Comparison Pioneer GM-D8604 vs Fusion FP-804

-A. Amplifiers with analogue signal processing. The design of their electronic circuits is such that the current through the amplifying stage is not interrupted during operation (unlike class B). Due to this, the output signal repeats the input signal as accurately as possible, and even at low powers the level of distortion is minimal. This allows the use of such amplifiers even in Hi-Fi systems. On the other hand, class A devices consume full power all the time, whether they are outputting a signal or not, while their power consumption is very significant, and the efficiency (and, accordingly, the output power) is quite low. In addition, this class is characterized by significant heat dissipation — especially at idle, when the power consumed is converted mainly into heat.

— A/B. This class of amplifiers belongs to analogue devices. Without going into technical details, we can say that it combines the principles of operation of classes A (high sound quality with low efficiency) and B (good energy efficiency, but relatively low sound quality). As a result, class A / B devices have a higher efficiency and lower heat dissipation than “pure” class A, and although they lose a little in sound quality, they significantly exceed “pure” class B in this indicator. Among these amplifiers are also found Hi-Fi level models.

— D. Amplifiers using digital signal proc...essing. Their main advantage is high efficiency, which provides good output power (significantly higher than that of the A / B-class). In addition, the dimensions of such devices are very compact. At the same time, the output sound quality is somewhat lower, it is more prone to distortion, and with the same sound quality and other things being equal, a class D model will cost significantly more than A / B. This scheme includes many single-channel (see "Number of channels") amplifiers designed for subwoofers — in this case, power is much more important than signal purity.

— B/D. Despite the name hinting at hybrid operation, these amplifiers are not a hybrid of classes B and D, but digital devices that have some design differences from traditional class D models (see above). According to some manufacturers, these differences allow for higher efficiency than analogue classes (see above), with a lower level of distortion than in the "regular" class D. However, such devices are quite expensive.

— G. A variety of analogue amplifiers designed to increase the efficiency of such devices and, accordingly, provide high power. The design of class G models is based on the fact that the amplifier is rarely used at full capacity. To optimize performance in such models, two voltage options are used to power the output stage, switched depending on the level (in other words, volume) of the input signal. At low volume, low voltage is used, and to provide high power, the device is transferred to high voltage. This not only significantly increases the efficiency, but also provides good sound quality, but the amplifiers themselves are complex in design and expensive.

Rated power output by the amplifier per channel when a load (speakers) with a nominal impedance of 1 ohm is connected to it (for more details, see "Maximum impedance"). By rated power, conscientious manufacturers most often mean the so-called RMS (Rated Maximum Sinusoidal) — the highest output power at which the amplifier is guaranteed to work for an hour without damage; it is much less than the maximum value (see below for more details).

In general, the higher the rated power, the higher the sound volume that the amplifier can produce (ceteris paribus, including the characteristics of the connected acoustics). This indicator also determines compatibility with car audio: the speakers connected to each of the channels should ideally have the same rated power (in fact, a deviation of 10-15% is allowed).

Rated power output by the amplifier per channel when a load (speakers) is connected to it with a nominal impedance of 2 ohms. For details, see "Nom. channel power (at 1 Ohm)”.

Rated power output by the amplifier per channel when a load (speakers) with a nominal impedance of 4 ohms is connected to it. For details, see "Nom. channel power (at 1 Ohm)”.

Rated power delivered by the amplifier to a load connected in a bridge circuit. For more information about the rated power, see "Nom. channel power (at 1 Ohm)”.

With a bridged connection, the speaker is connected not to one channel, but to two at the same time — the “positive” connector of one channel and the “negative” connector of the other are used. If the amplifier has a similar format of operation, then such a pair of channels operates in antiphase, due to which the power is summed up. This allows you to connect speakers to the amplifier, the power of which is twice the nominal power of the device: for example, at 150 watts per channel, 300 watts of acoustics can be bridged. If there are 4 or more channels, it becomes possible to use several speakers according to the "bridge" scheme. This is usually directly indicated in the specifications — for example, the entry "2x300 W" in the "Bridge connection" item means the ability to work with two speakers, each with 300 W.

The requirements for load resistance when connecting with a bridge are the same as for conventional; see "Maximum Resistance" for details.

The highest output power provided by the amplifier. It is worth noting that this indicator is not standardized, and different manufacturers may mean different values \u200b\u200bfor it — for example, the highest power of short-term, in a fraction of a second, peaks (power surges), the highest power that the amplifier can transfer for several seconds, or even the power at which the device will fail. Therefore, it makes no sense to compare different models with each other in terms of maximum power. But when choosing acoustics for an amplifier (or vice versa), this parameter can be very useful: it is desirable that the maximum power of the speaker be at least twice as high as that of the amplifier. This will reduce the risk that a power surge will damage the speakers.

The range of audio frequencies that the amplifier is capable of processing. The standard hearing range of the human ear is 16-20,000 Hz, but for some people these limits can be much wider. In addition, low-frequency vibrations, already inaudible to the ear, but extremely close to the lower threshold of audibility, are perceived by the entire surface of the body at high sound power, which creates the impression of the most saturated sound (although care must be taken with this, because infrasound can have a bad effect on well-being).

In general, the wider the frequency range of an amplifier, the richer the sound it can provide. However, this is not an unequivocal guarantee of high sound quality — a lot also depends on the amplitude-frequency characteristic, signal-to-noise ratio (see below) and other features of a particular device. Yes, and the connected speakers must also correspond to this range — otherwise the signal will be "cut off".

Also note that many monoblocks (see "Number of channels") have an upper range limit of only a few hundred Hz — these models are designed for use with subwoofers, and high frequencies for them would be an unnecessary overkill.

One of the main parameters that determine the sound quality of the amplifier as a whole: it describes the ratio of the useful signal (in other words, “clean” sound) and various extraneous noises. This takes into account almost all noise — both due to external causes (for example, electrical "pickup"), and created by the device itself (for example, due to heating during operation). Accordingly, the higher the signal-to-noise ratio, the less audibility of various interferences and the clearer the sound is obtained (of course, under normal operating parameters). The average for car audio is 95-100 dB, but in advanced models this value can be significantly higher.

At the same time, this parameter is not critical for monoblocks designed for subwoofers — most of the interference is high-frequency and will simply not be heard on the low-frequency speaker. The sound quality in this case is highly dependent on the characteristics of the speaker (much more than in multi-channel models), and is weakly related to the “noiselessness” of the amplifier.

Possibility of connection to the amplifier of the remote control. Note that the functionality of remotes for amplifiers is significantly different from other types of electronics. First, the connection is most often carried out by wire. Secondly, the remote itself provides a minimum of adjustments — most often it controls only the Bass Boost function (see "Functions"), allowing you to quickly adjust the bass level depending on the track being played. However, remote control is still significantly more convenient than changing settings from the panel on the amplifier case.