The car speakers are the centerpieces of any loudspeaker. A speaker can produce sound without a speaker, but it is the combination of one or more speakers with a cabinet that gives the speaker. As far as the manufacture of loudspeakers is concerned, many technologies coexist. We will try to shed a simplified light on these different technologies of sound emission.
The electrodynamic speaker
This is the most common. It uses a membrane integral with a coil immersed in a magnetic field. The shape of the membrane depends on the frequencies to be reproduced: cone for the bass and midrange registers, rigid or flexible dome for the midrange and treble. There were experiments with flat membranes but the results were disappointing. A cone loudspeaker has a membrane that must be as rigid as possible.
It is held in place by 2 suspensions:
The device visible from the outside and the back, called spider, which keeps the coil perfectly centered in the gap. The half-roll suspensions offer a large travel, essential for small diameter speakers. The pleated paper suspensions are more rigid and mostly used on large diameter speakers. The membrane itself can use a lot of materials. Each constructor has its own methods.
Examples of electrodynamic speakers
Examples of electrodynamic loudspeakers: on the left, a soft dome tweeter charged to reproduce the high frequencies, on the right, a composite bass-midrange.
The dome speaker
Dome speakers exist with and without throat adaptation. Mounted flat, the dome radiates very widely and offers a good transient response. Placed at the center of a phasing surface (Mackie, Genelec), efficiency is improved and directivity better controlled at different frequencies. The field, very wide, limits the range of tweeters and dome-shaped mediums to a few meters.
The compression speaker
Compression loudspeakers use a metal dome membrane loaded by a horn via a phasing piece. The pavilion greatly improves performance and directivity. The latter is much smaller, but much better controlled. The range is also much better.
- By comparing two speakers at one and the same level, one with a dome midrange and the other with compression, we find:
- A balance roughly equivalent to 2 m of speakers.
- A very downward balance for the domes from 5 m while the compressions keep the same balance. The bass is more present when you are far from the speakers, compressions are more linear when you are more than 5 m from the speakers.
The coaxial speaker
2-way speakers usually have 2 speakers placed one above the other. For better sound propagation, positioning on the same vertical axis is desirable. Some manufacturers have developed coaxial speakers in which the tweeter (high-pitch speaker) is placed in the center part of the woofer.