Is this to many speakers for a 4,500 cube room? A soild wall of JBL 3732, 4645 & 8340 - AVS Forum
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Old 08-21-2014, 01:13 AM - Thread Starter
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Is this to many speakers for a 4,500 cube room? A soild wall of JBL 3732, 4645 & 8340

I'm days (if not hours) away from making a purchase and wanted to see if you guys thought this was just to much for a 17'x30'x9' 100% dedicated theater room (about 4,500 cubic feet & not for music listening)? The plan is to use the following speakers based on what I've read and what people have said on this site:

LCR = JBL 3732
Subs = 2 JBL 4645
Surrounds & Rears = 6 JBL 8340
Crown Amps


Is it better to BiAmp or TriAmp the 3732's?


Also, I know the 4645 sub will drop off under 20hz and that worries a lot, but I'm not sure why it worries a lot. lol Maybe because I read everyone else wanting to go super low. Part of me kinda trust JBL to make a good speaker. Do I need under 20hz sub to fill 4,500 cubes and get that true theater bone pounding experience? Because it's not easy to find a good sub that will fit behind the screen (about 18" deep) without building one myself. The 4645 gets great reviews above 20hz. Honestly, do you think I will seriously notice not have a sub that goes under 20hz with this set up? The 3732's have two 15" in each, but they only go down to about 30hz.


BTW, this site is VERY addicting. The last 3 days I think I've spent 30 hours searching old threads. There are SOOOOOO many smart people on here that go above and beyond to help others. Great site guys!!!!!!






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Old 08-21-2014, 06:26 AM
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That system is going to be insane. As for the subs, the closer you get to the corners (corner loading) it should increase the bottom end a little so placement could help. Those subs are very sensitive for subs which is great but yea they don't that low compared to many subs around here. Like I said the room could help. Of course you could DIY a few subs with some SI 18 drivers etc and you could be sure to reach down as low as you'd ever want and for the price of 2 of the JBL subs you could build 6 to 8 SI subs.
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Old 08-21-2014, 06:57 AM
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Using mains that go to 30Hz is wasted space and money when the load below 60Hz, if not 80Hz, is handled by the subs. Mains that go to just below the intended crossover frequency will be smaller, and cost less, money that's better invested in four subs instead of two, for smoothing of in room response. The sub placement seems arbitrary, based on where they'll fit, rather than where they'll work best. On that read this:
http://www.harman.com/EN-US/OurCompa...s/multsubs.pdf
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Old 08-21-2014, 08:34 AM
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I ascribe to the theory that nothing is too much :-)

But if you read around with the folks to go with JBL pro stuff, I think you may be going a bit overkill. You're using speakers designed for very large professional theaters. I think you'd be better served using the 3722 (or even smaller - 3677?) and saving a bunch of money. Also, I would recommend using different subs - something from JTR or Seaton would give you better extension and frankly more power across the board. Probably about the same money as well due to not needing external amplification.

But, if it makes you happy, screw it that will be awesome up front. Only other issue I see is the 8340a is pretty damn large, and I you have seats against the side walls and back walls. The side/surround speakers are going to be hanging over your guest's heads as currently designed.
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Old 08-21-2014, 08:44 AM
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Yeah I agree about them being way too much for your room. I think the JBL 3677 is a great choice for a personal theater, and with the extra money buy yourself some good subs. You could even DIY a bunch of SI subs as was mentioned above, that would get you excellent bass down into the single digits.

The 8320 is a smaller option for surrounds.
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Old 08-21-2014, 08:47 AM
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A few questions/suggestions:

(1) Is you rear row of seats really up against the back wall like that? Will make it very difficult to do rear back surround speakers effectively. You won't get any real surround effects in those two seats in the corner. If no one will ever seat there, less of an issue.

(2) Those subs need a lot of EQ to even reach 20hz.

(3) You need to ensure that 15 feet back is sufficient for those speakers since the drivers are so far apart.

(4) I love overkill as much as the next guy but I would probably step down to the 4722n for mains in that size room and spend the difference on more subs. I don't think you could even really tolerate enough loudness to tell the differences between the two in your room. 4722n would also require less amps as they have passive crossovers. Bi-amped/Tri-amped mains are unnecessary complexity, in my view. I am sure you will also need an active crossover network somewhere in your signal chain with the 3732s.

If the 8340a are too large, can also consider the new klipsch kpt-8000 surrounds

**as I type this, I see some other folks have also commented on the mains and surrounds***
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Old 08-21-2014, 09:30 AM
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3732 is totally overkill.
4722N will be perfect.
3677 if you wanna go budget.
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Old 08-21-2014, 09:35 AM
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CODY, I've had JBL 3731s in room quite a bit smaller than yours and overkill never came to mind. No I wasn't using them anywhere near their capabilities but that wasn't the point. That's just overhead for reference level listening. I also had 3677s for years. Same scenario, not close to ever maxing those out either. The 3731s are very detailed and have fabulous midrange. For my set up I biamped vs triamped. Regarding subs, you'll have impact for sure but myself I'd like more extension. You can achieve that with transducers or a different sub design or different subs altogether. Right now I'm trying to integrate several pro midbass cabs up front to cover 35/40hz to 120hz with several high excursion nearfield subs to cover the rest of the way on down. I also have several Crowson transducers. I want it all

As was also suggested, I've heard nothing but good about the 4722n although I haven't heard them myself. I would ditch the third row you had pictured as it's too close to the back wall. I'll also add that you definitely will want room treatments, in any room but especially for the likes of the 3732. You don't want all that power and not be able to harness it.
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Old 08-21-2014, 10:49 AM - Thread Starter
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Really appreciate so many of the really smart and long time users helping me on this. I'm going to listen to you guys and make some changes. I've removed the back seating (and understand the 2 seats against the wall under the surround will suck), updated the LCR speakers to 4722N's and will go with some DIY subs. Does this set up work better for the size room?

BTW, The site Bill has has also been a big help and the link to JBL's sub tests (he posted above) really helps me understand the importance of placement for subs. I'm going to work on the sub placement and try getting one near the back.

What would be the best (or at least really good) DIY sub for behind the screen? Looking to keep the depth to about 18" to 20" max.



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Old 08-21-2014, 11:44 AM
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For subs, venture over to the DIY section and you'll get all the help you need. In terms of depth, if you build your own enclosures it allows much more flexibility to reach your particular needs. For example if you want more shallow depth then you make up the cubic volume by going taller/wider. Just make a thread posting your desired dimensions and performance expectations and the gurus can help model what you need.
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Old 08-21-2014, 11:58 AM
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You can get a pre-cut flatpack for the Stereo Integrity 18" woofer from www.diysoundgroup.com (http://www.diysoundgroup.com/sealed-...flat-pack.html)

The Cabinet is 20" deep, so right at your max depth; build yourself 2 or 4 of these and you will have some impressive bass. You just need external amplification, but as was mentioned the guys over in the DIY forum are very helpful and there are numerous build threads for the SI18 subs.
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Old 08-21-2014, 12:34 PM
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If you're not comfortable with DIY, you have enough depth there to put a Seaton Submersive Master/Slave behind the screen (they're 17.75" deep). That would give you the bass you need. You could also then eliminate the crown amps entirely from the equation. M/S combo is typically ~4k shipped with all connections needed. Not sure how that compares to the crown amps + DIY subs + whatever you value your time/labor at.

I can't tell in your pic how wide your steps are, but could you center the rows of seating with steps on each side? That would solve your side placement issue, though I understand the room might just not be wide enough. If you don't already have the seats this could be solved by getting slightly narrower seating such as Palliser Pacifico. A 4-seat row of them in the same configuration you show in your pics is only 119" wide, leaving you just over 3' of space on each side of the seating which would be more than enough, and make all seats function much better.
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Old 08-21-2014, 01:00 PM
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Seaton is a great choice, of course.

If you don't want to DIY, here are a few other commercial choices that have at least one dimension = 18.5 inches or less

Four Reaction Audio 215x - $4,000 - 4,000 watts RMS and would contain 8 fifteen inch drivers (sealed)
Two Powersound XV30Fse - $3,000 - 1600 watts RMS and would contain 4 fifteen inch drivers (ported)
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Old 08-21-2014, 01:18 PM - Thread Starter
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I would LOVE to get a Seaton or JTR, but I think you guys are right and I should just build my own. I pretty good working with my hands.

I'll check in on the DIY sub page and get some ideas. Thanks a million for all the help!!!!!

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Old 08-21-2014, 01:30 PM
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That is going to be one hell of a system! You ought to do a build log, there is a sub-forum for that and a lot of VERY helpful people should you have any questions/concerns.

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Old 08-21-2014, 01:31 PM
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Sweet, good luck. It will be a fantastic space when you're done with it regardless - you're picking from options that are in the top percentile of performance
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Old 08-21-2014, 01:39 PM - Thread Starter
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If it helps anyone in the future as much as you guys have helped me I would be happy to do it.

Just placed the order for all the speakers! You guys have a AWESOME site and my neighbors hate you all. lol



Quote:
Originally Posted by Transmaniacon View Post
That is going to be one hell of a system! You ought to do a build log, there is a sub-forum for that and a lot of VERY helpful people should you have any questions/concerns.
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Old 08-21-2014, 01:55 PM
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Where did you place your order from? I'm about to order 3 3677s and have been shopping around for best pricing. You can PM me info to keep it off the public forum
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Old 08-21-2014, 03:03 PM
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Unless you already have the Crown X4000s (and because they are on closeout for $299), there is no way you need really need 1350 watts per channel into those 4722n speakers. The price difference is small between the x4000 and the x2000 though, so it's rounding error in the grand scheme of things.

Also, you will need several 18s to keep up with the rest of your system. I suggest at least four of them, running each pair off a bridged x4000.

This will be a killer system in your room and will be running at less than 10-15% of its potential even at ear-bleeding levels.
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Old 08-21-2014, 03:30 PM - Thread Starter
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Where did you place your order from? I'm about to order 3 3677s and have been shopping around for best pricing. You can PM me info to keep it off the public forum
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Old 08-21-2014, 03:32 PM - Thread Starter
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You guessed right. Picked up a bunch of the Crown amps when they were on sale. The price for a X2000 and X4000's was so close and the X3000's were the same price as the 4000's, so just bought X1000's and X4000's.

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Originally Posted by Davecraze View Post
Unless you already have the Crown X4000s (and because they are on closeout for $299), there is no way you need really need 1350 watts per channel into those 4722n speakers. The price difference is small between the x4000 and the x2000 though, so it's rounding error in the grand scheme of things.

Also, you will need several 18s to keep up with the rest of your system. I suggest at least four of them, running each pair off a bridged x4000.

This will be a killer system in your room and will be running at less than 10-15% of its potential even at ear-bleeding levels.
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Old 08-21-2014, 03:38 PM
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Quote:
Originally Posted by C O D Y View Post
Really appreciate so many of the really smart and long time users helping me on this. I'm going to listen to you guys and make some changes. I've removed the back seating (and understand the 2 seats against the wall under the surround will suck), updated the LCR speakers to 4722N's and will go with some DIY subs. Does this set up work better for the size room?

BTW, The site Bill has has also been a big help and the link to JBL's sub tests (he posted above) really helps me understand the importance of placement for subs. I'm going to work on the sub placement and try getting one near the back.

What would be the best (or at least really good) DIY sub for behind the screen? Looking to keep the depth to about 18" to 20" max.






I like this much better! BTW, this system/room is going to be awesome!

Still, I would suggest putting a bare minimum of 6.5 feet in between the rows, maybe even 7 feet. I have 6.5 feet in between mine and I feel like if they were any closer the feet of people in the back row would be too close to heads in the front row when both rows are reclined.

Also, I am 11'3" away from my screen in the front row (head to screen) and my screen is 12'3" wide. You could easily move up the front row some more and that takes care of distance between the rows.

That far right seat in each row that is right next to the wall - terrible seat for acoustics but no big deal IMO. Just put people in those seats that can't tell the difference anyway when you have a movie night.
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Old 08-21-2014, 03:42 PM
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Oh, I also love love love that you have a sweet spot seat in the dead center. That is a must IMO, especially if you ever plan on listening to music - but even if you don't it's a must have.

Love the idea of the bar in the 3rd row. I have a bar table in my room and it's nice to have when I or others want to bring down food. The bar is perfect for this obviously. Also, at larger gatherings like the super bowl people love to stand around anyway while they watch/drink/eat.
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Old 08-21-2014, 03:46 PM
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One more thing, this time about the surround speakers.

I have found that if I have the surrounds directly to the side of my head the surround effects become more directional and it seems more fake. If your head is a little bit in front of where the surrounds are (or if your head is behind too, it seems to work both ways) the surround effects are much more believable and less directional.
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Old 08-21-2014, 04:27 PM
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For the Atmos speakers, I would have gone with the JBL Control 226C/T. They are a better match for the fronts and surrounds.

They use a coaxial design with a hf compression driver. High output, fully engineered back boxes, better dispersion and will look better in the ceiling.

Last edited by ifor; 08-21-2014 at 04:33 PM.
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Old 08-21-2014, 04:33 PM
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Quote:
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That far right seat in each row that is right next to the wall - terrible seat for acoustics but no big deal IMO. Just put people in those seats that can't tell the difference anyway when you have a movie night.
I agree, if you could move both rows to the left 10-16", that would greatly improve the sound in those seats. It looks like you have enough room to remove a little from the aisle, so...try and move them if you can.

You could even place a small table between the seats and the wall to have somewhere to place food or drinks.
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Old 08-22-2014, 08:33 AM
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Quote:
Originally Posted by ifor View Post
For the Atmos speakers, I would have gone with the JBL Control 226C/T. They are a better match for the fronts and surrounds.

They use a coaxial design with a hf compression driver. High output, fully engineered back boxes, better dispersion and will look better in the ceiling.
That is a great suggestion.

I had no idea there existed out in the marketplace inceiling speakers with compression drivers. I guess you learn something new every day.
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