Home Theater Subwoofer Setup

October 17, 2004

hsu_stf-3.jpgMore often than not, the number one piece of home theater gear I see setup incorrectly is the subwoofer. I’m not sure if it’s the fact that by and large subwoofers are new to the majority of first time home theater owners or that there is so much misconception about how their supposed to work in general. Regardless I want to, hopefully, shed some light on their use so you can get more out of them. The most important thing to keep in mind is that a subwoofer isn’t supposed to increase the apparent volume level of bass in a room. They’re only supposed to augment the bass extension of your main channels.

Sounds simple enough, but walk into almost any mass market electronics retailer and ask to see a “home theater” demo and you’ll likely get the big slam bam way to damn loud, don’t you want to impress your friends with this demo. This isn’t home theater, it isn’t even really audio, it’s a hokey sales pitch at best and totally irresponsible at worst. This is the type of sound you don’t want. For example, really nice front channels and superb front end equipment with enough clean power to drive the speakers, 9 times out of 10 sound better alone than just throwing in a subwoofer in and cranking it up, it’s in the setup…


A subwoofer, in my opinion at least, should just extend the range of your existing front channels down to lower frequencies. How low really depends on how good your front channels are and how much you want to invest in the sub. But not all good subwoofers need to cost an arm and a leg. Models from HSU research, B&W, and others, offer serious performance for under a thousand dollars. But shop around and audition as many as you can, as even $500 retail can buy a winner.

Alright now you’ve got your bass maker, what’s next? Often the number one mistake I see is improper frequency crossover. I can’t tell you how many times I’ve walked behind a client’s subwoofer and turned the crossover back by almost 50%. Folks please do this if you do nothing else, don’t mistake the volume and the crossover controls for one another. The volume does just that, it turns the internal amplifiers volumes up and down. Ideally your sub should never be able to play “louder” than your main channels. In other words, if your mains are at “5” and your sub is at “7” you’re never going to accurately hear what’s on the soundtrack.

The crossover controls might be a little harder to dial in, but the theory is the same. You want to match the crossover relative to what your mains are capable of doing. If you have decent main channel speakers and they’ll play comfortable down to say 75hz, then by all means let them. Don’t set your sub to 100hz. You’ll be wasting at least 25% of the amps headroom and have a “collision” of frequencies that rarely sound meshed. What you want to do is find out how low your mains will play, either with a sound meter and some sort of test disc, or check your manufacturer’s specs and hope they are at least somewhat accurate.

Then set the sub just above that range and then use a disc such as Digital Video Essentials or the AVIA guide to home theater and find the sections that contain “pink noise”. Play those sections in a loop and slowly turn down the crossover control on your sub until you hear distinct differences in the main channel’s and subwoofer’s frequency ranges (mid/low and lower) and then slowly turn it back up until they blend. Go any higher past the point they blend and you’ll be wasting amplifier headroom. Go any lower and you’re likely to create a “bass gap” between the point your main channels drop off in bass response and where the sub woofer starts.

Summary:

Like almost anything else in home theater sound and setup, a little experimentation goes a long way. Play around with your subwoofer’s settings and you’ll be rewarded by deep, impactful bass and a better interpretation of what the director and sound engineer intended.



Posted by Bryan Greenway | | Filed Under Home Theater How-to


Comments

  • sean

    I’m building a home theater system and have installed all of my in ceiling speakers and ran all of my HDMI wires, CAT5, phone and ever other wire you can think of. Now it’s time to buy the stereo to run the entire house. I need a two zone system so I can play music in the rest of the house while running the movie room. I have a simple 5.1 system in the theater but have 6-8 more speakers to run in the rest of the house. Any suggestions would be great.

  • sean

    I’m building a home theater system and have installed all of my in ceiling speakers and ran all of my HDMI wires, CAT5, phone and ever other wire you can think of. Now it’s time to buy the stereo to run the entire house. I need a two zone system so I can play music in the rest of the house while running the movie room. I have a simple 5.1 system in the theater but have 6-8 more speakers to run in the rest of the house. Any suggestions would be great.

  • I have a velodyne SPL 1000 subwoofer. It has Low pass crossover 40 to 120Hz. Also, a phase adjustment 0 – 180. It also has crossover switch-Internal x-over/subwoofer direct. Thing is whats the best setting for good bass response without overload? I have an integra amp 120 total x 7. Has eq setting in menue. However, receiver has eq setting at 80Hz, 250Hz, 800Hz. 2.5KHz, and 8KHz. What do those frenquiy mean? What frenquency is high, what’s low? What are good settings for sub and main speaker frenquencies?

  • William

    I have a velodyne SPL 1000 subwoofer. It has Low pass crossover 40 to 120Hz. Also, a phase adjustment 0 – 180. It also has crossover switch-Internal x-over/subwoofer direct. Thing is whats the best setting for good bass response without overload? I have an integra amp 120 total x 7. Has eq setting in menue. However, receiver has eq setting at 80Hz, 250Hz, 800Hz. 2.5KHz, and 8KHz. What do those frenquiy mean? What frenquency is high, what’s low? What are good settings for sub and main speaker frenquencies?

  • B.Greenway

    Hi Bill, high cut would be but phase is used to blend the sub with the mains.

  • B.Greenway

    Hi Bill, high cut would be but phase is used to blend the sub with the mains.

  • bill

    hi, good article–my manual refers to “HIGH CUT” and PHASE—are these crossovers or ?? thanks BIll

  • bill

    hi, good article–my manual refers to “HIGH CUT” and PHASE—are these crossovers or ?? thanks BIll

  • B.Greenway

    Hi Ken, possibly by using speaker level inputs on the sub if that’s an option. Otherwise your options are obviously limited.

  • B.Greenway

    Hi Ken, possibly by using speaker level inputs on the sub if that’s an option. Otherwise your options are obviously limited.

  • Ken

    hi and well done with the article. I have come by a powered sub (Kenwood) and would like to use it with my system. It only has a single line in input. My Phillips proligic amp does not have a sub out. Is there a way i can connect the sub?

    thankyou…

  • Ken

    hi and well done with the article. I have come by a powered sub (Kenwood) and would like to use it with my system. It only has a single line in input. My Phillips proligic amp does not have a sub out. Is there a way i can connect the sub?

    thankyou…

  • B.Greenway

    Right you are SubGuy, however if you’ll take a look at the articles date it was quite some time ago and receivers with sophisticated bass management weren’t quite as common as they are today.

    By all means take my setup instructions the same whether you’re using the on-board crossover or the bass management controls in your receiver.

  • B.Greenway

    Right you are SubGuy, however if you’ll take a look at the articles date it was quite some time ago and receivers with sophisticated bass management weren’t quite as common as they are today.

    By all means take my setup instructions the same whether you’re using the on-board crossover or the bass management controls in your receiver.

  • SubGuy

    Most setup instructions have the crossover on the sub itself disabled, or turned up all the way if there is no way to disable it, with the bass management within the surround receiver used instead to roll off the bass from the main channels by setting them to large, and re-routing that bass to the subwoofer.

  • SubGuy

    Most setup instructions have the crossover on the sub itself disabled, or turned up all the way if there is no way to disable it, with the bass management within the surround receiver used instead to roll off the bass from the main channels by setting them to large, and re-routing that bass to the subwoofer.