# Subwoofer Amplifier Calculator (with Practical Examples)

A question that comes up often is

What amplifier should I use with my subwoofer? ????

⚙ We created a tool to answer this question.

It gives you the specifications for an amp that will work with your subwoofer. The tool can be used to select the size and specifications of an amplifier for an existing set of subs or an entirely new system.

## How to use the calculator

• Enter the impedance in ohm (Ω) and the wattage (W) of each sub.
• Select the configuration – Series or Parallel.
• The tool will provide
• Total Effective Impedance of the subs
• Total Subwoofer Wattage
• Required Amplifier Wattage range (min and max)
• Required Amplifier Impedance
• Refer to the amplifier data sheet to ensure that it is able to provide the RMS (root-mean-square) power at the specified impedance level.

## Example Calculation

Let’s use the following subwoofer from Sklar as an example. It has an RMS power rating of 1000 W and impedance of 2 ohm.

This is a Dual Voltage Coil subwoofer. And depending on how it is wired (see the picture below), the effective impedance is either 1 ohm or 4 ohm.

Assume it’s wired to give an effective impedance of 4 ohm, and two of these are used in parallel. In this case, the total effective resistance is 2 Ω.

Using the calculator, the recommended amplifier wattage is between 1800 W and 2400 W and the impedance should match the impedance of the sub at 2 Ω.

????The amplifier’s output impedance should not exceed this value otherwise there’s a risk that the speaker will draw more current and damage the amp.

The highlighted amplifier RP-3500.1D would be the most appropriate selection in this case. The specification of this amp is 2300 W at 2 Ω.

⚡ Subwoofers are designed to handle a certain amount of power as indicated by the Watt rating in the product table above. If the amp provides too much power, it can cause the voice coil in the sub to overheat and possibly even burn out. The risk to damage is higher if the subwoofer enclosure is not properly ventilated, as the excess heat can quickly build up inside.

## Background

### What is a subwoofer?

A sub woofer is a type of audio speaker that can produce low-frequency sound waves, also known as bass. The frequency range of a subwoofer is between 20 Hz and 200 Hz. Certain types of music such as House and Rap benefit from a boost in performance at these low frequencies.

Here is a picture of a car fitted with subwoofers

### Does a Subwoofer need an amplifier?

A subwoofer is a speaker and like any other speaker it converts electrical output from a playback device like a CD player, turntable or phone to an audio signal.

The subwoofer itself consists of a magnet, voice coil and diaphragm shown in the picture below. An amplified electrical signal is required at the input.

Many subwoofers like the one in the picture below do not require an amplifier at the input as they have one built-in. If a subwoofer needs to be plugged into the wall, it has an amplifier inside.

The subwoofer shown in the picture below on the other hand, does not have an amp inside. The calculator on this page can be used to find a suitable amp.

### What is a Subwoofer Amplifier?

A subwoofer amplifier is specifically designed to enhance performance by providing additional power and clarity. It enables the subwoofer to produce deep bass sounds at high volumes without distortion. As a result the amp has to boost signals in the range of 20 Hz and 200 Hz.

### Can I run a high power sub with a low power amp?

While it’s possible, we do not recommend it. Reason being that as the volume is increased, the amplifier can start clipping. Clipping is essentially distortion to the analog signal that occurs as the amplifier is pushed to its limit. The picture below shows a clipped sine wave.

This is for a single sine wave. An audio signal consists of multiple sine waves that are added together across a wide frequency range. In the frequency domain, this looks like a number of spurious peaks*. These extra peaks can damage the subwoofer. Hence it is not a good idea to use a low power amp with a high power subwoofer.

*The square wave harmonics calculator shows the magnitude of the harmonics – essentially this is what is created when clipping occurs.

### Can I use a 500 Watt Amp with a 1000 Watt Sub?

As mentioned, we do not recommend using a lower wattage amp with a higher wattage sub. Increasing the volume on the amplifier will cause output saturation and clipping. This will damage the sub.

For a 1000 W sub we recommend using an amp with output power between 900 Watt and 1200 Watt (using the calculator on this page). Another important consideration is that the impedance should be matched. If the power rating of the amp is 900 Watt at 2 ohm, make sure that the sub impedance is 2 ohm.

### Can I use a high power amplifier with a low power subwoofer?

Yes a high power amp can be used with a sub having lower power. The precaution here is not to crank up the volume very high as you will damage the subwoofer. Although it’s more likely that you will damage your hearing before the sub.