Everything You Need To Know About Sub Out Vs LFE - Vita Audio

Everything You Need To Know About Sub Out Vs LFE

Confused by audio connections? You are not alone! 

If you have had enough of spending hours on end trying to work out what to plug into what port, you have found the right place.

Everything You Need To Know About Sub Out Vs LFE

We have put together this quick guide to take you through everything you need to know about LFE connections and sub out.

With this information, you will be able to conquer just about any audio system!


A sub-out may also be called a subwoofer output. This is the output port on any audio receiver that is designed to connect active subwoofers. 

These output ports may be on some theater receivers or some models of stereo receivers. Generally, active speakers are usually connected to receivers by one of these sub outs.

A sub out port on a receiver or an integrated amp only transmits low bass frequencies to the subwoofer.

High frequencies are then filtered out of audio signals at the sub out port. This means that just the low frequencies – the base notes – will transmit.

All sub outs are typically connected using LFE cables or RCA cables.

LFE Channels

LFE basically means Low Frequency Effects. An LFE is a band-only audio channel which is used to transmit low frequency or intense audio.

Think of a movie theater – an LFE Channel will be used in any movie theater’s audio system to create distinct sound effects in things like movies.

LFE Channels are used to relay bass-only sounds to subwoofers and typically have a frequency somewhere between 3 and 120 Hz.

These channels will transmit discrete content – information that is delivered on multiple channels – from a receiver to the speakers. This information is usually sent via encoded audio tracks. 

Originally, LFE was only used in movie production and allowed movie theaters to get deep and intense audio when projecting movies. This is because the LFE system allowed for the possibility of additional subwoofers. 

Usually, LFE is discovered in multichannel audio systems like an at-home surround sound setup. These speakers can also be described as 5.1 which just means that five channels are full range with one additional LFE channel.

LFE And Sub Out: The Differences 

From a technical point of view, LFE and sub out are pretty similar. This is because they perform the same function – the transmission of bass or low frequency sounds.

Because they do the same job, it can be simple to think that they are essentially interchangeable. This is wholly incorrect.

The volume of data that is carried by a sub out versus an LFE channel is vastly different. This alone is enough to make them very distinguishable from each other.

Data Transmission

Sure, LFE and sub out ports both carry low frequency sounds. And, yes, they both filter out high frequencies.

However, the differences in information transmission capabilities mean that the sound that will eventually come out of the speakers will be quite different.

A subwoofer output will carry some or all of the data from the audio signal. LFE Channels, have been designed to supplement all the bass content in the audio signal.

This means that LFE bass audio has more data to relay in any given signal, and these additional elements of the audio will be relayed to the speakers.

The extra pieces of audio from an LFE that would have been missed by a sub out can tend to be more cinematic.

Crashes, explosions, gunshots, and similar sounds are most commonly missed by using a sub out port but will be easily detected using an LFE Channel.

LFE Channels essentially function to produce these types of sounds when you watch a movie.

This is because they require additional bass data to sound realistic, and LFE supplements relayed information that comes down the main channels.

All of this additional information is then sent to the speakers – usually a surround sound system – to create more realistic audio in whatever you are watching.

LFE And Subwoofers

LFE and sub out ports can work together to create great audio – remember that subwoofers are an essential part of any sound system. 

The subwoofer on your audio device could have an LFE and RCA channel. You may even have a couple of extras to choose from. Keep in mind that any LFE Channel on a subwoofer is technically an LFE input.

The LFE input gives you a port so that you can then connect the receiver to your subwoofer.

Most subwoofers today will have at least one built-in LFE input channel that combines the two channels – the left and the right – that comes from your receiver.

This means that you just need one RCA cable to connect your LFE and subwoofer to the receiver.


Remember that not all subwoofers will have LFE connectivity available. Some systems may not have any LFE connectivity at all.

A subwoofer that does not have an LFE input will have an RCA connection or possibly a stereo connection wire.

That said, most systems available today do have an LFE input option. This means that you can connect your receiver or amplifier to your subwoofer with little issue and great audio.


If you are unable to connect to an LFE Channel, you will be able to use an RCA connection. RCA has left and right channel input connections for a subwoofer. 

RCA input connections may not be labeled but LFE input channels usually are. Look out for a port that says ‘LFE’ near it.

If you are unsure, don’t hesitate to double-check your manual or contact the manufacturer for more information.

Using LFE On Your Subwoofers

If you do have LFE connectivity, there is no reason why you shouldn’t connect up your subwoofer when you are getting your audio system set up.

LFE is guaranteed to enhance the overall bass content of whatever is being played. For a movie, you will experience more realistic sound effects.

If music is more your thing you can enjoy a more rich sound, possibly with greater nuance.

Subwoofers are purpose-built to relay bass sounds to the speakers. LFE Channels can transmit the lowest possible frequencies in any audio source. Using LFE is therefore going to give you the best possible quality bass sounds.

Keep in mind that you may need to adjust the speakers when using LFE so that they can cope with the new bass noise.

You will need to find a full-range or large level to get the best results. Your speakers will now be able to get all the information that is relayed by the LFE Channel.

You also need to remember that LFE inputs on a subwoofer allow you to connect an AV receiver to the same subwoofer with just one connection.

This will help limit the number of cables when you are setting up. Fewer cables mean you are less likely to get lost, and thus you have become an audio master!

Connecting A Subwoofer LFE Input To A Receiver Sub Out

It is possible to connect a sub out port on an AV receiver to an LFE input port on your subwoofer. This can be done with a cable that has RCA connectors on either end.

This setup will mean that the subwoofer output sends bass signals that have been filtered to your subwoofer, including data from the LFE Channel.

You can connect the subwoofer’s LFE to your sub out from your receiver to connect a subwoofer to your speakers, or even your amplifier.

This is possible because stereo receivers and amplifiers both tend to be built with appropriate output ports that are compatible with LFE connectors. 

If you do this, you can connect the sub-out on your amplifier or receiver to the LFE input port located on your subwoofer.

LFE Uses

We have already mentioned that LFE is great for movies, and was developed with movie theaters in mind. Modern surround sound systems use a similar setup to create high-quality and encompassing sounds during the movie.

This does not mean that LFE is limited to just movies. 

You could use an LFE connection for video games to create an impressive gaming setup.

Doing this will have a similar effect as LFE has on movies – more realistic and layered sounds for bass or low frequency audio like gunshots or explosions.

If music is more your thing, you should consider LFE connectivity if possible. Your system will need some music processing formats or more than a two-channel signal, otherwise the subwoofer will not receive any LFE signal.

If you can connect to listen to some tunes, you can sit back and enjoy an invigorated bass sound and the additional nuances that come with an outstanding audio setup.

Final Thoughts

LFE Channels and sub out ports are pretty similar as they both deal with low-pitched audio. But remember that these aren’t the same thing. 

A sub out port is purpose-built to relay low frequency signals or bass signals to your subwoofer. An LFE Channel, on the other hand, is a separate channel with its own content.

This channel will transmit dynamic and emphatic audio effects like gunshots or explosions and is primarily used for surround sound.

If you enjoyed this article, you might enjoy our post on ‘Alternatives Now That Needle Doctor Is Out Of Business‘.

Jacob Stable
Latest posts by Jacob Stable (see all)