You can, but the timeing would come into consideration.
Give it a try and if you like it, go with it. |
Sub bass should not be directional. You should not hear where it is coming from when set up properly. It may take a while to get it right so be patient. |
When I first got my subwoofer I had it sitting directly behind my side of the couch via wireless connection. A friend of mine came over to hear the subwoofer and assumed that he was hearing the "before" since he didn't see the subwoofer. He was, however, wondering why I need a subwoofer based on what he was hearing. It's now next to the right channel speaker because the wireless connection didn't play well with my wireless printer or internet connection.
I believe that they have done studies showing that people can't pinpoint a direction below 80 Hz. |
It should be non-directional but the timing issues remain, anyway, especially with wireless connections that introduce 10-20msec or more of delay. This can work but putting the sub up front with a wired connection makes it a lot easier.
Kal |
Dual stereo L/R time aligned subs matched up with the mains is the way to fly. Even if you cross over the subs at 40hz the actual cabinet enclosure acts as a giant passive radiator creating at least 4th order harmonics that need to be blended in to the mains. It is very easy to hear the placement of one and near impossible to hear the two as described. Each woofer will greatly benefit in speed and transparency if the cabinet is direct coupled { use brass] to the mass of the floor. Direct coupling {use brass] the woofer cabinet to the floor will limit the upper harmonics into the midbass and beyond resulting in much more clear mids in the main speaker pair. Tom |
Good answers...and the truth is..yes and no...based on the above.
In the old days of analog only, the answer was yes. Drive by a bar/dance club at night and you will only hear/feel the bass....sometimes the voices...but try to hear a cymbal... |
It's I've read, but not what I've heard. |
"
In the old days of analog only, the answer was yes. Drive by a bar/dance club at night and you will only hear/feel the bass....sometimes the voices...but try to hear a cymbal..."
Irrelevant. That has to do with sound absorption issues.
Kal |
The basic anwser is yes, bass is non directional in an any channel rig, but at different frequencies for different people. Some people start loosing the ability to discern where bass comes from as high as 120hz, by the time you get to 80 hz, no one can tell where it comes from. |
I've got one sub near side wall, plane is slightly behind me, and another next to one of my mains. Both crossed well below 80Hz they work very well and direction is unnoticable. |
Try putting the sub in a corner... |
"Try putting the sub in a corner..."
Only if you want to excite all the primary modes of the room.
Kal |
You can hear where the bass originates even below 40 hz. Again the box/enclosure is a giant passive upward frequency generator. A 40 hz crossover point will not stop the box from being pressurized above that selected frequency. You will increase the sound stage image size by roughly thirty percent with the proper implementation of time aligned stereo subs. Ground the subs to the floor
Tom
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Mitch4t,
Sorry, I just realized that I did not completely answer your question... Also yes, you can put a sub behind you. Back at Marcof Electronics seems like 300 years ago, we had our own sub design. We buit an 8, 10, 12 & 15 inch model.. At some time or another we had tried each of these sitting right behind us, Maybe 2 feet, while the speakers were about 8 feet in front of us. Once spl was matched, they all worked well, undetectable. |
"Again the box/enclosure is a giant passive upward frequency generator."
Only if the design/construction is incompetent.
Kal |
I still find this research pertinent and it will answer some of your questions.
http://www.harman.com/EN-US/OurCompany/Technologyleadership/Documents/White%20Papers/multsubs.pdf |
Kal
A room an enclosure and free air are all passive radiators so they all must be incompetent. Tom |
08-15-11: Theaudiotweak
"You can hear where the bass originates even below 40 hz".
Well maybe if crossed at 40HZ @ 6 db per octave, maybe, but crossed @ 12, 18 or 24 db per octave. I wish that I could quote some test somewhere, but I have had hundreds of people demo subs that had no idea where it was, even when sitting on it crossed @ 80HZ @ 24db per octave.
I guess it is possible that your hearing is more sensitive at those frequencies than others or you could be dealing with room nodes???
No disrespect intended, its just that we have tested this theory countless times.
I have seen cars rattling windows a block away and no one could tell where the boom came from until it drove right past us...
Have you done some testing to substantiate this? |
Theaudiotweak:
A room an enclosure and free air are all passive radiators so they all must be incompetent. C'mon. The dimensions are quite different and, therefore, so are the frequencies. Besides, those are a constant so that adding a sub will make no difference in their effect. There is a lot known about the science of acoustics but it always amazes me how few audiophiles make the effort to learn about any and prefer to rely on hear-say. Kal |
And their are those who look beyond what has been published yesterday. The most important word you posted is 'hear' A box has boundaries and so does a room. When pressurized they generate upward harmonics even from applied electrical slopes of 24db. I have used eight different pairs of stereo subs over the the last twenty nine years in four different homes. I would never again consider using a single sub in my music room. Tom. |
Timlub
Back in the day when I first began to use stereo subs I also used Marcof inner connects the ones that were black. I also had the latter blue ones but the black ones sounded as if they had less phase shift so I sold those off the blues and stayed with the blacks. The battery powered pre-preamp was also excellent and worked well with my Accuphase AC2 and the Denon 103d and 103c.I also stopped by your location in the St.Louis area.
Thanks for those products. Tom |
Thanks Tom,
As you might expect, I've got quite a stash of Marcof innerconnects, I also use our speaker cable. We experimented greatly with litz, different braids, wire guage etc. I am using some that we never manufactured, but they are closer to what you have than the blue (se) models. Ed still says he still has PPA-2 head amps. They were a significant step up to the PPA-1 that sold so well. I agree completely about stereo subs, I just haven't heard one crossed @ 40hz that was directional. You may be one of the select few that can recognize this. |
"You will increase the sound stage image size by roughly thirty percent with the proper implementation of time aligned stereo subs." - Theaudiotweak
Where does the 30% figure come from? There must be some science and math associated with such a statement.
I've always assumed that 45% of all statistics are made up on the spot, you can quote me. |
Several first time visitors when hearing the system with their eyes closed were asked to point in both directions where the sound stage ended..it was a foot or two beyond the main stereo pair. When asked to do the same with the same recording the same volume only this time with the subs on.. they pointed with both hands in a plane that was parallel with the speakers,extending from wall to wall 21 ft. This physical description came from one person at a time having two eyes and two ears and two arms. There is also an increase in stage height as well as an increase in image stability between the stereo pair with the subs engaged. Tom |
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Rather than stuck in a box I will accept "off the rails" as a compliment. Thanks Tom |
Have you done that same experiment with a single sub places behind the listening position? It makes sense that that having more bass will better "fill" a room and this is what I think you're describing. |
Theaudiotweak:
Rather than stuck in a box I will accept "off the rails" as a compliment. Thanks Tom I applaud the consistency of your misapprehensions. |
Mceljo
No I have not done a single behind the chair sub but I may add a third off to the left side of my room some 14 feet back from my listening chair. I am sure there is a void this 3rd may fill that hole where ever it is.
Soundstage presentation is one of the most important sonic attributes to me. The wave launch alignment pairing of subs and the mains is crucial to make all this happen visually. The subs I currently engage, in the same way as the past three pairs have less bass weight but better mid range. How can a woofer have better mid range especially when crossed over so low..better box design [the box is a passive radiator] and better coupling [brass] extraction of resonant energy to the greater mass of the floor. Tom |
An audible and visual floor to ceiling wall to wall sonic presentation. No holds barred and no apprehension of scale or contrast. The 3rd sub may add some weight but I cannot allow it to alter the time and phase coherency I currently have. I would have to blend a mono signal into this 3rd sub at a reduced level from the front pair so as not to disrupt the front stage visually. Tom |
Richard Vandersteen and I were talking about this very topic, and he likes even more subs than 2....he likes 3 and even 4. The reason is you get a more even projection of the sound. Yes even with his 7's he gets better midrange and highs by using multiple subs. |
Theaudiotweak - I wasn't thinking of adding a third sub as much as wondering if you had done the same experiment with a single sub in a different location to see what people perceived about the listening stage. |
No I have never tried that. It would be mixed mono and not stereo and there would't be the close chance of aligning the voice coil of the mains and the subs. I have used a single sub of the same pair while I was doing a mod on its mate. The single playing sub was not moved and I could hear where it was placed even in mixed mono. I think at that time it was the Paradigm Servo 15 pair. They always have flanked the mains. Tom |
I'd be interested to know if your test people that evaluated the soundstage difference would have different results using a single subwoofer. I suspect your ability to pinpoint the subwoofer is much better than even the above average Joe. |
I have had a number of people be part of this demonstration some listeners with a great deal of experience others who think an I-Pod is highest of fidelity. None however with just a single sub. Tom |
How can you be sure that the difference in soundstage results from having two stereo subs located as you have them and not just a result of any sub placed anywhere? |
I have modded pairs of subs before...one at a time. I always had one to listen to and ran it in mono. I left the sub that played in the the same position as when it was part of the stereo pair. I also have a Velodyne smps digital eq which is mono only and eq'd and ran my current stereo pair of subs from this digital box. I had more bass but a worse sound stage and bass tone that was to me less life like and enjoyable. I removed this box from the system. Tom |
Yes, assuming that levels are matched, you have a 4th order electrical low-pass filter, and your sub-woofer is free of distortion, port noise, and rattles
One caveat is that stereo bass with phase differences between the two ears can create a sense of envelopment although you can't localize it.
The counter argument to that is that random, asymmetric placement of multiple sub-woofers produces more uniform frequency response above the room's fundamental resonance and avoids one-note bass problems. |
Very low frequencies like 40Hz and below start to become omnidirectional but their harmonic content doesn't, and this makes many woofers localize. I can always tell where a subwoofer is in someones room. I recommend stereo subs unless they are crossed 30Hz or lower. |
"Irrelevant. That has to do with sound absorption issues."
Semi-correct, actually a bit more about wave length and dispersion......
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as a P.S. to my last response, you might through a little waveguide theory in there as well.... |
