No Subwoofer and Large Front Speakers – Where Does the Bass Go?
Not all of us start out with full surround sound systems. I know I didn’t. Usually, we have a couple of speakers that we use as fronts, add some surrounds and center, and then a subwoofer when we can afford it. The key is that many of us live without a subwoofer for far longer than we would like to admit. But if you’ve bought large front speakers, do you need a subwoofer for the bass? Where does that bass go? Are those lowest notes just ignored? Let’s discuss.
LFE Channel Overview
We often think of our subwoofers as the speakers that play the bass that our other speakers can’t handle. But that’s not all they do. The subwoofer gets its own information. This “LFE” or Low Frequency Effects channel is the .1 in a 5.1 or 7.1 system. These very low bass notes are designed to be played by subwoofers and not your front or other speakers. So, if you’ve indicated in your speaker setup that you don’t have a subwoofer, what happens to these lowest notes? Not only the ones designed for the subwoofer, but those that were taken from the other speakers set to small?
AV Receiver Defaults
First of all, if you tell your AV receiver that you don’t have a subwoofer, it will default to setting your front left and right speakers to large. You will be able to specify all your other speakers as “Small,” but not your front left and right. There is a reason for this.
Well, AV manufacturers know one thing above all others – no sounds are ever lost. If there is a sound in a mix, it is going to be sent to a speaker. As we’ve discussed, any sounds below the crossover setting for a speaker set to “Small” is sent to your subwoofer. But you don’t have a subwoofer. Something needs to get those sounds. Therefore, your AV receiver forces you to set your front left and right speakers to Large. Those front speakers will now get any bass that would have been played by your subwoofer…if you had one. When we look at this manual for a Marantz AV receiver, we see it laid bare:
“Sound below the crossover frequency is cut off from the output of the speakers set in “Small”. This cut off bass frequency is output from the subwoofer or front speakers.”
Without at least one set of speakers set to “Large,” the bass from the subwoofer LFE channel (the .1) won’t have a place to go. You can see this in your AV receiver’s settings. You can often select to send the LFE bass channel to both your subwoofer and your front speakers if they are set to Large. Now that your front speakers are automatically set to “Large,” that’s where the LFE information will go. Even if large speakers aren’t really designed to play bass that low.
Why Front Speakers get Subwoofer Bass
Why would your AV receiver assume that the front left and right speakers would stand in for the subwoofer? The answer is easy. If any speaker in your system is going to be larger and more capable, it is your front left and right speakers. They do the most work (they can even stand in for your center speaker if you don’t have one) and are the only speakers that are used in every sound format. They get the most use and are the most likely to be the most powerful. If you are going to have a pair of speakers that could reproduce bass intended for your subwoofer, it is your front speakers. Thus, any bass that doesn’t have a place to go is sent there. Easy!
Does it make a difference turning off the feature lpf of lfe when not having a subwoofer and when the fronts are set to large? I know in this case the bass goes to the fronts from other speakers with crossover setting, but does the .1 lfe also get to the fronts? Let’s say we turn off the setting so instead of standard 120 Hz it’s set to off. Will this make any difference? Or not as the fronts are producing a full range of hz?
If you have no sub, the LFE channel does to the mains. I don’t think there is a way to “turn off” LPF for LFE but it wouldn’t matter if there was. All the sounds go to the fronts.