Setting up a sound system is not a wham-bam-thank-you-ma’am process. Typically, there are different steps and components to use in the setup from start to finish. If you are not familiar with each component and what it does, you may feel overwhelmed. Even for someone with experience with a sound system, it may be a little confusing knowing how to connect one component to another.
What is an Active Subwoofer?
An active subwoofer is a powered subwoofer. That means the subwoofer already has its power source. More times than not, the power source is a built-in amplifier. So, there is no need to connect it to an external amplifier. You simply connect the subwoofer to a power source, and you are good to go.
An active subwoofer does not usually need an amplifier for increased sound output. However, you may want to connect it to an amplifier to transmit data. In such a situation, you can use an RCA cable.
Another reason you may need to make this connection is if you need to work with a set of passive speakers. The amplifier built into the subwoofer works only for the subwoofer. Thus, it cannot work with the speakers. Only an external amplifier will power the speakers. Therefore, you need to connect it using an RCA cable to the subwoofer. However, the subwoofer will work well without an amplifier because it is already active.
Matching a Subwoofer to an Amplifier
It is important to get a suitable amplifier for an active subwoofer to improve the sound output. Check your subwoofer’s specifications and make an amplifier choice based on them.
● Check the Impedance
The impedance is the load that the subwoofer will transfer onto the amplifier. You’ll usually find it in the back of a speaker and listed in ohms. The power that an amplifier puts out will depend on the load it carries. So, if the numbers on the subwoofer and amplifier do not match, the results will not be satisfactory.
● Check the Power Output
Root Mean Square or RMS watts is a speaker’s power output measurement. The RMS of a subwoofer is the power it can comfortably carry without distorting its sound output. The RMS on an amplifier is the power it can comfortably deliver without causing any damage.
The ideal amplifier should be able to deliver 75% to 150% of the RMS watts of your subwoofer. Additionally, ensure it is up to the task according to the subwoofer’s impedance when you find one.
How to Use an Active Subwoofer
To use an active subwoofer, make sure you connect it to a power source. Also, ensure that you connect it using a surge protector. Subwoofers do not come cheap, so you may want to protect yours from sudden power surges.
Connect the receiver to the subwoofer’s LFE using the provided cable. Ensure the cable goes into the input hub on the subwoofer from the output hub on the receiver. However, if the subwoofer is not LFE-enabled, directly connect it to the main speakers. First, connect the receiver’s output to the subwoofer to do it. After that, make a connection between the subwoofer and the speakers.
Now, if the speakers can adjust, set their volume low. That way, you route low-frequency sounds to the subwoofer for better output. Then, find the lowest frequency at which the subwoofer can cleanly produce sound and set the crossover 10 Hz above that.
At this point, locate the switch that controls the speakers’ phase. Typically, it ranges between 0 and 180. Put on a movie or some music to find the correct setting and use deep bass. Next, turn the switch until you find the suitable setting for your speakers. Finally, adjust the volume to your preferred level.
When to Use an External Amplifier with a Subwoofer
Only a passive subwoofer needs an amplifier since it does not have an amplifier built into it. Thus, its sound output will need a boost if you want to get the best out of it. That is where an amplifier comes in.
If you need to connect a subwoofer to an amplifier, there are three ways to try it. The first is through an RCA cable. The second is through the LFE subwoofer output. The third is a connection made through the amplifier’s speaker output.
● Using RCA Cables
Take a look at the line-in and out on the subwoofer. If both use RCA, get an RCA cable and make the connection. The cable may have split ends, and if it does, you will find right and left ports into which the split ends should go. So, plug the ends into the corresponding ports. Also, check the amplifier for right and left RCA plugs tailored for the subwoofer output. Make the connection as needed if you find the plugs.
● Using LFE Subwoofer Output
This method is perhaps the preferred method for connecting a subwoofer to an amplifier. Examine the amplifier to see if it has a subwoofer output. Get a low-frequency effect or LFE cable and make the connection if it does. Plug the cable into the port labeled “subwoofer out” because you may not find a specific port labeled LFE.
● Making the Connection through the Amplifier’s Speaker Output
Hook the connection up using its speaker output if the amplifier has spring clips. Follow the same steps as when connecting a stereo speaker, but keep an eye on the channels. Sometimes, you will find two spring clip sets on the subwoofer, one for the “speaker out” and the other for the “speaker in.” Other times, you will find only one spring clip set.
Two spring clip sets mean there is room for other speakers to connect to the subwoofer. On the other hand, one spring clip set speakers and subwoofers will share the same receiver connections. It is pretty easy to make this connection, especially if you know your way around sound systems.
Choose the Best Location for Your Subwoofer
Consider a few factors if you aim to connect an amplifier to an active subwoofer to make the sound louder. The external amplifier may not improve the sound the way you want, and the problem may stem from your subwoofer placement.
The part of a house or room where you place the subwoofer will make or mar the sound. Putting it in a room corner will improve the sound and make a difference. If you have a small subwoofer, keep it about four feet away from the main speakers. The same does not apply to a large subwoofer; just ensure you do not put it in an enclosed space.
Keep the subwoofer a third of the way from the surrounding walls. Keeping it too close to walls will cause it to produce distorted sounds and annoying vibrations. On the other hand, setting it right in the middle of the room reduces the feel of the sound it makes.
After correctly positioning the subwoofer, place your furniture in such a way that you get the most out of it. It is easier to move your favorite chair around the sub rather than the other way around. You can choose to move to different corners of the room and listen as the subwoofer works to feel its output. When you find the right spot, move the sub as close to it as possible without disconnecting anything.
Other Factors to Consider
Also, there may be materials in the house which absorb the sound and lower the output. Remove such materials for better sound output. If you are unsure what they are, try researching sound-absorbent materials.
Additionally, check the subwoofer configuration to ensure you set the specifications and crossover controls to maximum frequency. Poor configuration can inhibit the sound output and make it seem like the subwoofer is underperforming.
If all else fails, consider incorporating another subwoofer into the sound system. Depending on your specific needs, you can choose one with a lower sound capacity. While one subwoofer is usually enough for most sound systems, double subwoofers are becoming a thing. Dual subs make for better and more sophisticated sound output.
Connecting an active subwoofer to an amplifier is one of the most straightforward tasks to perform. It is not rocket science, and you will be able to set it up in no time. Simply get RCA cables and connect the subwoofer to the amplifier. Then, connect the subwoofer to a wall outlet to power it.
Remember that we call them active subwoofers because they already have built-in amplifiers. Therefore, there is usually no need to use an amplifier on your subwoofer unless you want to transmit data, improve the sound output, or have a set of passive speakers you need to activate.
Additionally, the location can significantly affect the sound output of your subwoofer. Thus, before you think that your subwoofer is not giving the best output, consider checking its location first.
Every type of amplifier will not work with your subwoofer. In such a case, choose an amplifier based on the subwoofer’s specifications. Take time to do your research and check for compatibility. If you are unsure what to do, ask for help from the nearest appliance store.
John Fleming is the senior editor for Audiophilez.com, covering everything from headphones to smart speakers. He is a graduate of Music Production and Technology. Before Audiophilez, John began his career as a staff writer for two different magazines, where he became a skilled storyteller across different mediums. When he isn’t writing, he can be found biking, reading books, and playing the piano.