Confusion and debates around amps, watts, and ohms have been around ever since people started putting subwoofers in their cars. One of the questions that you often ask when you want to build an audio system is whether to use a 2ohm speaker or a 4ohm speaker. Well, when connecting a speaker to the amplifier, the ideal norm is to match the impedance of the speaker with the output rating of the amplifier. The best sound is produced only when the speaker has matching impedance with the amplifier’s output rating. However, watts and ohms have to go through a series of math formulas that link the two intimately so that, if one undergoes a change, the other changes, too.
Hence, the question is still there. Should you design something for a 2ohm speaker or a 4ohm speaker? In the following article, we will see the comparisons between 2ohm speakers and 4ohm speakers.
Overview: How They All Work
An amplifier provides the electrical pressure in a circuit. The watts measure how much power that is released by the amplifier as work, whereas the ohms measure the resistance against the electrical pressure. Using one of the math formulas, we can calculate that an amp that delivers 100 watts power through a 4ohm speaker would produce 200 watts power if matched with a 2ohm speaker.
At the core of every speaker is a voice coil; that’s a device that puts the electrical resistance and performs the work. Meanwhile, the amplifier is the one that provides the power. The resisting property of the coil is called impedance, which is measured in ohms.As a note, the terms ‘resistance’ and ‘impedance’ are sometimes interchangeable (the two are not the same, but ‘resistance’ is usually used to generalize ‘impedance’).The lower the speaker’s impedance, the easier it is for the amp to supply power. However, problems arise when the resistance/impedance is too low, leading to the amp producing a higher output. If the amp continuously puts out more power than the intended level, the amp may overheat, and then, hopefully, the amp will be shutting down instead of burning up.
In other words, the capability of the amp has to be considered first before you apply any load to it by hooking up a speaker. Usually, the specs of the amp include the information regarding the amp’s minimum impedance requirement. Nearly all amps nowadays can drive a 4ohm speaker. Most amps can work with 2ohm speakers on each channel, but not if the channels are bridged. There are some amps that can drive 1ohm speakers.
So, if you have already checked your amp’s specifications and it is actually able to run both 2ohm and 4ohm speakers, you may ask yourself whether you should match it with a 2ohm speaker/subwoofer or a 4ohm speaker/subwoofer.
Depending on the size of the speaker or subwoofer and the brand, a 2ohm speaker / subwoofer can be priced between $50 and up to $200. As explained above, when talking about ohms, it indicates the amount of resistance that the speaker would provide to the electrical pressure produced by the amp. A lower impedance level means less resistance. Hence, the output higher will be higher. Generally a speaker with a low impedance level would produce loud, powerful sound. Even so, this does not necessarily mean that the sound quality is better. In fact, it is usually the contrary; a louder sound that is created due to a low resistance level usually has a low sound quality. This is because the sound waves become less defined and less accurate, causing some loss of details.
4ohm Speaker / Subwoofer
A 4ohm speaker / subwoofer is usually priced between $20 up to $180. Compared to a 2ohm speaker / subwoofer, a 4ohm speaker / subwoofer would produce a less loud sound due to the higher electrical resistance. That is not necessarily a bad thing, unless you are going to install an audio system for a particularly large room. Interestingly, a 4ohm speaker / subwoofer generally produce better sound quality than a 2ohm speaker / subwoofer. This is because, with more resistance, the sound waves become more compact, more defined, and thus more accurate. However, very fine sounds may get loss in the mix because they are produced with lower volume levels.
2ohm vs. 4ohm Speakers / Subwoofers
We have seen above the differences between 2ohm and 4ohm speakers / subwoofers. Technically, the two kinds only differ in resistance levels, output levels, and thus loudness and sensitivity levels. However, how significant are those differences?
The loudness and sensitivity levels can be measured in dB. The calculations are rather complex, so let’s go straight to the real numbers. Let’s say that you have a 2ohm subwoofer. At 2.83 watts, it can produce 93 dB sounds. How about a 4ohm subwoofer? At the same wattage, the subwoofer will produce 90.5 dB sounds. The difference of just 2.5 dB is hardly noticeable, unless you are quite an audiophile.
For the sensitivity, let’s say that the 2ohm subwoofer at 1 watt is giving 86.4 dB sensitivity. How about the 4ohm subwoofer? At 1 watt, it would be giving 86.6 sensitivity. The 4ohm speaker is technically producing a better sound quality than the 2ohm speaker, but the 0.2 dB difference is hardly noticeable at all.
As you can see, the differences between 2ohm and 4ohm loads are not very significant. A 2ohm speaker would produce slightly louder sounds, but the increase is very marginal. A 4ohm speaker would have better sensitivity, but the difference is hardly noticeable at all. It is much more important to match your speaker impedance with the amp’s requirements.
|- Lower electrical resistance||- Higher electrical resistance|
|- Causes the amp to produce higher watts||- Causes the amp to produce lower watts|
|- Delivers a louder sound than 4ohm at the same wattage||- Delivers a softer sound than 2ohm at the same wattage|
|- Delivers a somewhat poorer sound quality||- Delivers a somewhat better sound quality|
In general, 2ohm speakers / subwoofers would produce slightly louder sounds and somewhat poorer audio quality due to the lower impedance. 4ohm speakers / subwoofers would produce slightly softer sounds and somewhat better audio quality due to the higher impedance. However, it is much more important to match the speaker’s impedance with the amp to avoid potential overheating problems.