Last Updated on November 29, 2022 by Norvan Martin
When using a powered subwoofer in your speaker system, you need to choose the correct bass settings to ensure maximum performance. One of the most important settings is LFE+MAIN or LFE. LFE+MAIN or LFE are subwoofer bass settings, often referred to as subwoofer modes.
Choosing the correct bass settings/subwoofer mode will ensure that your amplifier or receiver and speakers will work efficiently with your subwoofer. In this article, we will discuss what is LFE+Main and when to use this setting.
Why Set LFE+MAIN?
It is important to set LFE+Main because this will determine if you will get the desired sound quality by correctly configuring these settings.
Setting Your Speakers To LARGE or SMALL and LFE+MAIN
Before configuring LFE+MAIN, you need to consider whether your speakers are set to SMALL or LARGE first.
You will find the SMALL and LARGE settings in the speaker configuration menu. Here is how these settings affect LFE+MAIN:
1. When The Speaker Channel Is Set To ‘Small’
When the speaker channel is set to SMALL, the bass setting or subwoofer mode menu can be set to LFE or LFE+Main. Doing this will pass all frequencies under the crossover point to the Subwoofer.
2. When The Speaker Channel Is Set To ‘Large’
When the speaker channel is set to LARGE, the bass setting or subwoofer mode menu can be set to LFE or LFE+Main. Doing this will duplicate the low frequencies to the Subwoofer.
If you set the bass setting or subwoofer mode to LFE, then nothing will output to the subwoofer except for the LFE from a Dolby or DTS encoded track.
An Explanation of LFE+MAIN and LFE
Now that we have discussed what settings to choose and the effect they will have on your subwoofer, it’s time to delve more into what these settings are.
The 5.1-surround mix is made up of five full-range main channels. These are Center, Right, Left, Right Surround, and Left Surround). It also consists of a subwoofer which is powered by a band-limited LFE channel.
LFE stands for Low Frequency Effect. It is available on all 7.1 or 5.1 DTS, and Dolby encoded audio tracks, and a dedicated “.1” channel in the surround mix. This is mostly for movies and so on because it is multichannel.
For stereo (2.0 or left and right audio), subwoofers handle that too. Typically, the frequency is cut off at 80 Hz. To learn more, check out our article on what you should set your subwoofer low pass filter to.
It is an effects channel used in the optical track because there is not enough dynamic range in the optical channels for Low Frequency Effects.
This is why as we mentioned before, 5.1 systems have 5 channels plus a sub-channel plus the LFE channel.
The channel is known for its exceptional ability to improve music and sci-fi environments. LFE also contains approximately 10% of the low frequencies that we hear in movies.
LFE+MAIN refers to sound systems with the receiver’s bass-subwoofer mode menu option that can duplicate the low-frequency signals and send them to the main speaker and the subwoofer.
This makes it incredibly easy to integrate the sub correctly. In this case, the low frequencies output to the subwoofer whether the speaker channels are set to Large or Small.
Understanding Your Chosen Setting’s Sound Effects
If you access the receiver’s subwoofer mode menu option and select LFE, you will have set the low frequencies from the .1 and speaker channels to “Small” in the configuration menu to output from the sub.
On the other hand, if you choose LFE+MAIN, the low frequencies from your speaker channels will begin to output to your sub. You are assured of low frequency output to the sub whether you set your speaker channels to “Small” or “Large.”
Your choice of LFE+MAIN or LFE has a direct impact on the quality of sound. From a sound engineer’s perspective, the low-pitched sound effects that are in the 20Hz range are the most difficult to reproduce.
For example, one may struggle for hours to reproduce sounds like the ones used to simulate a rocket launch, earthquake, explosion, or submarine changes without success. The fact of life is the ears are designed to be highly sensitive to sound at high frequencies. This means it takes a significant amount of amplification for the human ear to hear them. Our bodies often feel sounds with low frequencies must faster, though.
Amplifiers, cabinets, and subwoofers find it quite difficult to produce sound at high volumes. If you try it, you are highly likely to encounter problems like unwanted rattles in wooden speakers, power amplifier distortion, and excessive “chuffing” sounds for the port of your bass-reflex speakers.
And, this is where LFE+MAIN comes in. As we have seen, LFE allows the low frequencies of speaker channels that you have set to “Small” to output from the subs. LFE+MAIN amplifies the low frequencies from all your speakers and sends them to the main speaker, whether you set them to “Large” or “Small.”
Considering Speaker Size When Setting LFE+MAIN
Understanding the speaker size is also essential for proper bass management. We have been talking about “Large,” which means full-range speakers that can play down to 20Hz.
On the other hand, the small speakers, “Small,” lack the capacity to play down to 20Hz irrespective of whether they are more than 6 feet tall.
In this regard, the speaker size setting is referring to the frequency extension.
Whenever you set your speakers to “Small,” you are allowing your sub to perform its job. The speaker gets relieved from trying hard to create the lowest frequencies. This gives the speakers a new life and allows them to play the appropriate frequencies perfectly.
Your subwoofer is also happy to steal the show when producing low-end bass. So, this is a better way to protect your subwoofer than playback the LFE channel, which is delicate. Remember that this particular channel is hardcoded into 5.1 or 7.1 soundtracks.
It is the bass management settings that add your sub’s duties and feed them some frequencies that may easily get lost in the main speakers.
When you set the speakers to “Large,” all the bass, including the 20Hz signals, go to the speakers. The subwoofer gets no signals. This is extremely dangerous, given that many speakers are not genuinely “Large.” The towering sizes are often misleading.
After considering the size of the speakers, we can now see why LFE+MAIN remains the best option in many scenarios.
You get better quality, whether you use small or large speakers. But you can also set them to “Large” and double the low frequencies and then send them to the sub.
When to Use LFE+MAIN
LFE-MAIN is always the best choice whenever you are playing back PCM (2-channel) audio.
Using LFE alone may not give you the best output at such a moment. In contrast to MAIN, LFE provides bass-only sound (<120 Hz.).
Moreover, it has no direct impact on the directionality of the soundtrack. In other words, the purpose of LFE is to supplement the overall bass content.
Film formats with a separate LFE channel are always combined with the bass from the MAIN in the proper acoustic mixing ratio for the best experience. When you are playing PCM-based audio, LFE+MAIN guarantees you the desired low frequency.
On Handling the Subwoofer Itself
Once you have decided to use LFE+MAIN, ensure you have an efficient AV receiver with the needed bass management controls.
And then start by setting the sub’s low-pass crossover to the highest setting. This way, you prevent the subwoofer’s crossover from hanging up with that of the receiver.
If you notice a peak that you cannot manage with ease at the crossover point, you can dial it back and tamper it off a bit. The idea here is to make sure that the subwoofer is free to playback whenever you want.
You can also use the phase controls on the subwoofer. Some subs have switches, while others have a rotating dial. If you have difficulty getting a smooth response on your subwoofer and cannot move it to another location, you can experiment with the switch.
Using LFE+MAIN to set your home theater is simple if you understand the different speaker sizes and the impact on the sound. Hopefully, the information we have presented here is enough for you to understand what LFE+MAIN means and use it with ease.
You can rely on the basic principles to get practicing and experiment with various techniques to have a great home theater.
Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics.