Amplifiers are classified by different class ratings (A, AB, D, etc.) and categorized by the number of channels they provide (mono, 2-, 4- etc). The class of an amplifier refers to the amplifier’s internal circuitry. Class A amplifiers have the highest sound quality, but are the least efficient and do not dissipate heat very effectively. Class AB amplifiers run more efficiently and dissipate heat better than Class A amplifiers. This is why Class AB amps are more reliable and produce lower distortion in comparison to Class A amps. In terms of the angle of flow for the input signal, Class A and Class AB amplifiers have analog designs, while Class D amplifiers have switching designs.
|Class D Amp|
Class D amplifiers are more efficient and produce less heat than Class AB amplifiers. While Class D amps are more susceptible to distortion than Class AB amps, this distortion is usually filtered out by the low-pass filter and is inaudible to the human ear. Mono amplifiers are single channel amps, but they can be used to power more than one subwoofer. Mono amps typically produce more power than multi-channel amps, which makes them ideal for powering subwoofers. Class D mono amps are the most efficient of all amplifier designs because they draw less current and as a result generate less heat in comparison to the classic mono amplifier design.
Multi-channel amplifiers come in the 2-channel, 4-channel, 5-channel, and 6-channel variety. 2-channel amps can power two subwoofers in stereo, or you can combine the channels (or “bridge” the amp) to create a single channel for powering one subwoofer. 2-channel amplifiers use class A/B circuitry, which is usually not stable at lower impedances. If you bridge a 2-channel amp down to 1-channel in order to get maximum power, it will be less stable. 2-Channel amps are commonly used in single cab trucks, 2-door coupes or any other vehicles that don’t have rear speakers.
A 4-channel amplifier can power four speakers, or you can bridge the channels to a 2-channel output for powering two subs. 2-channel and 4-channel amps are also used to power component speaker systems. You can power two sets of speakers from a 2-channel amplifier stable at 2 ohms. If you do so, this will make the amp more susceptible to overheating, and you will not be able to fade between the two sets of speakers. This is why a 4-channel is the optimal choice for powering 2 sets of speakers. Most 4-channel amps can bridge down to a 3-channel or 2-channel amp for more power out of the bridged channels. However, when bridged, the stability is decreased.
4- 5- and 6-channel amplifiers are used for systems with a combination of full-range speakers and subwoofers. For example, you could use a 4-channel amplifier to power a pair of speakers through two channels and bridge the remaining two for powering a single subwoofer. You can also run multiple two channel or mono amplifiers to power systems with numerous speakers. 5-Channel amps act like two amps in one. You get a 4-channel amp to power four door speakers and a monoblock amp to produce a higher power output for a subwoofer. These are great for any vehicles with limited space. 6-channel amps are rare, but they are used for marine applications or larges SUVs. 6-channel amps feature six low power speaker outputs to power 3 sets of speakers.