When it comes to bass management, it is essential to know what to choose between LFE and Line-in for your subwoofer.
In LFE, the low pass filter on the subwoofer is bypassed and your receiver/pre/pro will be responsible for setting the crossover frequency. However, when using line-level outputs on your receiver and line-in inputs on the sub, the subwoofer handles the crossover.
Both LFE and line-in connections are line-level connections. They both use RCA connectors to transmit the low-frequency signals from the processor to the subwoofer.
Any of these connections can be used in a home theater set up depending on the inputs on the subwoofer and the outputs on your receiver/pre/pro. However, when using line-in connections, ensure that you can properly and manually set the crossover using the subwoofer’s low pass filter knob.
But for a better understanding, let us look at each of these options in more detail.
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LFE on a Subwoofer explained
LFE is a general acronym that stands for Low-Frequency Effects. These effects are bass effects such as thunder and bass effects in general usually signals of below 120 Hertz.
On a subwoofer, LFE is a connection that sends these low-frequency signals from a receiver/pre/pro to the sub where they are reproduced. This is done using a single LFE RCA cable. But in this case, the receiver will determine the crossover frequency by bypassing the crossover (Low Pass Filter) on the subwoofer.
This is the most common home theater connection for bass effects as it is much easier to set the crossover using the receiver.
Most receivers and other processors will have automatic calibration software that sets the crossover setting and other calibration settings removing the hassle of having to do it manually. This is one of the reasons why you may use the receiver to set the crossover instead of the subwoofer.
However, you can manually set the crossover on the receiver/pre/pro for fine-tuning to your liking.
Line in inputs in a Subwoofer explained
Just like LFE, line-in connections also transmit the low-frequency signals from your processor to the subwoofer.
These connections use two RCA cables for the left and right connections but in this case, the crossover will be set using the Low Pass dial on the subwoofer.
Setting the crossover manually using the sub’s dial is more complicated than automatically doing it using calibration software. But it can be done depending on how low your main and surround speakers can go.
Typically, you will want to set the crossover on your sub at a frequency of between 80 Hz and 120 Hz for a seamless roll-off from your speakers to the sub.
Which connection should I use?
The LFE is the recommended connection for most home theaters but if you can comfortably set the crossover manually, use the left and right line-in RCA connections.
Most people will also use the Line-in connections if they set their speakers to Large, LFE + main for double bass, and Small for the LFE connection.
In some cases, a subwoofer may have line-in inputs only without an LFE input and your processor may only have an LFE. If this is the case for you, you need to use a Y-connector to connect sub-out on your receiver to the line in inputs on the sub.
You can also turn off the low pass filter on the sub if it has a toggle to bypass its internal crossover.
Your receiver may have 2 LFE outputs but this is used for a 2-subwoofer set up with each connection going to a single sub.
What is LFE + Main?
LFE + Main is a setting on a receiver that allows you to duplicate and send bass effects to your main speakers and the subwoofer.
This setting is mainly used for systems with full-range left and right tower speakers with woofers capable of playing the lower frequencies.
The LFE + Main setup is also known as a double-bass setup but this is not preferred for most home theater settings. Double-bass does not mean that you have dual-subs.