Do you use a second sub for your rear channel?

If so, does it make a lot of difference in the realism? I've seen a few systems that have a Bluetooth sub that goes in the rear and the rear surrounds are wired to it. The system I'm hooking up will have a main sub and then a second sub in the rear (not Bluetooth, but wired). Does this work better for movies, or both movies & music?

 

I would think that the .1 Sub Channel output would take care of all low frequencies. In my opinion, another sub in the mix would just muddy the water. Possibly even cancel out things you want to hear accurately.

 

Don't most (all?) home A/V receivers channel the deep bass and LFE to the front anyway?

 

I've never heard of using 2 subwoofers as front and back. Generally those low frequencies are non-directional so you shouldn't really hear them as coming from the front or coming from the back.

However, many people here swear by using 2 subs instead of 1 as a way of getting more even bass throughout the room.

 

Well my Sub(JPW) is set up at tha Front(at a angle, but not in a corner) I think with Dolby Surround tha Rears are limited so might be pointless, but I believe Dolby Digital 5.1 onwards tha Rear are Full Bandwidth? could be wrong.. Idk? If you have a BiG room then maybe 2 x Subs would work(be Cool) but it'd take some placement and messing with as to not muddy tha Sound ..experimentation with position and crossover and overall volume level is probably tha key, I've dialled mine right down on tha Volume but still not 100% happy with it, on some CD/Movies it sounds Great and on others either too much or too little.. Still playing with it tbh(well when Neighbours are out) forgot just how much difference a Sub can make.. Makes me smile like a BiG kid!

atb

 

First, the more subs the better. The more subs that you use in the room, the more even the sub-bass is. There are two separate things I am speaking about here.

1) All low frequency information is not omni-directional. Even that is relative. The longer the wavelength, the less the human ear has the ability to localize it. Simple stated, 40Hz is omni-directional, 80Hz is not. 80Hz is one octave up from 40Hz, 20Hz is one octave down from 40Hz. This represents a range of two octaves.

In general, most people will set their crossover somewhere between 40Hz and 80Hz range. If using for HT, each speaker channel can have its own crossover point. For example, an average center channel speaker is usually a compact box design, with two midrange speakers, usually 4.25" to 6.5" and a 1"tweeter between them. This is referred to as a MTM arrangement. This small size enclosure, together will small size speakers, obviously, will produce a limited amount of bass, as compared to larger tower speakers on each side, for the fronts.

In a 5.1 surround sound system, there is a LFE (low frequence effects channel), information that the movie studios wish to designate as an LFE, such as the rumble during an earthquake, that information is automatically sent to the LFE's channel, which is connected to the sub or subs.

In HT, you may elect to engage "bass management", this is where you are taking a designated portion of the full range information being sent to each of the five channels and routing that portion to the LFE's channel. In the case of the center channel, everrything below 80Hz may be rerouted through the LFE's channel. This accomplishes two things. 1) If you are running a self powered sub, then the sub is using it's own power to power that information. That means that your center channle speaker will handle less information, taking a load off of it. And, your amplifier will not have to reproduce that portion of the information, making your amplifier work less.

Going back to my earlier statements, if you place a sub next to one of your front speakers and play an 80HZ tone through it, you will look directly at that sub and you will know exactly the direction, where it is coming from. If you and a 2nd, a 3rd or a 4th sub in the room, your ears will not be able to localize the information. Having a rear sub is even recommended in HT applications for that reason.

BTW, I always use a wireless rear self powered home sub (top of the line sub from Polk Audio, bought on 50% off sale), along with a large passively powered (powered by an external Crown Class D amplifier) commercial sub.

2) There are room nodes. Room nodes naturally occur in every room with walls, rooms having parallel walls, which are most rooms. More subs, properly placed (the key words here are "properly placed") will tend to smooth out and eliminate those nodes. How do you know if you have an issue with a node? If the bass is boomy at one place in the room and the bass is light in another place, that is a node. Even that is not necessarily a bad thing. If you like strong bass, and that strong bass signal occurs at your listening position, that my not be bad at all. If it is too strong, to the point of being boomy, simple turn down the volume on your sub. Problem solved.

Another fallacy, is that using a sub when listening to stereo, will result in boomy muddy sounding bass. It can be, but that is not necessarily the case.

Many people use there front tower speakers for both 2-channel stereo and HT. Tower speakers typically play down to 40 or 50 Hz. If my fronts play down to 40Hz, I would set my sub to crossover at 40Hz, with a steep slope, so that the sub is not playing at the same time (and frequency), as your bass speaker(s) in your towers.

Unless you have a crappy sub, what reason would you have for having muddy sounding sub-bass?

Bass itself is very misunderstood, most bass that you hear and feel in your chest is not that deep as you might think that it is. Most of bass that you hear in real world music is above 50-60 cycles.

Let's take a bass guitar for example, that and a bass drum (and floor tom's) are a low as the average person is going to experience bass in music. That is, unless you are a fan of contrabassoons or church pipe organs. Most musical groups from the 60's forward, who use amplified, but not synthesized music, employ the use of a bass guitar.

An open lower "E" string on a bass guitar is 41.2-cycles referencing a 4-string bass guitar with 24 frets). The high "G" (the 24th fret) will be 392 cycles. The harmonics, which occur along with the primary frequencies, will reach up to 4-5 kilohertz.

When you listen to a bass player, playing a solo, how often does he stand there, plucking his open lower G string? Not that often, I would think.

Most of the notes that a bass player is playing are 60-cycles and much higher, way above sub bass.

I will typically run 3-4 subs both with HT and 2-channel stereo. Sometimes, there is not enough bass and that is because the source recording itself, is light on Bass. A lot of music from the middle 60's does not have much bass in the recording, Beatles music and such.

Modern music, makes use of sub bass synthesizers, which, in addition to the real bass note, will also produce a note that is an octave below that. With synthesized music, notes of any frequency can be produced.

Since I have a preference in Jazz music, I enjoy nice effortless bass that is produced by a standing double bass. My system is designed with this in mind.

When extreme low, Dubstep type bass is employed, you know that the subs are there. And example of this is:

Crystallize - Lindsey Stirling (Dubstep Violin Original Song)



I use these remote AC on/off switches on various parts of my system, they operate off of a half dozen wireless radio channels.


The ones that I have have small key fob type switches with an on and an off button for each switch.

You could put one on your rear sub, and turn it on and foo any time you want to. You can do the same with your front sub.

S&G

 

I think you should use two subs for eby tang.

 

I have a sub under each rear channel speaker. The front channels have a combined sub channel going to two more subs. The preamp is set to: LFE=none, Front=big, Rear=big, Center=none. This way, movie LFE gets routed to all channels and is handled by all subs. Two channel music gets the front two subs, unless I use Matrix mode which will then use all four. Reasons for doing so are outlined by SandAndGlass, so I won't repeat it here.

I do have a question about the OP's setup...

Is the second sub in the rear just another copy of the .1 channel, or a unique signal?

 

Copy of the .1 channel

 

By all means, give it a shot. If you already have the gear on hand, that is. Search on 'distributed bass' for further reading. Try to avoid exactly symmetrical placement of front and rear subs. Experiment.