical power output of the power amplifier. What should be noted here is that the formula generally determines the output power of the channel amplifier. The stage monitor speakers can be determined as 30%-50% of the main channel power, the output power of the subwoofer amplifier can be determined as 100%-150% of the main channel power, and the auxiliary speaker amplifier power can be determined as 50% of the main channel power. %-100% sure. Never use gross estimates and rely on imagination to determine. If determined in this way, the result will be either waste (selecting too large a power) or failure to achieve the effect, which can easily cause damage to the amplifier (selecting a small power), unless you are very experienced.

How to make good use of the power amplifier in your audio system

     How to judge the quality of a power amplifier. For a power amplifier, many people often cannot judge its quality. Merely relying on the indicators provided by manufacturers is often very similar and confusing, but depending on the price, in some cases, high price does not mean that good products will come. Today, the author will talk about how to judge the quality of the power amplifier from the actual use situation. Of course, using instruments to test the indicators is another matter.

Get an amplifier,

We can simply judge from the following aspects:

1. Appearance and packaging - For the external packaging of the power amplifier, first of all, check whether the packaging box is upright, whether the printing is exquisite, whether the information is complete (specifications, origin, passed certification, etc.), and then whether the shock-proof filling material of the packaging is environmentally friendly. Those that are well packaged, reasonable, and environmentally friendly can be considered good amplifiers.

2. Check the appearance of the power amplifier to see whether the surface treatment of the panel is fine, whether the shell plate is thick, whether the screws and screw holes are accurately located, whether the knobs, connectors, and character printing are accurate and clear. If they are all relatively good, it can also be considered that the quality of the power amplifier is good.

3. Open the power amplifier and check whether the volume and weight of the toroidal transformer match the marked output power, and whether the appearance is rough. Then check whether the filter capacitor is a genuine product, and whether the capacity and withstand voltage are sufficient (generally the capacity is 10000uf and the withstand voltage is 100- -200v) Whether the wiring is clear and reasonable, especially for high-power tubes: - Look at their number. As the output power increases, the number of high-power tubes can be configured from 8 to 24 or even more.

4. Judge the protection circuit to see if the protection circuit module is relatively simple. A regular protection circuit has functions such as overcurrent, overvoltage, overtemperature, and delay. A poor amplifier only has a power-on delay and no other protection measures, and the circuit is very simple.

5. When the power is turned on, the fan noise is low, there is no transformer vibration, and there are no other abnormal sounds. Otherwise, the amplifier is a defective product.