Comparison JBL Stage3 627 vs JBL GX-642

The size of the speakers of the acoustic system; in speakers with different driver sizes (component and coaxial, see "Type"), the size is determined by the diameter of the largest (woofer) driver. The size of the speaker determines primarily its ability to work with low frequencies. It is believed that acoustics up to 4 "is practically not suitable for low frequencies (regardless of the frequency range), 5-6" refers to the average level, and speakers of 6" or more even allow you to do without a subwoofer. Also, the size affects the installation options. So , some cars may provide seats for acoustics of a certain size — this limits the choice.And for large acoustics, there may not always be a place in cars with cramped interiors.

Rated power of the acoustic system. Most often, the average (root mean square) sound power is indicated as rated.

The most obvious point related to this characteristic is the volume of sound: the more powerful the sound system, the louder the sound it can produce, all other things being equal. In addition, compatibility with an external amplifier depends on this indicator: its power should not exceed the power of the sound system, otherwise overloads and damage to the speakers are possible.

The maximum power of a short-term (up to several seconds) incoming signal that the speaker can withstand without physical damage. Just like the nominal power, it matters for the selection of acoustics for an amplifier (or vice versa): it is believed that the maximum power of the speakers should be at least 2 times higher than the maximum power of the signal source.

The total audio frequency range reproduced by all speaker speakers.

Obviously, this range should not be too narrow, so that the acoustics do not cut off the lower and/or upper frequency limits of the reproduced sound. At the same time, the human ear perceives sound within 16 Hz - 22 kHz, and it simply does not make sense to provide speakers with a wider frequency range. We also recall that in mid-frequency acoustics and tweeters, reproducible frequencies are limited due to specialization (for more details, see "Type"). And the overall sound quality will depend not only on this indicator, but also on a number of other features.

The term "impedance" refers to the electrical resistance of AC systems whose DC resistance is very low, such as loudspeakers. In modern car audio, the most common impedance is 2, 4 or 8 ohms. This parameter has practically no effect on the sound quality — it serves to select the optimal combination of acoustics and an external amplifier. If the speaker impedance is higher than that for which the amplifier is designed, the sound will be quieter than necessary, and if the impedance is lower, distortion in the sound is possible.

This parameter determines the volume of the sound of a particular speaker when a certain standard signal is fed to it. Typically, this is considered a 1 W signal with a frequency of 1000 Hz. The higher the sensitivity, the less the speaker is demanding on the power of the amplifier. So, it is believed that for acoustics connected directly to the car radio, the sensitivity should be 80 dB or more; for less sensitive systems it is recommended to use a separate amplifier.

Size of the low-frequency speaker(s) provided in the speaker system.

This size is specified only for models with separate bass speakers. In such acoustics, it is the LF emitter that is the largest (this is due to the physical characteristics of the bass range). Accordingly, the space occupied by the entire system is determined mainly by the diameter of the LF speaker. And since the power and richness of the bass also directly depends on the size of the emitter, then when choosing, you have to proceed from a compromise between the capabilities of the acoustics and the available space in the car.

The mounting depth of car audio is, in fact, the size of the speaker in depth. Note that for component sets (see "Type") this parameter is given for the largest speaker, and for case models it is generally irrelevant.

The mounting depth, along with the diameter of the speaker (see above), determines the amount of space needed to mount the speaker — in this case, how deep a niche would be required for normal mounting. At the same time, the larger the speaker, the larger, usually, the installation depth. And with similar diameters of equal size, a more powerful model is likely to be more “deep”.

The smallest amount of space — up to 15 mm deep — is required by some tweeters. A depth of 16 – 30mm is normal for tweeters and very shallow for general range speakers, most of these models have a depth of 30mm or more. At the same time, full-range speakers are usually "recessed" by less than 60 mm, component systems — by less than 90 mm, and more depth may be required only for some coaxial and mid-range models and, oddly enough, tweeters.