Getting the Correct Subwoofer Settings for Home Theater
Bass management is a term that gets thrown around a lot in online forums and technical users guides. What we’re really talking about here is setting up your AV receiver to work correctly with subwoofer. There are settings on your surround receiver and there are settings on your sub. Getting the correct subwoofer settings for home theater means correctly configuring and understanding both. This guide will take you step by step in doing just that. After the basic settings are configured, you can then dig in to your heart’s content making even more specific tweaks and adjustments to your system. Setting up your subwoofer properly will almost always affect your entire system and is well worth it for those looking to achieve the best possible movie-watching or music-listening experience.
Before we begin let’s define some important terms you’ll need to know:
- Low-pass Crossover: The frequency below which your subwoofer will be working and the frequency above which your main speakers will be reproducing frequencies for anything sent to the LFE or sub channel. The low-pass crossover is typically variable from 40Hz to somewhere around 160-200Hz.
- High-Pass Crossover: The frequency above which your speakers will take over. This is a setting most commonly associated with a subwoofer that has speaker level outputs for connecting satellite speakers. The high-pass crossover is typically fixed on subwoofers that have this feature.
- Large speakers: These are speakers which are truly full-range and play down to 20Hz.
- Small speakers: These are any speakers that do not play down to 20Hz.
- LFE: This stands for Low Frequency Effect and is a the dedicated “.1” channel in a 5.1 or 7.1 surround mix. The LFE channel has specific information associated with it that enhances music, explosions and sci-fi environments.
- Both or LFE+Main: Most systems have a mode whereby the bass frequencies below the AV receiver’s crossover point are sent to both the subwoofer and the main speakers. You can feel free to experiment with this mode, but in my experience it yields unexpected results and should be avoided.
What’s the Big Picture?
Surround receivers vary in how they address bass management, but typically there is either a global setting for a low-pass frequency setting, or a per-channel low-pass setting. The idea is that you want to supplement your speakers with a subwoofer to handle frequencies they cannot reproduce, or cannot reproduce with enough authority. A subwoofer, by design, is made to handle the frequencies that make your main speakers want to cry for their mamma. Getting the correct subwoofer settings for home theater will involve setting each component properly so they work with each other—not against each other.
If you don’t configure bass management properly, you’ll find that your low frequencies can be muddy and you can really end up with sub-par sound. I’ve been in rooms where the subwoofer was playing back frequencies so high, you could hear dialogue coming from the 10-inch woofer! That is NOT what you want your subwoofer to be doing. Aside from the muddy sound, setting the crossover incorrectly doesn’t allow the sub to push volume out in a way that it’s designed to do. But it also does something else. If your speakers are set incorrectly, they will be receiving frequencies for which they were never designed. Just because they can’t play back 20Hz doesn’t mean they aren’t trying like crazy! That results in muddy sound throughout the range of frequencies for which they are better suited. It’s just all-around bad. Because of this, we want to be sure and optimize our settings.
How a Crossover Works
A crossover is built into every two-way or greater speaker. It controls what frequencies go to what driver. Without a crossover, a tweeter would be getting the same signal as a woofer—and vice versa. It’s always better when each driver gets the range of frequencies for which it is designed. Now, if you take that principle and apply it to the subwoofer you get the same thing. A subwoofer is like a low frequency driver for your main speakers—just one that is separated on its own.
You want to set the crossover such that the frequency is the point at which your main speakers are comfortable handling the audio above the crossover point, and the subwoofer can make due below. THX recommends 80Hz for most systems, but satellite speakers that can’t reproduce very low frequencies and larger tower speakers that are nearly full-range will require custom settings.
In some systems, you’ll have an easy time setting the crossover because all of your speakers will be the same or have the same frequency response. On other systems, setting the crossover will be more difficult because your main speakers will play lower than your surrounds. On these systems we recommend setting the crossover to the frequency required by the smallest speaker in the system—the one that doesn’t play down as low as the others. There is an exception to this, however, we don’t advocate setting the crossover above 100-120Hz regardless of your speakers. At frequencies this high, your subwoofer will likely just be putting out a lot of muffled sound, so if you have nicer main speakers but you carry a pair of satellites as your surround speakers, consider catering to your better speakers. This will leave some gaps in the surround, but I tend to want to prioritize where the majority of my sound is coming from—and that’s up-front.
Checking Your Work
One of the best tools to check your work when dialing in the subwoofer settings for home theater is a bass frequency sweep. This is a tone that starts at a higher frequency and drops down low, showing you how exactly your system is handling the transition from the main speaker to the sub. You can find sweep tones like this on any THX-certified movie. Just look for the THX logo on the front, pop the movie in, and look for the THX Optimizer app in the Extras of the menu system. If there is a huge dropout in frequencies when you run this test, then you may have to either change the crossover frequency so that it’s higher, or even move your sub around a bit to see if it changes the acoustical effects on the low frequencies.
You want a nice smooth transition from the 200Hz starting frequency down to the 20Hz ending frequency. You won’t ever have a perfectly smooth transition, but you want to get as close as possible. Use this test to set the crossover at its optimal setting.
Understanding Speaker Size
We defined Large and Small speakers above, however it bears some repeating because…well, frankly, no one wants to listen to me. I don’t care if your speakers are 6 feet tall—if they can’t play down to 20Hz you should set them to “Small”. In this way, the speaker size setting isn’t really for speaker size at all. It’s referring to the frequency extension—particularly on the bottom end.
When you set your speaker to Small, you’re allowing the subwoofer to do its job. And that is a good thing. It alleviates the stress on the speaker of recreating the lowest frequencies (which move the driver more than higher frequencies do, albeit at a slower rate). It ends up giving your main speakers new life. Now, they can play back the frequencies for which they have the most affinity and capability. And your subwoofer is “happy” too because it gets to steal the show on low end bass response. It’s really a win-win no matter how you look at it.
So setting a speaker to Small gives you subwoofer something to do other than play back that dedicated LFE channel (remember that?). The LFE is hardcoded into a 5.1 or 7.1 soundtrack, but the bass management settings add to the subwoofer’s duties—feeding them those pesky frequencies that would get lost on your main speakers.
And we’re not suggesting that you may not want to experiment with some of these settings, but it’s important to understand what’s going on and how bass management will affect the output of your low frequencies. You want to hear everything, and you want to hear it in the best way possible. Re-routing low frequency information to your capable subwoofer is a great way to make sure those subsonic hits and deep bass notes get the proper airing they deserve. I’ve had tower speakers that go way down to 32 Hz and I still set them to Small. It seemed ludicrous at the time, but in the end it produced much better sound and the main speakers shined for the mid-bass frequencies and up.
On the Subwoofer Itself
When you have a capable AV receiver with adequate bass management (crossover) controls, always set the subwoofer’s low-pass crossover to its highest setting. That way, the crossover on the subwoofer doesn’t gang up with the crossover of your AV receiver. If you ever notice a huge peak at the crossover point—one you can’t eliminate by moving the sub around a bit—then feel free to dial back the crossover to see if you can taper it off a bit. But in general, you want to make sure the sub is free and clear to play back whatever it is given.
There are also phase controls on a sub. Some have a switch that is either 0 (in phase) or 180 (out of phase) while other subwoofers have a rotating dial. If you can’t quite get a smooth response on your sub and you are unable to move it to a new location, experiment with this switch. Adjusting phase on a subwoofer is very similar to what happens when you move it along a wall. It adjusts the waveform slightly, and that, in turn, changes where the peaks occur in the room. We always try to get the best sound at the 0 setting, but the phase control can be a lifesaver when all else fails.
When setting the volume on your subwoofer I typically start at a lower setting until I understand how loud its going to be when my movies and music are playing. Once you know you’re not going to get blown away, you can usually set it at the mid-point setting and go from there. Once configured, the AV receiver will control the volume from then on out. These particular subwoofer settings for home theater use ensure that you use the full potential of each component.
Now Get Experimenting!
Hopefully this is enough information for you to get practicing. What you really want is a system that plays nice and loud, and nice and low—but without distortion. Use these basic principles and you’ll be well on your way to excellent home theater sound that will make your neighbors jealous…or really, really angry depending upon whether or not you invite them over to listen with you!
Have any other suggestions for getting the best bass response or configuring a subwoofer? Let us know your opinion on Facebook or comment below and join in the discussion.