Comparison Blaupunkt GTA-475 vs Calcell VAC 90.4

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.

— DSP processor. The digital audio processing processor improves the overall sound quality and provides additional options for its adjustment. One of the most important functions of DSP is time correction: it allows you to adjust the operation of acoustics so that sound from speakers located at different distances from the customer reaches him at the same time. This coordination significantly improves the sound experience.

The presence of a processor significantly affects the price of the amplifier, but in most cases it is a justifiable price to board for the sound quality. But the clear disadvantage of “processor” models is the complexity of installation and configuration; for this it is best to contact a specialist.

— Phase adjustment. The ability to shift signals entering different channels of the amplifier in phase relative to each other; The phase shift in this case is a small, fraction of a second, delay of the signal on one of the channels relative to the other. The need for such a setting is due to the fact that the speakers on different channels (including the subwoofer) may be at different distances from the listener; Because of this, as well as due to the peculiarities of signal processing, the sound from them may arrive with some desynchronization. By adjusting the phases, you can eliminate this phenomenon and achieve the highest quality sound.

— High voltage in...put. This input is useful if the radio does not have a special connector (line output) for the amplifier - it allows you to use the signal going to the speakers when connecting. Such a signal is much more powerful than at the linear output, and outputting it to the standard linear input of the amplifier can damage the device; the high-voltage input will cope with the task without any problems. It must be borne in mind, however, that the high-voltage connection is more of a backup option than a full replacement for the linear input. The fact is that before entering the external amplifier, the signal passes through the radio's own amplifier, which introduces additional distortion.

— Bass Boost function. As the name suggests, this feature is designed to enhance the sound at low frequencies, resulting in a more powerful and rich bass sound. It will be especially useful if the amplifier is planned to be used with a subwoofer. The simplest options involve enhancing the bass without adjustments; more advanced models allow you to adjust the frequency range and degree of gain.

— Infra-low-pass filter (FINCH). This function is relevant primarily when connecting an amplifier to a subwoofer; it allows you to minimize reproduced infrasound - vibrations whose frequency is below the human hearing threshold. There are several purposes for this adjustment. Firstly, high-power infrasound can cause poor health and even health problems. Secondly, some of the power will be spent on its reproduction, which will negatively affect the audible sound. Thirdly, ultra-low frequencies greatly wear out the cone and can even damage the speaker. In some amplifiers, the FINCH has frequency adjustment.

— Low pass filter (LPF). Thanks to this function, the customer can separately change the volume of the bass sound, adjusting the sound to his own preferences and features of the environment. It will be especially useful if the amplifier is used for both the main acoustics and the subwoofer - the low-pass filter will actually work as a volume control for the latter.

— High-pass filter (HPF). The high-pass filter is used to fine-tune the sound - it allows you to separately adjust the volume of high frequencies without affecting the rest, and thus change their share in the overall sound picture.

The presence of a thin layer of gold on the amplifier connectors. The role of this function is not only decorative, but also, first of all, quite practical: gilding protects the contacts from oxidation, has a very low current resistance, and also provides a tighter contact than the usual metal coating of the connectors. All this reduces the likelihood of interference from the point of contact.

The rating of the fuse installed in the amplifier is the current strength, at which the fuse operates, opening the circuit and de-energizing the device in order to avoid unpleasant consequences (see "Protection — Short circuit protection"). In some models, several fuses can be installed — in this case, this is usually directly indicated in the characteristics, and the current required to operate the protection corresponds to the sum of the ratings. For example, the rating marked "4x25 A" corresponds to four fuses that operate at a current strength of more than 100 A.

This parameter determines, first of all, the features of the power connection: it is desirable that the fuse in the corresponding section of the on-board network of the car be of a higher rating than in the amplifier, otherwise it may burn out at a current that is quite normal for the device. In addition, the fuse rating is related to the power rating of the amplifier and can be useful if you have doubts about the reliability of the data specified by the manufacturer. There are special formulas that allow you to calculate the maximum possible rated power depending on the fuse rating and device class (see above).