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Discussion Starter · #1 ·
I am trying to decide whether or not to go with one infinite baffle sub or set up subs for each of the front left and right speakers and subs for each of the surround speakers.

The main speakers are Magnepan 1.6's. Either way, the crossover point would probably be set at 80 hz.

Will I gain anything by having stereo bass or just create a lot of setup headaches?
 

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Using subs for each channel would create dips and peaks that the best EQ and RTA in the world could not rectify. I would use one, or a second sub in mono and implement the bass management feature of your prepro. This will result in even bass response from all six channels. In your proposed scenario you would have to buy six subwoofers, the six being used to monitor the LFE channel. Physically locating subwoofers in five locations in a room usually results in wildly varying bass response on the different channels. Bass Management creates five full-range speakers with the identical 20-20KHz response. You really need to know what you are doing using more than one sub. You could stack two sub cabinets in a front corner, or place them asymmetrically to smooth out standing waves and create better dynamic range, or as you suggested, "bass imaging" like in this drawing: http://www.hometheaterhifi.com/qa/qa2002/qa296.html
 

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I have found that my bass response is fairly flat even without a parametric EQ. I have full range speakers on all 5 channels rather than using a subwoofer. My bass stays flat all the way down to 25Hz +/-2db. I tapered it off at 25Hz to keep from tripping the breaker, but I had it flat to 15Hz +/-2db for a while - all without a parametric EQ.
 

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hometheateguy

I am surprised to see you argue against multiple sub-woofers as Russ typically uses 6 and Keith Yates as many as12 subs in their installations. If you were to place both subs in the same area it could cause the room anomalies Hometheaterguy describes. But if you placed them in different areas of the room, such as the null pressure zones ( as Russ has taught us to do - of course, identifying these null pressure zones is an other story ) it can smooth out bass response. In fact, Russ has argued for this for years holding that multiple subs rather than exacerbating room modes will fill in the peaks and dips one sub would cause.


But as I have never had the privilege of Russ' clientele so I can only report that installing 2 subs did not adversely effect the bass response.

I would think the greater problem would be finding a sub with the speed to integrate with your Magies.


Alan
 

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Alan, read twice and post once. RE-read my post. I did not argue against multiple subs. I said be careful in the placement and equalization of multiple subs. What I did say is using subwoofers for all 5 channels is detrimental. James wanted to: place "subs for each of the surround speakers".
 

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This area seems to be one of a somewhat controversial nature. While apparently it is possible to smooth out response (a paper I read from someone at Harmon Kardon said 4 subs is just about the optimal spaced equally on each side of room), others like Tom Nouisane say that the cost/benefit ratio is not good as opposed to one sub, generally in the corner-especially if you don't have the ability to measure and fine tune. So lots of opinions.
 

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Quote:
I have full range speakers on all 5 channels rather than using a subwoofer. My bass stays flat all the way down to 25Hz +/-2db.
Were those measurements taken with all five speakers running simultaneously? If not, check it that way; you’ll probably find the results will not be that good.
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In fact, Russ has argued for this for years holding that multiple subs rather than exacerbating room modes will fill in the peaks and dips one sub would cause.
For those of us who would prefer to fill our rooms with seating or home furnishings rather than a plethora of black or wood grained cubical boxes, a single sub with a parametric equalizer will do a better job for a fraction of the price.
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I read from someone at Harmon Kardon said 4 subs is just about the optimal spaced equally on each side of room)...
That would be the Harmon paper at this link: http://www.harman.com/wp/pdf/multsubs.pdf . If you note near the bottom of page two, it specifically states that the results of the study are only valid in a similar room.


This is what people consistantly fail to understand, that any tests of this nature are relevant only in the room they were conducted in, or one very similar. So unless you happen to have an identical room, take the conclusions with a grain of salt. The same with Mr. Hershelmann’s theories.
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Tom Nouisane say that the cost/benefit ratio is not good as opposed to one sub, generally in the corner-especially if you don't have the ability to measure and fine tune.
I personally give a lot of credence to Tom Nousaine. Unlike a lot of other experts, he is the only one I’m aware of that has conducted and published tests in numerous residential settings.


Regards,

Wayne A. Pflughaupt
 

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Wayne,


You are correct about the room but I am sure you will agree that this area is one were the "experts" disagree. By the way, I too place a lot of credence with Tom's opinions. He is pretty easy to aske questions of at the google groups also.


Randy
 

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Matthew Polk agrees on multiple subs placed asymmetrically, not stacked. He also abhors equalization.
 

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I don't know who is right and like Wayne says the room can be king, but do we know any speaker manufacturers who argue against mulitple subs-there may be some but I am not sure who:)
 

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M&K Professional (M&K Sound, www.mksound.com ) swears by multiple subs (stacked in corners), or placed behind the listening position see this picture: www.mkprofessional.com Doug Osbourne, the Directer of Marketing for M&K concurs with multiple subs. Russ Hershelmann in his CEDIA seminar called "Home Theatre: Essential Elements' in'95 said "use twice as many subs as you think you will need". And he told me "multiple subwoofers placed asymmetrically yields the smoothest bass response". Polks "Home Theater Handbook" elaborates: "multiple subs provide better dynamic range and smooth out standing waves". Russ has only one M&K sub (dual 12s in a push-pull sealed cabinet) in his Disney gig ( www.uhte.com ). He does have Bass Shakers though. The majority in this matter is room size (more bass for more cubic feet) and room acoustics.
 

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But.....Tom Nousaine generally will argue against it for a few reasons one of which is cost/benefit and.....he is not trying to sell subs. Don't get me wrong I am not saying one way or the other, but motivation does give me pause. Here is one of his remarks on google as to another downside:



"There's a new theory about using 4 subwoofers at 1/2 wall distance on the four

walls of a shoebox room. The idea is to cancel the length, width and maybe even

the height modes, thereby smoothing in-room response.


I've done this experiment as well. It is true that such an array will produce a

slightly smoother in-room dynamic response capability (notice the operative

word ....slightly) at a quite significant SPL penalty (typically 3 dB in an

area where getting enough is a big issue) at a 4 times cost increase. "
 

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Anymore sub cabinets above two may produce more sound pressure and headroom, but it is risky as it can produce wildly controlled bass response and actually be detrimental.
 

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Discussion Starter · #14 ·
Those of you that argue against multiple subs, do you also argue against multiple full range speakers? At what point do you crossover your full range speakers? My thought in using multiple subs was to create full range speakers without replacing my more limited speakers.
 

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6000cf, or more M&K Pro (Doug Osboune) says a third sub is acceptable. Commercial theaters and IMAX have more leeway.
 

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James,


Yes, full-range speakers are the functional equivalent of multiple subs, as far a low frequency performance is concerned.


My space is about 6200 cubic ft. (includes all areas open to the living room, including dining room, kitchen, etc.). I’m using two 12†DIY Shiva-based subs in 2.5 cubic ft. sealed enclosures, powered by an Adcom amp at 325 watts per. They are barely getting the job done; I know I could use a pair of 15’s but I can’t decide if I want to live with enclosures larger than what I have. Unfortunately home theater (emphesis on home) usually requires some compromises in performance.


The following is not intended to dis hometheaterguy, because I see the point you’re making - that the pros often have conflicting opinions. That said:
Quote:
M&K Professional swears by multiple subs (stacked in corners. Russ Hershelmann in his CEDIA seminar called "Home Theatre: Essential Elements' in'95 said "use twice as many subs as you think you will need".
I have to wonder where these people live. Have they ever seen a system set up in a small apartment? Or in a bonus room above a garage? Are we supposed to believe places like this need a stack of subs in the corner??


When it gets right down to it, you have to have a very large space before you might need multiple subs. Rooms 3000 cubic ft. and under can easily be served by a single capable sub.
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Matthew Polk agrees on multiple subs placed asymmetrically, not stacked.
Been there. I’ve tried two subs places asymmetrically in two different rooms, and measured performance in each case was far inferior to what I got with both subs placed in the same corner. Again, all this advice from the pros is good and fine, but it’s best for people to experiment and evaluate their own rooms and do what works best for them.
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He also abhors equalization.
Take a look at Polk’s website and you’ll see why. Any equalization requires a sub with ample headroom from both the amplifier and the driver’s excursion capabilities. Small-driver, low-powered designs like Polk’s run out of headroom in a hurry. Thus it seems to me his recommendation to use many of his little subs seems self-serving, as Randy noted.


Regards,

Wayne A. Pflughaupt
 

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True, experimentation is the key.
 
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