Help: Speakers

Speaker Types

Speakers come in four basic forms:-

• Dual cone
• Coaxial (also known as 2 way, 3 way, etc ).
• Components
• Subwoofers

Dual Cone Speakers Dual cone speakers use a secondary cone within the centre of the main cone (see illustration). The inner cone has a lower mass than the main cone, resulting in resonance at higher frequencies. This helps to improve the high frequency response of the speaker. Ultimately however, treble level and dispersion can never match that of either coaxial or component speakers.
Coaxial Speakers Coaxial speakers (often referred to as two way, three way or similar) use additional drivers mounted within the main cone (see illustration). Two way coaxial speakers use a tweeter within the main cone to give much better treble response and dispersion than a conventional dual cone speaker. Three and four way coaxial speakers use a tweeter (or tweeters), plus a midrange driver (or drivers). The main benefit of coaxials is that they are relatively cheap to produce, and virtualy all will give better response than a dual cone speaker. Mounting the tweeter within the centre of the main cone does however degrade sound quality, and very few coaxials will perform as well as a good component kit.
Component Speakers Unlike most other speakers, component systems use a seperate tweeter, which can be mounted completely independently from the mid/bass driver. This allows the tweeter to be mounted in a better optimised location. Sound quality is further enhanced by the fact that the tweeter no longer interferes with the output from the mid/bass driver. Additionally, external crossovers are used, which divide the full range signal into seperate low (bass) and high (treble) frequency signals, with these then fed to the mid/bass driver and tweeter respectively. This again improves efficiency of each driver, further improving the resultant output.
Subwoofers Subwoofers are designed with one sole purpose - to reproduce very low frequency sound (ie. bass). To get an overall balanced sound, most subwoofer systems will require around three times the power of the main system speakers. As a result, they use large magnets, bigger surface area, and have much higher excursion (vertical cone movement) than full range speakers. To function effectively, most subwoofers need to be mounted in a correctly sized enclosure.

Power Handling

Probably the biggest myth within the car audio field is that power handling equals volume, and that a speaker that handles more watts will always be louder. Generally speaking, this can lead to major problems including damage to speakers and/or amplifiers. A well matched system with a relatively conservative power rating can easily outperform a badly matched system utilising speakers with vast power handling.

As a general rule, the best speaker to choose is one with an RMS power figure just above the RMS power output of the amplifier (or head unit) it is being powered from. This helps to ensure that the speaker can handle the thermal demands placed on it by the amplifier.

Speakers with high power handling generally have a low sensitivity. When run from an under-sized amplifier, the end result tends to be disappointing. As a result, the user inevitably tries to force more power from the amplifier than it can safely deliver. As this happens, the DC content within the amplifier's output signal increases. The voice coil within the speaker is designed to handle AC current. As the level of DC increases, the thermal effects on the speaker's voice coil increase drastically, causing burn voice coils and melted coil coatings. Very often, this causes a drop in voice coil resistance, which can cause the amplifier to fail.