Sub Out vs LFE: All You Need to Know!

Geek Musician is reader-supported. We may earn an affiliate commission when you buy through our links

Do you find audio connections complicated as well? Have you spent time flipping through audio ports trying to figure out where to insert what? Then this article is meant for you. This article is going to explain what sub out and LFE connections are.

What is a Sub Out?

A sub out (or subwoofer output) is an output port on audio receivers designed purposely to connect to active subwoofers. This output port can be found in home theatre receivers and some stereo receivers as well. Most active speakers are connected to receivers via sub out.

Just as I talked about in my previous article, titled “Sub Out vs Pre Out,” sub out ports on receivers and integrated amps send only low bass frequencies to subwoofers. In sub-out ports, high frequencies are filtered out of the audio signals. This leaves only the low or bass signal, which it transmits. Sub outs are connected using RCA cables or LFE cables.

What is LFE Channel?

The acronym LFE stands for Low-Frequency Effects. This is a band-limited audio channel that is used to send intense and low-frequency audio sounds. An LFE channel is dedicated to producing emphatic sound effects in movies. 

LFE channels are designed to deliver bass-only sounds or information to subwoofers during movie sound productions. These sounds have a frequency range that is between 3-120 Hz.

LFE channels send discrete content from a receiver or digital theater system encoded audio track to speakers. Originally, LFE channels were made to transmit audio from movie productions. They were meant to deliver separate bass sounds to additional subwoofers at cinemas.

LFE can usually be found in multi-channel audio devices like 5.1 surround sound home theatre receivers. A speaker setup that is described as being 5.1 simply means it has five channels that are full range and one additional channel that is LFE.

Differences Between Sub Out and LFE

Technically, subwoofer output and an LFE channel are primarily similar. They are similar in terms of function. Sub out and LFE ports are both designed to transmit low or bass frequency sounds, so it is easy to assume that they are the same. 

However, hold on to that assumption because a sub out is not the same as an LFE channel. There is one particular thing that distinguishes a sub out and an LFE channel. That is what I am going to talk about next.

Amount of Information Carried

Subwoofer output ports and LFE channels carry bass signals. They filter high frequencies from audio signals and transmit only the bass frequencies. However, they do not carry the same amount of information. 

The elements of the bass signal they both carry are what sets them apart. That is why an article from Wikipedia mentions that the content produced from an LFE channel is different from the content from a sub-out jack.

Subwoofer outputs may carry either some amount of or all the bass information present in an audio signal. On the other hand, LFE channels are specially engineered to supplement the total bass content in audio. Thus, LFE channels carry additional bass information present in a particular audio signal. These additional sounds include; sounds of gunshots, crashes, explosions, etc.

LFE channels are dedicated to producing these sounds you hear from your speakers when watching a movie at home or at the cinema—this additional bass information carried by LFE supplements the bass information that is in the main channels. The additional bass information which is transmitted by LFE channels is usually sent to the surround sound system.

What Is LFE on Subwoofers?

Subwoofers are one of the integral components of home theatre systems. They may come with a number of input ports which include; an LFE channel, RCA channel, etc. The Low-Frequency Effects (LFE) channel found on subwoofers is known as LFE input.

This LFE input channel provides you with a port where you can connect your subwoofer to a receiver. Nowadays, most subwoofers have a single LFE input channel. This single LFE channel combines the left and right channels coming from your receiver. An LFE on your subwoofer can be connected to your receiver through a single low-frequency effects RCA cable.

Do All Subwoofers Have LFE?

Not every subwoofer has an LFE input connection on them. Some do not come with any LFE channels on them. The subwoofers which do not have LFE input connections usually come with RCA connections or wired stereo connections.

Most of the subwoofers available and made today are equipped with an LFE input channel which enables you to connect your subwoofer to a receiver or amplifier. Aside from LFE input, another type of connection that can enable you to connect your subwoofer to receivers or amplifiers is the RCA connection.

If your subwoofer does not have an LFE channel, it will have an RCA input. This RCA comes with the right and left channel input connections for your subwoofer. This article speaks extensively on RCA. Reading it will help you understand RCA connectors, so do well to check it out.

A subwoofer that comes with an LFE input will have one of its ports labeled with LFE next to it. However, if your subwoofer does not have any input labeled as LFE, consult your manufacturer’s manual for clarification.

Should You Use The LFE on Subwoofers?

You should use the LFE channel if it is available on your subwoofer when setting up your home theatre system. LFE channels help to enhance the total bass content of the sound being played.

Subwoofers are designed purposely for emitting low-frequency sounds. LFE channels transmit the lowest frequencies in audio productions. Thus, when you use the LFE channel on your subwoofer, you get the best low-frequency sound.

When you use the LFE input on your subwoofer to carry sound, the appropriate bass sound is received by your subwoofer. This makes the final audio quality produced sound accurately. It also helps to reduce the audio burden on other channels.

When using LFE channels, it is advisable to adjust the level of the speakers to a large or full-range level. This will enable your speakers to output the full range of signals that are being transmitted by the LFE channel.

Also, LFE inputs on subwoofers enable you to connect your AV receiver to a subwoofer using one connection. This means you do not need a lot of cables when connecting to the LFE input on subwoofers. Thus it is difficult to get confused about where to fix a particular cable when using the LFE input port on your subwoofer.

Can I Connect Receiver Sub Out To A Subwoofer’s LFE Input?

You can connect sub-out ports on AV receivers to LFE input ports on subwoofers. You can do this by using a single audio cable with RCA connectors on both ends. When you do this, the subwoofer output port sends out low filtered signals, including LFE information, to your subwoofer.

Connecting the sub out from your receiver to a subwoofer’s LFE input is one of the ways of connecting subwoofers to receivers or amplifiers. This is because a lot of amplifiers and stereo receivers are built with subwoofer output that supports the LFE connection at the subwoofer end. 

This allows you to connect the sub-out port on your receiver or amplifier to the LFE input port on your subwoofer.

Conclusion

Sub out ports and LFE channels are similar. They both send out musical notes and sound effects that are low-pitched. However, they are not the same. So do not confuse a subwoofer output with an LFE channel. 

A sub-out port is designed to send out pure bass or low signals to subwoofers. An LFE channel is a dedicated audio channel with its own content. It is responsible for delivering emphatic sound effects like explosions, gunshots, etc., in movies.