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| Home Theater Subwoofers How to Get Great Bass in Your Home Theater |
Subwoofers
Subwoofers create much of the "Wow!" factor for your home theater. When that
explosion hits you right in the gut, that's your subwoofer in action. Subwoofers
have always been an important part of a home theater speaker system but with
the advent of digital surround sound systems, they are even more important.
Home theater speaker configurations are denoted as 5.1, 6.1 or 7.1. These
numbers stand for the number of full range channels and the additional LFE or
low frequency effects channel.
The LFE allows directors and movie sound designers to have a channel dedicated
to bass information that is strictly for effect. Explosions, trucks driving by, car
doors slamming, music, etc. All these sound track elements have a great deal of
low frequency information. The ability to have a supplemental sound track channel
specifically for this bass information is one of the main reasons subwoofers are so
important for your home theater.
The other channels are full range (20Hz-20KHz) and can have substantial bass
information in them as well. Before the advent of digital surround sound systems,
this was not the case except for the left and right front speakers. If your main
speakers can not handle bass well, you can route the bass from these speakers
to the subwoofer, along with the LFE information. Relieving your main speakers
from the task of producing the low bass will usually make them sound much better
and give your home theater system much better bass performance.
This redirection of the bass frequencies away from the main speakers is
accomplished by setting the speaker size to "small" in the set up menu of your
surround sound processor or A/V receiver. With most high quality surround
processors and surround receivers, you will have a choice of crossover
frequencies. The crossover frequency is the point in the audio spectrum where
the sound is divided and sent to the appropriate speakers.
Another benefit to setting your surround processor or receiver this way is that the
amplifiers that power your main speakers will not have to dedicate any power to
the bass frequencies. Bass is the most demanding frequency range, in terms of
output, that an amplifier must reproduce. Bandwidth limiting the main amplifiers in
this way will increase their headroom, allowing them to play louder and much more
dynamically before distortion sets in.
Making alot of bass requires moving alot of air. To do this, the speaker cone must
be large in diameter or move a substantial distance back and forth, preferably
both. It must not distort the sound when doing this. The trend in subwoofers today
is toward smaller boxes. This allows more placement options and intrudes less on
the room's aesthetics. Because of advances in digital amplification and materials
science, it's no longer necessary to have a huge subwoofer enclosure to get
credible bass.
Many of the smaller woofers do a great job, albeit usually at an increased cost
over similar performing subs in a larger enclosure. They move as much air as a
larger woofer by putting a special, extra long stroke driver into a small cabinet.
They then use a very powerful, digital amplifier, and usually some type of digital
signal processing or servo control to make the woofer cone travel a long way.
Some of these small subs have woofer cones that have over an inch of peak to
peak travel!
Most subwoofers used in home theater applications are powered units with the
amplifier built in to the speaker enclosure. Some have an external amplifier that is
located in the equipment rack or cabinet. This is especially true of in-wall subs,
obviously. Subs that have only a speaker level input are not the best choice for
home theater applications.
Subwoofer Placement - How Many Subwoofers & Where to Put Them?
The latest research on subwoofer installations in small rooms (That is all rooms for
the purposes of home theater) indicates that multiple subwoofers are critical. This
is not just to give the room more bass, although you can accomplish that as well.
The more cone area and motor driving those cones will allow more air to be
moved, and deliver more bass into the room. This increases the headroom of the
subwoofer system, allowing the subwoofers to work less to deliver the same bass
response and gives a higher maximum output level.
The larger benefit, however, comes from the way those multiple subwoofers
interact with the room and how they excite the different room modes. The problem
is getting great bass response throughout your home theater, at every seating
location. It is a much more difficult proposition to get great bass response
throughout the room than it is to get at any one location. Multiple subwoofers,
correctly placed, allow the maximum number of room modes to be excited. Doing
so will give smoother frequency response at every seating location by minimizing
the height of response peaks and depth of response nulls. The response peaks
can then be reduced with a good parametric equalizer. The nulls, or response
dips, are reduced in severity by using multiple subwoofers. This is advantageous,
because you cannot get rid of bass response nulls with an equalizer. This is
because nulls are created by cancellation and you cannot boost something that
has been destroyed.
When using multiple subwoofers in a home theater, or any other listening room,
they should be placed on the floor, in the front corners, in the case of two subs.
When using four subs they should be placed on the floor, at the mid points of
each wall. The use of multiple subwoofers in this way provides rather dramatic
improvements in bass throughout the room. The bass will be less boomy, with
more articulation and power. You and your theater watching friends will be much
happier.
Subwoofers create much of the "Wow!" factor for your home theater. When that
explosion hits you right in the gut, that's your subwoofer in action. Subwoofers
have always been an important part of a home theater speaker system but with
the advent of digital surround sound systems, they are even more important.
Home theater speaker configurations are denoted as 5.1, 6.1 or 7.1. These
numbers stand for the number of full range channels and the additional LFE or
low frequency effects channel.
The LFE allows directors and movie sound designers to have a channel dedicated
to bass information that is strictly for effect. Explosions, trucks driving by, car
doors slamming, music, etc. All these sound track elements have a great deal of
low frequency information. The ability to have a supplemental sound track channel
specifically for this bass information is one of the main reasons subwoofers are so
important for your home theater.
The other channels are full range (20Hz-20KHz) and can have substantial bass
information in them as well. Before the advent of digital surround sound systems,
this was not the case except for the left and right front speakers. If your main
speakers can not handle bass well, you can route the bass from these speakers
to the subwoofer, along with the LFE information. Relieving your main speakers
from the task of producing the low bass will usually make them sound much better
and give your home theater system much better bass performance.
This redirection of the bass frequencies away from the main speakers is
accomplished by setting the speaker size to "small" in the set up menu of your
surround sound processor or A/V receiver. With most high quality surround
processors and surround receivers, you will have a choice of crossover
frequencies. The crossover frequency is the point in the audio spectrum where
the sound is divided and sent to the appropriate speakers.
Another benefit to setting your surround processor or receiver this way is that the
amplifiers that power your main speakers will not have to dedicate any power to
the bass frequencies. Bass is the most demanding frequency range, in terms of
output, that an amplifier must reproduce. Bandwidth limiting the main amplifiers in
this way will increase their headroom, allowing them to play louder and much more
dynamically before distortion sets in.
Making alot of bass requires moving alot of air. To do this, the speaker cone must
be large in diameter or move a substantial distance back and forth, preferably
both. It must not distort the sound when doing this. The trend in subwoofers today
is toward smaller boxes. This allows more placement options and intrudes less on
the room's aesthetics. Because of advances in digital amplification and materials
science, it's no longer necessary to have a huge subwoofer enclosure to get
credible bass.
Many of the smaller woofers do a great job, albeit usually at an increased cost
over similar performing subs in a larger enclosure. They move as much air as a
larger woofer by putting a special, extra long stroke driver into a small cabinet.
They then use a very powerful, digital amplifier, and usually some type of digital
signal processing or servo control to make the woofer cone travel a long way.
Some of these small subs have woofer cones that have over an inch of peak to
peak travel!
Most subwoofers used in home theater applications are powered units with the
amplifier built in to the speaker enclosure. Some have an external amplifier that is
located in the equipment rack or cabinet. This is especially true of in-wall subs,
obviously. Subs that have only a speaker level input are not the best choice for
home theater applications.
Subwoofer Placement - How Many Subwoofers & Where to Put Them?
The latest research on subwoofer installations in small rooms (That is all rooms for
the purposes of home theater) indicates that multiple subwoofers are critical. This
is not just to give the room more bass, although you can accomplish that as well.
The more cone area and motor driving those cones will allow more air to be
moved, and deliver more bass into the room. This increases the headroom of the
subwoofer system, allowing the subwoofers to work less to deliver the same bass
response and gives a higher maximum output level.
The larger benefit, however, comes from the way those multiple subwoofers
interact with the room and how they excite the different room modes. The problem
is getting great bass response throughout your home theater, at every seating
location. It is a much more difficult proposition to get great bass response
throughout the room than it is to get at any one location. Multiple subwoofers,
correctly placed, allow the maximum number of room modes to be excited. Doing
so will give smoother frequency response at every seating location by minimizing
the height of response peaks and depth of response nulls. The response peaks
can then be reduced with a good parametric equalizer. The nulls, or response
dips, are reduced in severity by using multiple subwoofers. This is advantageous,
because you cannot get rid of bass response nulls with an equalizer. This is
because nulls are created by cancellation and you cannot boost something that
has been destroyed.
When using multiple subwoofers in a home theater, or any other listening room,
they should be placed on the floor, in the front corners, in the case of two subs.
When using four subs they should be placed on the floor, at the mid points of
each wall. The use of multiple subwoofers in this way provides rather dramatic
improvements in bass throughout the room. The bass will be less boomy, with
more articulation and power. You and your theater watching friends will be much
happier.
If you'd like to build your own high performance
home theater subwoofer, check out
home theater subwoofer, check out
Home Theater Subwoofers
1 Touch Movie.com
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Copyright 2004-7 1 touch movie.com
Home theater and Automation Guide
All rights reserved.
Home theater and Automation Guide
All rights reserved.