How to set up a subwoofer

DIY: How to set up a subwoofer Take our easy-to-follow procedures to integrate your powered subwoofer into a component-level home theatre system.

1. Getting started
2. What you'll need
3. Make the right connections
4. Adjust your receiver's setup menu
5. Adjust the sub's volume level
6. Verify the sub is operating in phase
7. Find the optimal position for the sub

1. Getting started
Everybody knows subwoofers deliver floor-shakin' bass, but they can also pump up the realism and sound quality of your home theatre. Or not. If you plopped your sub behind a potted plant, you're probably missing out on most of the sub's potential. We'll take you through the process of connecting, setting up, calibrating, and placing your subwoofer. Invest an hour or two following our step-by-step process, and you could very well end up with a home theatre that offers dramatically improved sound.

2. What you'll need

THX-certified subwoofer cables from Monster Cable.
Before you get started with this project, we recommend that you have the following:
  • An A/V receiver
  • A surround speaker system with subwoofer (5.1-, 6.1-, or 7.1-channel configuration)
  • A long subwoofer cable

Assuming you already have a full home-theatre audio system with an A/V receiver, surround-sound speakers and a subwoofer, the cost of the performance upgrade ranges from nil (if you don't need additional cabling) to less than AU$130 for a new -- and possibly longer -- subwoofer cable. For example, a MonsterBass 300 cable over seven metres long goes for around AU$80. That length might seem a bit extreme, but it may come in handy even in an average-size room, especially when you're running it along a baseboard to keep it out of sight. Also, keep in mind that you may wind up moving the sub to the opposite end of the room from your receiver in order to get the best sound.

Depending on the size and weight of your subwoofer, you might want to enlist the aid of a strong buddy to do a bit of heavy lifting. It's also helpful to have a second pair of ears to verify your listening tests.

Tip
Before starting this project, read the setup portions of the owner's manuals of your A/V receiver and subwoofer. They should contain information relevant to your specific models beyond the generalities we present here. If our recommendations conflict with the manuals' advice, stick with the manufacturers' methods.

3. Make the right connections

Channel bass signals from your receiver's sub-out to the subwoofer.

Subwoofers' connection schemes vary; some have just one input, while others separate left and right RCA jacks. In most cases, however, you'll just need to run one cable from your receiver's sub-out jack to the subwoofer. If your sub has direct or bypass inputs -- or a switch labelled Bypass -- we recommend using those connectors or that switch.

Tip
If your sub doesn't have a bypass or direct input, raise the sub's variable crossover filter control to its highest setting. That might be somewhere around 150Hz to 200Hz.

We strongly recommend the above hook-up technique, but if your receiver lacks a subwoofer output and your subwoofer has speaker-level inputs, hook up them to your receiver's front right and left speaker terminals, just as you would with the speaker's connections. (Take care not to reverse the plus (+) and minus (-) connections on the subwoofer and receiver.) This hook-up method will require doubling up the wires on the receiver's connectors, so you'll wind up with two wires on the red (+) and another two on the black (-) left and right connectors. Alternatively, if your receiver has A and B connectors and you're not using the Bs, go ahead and hook up the sub cable to the B connectors. Just remember to turn on the B speakers, or the sub won't make any sound.

Warning
CNET.com.au is not responsible for any injuries or equipment problems that may occur during or after you connect your subwoofer. Consult the relevant instruction manuals and warranty information before making any changes to your system's setup.

4. Adjust your receiver's setup menu

Configure the receiver's menu to integrate the sub with the rest of the speakers.

A/V receivers always have some sort of setup menu that appears on the receivers' front-panel display. Most AU$650-and-up models also feature easier-to-use onscreen menus, which are displayed on your TV. In either case, these menus typically cover every aspect of setup such as multiroom configuration and assigning digital inputs. You'll also find the vital controls that allow the receiver to send signals to the subwoofer via its sub-out connector, mentioned in the previous step.

To access the subwoofer options, you usually need to enter the speaker-setup menu. Then find the toggle or submenu that lists Subwoofer: On/Off, and select On. (Some receivers use other language such as Subwoofer: Yes/No.) Once engaged, the receiver will route the low-frequency bass effects to the subwoofer when needed.

Also important: Select the size of the satellite (front, centre, and surround) speakers. Large doesn't refer merely to the size of the speaker's cabinet; the speaker's woofer size is just as relevant -- anything smaller than six inches is always considered small. Then again, a lot of satellites with six-inch woofers still sound better when set to Small. Experiment with movies and music at both settings and see which sounds best to you.

Most -- but not all -- receivers let you select the crossover point (also called low pass filter) for the subwoofer; that determines the upper frequency limit of sound the receiver sends to the subwoofer. With large satellite speakers, set the crossover to 80Hz or 100Hz; for smaller sats, start with a higher crossover point, 120Hz or even 150Hz.

Tip
If you've hooked up your subwoofer with speaker wire instead of the interconnect cable we discussed in step three, set the front speakers to Large. Since the speakers will receive lots of bass, even if they can't reproduce it, they may distort at high volume levels. That's especially true for very small speakers or ones with four-inch or smaller woofers.

5. Adjust the sub's volume level

Fine-tune the sub's volume to eliminate boomy bass.

Precisely dialling in the proper subwoofer level takes time. Start with the subwoofer's level (volume) control set to its mid position and play some bassy CDs or DVDs (hip-hop music or an action movie, for example). Turn the sub level up or down so that the bass balance sounds right to you. What you'll soon discover is that some CDs and DVDs have a lot more bass than others.

What you're shooting for is a level that sounds about right for the majority of your discs. Don't be surprised if you find yourself refining that level over the following days; it can take a long time to get it just right. You can set the level either from the receiver's setup menu or using a knob found on the subwoofer itself. Even if you have a sound pressure meter, don't use it to set the subwoofer's volume; it's not all that accurate in the low-frequency range in which subwoofers operate.

Tip
Some folks like to have more subwoofer bass when watching DVDs, so you may need to turn up the sub's volume for DVDs, then crank it back down when playing music.

6. Verify the sub is operating in phase

Calibration discs are highly recommended for optimising performance.

When the woofers of your satellite speakers and the subwoofer's woofer move in and out in sync with each other, the system is said to be in phase. The alternative -- when the speakers and subwoofer are moving out of sync with each other -- produces uneven sound in the sonic range where the sub and satellites' bass overlap and cancels each other out. The audible effect of a system that's out of phase is less bass.

Fortunately, the phase switch found on most subwoofers offers an easy solution to the problem. To determine if your sub's phase is correct, play music with a lot of bass for a minute or so. Then walk over to the sub, flip the phase switch to the other position, and head back to the couch. The right (in-phase) position will yield more bass; the wrong (out-of-phase) position will actually cancel the bass where the satellites' and sub's bass overlap. In some cases, the difference between in phase and out of phase will be very obvious, and sometimes it can be fairly subtle. It's just a matter of finding the right piece of bassy music that highlights the overlap. If you have friends helping out, they can sit by the sub and flip the switch while you listen for the phase position that yields the most bass.

7. Find the optimal position for the sub

Corner loading for stronger bass effect.

Exactly where in your room you plop down the sub can make or break your bass. We can't stress this strongly enough: the best subwoofer in the world, poorly placed, will be at a huge disadvantage.

Room acoustics are notoriously unpredictable, so hard-and-fast rules are pretty scarce. That said, the classic corner position is a good starting point, as long as said corner is in the general vicinity of your main speakers. The corner will likely yield the most bass, but the sound may not be the best, most smoothly integrated with your satellites. Or the corner spot may sound overly boomy or heavy. Another simple setup option involves placing the sub directly behind or to the side of either the left or right front speaker.

Tip
Some folks like to have more subwoofer bass when watching DVDs, so you may need to turn up the sub's volume for DVDs, then crank it back down when playing music. The goal is to have the deepest, most powerful bass, without overpowering your main speakers. Ideally, you shouldn't be aware of the sub as a source of sound.

Want to play? You could try putting your sub in every possible position in the room to find the magic zone where the bass is both deep and tight, but we have a better idea. Move your comfy chair or sofa out of the way and temporarily put the sub in your prime listening position. Play music with lots of bass and set your disc player to repeat a 10- to 20-second section with a variety of bass notes -- we use Holly Cole's Temptation CD. Now take a little stroll around your room, slowly walk, or better still, crawl on your hands and knees (really!) around the perimeter, then out in the middle of the room. Chances are, you're going to hear a wide variation of the quantity and quality of the bass. It may nearly disappear in some spots, and in other places, the bass will be oppressively heavy. Keep moving and you'll probably come across a point or two where the bass is nicely balanced; all the notes should be equally loud. Assuming at least one of those spots is domestically and aesthetically acceptable, move the subwoofer to that point. (Now you'll be glad you invested in that extra-long cable.) Next try a few different bass-heavy CDs and DVDs to confirm the position. Once you're sure, place the sub in the spot that sounds best to you.

Most subwoofers aren't magnetically shielded, so they may distort the picture tube of a CRT (tube) TV or PC monitor, which could result in permanent damage. Place the sub a metre or so away from any tube set; if you see any picture distortion, turn off the TV and move the sub farther away from the TV.

If the sound is still boomy, try getting closer to the sub. Check out the coffee table and end table positions. Most likely these won't be the best locations for achieving the deepest, baddest bass, but they minimise the negative effects of problem rooms.

Now that you have the perfect location for the sub, reconfirm the level, phase, and crossover settings we covered in steps four, five and six.

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Add Your Comment 5


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nbl posted a comment   

i got two 12" car subs and i wanna know wats best for that in a home

 

dill dogz posted a comment   

hey! i love sub woofers there the best!

 

John G-K posted a comment   

A nearby facility has a sub woofer system, which is used in the early hours of a morning. Deep pulsations can be felt in my house even though the facility claims they turned the subwoofer down to an inaudible level in their location. What are the dynamics of sub audible sound transmission , and how do we overcome the problem ?

 

Jcozochi posted a comment   

How would two 500 watt subwoofer with frequency bandwidth of 18-200 Hz and and the other 20-200 Hz compare.

 

bassman posted a comment   

PLEASE I,m tired to see people who says that they have some degree in this technology mustering the wrong advices,If you want to set up PROPERLY a SUB use the techinician manuals of the DOLBY CINEMA PROCESSORS,go to www.film-tech.com and download it fro FREE,I use them every time I do installs and by the way the cheapest,used cinema processor will sound BETTER that most expenciest,fanciest home theater equipment you can buy




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