Most people only look at the sizes and output power of different models when choosing a new sub for themselves.
While this approach isn’t entirely wrong, subwoofers are much more complex than this and you also have to look at other specs such as wattage, single/dual voice coil, and impedance.
If we talk about impedance, there are two common types of subwoofers: 2-Ohm and 4-Ohm subwoofers.
Below we will analyze how these two types of subs are, how they are different form each other and which one you should choose for your vehicle.
First one are the 2-Ohm subwoofers. As their name suggests, they come with 2-Ohm impedance.
For those who don’t know, impedance refers to the load speaker(s) puts on an amplifier. In other words, impedance is the resistance which resists the flow of current that is required to power a speaker.
Since the SI unit of resistance is Ohm, it’s also used to measure the impedance. Lesser impedance generally indicates that your sub needs low amount of power to produce sound.
Up next we have 4-Ohm subs that come with 4 ohms of impedance. It means the power will face more resistance for these subs to work. They come with a bigger voice cil that has more winding turns which makes them slightly heavier than their 2-Ohm siblings.
2-Ohm vs 4-Ohm Subwoofers
Since 2-Ohm subs have lower resistance, they’re easier to be powered and can produce relatively more sound output than ones with 4-Ohms at any given wattage.
4-Ohm subs generally produce lower-volume sound as they come with more resistance, but the bass they offer is of higher quality (thanks to extra winding)
A big drawback of low-impedance subs is that can they can draw a lot of power from your amplifier. While this is not a big issue most of the times, it can cause amps to overheat, blow fuse, or go into protect mode in some cases.
On the other hand, 4-Ohm subs don’t draw as much power from the amp as 1-Ohm or 2-Ohm subs which results in their comparatively longer lifespan.
2-Ohm subs are generally costlier than 4-Ohm subs but it also depends on the brand and the build quality of any individual subwoofer.
What to do if You Have Multiple Subwoofers
In case you have multiple subs, the total resistance will depend on the wiring option you choose.
In series wiring, you will wire one subwoofer after the other in a series. It means the total resistance will be the sum of both their resistances. So if you have two subwoofers of 2-Ohm resistance, the total resistance in series wiring will be 4 Ohms.
In parallel wiring, however, the total resistance is determined by dividing the resistance of any individual subwoofer (given both have same resistance) by the total number of subs you have installed at that time. So, for example, if you have two subwoofers with each having two-Ohm resistance, the total resistance in parallel wiring will be one Ohm (2/2=1).
To go with a 2-Ohm or 4-Ohm subwoofer will depend on how you want your sub(s) to perform. If loud sound is your first priority, then 2-Ohm sub(s) will be good for you.
But if you care more about accuracy than volume, then a 4-Ohm sub will suit your better.