Ode about true power or loud and quiet Watts

Anyone who has ever encountered the choice of sound equipment had a question about the power, and more precisely, the volume, for example, the speaker system or the receiver. I suppose that many have heard from “caring” vendors or have noticed in advertising materials information about the power of 30, 50 or, for example, 100 watts. When this happens to me to hear (see), I think hard about what kind of power it is. Systems from the Middle Kingdom, for example, allegedly "give out" transcendental thousands of watts, while sounding quieter than ten watt tracts from other manufacturers.

Due to the orientation on the power values ​​of the amplifying technology and acoustic systems, a lot of confusion arises that prevents buyers from purchasing and sellers to sell sound equipment. Under the cut, I will talk about the existing standards of power, as well as what marketing tricks help some manufacturers to declare “high” formal power, with fairly modest real characteristics.

What determines the volume?

Just in case, I will once again write about what loudness is and which factors exactly determine it for a particular path. Of course, today for most people the truth is that high power does not always speak of high volume - an open secret, but you never know ...

So, the volume is:

“Subjective characteristic, it is determined by the intensity
sound proportional to the square of the amplitude (A) of the sound pressure (SPL), and
the sensitivity of the organ of hearing depending on the frequency of the sound. ”

So, power is not the only effect on the final sound pressure (SPL). The volume of the path determines the combination of the sensitivity of the acoustics with the power of the amplifier. The lower the sensitivity of the AU, the more powerful UMZCH will be required in order to “shake” it.

At the same time, an increase in sound pressure of 3 dB requires a doubling of power. For example, a speaker system with a sensitivity of 90 dB creates a SPL = 90 dB when applying 1 W of power to the speakers (1 meter distance). To increase the SPL to 93 dB, it is necessary to increase the power to 2 W, to 96 dB - to 4 W, to 99 dB - to 8 W, etc.

“Soviet” and “Chinese” Watts

But nevertheless we will return to standards of power, as to the main tool of marketing manipulations. “Soviet” and “Chinese” Watts are a “popular” division of power standards, which appeared 20-25 years ago. Then the most affordable and popular equipment on the market was a new one from the Middle Kingdom or the old one from the USSR. The rest was either not supplied to the Russian Federation (due to the dominance of the Chinese centers), or it was indecently expensive for 80-90% of the population of the Russian Federation.

The “Soviet” watts were considered honest, while the Chinese, respectively, were not very. Although with the Soviet, too, everything is not so simple. The power characteristics of the amplifier in the USSR were determined by GOST 23262-88, which instructed the manufacturer to indicate the rated power in the device passport.

Rated power is determined at the average position of the amplifier volume control, at which the other parameters of the device correspond to those stated in the technical description.

In other words, GOST left for the manufacturer the right to specify the power that corresponds to the lowest value of the nonlinear distortion coefficient. The indicators, as a rule, were adjusted to the requirements of the standard for the device complexity class. The power was indicated both in amplifiers and in speakers (indicated the amplification of which nominal power was calculated for the acoustics).

At the same time, according to tehpoisk.ru, sometimes this led to problems. For example, distortions like “step” that occur at low volume levels in class AB amplifiers were not taken into account. The distortion level could decrease with an increase in the output power of the signal to nominal. At the same time, at medium and low volume levels, the signal was significantly distorted.

Also in domestic equipment one can meet such a parameter as sinusoidal power (maximum sinusoidal power) - this is the power at which the UMZCH or acoustics are able to work for 2 hours with a music signal without physical damage. Such power is not limited by distortions, its limits are determined only by thermal and mechanical damage. Sinusoidal power is usually 2-3 times more than the nominal.

A typical example of speculation in sinusoidal power is the legendary S-90. Their nominal power was 35 W (by the way, the first version of the acoustics was called 35AC-01), and the sinusoidal, evasively named in the passport documentation, was 90 W. The nominal one was also indicated, but the second in a row, which can be considered almost harmless, by today's standards, is a marketing manipulation.

Compared with the Chinese from the 90s and the beginning of the zero, the case of “Radio Engineering” with the S-90 seems to be completely innocent. I still remember how the dull basement copyists of the Matsushita offspring with the consonant name Panansonica (the spelling of the decoders kept) left on their craft a “proud” and noticeable inscription: 5000 watts.

In this case, it’s about PMPO (Peak Music Power Output), i.e. o the maximum power that the speaker can withstand in principle, and the amplifier is able to produce without thermal and mechanical problems. The test is carried out for one to two seconds with a 200 Hz signal.

Such values ​​are usually 20-30 times higher than the nominal value and it was customary to call them Chinese. In recent years, to the credit of Chinese manufacturers, they abandoned the use of PMPO and began to use RMS.

Among the domestic passport characteristics can also be found the maximum short-term power (analogous to PMPO), passport noise power (analogous to sinusoidal, but pink noise is used in the test instead of a musical signal).

DIN, RMS, AES, IEC and other abbreviations

Today, the ill-fated PMPO is indicated extremely rarely and, as a rule, as an additional parameter that does not carry the marketing burden. Gostovsky nominal and sinusoidal power is also quite difficult to meet. But this does not become easier. In numerous UMZCH and AS of modern production there is no uniform standard of power. Frequent and frank marketing manipulations.

To begin, perhaps, with the standard DIN 45500 (known for the first time standardizing the concept of HI-FI), in which DIN Power is measured by applying a 1 kHz signal to the input of the device for 10 minutes. Power is measured when 1% THD is reached. The standard is almost identical to the EIAJ adopted by the Japanese Association of Electronic Industries.
(Electronic Industries Association of Japan).

The standard also provides for another type of power measurement - DIN Music Power, which describes power close to the definition of sinusoidal and passive noise power, i.e. the value of continuous load music signal without the risk of damage. The typical DIN music power is slightly higher than DIN.

The standards of this standard are correlated with the concept of IEC Power according to IEC 268-5 (standard of the International Electrotechnical Committee, second edition 1989-07), which defines the duration of the load - more than 100 hours.

RMS (Rated Maximum Sinusoidal) - limiting sinusoidal power, i.e. one in which the sound reproducing device can operate for one hour with a real music signal without damage. As a rule, it is 120-250% higher than the Gostovsky nominal and 20-25% more than DIN Music Power.

To RMS as close as possible standard AES2-1984 (Audio Engineering Society). The difference between AES Power and RMS lies only in the time it takes the device to work - it takes 2 hours for the AES standard.

Also may be indicated so-called. program power (Program Power or PP), which in principle can be any, because not standardized. It is considered that Program Power is 2 times more than RMS, but this is not mandatory. PPP gives no less vague notions of power, i.e. Peak Program Power (Peak Program Power), which is 2 times more than PP.

A typical example of the difference in the indication of power can serve such well-known and respected speakers as Dynaudio and DALI. The first ones indicate “Passport power, IEC”, that is, in fact, DIN, the latter are generally limited to the concept of “recommended power” and indicate the power range.

STI manipulations

There is a different IHF standard from DIN Power and EIAJ, developed by the US National Institute of Standards and the Institute of High Fidelity, in which power is measured at 0.1% non-linear distortion.

Similarly, any manufacturer can enter its own standard for calculating power, which will allow him to write in front of the word Power any numbers he deems profitable. In such calculations, it is possible to bring the values ​​of SOI to any maximum, for example, to 15-20%, which would entail an increase in the formal “power”. Moreover, the RMS values ​​may change this way.

Sly receiver

The next ambiguous point concerns the calculation of the power of the multi-channel receiver. So when testing, there is a “beneficial” for distortion of reality the division of power. The measurement results will please the eyes, but not the neighbors' ears. This is due to the method of measuring one loaded of six, eight or ten channels, which formally gives a supposedly power gain.

In order not to be mistaken, estimating the actual power of the device, one should look for the posts “all channels drive” in the column where the power is indicated, if not, then the measurements were probably carried out with a load on one channel. And I am almost convinced that without such an inscription, the declared power characteristics do not correspond to reality. The nominal (according to GOST) power, which (taking into account the use of a class D amplifier) ​​will be no more than 80% of the power consumption, and with amplifiers of other classes - even less.

Dry residue

To summarize and demonstrate materiality in the difference in power, I suggest a small comparison using the example of the same S-90. In this case, I will give only approximate calculated values ​​(actual measurements may differ), but this will allow you to understand how much the standards that you can face today differ. So, Radio Engineering S-90:

Thus, we obtained 7 different values ​​in 11 different standards.

From the foregoing, we can draw conclusions:

I can also recommend for optimal amplification and at the same time safe operation of a pair of amplifier + speakers for studio and home use, choose the nominal (or IHF) power of the amplifier twice the acoustics power according to the AES standard.

For concert equipment that uses live voice and dynamic instruments, there is another rule - the nominal gain power is equal to the acoustics power according to AES.

A wide range of amplifiers , receivers and other sound-reproducing equipment is presented in our catalog . You can purchase high fidelity speakers from us.

Source: https://habr.com/ru/post/411175/

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