In the journey to evaluate which amplifier to buy for your car audio systems, it is essential to determine as to how many channels should the amplifier have, and it still remains as one of the biggest factors in deciding the type of amplifier.

So, if you were specifically keen to look for an amplifier to power your subwoofers, more often than not, you would only need a single or what is popularly called as the “mono” channel – Class D amplifier, even in the case of multiple subs being run in concurrence.
We could achieve this application by wiring the voice coils of multiple subs together in a series or in a parallel configuration, which passes on a certain amount of load (in ohms) to the amplifier depending upon how the amplifier wiring is done, and the specific ohm rating of the voice coils in use (usually 2 ohm or 4 ohm).

 

The Wiring Conundrum

Here is an example of voice coil wiring configurations in series, as well, as in parallel:

 

 

So, while voice coils wiring is done, either in series or in parallel, each voice coil is rated at either a 2 ohm load or 4 ohm load, and, furthermore some subs have only one voice coil where-as, others have dual voice coils. Therefore, there are quite a few different wiring configurations possible. The most important aspect to remember, however, is that amplifier must be capable of running the ohm configuration (or the load) that it is presented to it.

 

For instance, many amplifiers are not even stable at 1 ohm, and, thus, they overheat if the subs wiring is done incorrectly.

 

Let’s look at 2-Channel Amplifiers
So, what about amplifiers with more than one channels? A significant proportion of 2 – 4 Channel amplifiers fall in the Class A/B Category and are designed for powering the front stage (i.e., mid-bass and the tweeters).

 

Here it is important to note that, Coaxial speakers combine the mid-bass and tweeter into one speaker, in which the tweeter is mounted in the Center above the woofer cone (as well as the crossover, which is basically a type of resistor).

 

Where-as, Component speakers separate the woofer and tweeter for an improved imaging and commonly include an external passive crossover network. Where-as, woofer and the tweeter are physically separated, external crossover gives the capability to employ one Amplifier channel for powering them instead of two. In majority of the cases, the component speaker systems will need only two Amplifier channels to empower all the four speakers.

 

When it comes down to deriving the most optimum sound quality, a great proportion of users utilize an active crossover system itself, which essentially means that every speaker has its own amplifier channel and, in that case, passive crossovers are not used, since each speaker channel is feeding into a Digital Sound Processor/Equalizer unit, which allows every speaker to be set to a particular crossover frequency as well as power configuration.

 

This implies that, if a component speaker set is being actively run, it would require four channels to operate for a two-way system and would require six channels for a three-way system. Also, interesting to note here that, some of the high-end passive crossovers are bi-amplifier capable, which allows to empower each speaker with their own amp channel and still using the passive crossover in-place of a dedicated Digital Sound Processor unit.

 

4 Channel Amplifiers: What For?

Another common-place situation is, to use 4 channel amp to run both the speakers and subwoofers. In this setup the amplifier is usually set into the bridged mode for the rear channels, where-in the front two channels are in charge of powering the front coaxial or the component speakers, and the two rear channels are bridged into a single, and more powerful channel to run subwoofer(s).

 

This can very well be a viable option for saving space as well as costs associated with running multiple amps for speakers as well as subwoofers. However, the downside to this is that, majority of 4 Ch Amps do not shell out power enough for larger subwoofer setups.

 

So, What About 5 Channels Then?

Basically, 5 Channel amplifiers could be an aggregation of amplifiers, for example, the two front and two rear channels as Class A/B to run mid-bass and tweeters, while the fifth channel can be its own Class D subwoofer amplifier.

 

5 Channel amplifier can be a viable option, if one wants to run four speakers instead of the two for the front stage, and, still providing an extra subwoofer channel.

So, again, this can help improve space efficiency and work as a cost saving measure, but like a 4-Channel amp in bridged mode, it would still not provide sufficing power for the large subwoofers. Here, Active crossover systems commonly take this a step further and utilize a separate amplifier for tweeters, mid-bass and the subwoofers. This gives a significantly higher and a more accurate ability for delivering the correct amount of power output to each type of speaker.

 

And, the Monoblock Amps

Monoblock amplifier is a single unit (“block”) in-control for boosting a single channel (“mono”). The inner parts of a monoblock amplifier amplify a single channel instead of being shared between multiple channels. Monoblocks, therefore, are bigger, bulkier and more expensive (per channel).

 

Simply put, monoblock amplifiers can be employed to boost any specific single channel of the audio system. Also, only a single monoblock amplifier is required if there’s only one audio channel (i.e., a mono signal).

 

Monoblock amplifiers are particularly of use when driving subwoofers, that said, a monoblock amplifier can power multiple subwoofers as well, if the need be (wired in series or parallel configuration, depending on the level of impedance the bridging needs).

 

Monoblocks usually have 2 or more sets of terminals, and these terminals are labelled by polarity, either positive (+) or negative (–). If you chance to notice two side-by-side + terminals and two side-by-side – terminals, it simply implies that the amplifier could easily connect two speakers (in parallel).

 

How All This Is Powered?

Amplifiers are supplied power by your four-wheelers alternator and depending on how many amplifiers, the alternator powers, one may need to upgrade to a higher config. alternator.
Addition or upgradation of batteries is also helpful as well, however, if alternator amperage is not sufficient enough to charge batteries, enough power is simply not going be available from the alternators.

With all of these different options and different amplifiers available, it can be confusing enough to determine which one to go for. Typically price and warranty are the main factors in decision making, but one should also factor in how much space is required to be dedicated for the audio equipment inside the vehicle.