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Home theater subwoofer setup

Tips to help you tune up your bass

By

James Ralston

James Ralston is Crutchfield's Web Editor for Home Audio/Video. He joined the company in 1994 as a member of the sales department and began writing about A/V gear in 1999. James attended the University of Virginia, receiving a Bachelor of Arts degree in English Literature. Since arriving in the Charlottesville area, he has been active in the local music scene, playing drums in a variety of musical projects ranging from world beat, to blues, to instrumental improv.

Definitive Technology SuperCube 6000 sub

Definitive Technology SuperCube® 6000 powered subwoofer

You've just fired up a Blu-ray movie on your new surround sound system. The screen momentarily goes blank: here comes the main feature. No — it's a THX demo! (You weren't expecting that.) Imaginary objects zip around your head in 3D space...this is promising. And then that famous tsunami-wave of sound, THX's audio "logo".... But wait, where's the bottom-end? Where's the spine-tingling bass?

If your home theater system's bass output sounds too lean, or if it's muddy and distorted, a few key settings on your powered subwoofer and receiver can make all the difference. Here are a few tips to help your sub perform at the top of its game.

Set the crossover point

For the best possible sound, you want your front, center, and surround speakers to play only the frequencies they can handle, and your powered sub to play the rest — the deep bass frequencies. That's the job of your system's crossover. To use a common analogy, a crossover works sort of like a "sonic traffic cop," sending the right frequencies to the right speakers. But where should your sub leave off, and your other speakers begin?

To determine the optimum crossover point for your system, you should know what frequencies your main speakers can handle. In my own system, I've got small satellite speakers all the way around. The owner's manual told me they could go down to about 120 Hz, and I set my system's crossover accordingly. (For larger speakers, this number is usually lower — it's not uncommon for bookshelf speakers to get down to 50 or 60 Hz, for example.) Once you've set your crossover frequency to one that matches your speaker setup, sit back and give a quick listen. You can even experiment by adjusting the crossover frequency a little bit one way or the other...after all, what matters is getting your system to sound good to you.

subwoofer

This Polk Audio subwoofer has a separate unfiltered "LFE" input for use with a home theater receiver.

Check your subwoofer's "LFE" setting

What some folks may not know is that their system probably has two subwoofer crossovers, one inside their home theater receiver and another built into the powered subwoofer itself. And these two crossovers don't play nicely together. If they're both engaged simultaneously, you're probably not getting all the bass that you could.

That's where your subwoofer's "LFE" setting comes in. This acronym stands for "Low Frequency Effects" (not "Loud Family-room Explosion" or "Looking For Explanation"). "LFE" is just the technical name for your home theater receiver's bass channel.

This setting tells your subwoofer whether to use its own built-in crossover or the one inside your receiver. In most cases, the latter is the better way to go. That's because practically all home theater receivers built in the last several years have advanced digital bass management that not only tells your subwoofer what frequencies to play, but also tells the rest of your speakers what frequencies not to play. 

If you're using a home theater receiver with bass management, you want to disable your sub's built-in crossover to make sure it plays all the bass frequencies your receiver is sending through its subwoofer output. To do this, be sure to use your receiver's preamp-level subwoofer output, and your subwoofer's LFE input.

Some subs have a switch that lets you toggle between LFE (use this when you have a home theater receiver) and "normal" (use this when you don't). Others have a separate unfiltered LFE input.

subwoofer cable

Every link in the audio "chain" counts — use a quality subwoofer cable to make sure your sub receives a strong, clean signal.

What if my sub doesn't have an LFE option?

If you have an older receiver or subwoofer, LFE connections may not be an option. In that case, you can use speaker wire to connect to your sub's speaker-level inputs. Or you can go with a line-level connection that uses standard stereo RCA cables. If you use either of these connection methods, turn your subwoofer's crossover dial all the way up to help ensure that it won't interfere with your receiver's built-in bass management.

A few high-end subwoofers and receivers also offer an XLR connection, which is less susceptible to signal degradation. For the most part, you won't have to worry about this type of connection — your sub's owner's manual will be very clear if you should use it.

A quick note for stereo music listening

After the movie's over, you decide to kick back and listen to a new album you bought earlier. You're already familiar with the first track – it's got a killer bass line that should be kicking in... any second now.

If you plan to use your home theater setup for stereo music listening, too, then be aware that not all home theater receivers will send a signal to the LFE output when in stereo mode. Most do, but for those that don't, you'll notice a drop in the low-end when you switch from surround sound to stereo listening. Check your receiver's owner's manual to be sure. If your receiver isn't sending a signal to the LFE output, you can try using line-level or speaker-level connections to bring back the bass.

Customize your sub's sound for your media and your room

Many subs these days can be fine-tuned to match the material you're listening to, or optimized for the acoustics of your particular listening space. For example, your sub may offer presets like Movie, Video Game, Rock Music, Jazz Music, Sports, or Night Listening. You can switch from one to another based on the type of entertainment you're enjoying.

Of course, how and where you place your subwoofer in your room can impact the sound and quality of the bass. For example, subwoofers tucked away in a corner generally produce more bass, but can tend to sound "boomy." So some subwoofers have calibration options for adjusting the sound to fit your room, either by letting you indicate your sub's placement (corner, mid-wall, in-cabinet, etc.) or by taking sound samples and automatically tailoring the sound to suit your room. You can learn more about subwoofer placement in our article on home theater speaker placement.

Find the level that sounds best

Finally, there's your subwoofer's level control. It's a straightforward concept, no doubt. But this setting makes a big difference, so it's worth spending a few minutes tweaking and listening to get it right. Keep in mind that more bass isn't necessarily better bass. Try starting at a lower level and gradually bumping it up to where you're feeling plenty of punch, without sacrificing clarity. If you resist the urge to crank your sub's level control way up past twelve o'clock, you stand a better chance of achieving tight, clean bass, and well-balanced overall sound.

Of course, it's all a matter of taste. I'll admit that, for my own part, I probably tend to push my sub a little bit more than others might. But then again, when I pop in a THX-mastered movie disc, and that huge-sounding THX demo kicks in, it's like audio nirvana.

Last updated March 09, 2016
  • Russ from Soddy Daisy

    Posted on 7/22/2015 12:09:59 AM

    I have a receiver with one LFE OUT. Currenty I am running one sub, but have another that I am adding to my system. I split the connection with a Y female to two male with a L & R in to the current sub. I am wondering how best to add the new sub. A diagram would be very helpful. Thanks!!

  • Dave Bar from Crutchfield

    Posted on 7/22/2015 9:56:32 AM

    Russ, Powered subs vary all over the map with the type of connections they offer. Most that have a right and left line input don't usually require that both inputs are connected when using a mono LFE connection from your receiver. In fact many, like this MartinLogan Dynamo 500, reserve either the right (as in the case of the MartinLogan) or left line level input specifically for the LFE connection. You can probably just use one leg of your Y-adapter to connect your first sub, and the other leg to connect your second sub with an extension cable to reach it (unless your sub has a line out connection, as well, in which case you can just daisy chain the two subs together).

    I'll admit it can get a little tricky because of all the variation from brand to brand and model to model. If you bought your gear from Crutchfield, you can call Tech Support for free help hooking up your subs. Otherwise, it might be a good idea to check with the sub's manufacturer for specific advice.

  • Butch Repa from granger, tx

    Posted on 8/1/2015 12:36:10 PM

    I have an old school RCA 120watt sub from 10 yrs back and have checked numerous Places and they all told me that the newer stereo system s don't have the sub input mine hasso what exactly can I doit also has A 2 terminal connection for high level and low level input connection of speaker wire . can I use those to hook up and do receiver or am I just out of luck?

  • Dave Bar from Crutchfield

    Posted on 8/3/2015 11:37:23 AM

    Butch, I found an owner's manual for a 120 watt RCA powered subwoofer. I don't know for certain whether this is your exact model, but with any luck it might shed some light on your situation.

  • shannon from new port richey

    Posted on 8/23/2015 8:33:14 AM

    I connected my sub to my receiver with an RCA cable as recommended. I tried connecting the cable from the left and right output on the sub to the sub output on my reciever and no base at all. I am not sure if I have to change somethiing on my receiver to get the base to sound from the sub. I believe it is connected correctly. I do not have the remote for my receiver and it seems as though I may be able to scroll through more options on my receiver if I had the remote. I tried changing the settings on the receiver, but can only go from having the speakers all on or off. What am I doing wrong? Thanks for helping shannon

  • Dave Bar from Crutchfield

    Posted on 8/24/2015 9:53:51 AM

    Shannon, It's possible you may need to access your receiver's speaker configuration settings in the setup menu to tell it that you have a subwoofer hooked up to its LFE (Low Frequency Effects) output. If it doesn't think you have a sub connected, it won't send any signal through that output. Accessing those settings without a remote may be difficult. You might try referring to your owner's manual, or check online at the manufacturer's website if you don't have one. Good luck.

  • Victor from St cloud

    Posted on 9/30/2015 6:17:31 PM

    I recently purchased a marantz 1506 with 2 klipsch R26 towers, 1 R25 center and a SW10 sub for a 3.1 setup. I have all my connections set correctly and used recommendations via audessey . Yet my sub keeps popping almost out of sync. I don't have space to add SATs. Any advice?

  • Dave Bar from Crutchfield

    Posted on 10/1/2015 9:24:59 AM

    Victor, if it's an "out of sync", or phase, issue (basically, where the subwoofer's cone is moving in the opposite direction from the main speakers' woofers), try switching the "phase" control on your sub (if it has one) to the opposite setting. If it's more a matter of the subwoofer's cone actually popping or bottoming out, turn it down! Every subwoofer has its limits, and you may have just discovered yours.

  • Phillip Jost from Houston

    Posted on 11/5/2015 12:20:23 AM

    I have a set of Polk Audio RTI A9's powered by an Emotiva XPA-2 300x2 RMS amp (not bought from Crutchfield :(, sorry). My Def Audio SC4000 Subwoofer is connected through LFE to my Pioneer VSX-1124 receiver. The problem I have is the SC4000 is clipping at high volume when the towers aren't. Any recommendations?

  • Dave Bar from Crutchfield

    Posted on 11/5/2015 1:05:39 PM

    Phillip, Is it possible for you to turn down the volume level of the sub, either from the receiver's settings menu or on the back panel of the sub itself? If so, that's what I would do. Either that or get a bigger, more powerful sub that can keep up with your amp/speaker combo. If that doesn't work, you can also get expert Crutchfield Tech Support - 90 days-worth for only $30. Check out our tech support page for details.

  • Tim Dillenbeck from Santa Monica

    Posted on 12/24/2015 6:55:13 PM

    Re: shannon from new port richey "I tried connecting the cable from the left and right output on the sub to the sub output on my receiver and no bass at all. " It's not surprising to have no bass at all if you connected the sub's left and right OUTPUTS to your receiver's subwoofer OUTPUT. Try connecting your sub's INPUT to the receiver's sub OUTPUT. Chances are that should correct the problem. Preamp outputs to amp inputs; never preamp outputs to amp outputs. If your sub has L and R outputs, it likely also has L and R inputs. The sub outputs would either go to: (1) L & R satellite speakers, if the sub has additional built-in amp channels to power them, or (2) the L & R inputs of an external power amp driving unpowered satellite speakers, or straight to active powered speakers, such as found in many computer desktop systems. In either case the sub's outputs are usually high-pass filtered to screen out those low frequencies handled by the sub. Check your sub owner's manual or find a copy online. One last thing. Don't forget the subwoofer Polarity (0 to 180) switch. The wrong setting can often reduce the apparent bass response of a system, giving you the impression of "no bass at all." Good luck.

  • mark from cincinnati

    Posted on 1/10/2016 11:26:06 AM

    I have an infinity primus ps38 for about 8 years and now it sounds like wind is blowing through it I'm unsure as to what it is maybe you can guide me on the matter do I scrap it for a new one or can it be fixed.

  • Dave Bar from Crutchfield

    Posted on 1/11/2016 11:20:18 AM

    That's a tough one, Mark. Of course, if you purchased it from Crutchfield you can always call and talk to our techs to see if there might be a simple fix. If it's an extensive technical issue, I'm thinking that the cost of out-of-warranty repair may make it more logical to consider a replacement.

  • Ed Rieth from Phoenix

    Posted on 2/4/2016 8:29:18 PM

    About 15 years ago, LaserDisc was all the rage in my house and in my estimation, provided great audio. At that time, I ran the Pioneer LaserDisc player through a Pioneer receiver. The speakers were a small center and small rear satellites with two large floor standing cabinet speakers for the fronts. These were comprised of a tweeter, mid and 15" subs. Since that time, I've changed to a Sony Blu Ray player that runs through a brand new Denon AVRX2200 and the speakers are Boston Acoustics MicroSystem 9000II, with a single 10" powered sub. I just cannot seem to replicate the same bass "punch" while watching Blu Ray as I realized when watching movies on LaserDisc. I know it's not an issue with the receiver; it's far superior. Is the audio quality between LaserDisc and Blu Ray just that different or am I comparing apples and oranges between the two 15" woofers in the cabinets and the 10" powered sub? Any recommendations? I've just completed all my calibrations and am running the powered sub on LFE and it's set at 120Hz through the receiver. Thanks!

  • Dave Bar from Crutchfield

    Posted on 2/5/2016 10:07:54 AM

    Ed, I believe you summed it up perfectly: this is an apples and oranges situation. I'm quite certain that the Blu-ray format is capable of providing bone-crushing bass! My guess is that your 10" powered sub is simply not moving as much air as your old floor-standing speakers. A larger sub is probably the answer. Please get in touch (call, chat, or email) with our advisors for recommendations.