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Sub Out vs LFE – All You Need To Know

Setting up a home theater can be one of the most confusing and complicated activities you will have to do in your home. Planning your speaker array, running cables, and keeping everything plugged into the right ports can be enough to make your head spin. But, the benefits outweigh the frustrations.

So, when it comes to the subwoofer connection, I wanted to help you out with some specific tips. Particularly, I want to explain the difference between Sub Out vs LFE and when to use each one.

Because, no matter what you’ve heard, Sub Out and LFE are different and do different things for your home theater.

Sub Out vs LFE

What is a Subwoofer?

Let’s start with this. The average human ear can hear frequencies as low as 20Hz and as high as 20,000Hz (or 20 kHz). Anything lower than 20Hz is getting into the range of whales and elephants, and our ears just aren’t designed to detect these sounds.

We can still feel them in our bodies, however. When that bass booms and it makes your chest shake, you’re feeling sound waves around 20Hz or even lower.

What does it do?

The subwoofer on your home entertainment center is a big, powerful speaker used to produce bass sounds. These are often in the range of 20Hz up to 80, 100, or even 120Hz. Higher frequency sounds are directed to your woofers, and the highest sounds to your tweeters by the crossover in your receiver or amplifier.

The lowest sounds in music and movies get filtered to your subwoofer. It can make them boom without muddying up the sounds from your other speakers.

What is Sub Out?

Sub Out is a port used to connect to your subwoofer and is found on home theater and stereo receivers. This port is the most common way to connect a receiver to active subwoofer speakers.

The signal coming from this port is already reduced. It uses a low-pass filter to let out only the lowest frequencies in your audio. With many receivers, you can choose to set your crossover’s low-pass filter at 40, 80, 120Hz, or other levels as you see fit.

In most cases…

The Sub Out port will be an RCA port, or even a stereo pair of RCA ports that you can connect to using (normally white and red tipped) RCA cables. However, some Sub Out ports may use ¼” jack audio cables instead.

Either way, Sub Out is the standard way to connect a subwoofer to a receiver.

So What’s LFE, Then?

LFE stands for Low-Frequency Effects. This is a separate channel in digital audio that’s used to reproduce the very lowest of the low sounds from movies. These sounds range from 3-120Hz.

LFE was first created as a part of the Dolby sound in the 1970s. If you have a 5.1 or 7.1 stereo system, this is the .1 channel we’re talking about here.

Effects like underwater explosions, collisions, heavy weapons fire, and more can take advantage of the truly low-end range of human hearing. However, these sounds are not easy to hear and need to be turned up. So, the LFE channel is normally played back at 10dB louder than the other channels.

How does it work?

LFE was designed for use in movie theaters which had separate subwoofers for the LFE channel. Some subs would play the normal low-end, and others were dedicated to the low-frequency effects.

Therefore, when those sounds are played, they are louder and more powerful to give you an immersive movie-watching experience.

Sub Out vs LFE on Your Home System

Your Home System

If you’re like me and you don’t live in a movie theater but wish you did, you’ll have to content yourself with a home theater setup. So, the question is… what should you connect your subwoofer(s) to on your receiver – Sub Out or LFE?

On the one hand, they’re both very similar. After all, both ports are designed to let out the low and ultra-low sounds that rattle your teeth and thump your chest. But, they are different.

Sub Out will give you only the bass sounds that are filtered through your low-pass filter and fed to your subwoofer. Perfectly fine, and for a purely music-based setup, this is all you need. You can use AV cables to connect from your receiver’s Sub Out to your subwoofer’s In or Sub In port.

LFE gives you a boost for movie audio…

As we looked at earlier, the LFE signal is a band-limited, mono audio track. This track already has the higher frequencies digitally filtered out and only contains sounds in the 3-120Hz range. It also has enhanced content, with ultra-low frequency sound effects enhanced or amplified on it.

When you watch movies, you want to have your subwoofer connected to the LFE channel via the LFE port on your receiver. This will help to make sure that you get the best low-end sound for the best movie experience.

Connecting to Sub Out

Sub Out is the best connection to use if you’re setting up a home stereo system, not a home theater system. The LFE channel is a special digital audio channel on movies, and it’s not found in music recordings.

So, if you’re only playing music on your system, you can use the Sub Out port on your receiver to connect to your subwoofer. This gives you a signal that splits the appropriate low frequencies away and directs them to your subwoofer(s).

The crossover in your receiver will include a low-pass filter that’s either preset or adjustable, so you can decide how much of the low-end to send to your sub. This will ensure that your subwoofer plays the loud, clear bass sounds in your music while the mid and high-end don’t get muddied up.

Can you use LFE for music?

If your subwoofer only has LFE and no Sub In connections, you can still use that. The LFE is a mono connection that will also take in only the low end of your music.

Connecting to LFE

For movies, you want to use LFE. The good news is that today most subwoofers include an LFE input. This is a mono input jack that uses RCA cables to connect it to the receiver.

Even though you may have a 2 or 3-colored RCA cable (red, white, and yellow), you only need to use one plug to connect to your receiver. Most often, people use the white-tipped RCA cable to connect from the receiver to the subwoofer, but the color you choose doesn’t matter.

To connect:

  • Plug one end of the RCA cable into the receiver’s LFE or LFE Out port.
  • Plug the other end of the cable into the LFE or LFE In or LFE Main port on your subwoofer.

Troubleshooting Subwoofer Connection

Troubleshooting Subwoofer Connection

Now, let’s address a few problems with connecting a subwoofer that people may run into.

Do all subwoofers have LFE?

No, but most do these days. If you have a subwoofer that doesn’t have a port labeled LFE, though, don’t despair. You don’t need to worry because you can still plug the cable from the LFE on your receiver into your “In” input on your subwoofer.

The effect will be the same because the information from the LFE channel is already coming down the line from your receiver. Your subwoofer just picks up the signal and does its thing – it doesn’t have to do any thinking.

What if your subwoofer has 2 input channels?

Many, if not most, subwoofers have two input channels which are Left and Right RCA ports (usually white and red). Should you use a Y-connector to plug into both of them? Nope. That won’t add anything to your sound.

Instead, the two ports are there in case you want to plug two subwoofers into one system. You can plug one into the Left channel and the other into the Right channel. However, LFE is a mono signal, so it doesn’t matter if you plug it into the Left or Right input – either one will do.

What if your receiver doesn’t have an LFE port?

If your receiver is older, it may not have an LFE port. In this case, the LFE channel still exists because it’s part of the digital information on your movie soundtrack. However, it will have to come through the Sub Out port instead.

Again, this is no problem because the Sub Out is already a dedicated low-frequency port. However, you may need to check your crossover.

The LFE signal runs from 3-120Hz, so you should set the crossover at 120Hz to make sure you’re getting the whole channel. If you can set the crossover on your receiver, don’t go lower than 120Hz, or you’re going to miss some of the extra enhancement of the low-end sounds in your movies!

Want to Get a Great Home Audio Setup?

We can help with that. Check out our in-depth reviews of the Best Subwoofers for Music, the Best In Wall Subwoofers, the Best 7.1 Home Theater System, the Best High End Home Theater Speakers, the Best Powered Speakers, and the Best Bookshelf Speakers you can buy in 2023.

Also, if you need more info about subwoofers, take a look at our detailed articles on Difference Between an Active and Passive SubwooferHow to Connect a Subwoofer to an AmplifierWhy Do Some Subwoofers Have Left and Right Inputs, and Subwoofer Placement for more information.

And, don’t miss our comprehensive reviews of the Best Yamaha AV Receivers, the Best AV Receivers Under $500, and the Best AV Receivers Under $1000 currently on the market.

Sub Out vs LFE: Final Thoughts

Sub Out is designed for music, while LFE is a special channel made for enjoying movies. But, because our home systems don’t have the huge, dedicated LFE subs found in movie theaters, we can combine the low-end and enhanced low-frequency effects.

It’s fine to use Sub Out to your subwoofer for music and OK for movies too. But LFE is designed for surround sound and is the best way to connect a subwoofer to a receiver.

In a pinch, you can connect to either port and still end up with booming bass and deep sound effects. And that will put a tingle in your spine and make your movies magical.

Until next time, happy listening.

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1 thought on “Sub Out vs LFE – All You Need To Know”

  1. David J Crandon

    Hi Corey, great article. But one final question… How do I use LFE and sub out?
    I just bought a new Denon AVR-X 2700H, and a Klipsch LS 12 wi subwoofer. The subwoofer has a wireless connection which I’d like to use if possible, but not absolutely necessary. But mainly I use my AVR both for movies and music. So how do I make sure I get all the LFE effects, and good bass with music. If I connect the sub out of the receiver to the subwoofer will that still give me all the LFE effects? Thank you

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About Corey Hoffman

Corey is a multi-instrumentalist who has played in numerous bands over the years, some good, some not so good. He has also written countless songs and recorded five albums in professional studios across America. Today he is a hobby musician but still loves the guitar after over 15 years of playing.

He considers his writing as a way to share what he has learned over the decades with younger generations ad always can't wait to get his hands on the latest gear.

He lives just outside New York with his wife Barbara and their two German Shepherds, Ziggy and Iggy.

1 thought on “Sub Out vs LFE – All You Need To Know”

  1. David J Crandon

    Hi Corey, great article. But one final question… How do I use LFE and sub out?
    I just bought a new Denon AVR-X 2700H, and a Klipsch LS 12 wi subwoofer. The subwoofer has a wireless connection which I’d like to use if possible, but not absolutely necessary. But mainly I use my AVR both for movies and music. So how do I make sure I get all the LFE effects, and good bass with music. If I connect the sub out of the receiver to the subwoofer will that still give me all the LFE effects? Thank you

Leave a Comment

Your email address will not be published. Required fields are marked *

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