What Type Of Amplifier Do I Need For A Subwoofer

Norvan Martin
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So you have a subwoofer and you are wondering the type of amplifier would be most ideal for it?

Coming up with an ideal sound system could be a nightmare if you are not sure what system specifications you need.

However, getting a successful match between the amplifier and subwoofer seamlessly solves the puzzle.

Follow this guide to get the most simplified approach to selecting the right amplifier for your subwoofer for improved sound quality.

Power Matching Subwoofers and Amplifiers

If you want an amplifier that matches your subwoofer unit or vice versa, you need to get their specifications correctly matched. And with that, yes, you can solve the puzzle.

In this article, we will cover the key power-matching basics, planning for subs, and impedance matching.

You Have Subwoofers, Which Amplifier Do You Need?

If you have more than one subwoofer unit, you can consider wiring them together. However, you must check that they have similar coil types and have the same impedance rating. If they have different coil types, each sub will draw different amounts of power.

As a result, some subs will get underpowered while others will be overpowered. It is therefore recommended that each subwoofer is connected to its own amplifier for better sound quality.

Here’s the step-by-step guide to identifying the right amplifier for a subwoofer.

Step 1: Find Out The Power Rating Of Your Subwoofer

Generally, subs feature two power handling metrics – Root Mean Square (RMS) watts also known as continuous power handling, and Peak power handling (peak watts).

While the peak wattage of a subwoofer refers to the maximum amount of power the woofer can withstand without damage, RMS or continuous power handling is the amount of power it can handle on a continuous or regular basis.

amplifier power ratings

If you want the best sound quality, it is recommended that you match the RMS watts of the sub with that of the amp. Usually, RMS watts for amplifiers on the market will be indicated as a range of values within which the amp can be operated. Check the back of the amp for power ratings.

Once this is established, always keep the subwoofer at 75% minimum and 150% maximum RMS watt. If you are connecting more than one similar sub, calculate the total RMS watt by multiplying individual RMS watts by the number of subs available.

The amp you pick should therefore be able to supply between 75% to 150% of the total RMS rating of the combined subs.

Step 2: Matching Impedance

Impedance is a measure of electrical resistance. The most common types of subwoofers on the market are 2 ohms or 4 ohms rated.

Amplifier impedance rating

The above is the QSC RMX 2450 Power Amplifier which is a two-channel amplifier meaning it has two independent channels that can be used to power two separate audio sources. Each channel provides a power output of 450 watts into 8 ohms, 650 watts into 4 ohms, or 1200 watts into 2 ohms.

As opposed to matching RMS watts, matching impedance is much easier, especially with one or two subs. Always ensure subs are of similar impedance before wiring them together.

Step 3: Select Your Amplifier And Subwoofer

Generally, subwoofers are of two different types – dual voice coil (DVC) or single voice coil (SVC).

The DVC has two sets of terminals while the SVC has only one set of terminals. DVCs, therefore, have the advantage of more wiring options and are designed for greater power handling and higher performance. You can select any one of the two available options depending on your needs.

On the other hand, when selecting amps, it is more important to assess the amount of power your subs require.

Once you decide on the amount of power or the number of subs required, it is much easier to select the right amp. The two main amplifier systems available are single-channel amps (Mono) and 2-channel amps.

Mono amps are the best in the market because they produce the best base sound and can process a single audio signal with just one channel on the sub. Besides, many subs can be easily wired to mono channel amps and every sub still gets the same sound frequency.

Step 4: Matching The Amp With The Subwoofer

To enjoy an amazing bass, you should consider some of the combinations below:

1. One Single-Channel 4-Ohm Voice Coil Sub

Single-channel subwoofers are the most common type and are preferred because they are cheaper, simple, and more compatible with other systems. Moreover, if you bridge the output of the amp, you are more likely to get much more power.

Choosing The Right Amp For Single-Channel 4-Ohm Voice Coil Subs

A single channel 4-ohm subwoofer is best paired with a 2-channel amp. Bridge the output of the amplifier and you will enjoy amazing bass at a cheaper cost.

Avoid using mono amps with the single-channel sub because they are designed to give better performance at impedance levels lower than 4 ohms.

2. One Single-Channel 4-Ohm Dual Voice Coil Sub

This type of sub is much more flexible and has greater performance and power-handling abilities.

They have greater compactness and perform heavy-duty power handling. They are therefore a perfect match for mono amplifiers because mono amps have features that help deliver more power at impedance levels as low as 2 ohms.

Choosing The Right Amp For Single-Channel 4-Ohm Dual Voice Coil Subs

With a single-channel 4-ohm dual voice coil subwoofer in your store, you need a mono amplifier.

This is because mono amps are designed to deliver the greatest power at lower impedances, usually around 2 ohms.

Wire the dual voice coil sub in parallel with the amp to obtain a resultant impedance of 2 ohms to the amp.

3. Two 4-Ohm Single Voice Coil Subs

If you have two subs, we are talking about big bass. As mentioned with the single 4-ohm single voice coil subs, wire the two subs in parallel to output a 2-ohm impedance. The low impedance is most effectively used with a mono amp for maximum power output.

4. Two 4-Ohm Dual Voice Coil Subs

Having a dual voice coil sub will make you a sound master. With increased wiring flexibility, you will need a 2-channel amp. Bridge the amp to get a 4-ohm output for maximum power delivery to your set of dual voice coil subs.

Why Do Subwoofers Need An Amp?

The function of subwoofers is to enhance sounds with lower frequencies, and this function demands a significant amount of power.

Active subwoofers, which are usually designed as a part of much bigger sound systems, are calibrated optimally to function with the rest of the setup without causing any distortions due to insufficient power.

However, independent and separate subwoofers (also known as passive subwoofers) pose a risk of overpowering the receivers and general setup of the whole sound system.

How Do I Know What Size Amp I Need?

In general, you should choose an amplifier that can output power equivalent to double the program/continuous power rating of the speaker.

This indicates that an amplifier capable of producing 700 watts into an 8-ohm load is required for a speaker with a “nominal impedance” of 8 ohms and a program rating of 350 watts.

What Hits Harder 2ohm Or 4ohm?

Subwoofers equipped with low electrical resistance are able to transmit a louder sound than those with higher electrical resistance, which means that 2ohm subwoofers are much louder than 4ohm ones.

Can An Amp Be Too Powerful For A Speaker?

Yes. It is possible for Amplifiers to be excessively strong for speakers. There is a peak amount of electricity that speakers can convert into sound, and so in general, if the amplifier produces more electrical energy than the speakers can handle, distortion may occur, but the damage is rare.

Final Thoughts

When buying amplifiers and subwoofers, it is recommended that their specifications match those of your subwoofers.

The power handling capabilities and impedance of the amplifier and those of the subwoofer must therefore be matched.

Although most people tend to buy amps and subs separately, it’s best to get these devices at the same so you can easily match them.

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Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics. My email: [email protected]  Connect on Pinterest and Linkedin