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I'm considering building a crossover and sub setup for my center
channel. I was wondering if you all feel that your center channel
is getting enough full spectrum audio to bother doing this? The
hardware isn't too expensive, and I build my own boxes...but if
only one disk out of 20 has any sub audio in the center channel,
it obvously wouldn't warrent a sub.I've already got a kick ass folded horn on the sub channel of my 5.1
setup, but I was just trying to help get the fullness of the true
movie theater experience. You know behind those big screens are a stack
of speakers that would make Van Halen proud...including the center
channel...so why not do the same at home?Am I going overboard here?
TLR
Having spent most of my life trying to get the lowest octaves of music to be reproduced, now we have even louder lower things to mess with in HT. I have one 15" sub on the lfe that goes from 20 to 40 hz. Then I have two 8" subs from 40 to 110 hz. The subs are all place in the center. The 15 on top of my HT cabinet. One 8" on top of the center on top of the shelf that is over the top of the tv. The other 8" is centered overhead firing down onto our seating area in the rear between the surrounds. It is much much better than one sub. I would love to hear Roberts setup. I know mine really impresses people (especially me).
From the opposite end of the spectrum: I like to joke around and say that the only thing missing from the audio portion of my HT setup is one more sub. Currently, I only have 5. Having played around quite a bit, yes, there is significant bass contained in the center channel, IMO. A center channel sub can add significantly to your system, if you like to hit "reference" bass levels.I'm going to pick on one fairly well known sub: the Bag End InfraSub, which claims a flat response down to 8Hz. Reading that spec sheet, my goodness, who would ever need anything else? The problem comes in that the Bag End will only output a flat response at about 90dB. Reference level is 110dB at the listening position, according to THX standards. So the Bag End comes up very short, although it's published specs would lead you to believe otherwise. Their sub simply compresses way too much to be a real contender in HT bass.
Bag End is not alone, although they are one of the worst.
Now consider what you're asking a sub in a HT setup to do for the LFE channel: produce 110dB SPL, at the listening position, at 20Hz or so. Take a sub that is truly capable of producing 110dB at 20Hz; assume that it is ideally placed in the room to assure that response. Unless you're sitting on top of that sub, chances are you'll never come close to 100dB.
Remember: that's just the LFE channel.
Now, let's say that you have one sub, and all your bass is routed to that sub. That means that in addition to the LFE demands, that one sub has to churn out other channel's bass; let's generously say that amounts to 10dB.
In this scenario, in order to realistically achieve reference level, you'll need a sub capable of 120dB+ at 20 Hz.
Good luck finding *that* sub in the marketplace.
What does adding a sub to the center channel do? Well, if nothing else, it offloads some work from the LFE sub. This makes your system more dynamic, and helps to insure that the LFE sub isn't driven to compression.Currently, I have 2 Polk SRT subs and a Sunfire Sub devoted to Front L+R duties, and reroute center + LFE bass to the Front L+R. An additional pair of subs for the surround channels round things out. This is a system with a very strong bottom end, one that can produce reference levels at the listening position. There's a scene in Aliens where the bad critters knock at the airlock door to the lab; that "knocking" produces enough bass in my HT to shake the floor and everything attached to it.
I have had the Sunfire setup as the LFE sub, and re-routed center channel bass to it. The result: somewhat lacking in dynamics. A slight sense of compression, of strain during peak level passages.
I've also had the Sunfire setup as a center channel sub; that sounded great, IMO, and resulted in an extremely dynamic, cohesive front soundstage. The only thing that I felt was lacking was the very low end on certain passages; while the Polk SRT subs are super, they roll off below 20Hz, and adding the Sunfire in reinforces that really deep bottom end nicely. That was done before I built a dedicated 2 channel listening room, so I may go back to using the Sunfire as a center channel sub someday.
The bottom line: don't be afraid to play with different configurations. Yes, it can be a lot of work getting the subs to play nice together. Yes, your family and friends will treat you differently. But if you really want top-flight sound, it's the only way to go.
A final note: it is possible to build a sub that will produce adequate bass to meet the SPL requirement for all channels and then some. However, IMO, not having bass on the surround channels is a huge mistake. Although many claim that bass is omni-directional, there's nothing like bass that wraps around you from all directions. It really contributes very strongly to a seamless soundstage that places you in the center of the action.
Hi Bob,Insightful comments as usual. A lot changes when we're talking about true reference level playback. I've never played back a movie like "Twister" etc. on my system at reference level, and I doubt the sub could handle it.
Anyway, could you please look at my question in the speaker section a little ways down - "Bob W -...."
RichardH
**
There can be quite a lot of bass in the center channel during explosions, etc. but I think they reserve the really deep stuff for the LFE channel. In the movie theater they don't have any limitations, so they can put bass whereever they want it. With 5.1 mixes on DVD, I think they route most if not all of the *deep* bass to the LFE, or sometimes a little to the mains. I would bet that if your sub is up to snuff, you should be fine as is.Some people have said that pans will be better if you have full range speakers on the front channels, but I would think it would be only marginally better if you already have the sub near the center, and especially if you have full range mains.
BTW, what is a folded horn on the sub?
RichardH
I'm about to bring back to the shop my first sub, a jamo 410e, nom.power 100w, 10 inch, because, or im unable to fix the system correctly or its useless for my system. I have two full range sony speakers dated 1981 as front, rear infinity and b&w center channel.My receiver is onkyo 575 80 wpc.All this is regarding the use of the system for home theater, with dvd. Is it possible that since my front speakers are full range with a really big sub that in the specs goes down to 35hz?? the difference with the sub is minimal, or the system still benefits from it besides from preventing breakage during very low bass emissions of the sony speakers ? In addition to this i would also like to know if theres a difference between a sub, the jamo im trying now, whose sub is mounted "on the floor" and any other model which has the sub mounted on front. Im asking this because the room is not so good acustically speaking (very reflectant)and i get annoying vibrations with the sub. Could it be possible that getting a model with the sub mounted on front i could avoid or at least partially defeat that horrible fenomenon of standing waves ?
thankyoud@v
agreed
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