Adding a subwoofer to your home or car sound system is a great way to get the low-end deep bass that makes your music more immersive. But before you can plug a subwoofer into your amplifier, you need to know how to connect it properly.
Powered (Active) Subwoofers Do Not Need an Amp
A powered subwoofer, also called an active subwoofer, does not need an external amplifier because it has a built-in amp that provides the necessary power for it to work. However, you may still need to connect it to your amplifier for data transmission purposes (such as pairing passive speakers).
If you’re connecting a powered subwoofer, you’ll need RCA cables and a wall outlet for the powered sub’s power source. It’s also a good idea to use a line level RCA converter to scale down the speaker signals to a lower level that the internal amplifier can use. This way, you can get the same sound quality from your speakers and subwoofer as you would from an off-the-shelf RCA converter.
High-Level Inputs and Outputs
When you connect a subwoofer to your amplifier using its high-level inputs, it is able to see the same signal as your speakers, so there will be no time lag between the subwoofer and the speakers. This is important because it helps the audio from the subwoofer and your speakers to be more coherent.
But if you connect the subwoofer to an RCA output, it won’t be able to see the same signal as your amp, so there will be a small delay between the subwoofer and your speakers. This lag is very slight, but it’s enough to notice when you’re listening back-to-back with your subwoofer and your speakers.
For this reason, it is best to connect your subwoofer to the RCA outputs of your receiver or amp in parallel. This is because the subwoofer inputs and outputs are on different terminals, so it will be better to connect them in parallel: positive RCA speaker inputs to positive RCA speaker outputs and negative RCA speaker inputs to negative RCA speaker outputs.
You’ll need to read the label on your receiver or amplifier carefully so you can determine which jacks it has for its subwoofer outputs. This will help you decide which of the following methods to use:
A low-level subwoofer connection is a type of connection that uses RCA interconnect pairs, which can be used with any amp or receiver. The most common use for this type of connection is with AV receivers, but you can also connect it to any stereo amp with left and right pre-out connections or to a dedicated sub out port.
The exact type of cable to use is going to depend on the brand and model of your amplifier and subwoofer, but it usually includes a pair of speaker wires or RCA interconnects. You can also buy specifically designed subwoofer cables, but those are not essential to this process.