Subwoofer High Level Inputs vs RCA Inputs (Explanation)

What do all the inputs, outputs, and switches on the back panel of your subwoofer mean? At the first glance, anyone can tell that high-level inputs and RCA inputs are two completely different things found on virtually all subwoofers. But what’s the difference?

The difference between high-level inputs and RCA is the path an audio signal follows through each input. High-level inputs transport audio signals from the amplifier’s speaker connection to the subwoofer. Subwoofer RCA inputs take low-voltage audio signals from the amplifier to the subwoofer.

Subwoofer High Level Inputs vs RCA Inputs

If you’re new to the world of audio equipment, buckle up. Audio terms can get really messy, and the last thing you need right now is to plug your audio cable into the wrong input. In this article, I’ll explain the few notable characteristics of and differences between high-level and RCA inputs.

Also read: Subwoofer Line Level vs. Speaker Level (Simple Guide)

Subwoofer High Level Inputs vs RCA – Key Differences

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The differences between subwoofer high-level inputs and RCA can be seen right from the nature of the connector. High-level connectors have a series of speaker wires going into a multi-pin harness. An RCA input has a color-coded circular hole with a metal lining on the inside of the hole.

One RCA input accepts a single RCA connector, while a high-level input takes in multiple speaker wires on a single connector. That’s just about it in the physical description.

In terms of functionality, subwoofer high-level inputs transport an audio signal from the receiver/amp to the subwoofer through a speaker-level connection at the back of the sub. RCA inputs transport an audio signal from the receiver/amp low-level outputs to the RCA inputs at the back of the sub.

Is RCA High or Low Level Input?

Amplifiers and AV receivers use RCA to send audio signals to the amplifier or subwoofer through the preamp outputs. High-level inputs can also work in place of RCA if the receiver is an old model without RCA. Although the results vary in quality, here’s the truth about the red and white RCA inputs on your subwoofer:

RCA is a low-level input. RCA carries low-voltage audio signals ranging between 2V to 5V, a line-level signal that is yet to be amplified. At this stage, the line-level signal isn’t powerful enough to drive a speaker. It needs amplification for your speakers to produce audible sound.

You risk melting the wires if you pass a 10V speaker-level signal through your RCA. This further implies that RCA is indeed a low-level input.

Most modern-day subwoofers come with both high-level and RCA inputs. However, others only have one type of input — either a high-level or RCA input. This would’ve been a problem a few years back because RCA wasn’t so popular. But today, most subwoofers have a few RCA inputs at the very least.

Note: Some subs have RCA inputs labeled as “LFE.”

What Is High Level Output on Subwoofer?

We all love subwoofers because they are the foundation upon which our audio systems are built. Without a subwoofer in your entertainment setup, the rich, rumbling bass effects from your favorite movie would never come to life.

Sound already makes up half the experience. But to get any sound from your speakers, you must have plugged in the correct cables to the correct inputs.

A high-level output on a subwoofer is a connector that connects the speakers to your subwoofer. The high-level output on your subwoofer sends the processed and amplified signal directly to the speakers. Its voltage is powerful enough to drive your speakers.

In simpler terms, a high-level output is where you connect your speakers to the subwoofer’s rear panel. High-level speaker outputs are always color-coded in red and white.

Don’t mistake the speaker-level outputs for speaker-level inputs. Standard high-level outputs take the signal from your sub to the speakers. On the other hand, high-level inputs take the signal from your receiver/amp, through the speaker-level connection, and into the subwoofer.

These inputs also come in color-coded pairs. Red for positive and black for negative. You can use them to connect an amplifier to a radio/amp/receiver without RCA outputs.

High-level outputs aren’t only restricted to subwoofers. You may find them on your after-market amplifier, in which case you could run speaker wires directly from the amp to the speakers.

If you happen to have an amp without RCA outputs, you might as well hook it up to a subwoofer through its high-level connections and some speaker cables and still get the speakers to play some decent quality audio.

It’s always a good practice to check the inputs and outputs on the sub or amp you are buying to avoid the unnecessary cost of replacing some parts of your audio system or purchasing new sets of wires.

Why Do Subwoofers Have 2 RCA Inputs?

If you take a close look at the back of your subwoofer, you’ll notice that it has not one but two RCA inputs and outputs. Your first guess would be that these two inputs are for the right and left channels. That’s true because they are labeled R & L, standing for right and left. However, there’s more to it.

Subwoofers have 2 RCA inputs to split the signal for the left and right channels. Originally, RCA cables were designed for single-channel systems until stereo came into existence. The RCA inputs take in an audio signal from your AV receiver, amplify it, and feed it to the left and right channels.

Generally, subwoofer RCA inputs are a common type of connector used to hook up audio devices to power amplifiers. Two inputs on your sub exist to capture the incoming L + R content into the sub for a two-channel setup.

Most subwoofers come with two inputs because the audio frequencies are mixed for the left and right channels. Theoretically speaking, using only one input would mean that only one side of the channel will work. Practically, that’s not true. You can still use one input and get the subwoofer and the speakers to work.

One last thing: your sub’s left and right channels can also be used for your surround sound systems. If one input gets damaged, you can still use the other. The only problem with this type of connection is that the volume output will be much lower when using one input than using both.

Final Thoughts

The next time you’re shopping for a subwoofer, remember to check what kind of inputs there are on the back. It may not seem like much at first, but blindly dealing with the wrong connections could damage your speakers, amp, and other connected equipment.

Always check what inputs and outputs are at the back of the sub to avoid buying new wires, devices, and adapters.


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