How to Connect a Powered Subwoofer to Passive Speakers

Adding powered subwoofers to an existing PA sound system with passive speakers is easier than you might think.

The are several ways to achieve this, but the easiest and more straightforward method of connecting a powered subwoofer to passive speakers is to take the audio signal from the main outs of the mixer, feed it into the powered subwoofer first, then use the internal crossover of the sub to feed the amplifier that powers the passive speakers.

So basically, the subwoofer sits between the mixer and the amplifier that feeds the passive speakers.

The advantage of using this method is that you can integrate a subwoofer into an existing system without needing to use Aux Sends, Subgroups, or external frequency crossover. And it only takes a couple of extra XLR or TRS cables.

In this post, I will show you a couple of ways you can use to connect a powered subwoofer to passive speakers. Best of all, you can do it in just a few minutes using a couple of cables. If you have powered speakers instead and want to add subwoofers, check out this article as I explain that process in detail. Let’s get started.

Two Simple Methods to Connect Powered Subwoofers to Passive Speakers

The first method is by having the powered subwoofer sit before the amplifier that powers the passive speakers. Basically, the signal from the mixer goes first to the sub, then continues its path to the amp.

The second method is by connecting the mixer to the amplifier first, then using the line-out of the amplifier to send the audio signal to the powered sub. Please note that this method only works if the amplifier that powers the passive speakers has a line out for each channel. If it doesn’t, you must use the first method.

Before we continue with the step-by-step process to make the connection using any of the two methods, there are a few things we need to know, which I explain in the following sections.

Getting to Know Your Subwoofer’s Input/Output Structure

If you look at the back of your active subwoofer, you will notice several XLR or XLR/TRS Combo connectors used to receive and send signals to and from the sub (Check the image below for your reference).

Active subwoofers have a built-in feature called a “Frequency Crossover.” A crossover, also labeled X-Over for short, is an electronic frequency-dividing network that splits a full-range audio signal into several bands, namely Highs, Mids, and Lows. 

The subwoofer takes on the low frequencies and sends out the Mid/High frequencies to be amplified by the full-range tops or passive speakers, as is the case in this article.

In other words, to add a subwoofer to an existing PA system that uses passive speakers and an amplifier, we need to take the signal coming straight from the mixer, split it up into lows, mids, and highs using the sub’s crossover network to feed the correct frequency to each component.

To simplify things and connect a powered subwoofer to passive speakers, we take advantage of the built-in crossover feature that the powered sub already has, minimizing complexity while getting excellent results.

Getting to Know Your Passive Speakers Amplifier’s Input/Output Structure

As mentioned previously, leveraging the amplifier’s line-outs is the second method we can also use to connect powered subs to an amplifier that powers passive speakers.

Basically, with this method, you would leave the connection the way it is. All you would have to do is to locate the line-outs on the amplifier, then run cables from there to the powered sub’s input.

This method is perfect if you have a sound system already installed in a fixed location, such as a church or an event hall.

To locate the line-out on the amplifier, look in the back, as they are usually found next to the input channel. They are labeled “Line Out,” “Link/Out,” or “Thru/Out,” depending on the manufacturer. See the image below for your reference.

Cables You Need to Make the Connection

To connect the mixer to the powered subwoofer, you need to use balanced TRS or XLR cables, depending on the type of connector your subwoofer uses.

Most subwoofers come with balanced XLR/TRS Combo connectors for the input and XLR for the output (output meaning going to the Tops or, in our case, going to the amplifier that powers the passive speakers).

Some brands only use XLR for the input and output. So before picking up cables to make your connection, always check your powered subwoofer to know what cables to use.

Always use a balanced XLR or TRS connection when going from your mixer to the subwoofer, as it helps to avoid noise in lines, thus delivering better audio quality.

If you don’t have these cables on hand and need to buy them, here are a couple of links to Amazon. You can choose the length according to your needs, but please check what type of connectors your subwoofer uses before buying:

• Balanced XLR Cable
• Balanced TRS Cable

Steps for Connecting a Powered Subwoofer to Passive Speakers

Now that you know the input/output structure of your powered subwoofer and amplifier and have the correct cables on hand, it is time to proceed with the connection. Here are the steps for both methods.

Method 1 – Subwoofer Before the Amplifier

1. Before starting, confirm that all your equipment is turned off and that all the volume knobs and faders are down. This is to avoid sudden loud pops that could potentially damage your equipment.
2. Set the subwoofers on stage or where you need them at the venue and plug them into the closest power source.
3. Locate the “Main Outs” or “Main Outputs” on your mixing console and plug the XLR or TRS cables, one to the left channel and one to the right channel. Note: the type of connector you use will depend on your subwoofer’s input connector type. 
4. Take the other side of the left channel cable and plug it into the left subwoofer’s input. Do the same for the right channel subwoofer.
5. Take another XLR-to-XLR cable and plug one side into the left subwoofer’s “High Pass Output.” Take the other side of the cable and plug it into the “amplifier input” that feeds the passive speakers. Repeat the same process to connect the right channel sub.
6. Connect the passive speakers to the amplifier.
7. At this point, turn all the equipment on and set the volumes and gains to a proper level to run a test.

Here is a diagram depicting the connections you need to make using method 1. Use it for your reference.

If you don’t like having a bunch of cables all over the place messing up your setup, did you know you could connect most of your PA system wirelessly? If it sounds interesting, check out this article as I explain the process of connecting your PA system Wirelessly in detail.

Method 2 – Using the Amplifier’s Line Outs

1. As always, I recommend turning off all the equipment before making any connections. Also, don’t forget to turn down all the volume knobs and faders. That way, you avoid sudden loud pops that could damage your equipment.
2. Connect your passive speakers to the amplifier. Then connect the mixer’s main outs to the amplifier’s input. Basically, you want to connect your passive speakers as you always do.
3. Set the subwoofers on stage or where you need them at the venue and plug them into the closest power source.
4. Locate the “Line Out” or “Link/Out” on the amplifier and plug an XLR or TRS cable into each channel. One to the left channel and one to the right channel. Note: The connector you use will depend on your amplifier line outs and the subwoofer input. 
5. Take the other side of the cable coming from the Line Out of the amplifier and plug it into the subwoofer’s input. Repeat the same process to connect the other sub if you have one.
6. At this point, turn all the equipment on and set the volumes and gains to a proper level to run a test.

PLEASE NOTE: Never connect the output of the amplifier (the side that connects to the speakers) to the sub’s input, as this will immediately damage both of your equipment. Make sure you are taking the line going to the subwoofer from the connector labeled “Line Out,” “Link/Out,” or “Thru/Out.” If you don’t see this on the back of your amplifier, next to or below the input connector, your amp doesn’t have this feature, and you can’t connect the powered subwoofer using this method. In that case, as mentioned previously, you need to use method 1.

Here is a diagram showing the connections you need to make when using method 2. Use it for your reference.

Final Thoughts

Now you know if you were wondering how to connect a powered subwoofer to passive speakers. And as you can see, it is an easy task. I hope this post was helpful to you.

There’s so much to know when it comes to mastering audio! For more audio engineering tips and tricks, check out the rest of our informative blog articles here.