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Post by Todzilla on Nov 26, 2008 14:06:22 GMT -7
Hi guys,
It's been a while since I built my IB and now that I'm getting close to building my second media room in a new home, I was exploring drivers and was wondering what the current "king of the hill" or "best value" driver out there was. For those of you who don't remember my set up, I currently have an attic-installed manifold of 8 Dayton 15" IB drivers powered by an EP2500 in a series/parallel configuration at 8 ohms. I absolutely love my current sub. My new media room will be substantially larger, however, so I was thinking of going with a manifold of 8 18" drivers. From what I've read, "FI" makes an 18" driver specifically for IB installations. What other drivers should I be considering or should I consider going with more Dayton 15s? Although price is always a factor, it's not the most important factor. Both my wife and I consider this the most important room in the house and both of us know the value of an IB sub.
The room is 20'6" x 19'4" with ceilings that slope in at a 45 degree angle that becomes a flat ceiling at about 12' high. The room is built over an oversized 3 car garage and the manifold installation will be in the floor. I want my new sub to go as low and be as authoritative as my current sub. Thanks in advance for the input and opinions.
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Post by jman on Nov 26, 2008 15:08:13 GMT -7
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Post by ThomasW on Nov 26, 2008 15:32:30 GMT -7
Per jman's link Fi is the only company currently offering 18" IB specific drivers.
These have 30mm of Xmax so they move a bunch of air, 7.26L vs the 2.34L of your current drivers. So you might not need 8 of them.
Since the new room is virtually square, plan on using lots of bass traps....
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Post by Todzilla on Nov 26, 2008 16:26:38 GMT -7
Thanks guys,
The room will effectively be 18'6" wide and 16'6" deep once everything is done (screen wall, etc). I currently use bass traps in the front corners of my media room and lots of soundtreatment on the walls, which I will incorporate in the new room... Only 3 of the ceiling "walls" angle up. The rear wall is a straight wall... Does the exceptionally high and unique ceiling pose any special concerns?
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Post by ThomasW on Nov 26, 2008 20:16:31 GMT -7
Only 3 of the ceiling "walls" angle up. The rear wall is a straight wall... Does the exceptionally high and unique ceiling pose any special concerns? Don't know |
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Post by Todzilla on Nov 26, 2008 21:33:17 GMT -7
Fair enough... gonna be some blind faith involved... Would one Behringer EP2500 be enough to power 6 18" drivers? How about 8 of them? The drivers are 4 ohm drivers, so that means the amp would run hotter than it does now at an 8 ohm load... should I plan for two amps?
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Post by ThomasW on Nov 26, 2008 22:02:05 GMT -7
You can buy the Fi drivers in either 2 or 4 ohm, they're custom made to order.
As for amps buy one, try it out, buy a second if needed
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Post by Todzilla on Dec 4, 2008 15:36:52 GMT -7
If I run them at 4 ohms, how much power is that to each speaker? Say 4 drivers per channel...
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Post by Todzilla on Dec 4, 2008 16:20:45 GMT -7
BTW, I've decided to just take the plunge and go with eight 18's in the new room... Manifold size will be 90 inches wide, spaced between the floor joists (I'm guessing 16 inches on center), so 14 and a half inches or so deep, and 24 inches tall.  Everything in line with the front of the center and mains. The IB opening will be almost as wide as the screen and close to the width of the front sound stage, so it should be pretty sweet... at least it looks that way on paper. I'm getting real excited about starting this project... Wish I didn't have so many others to do first... should have never promised my wife I'd tile the floors first... ;D |
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Eskimo
Full Member
Bass-head
Posts: 143
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Post by Eskimo on Dec 5, 2008 6:59:12 GMT -7
Holy hell.. 8 Fi 18's??? Wow.  Here's what I consider "the" EP2500 power thread. The amp will make more power than this in short bursts and/or with higher THD, but this is steady state.. www.avsforum.com/avs-vb/showthread.php?t=855865Summary at 20hz, since that's what we care about. 4 ohm stereo - 635 wpc 2 ohm stereo - 815wpc 8 ohm mono - 1330 watts 4 ohm mono - 1950 watts (1khz, he kept popping the circuit breaker on the amp, so he didn't test 20hz) |
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Post by Todzilla on Dec 5, 2008 12:09:05 GMT -7
I guess my concern is that the FI drivers are only rated at 550wc... is this a concern?
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Post by Todzilla on Dec 5, 2008 12:12:45 GMT -7
Hey Eskimo,
How would you recommend wiring these 8 drivers to the EP2500? I plan on ordering the 4 ohm drivers.
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Post by ThomasW on Dec 5, 2008 12:33:06 GMT -7
I guess my concern is that the FI drivers are only rated at 550wc... is this a concern? Not really. With 8 drivers you're going to have a Spl that exceeds 100db/1w/1m. How would you recommend wiring these 8 drivers to the EP2500? I plan on ordering the 4 ohm drivers. Wire pairs in parallel (= 2ohm load) , then series wire 2 pair (= 4 ohm load) for each channel of the amp. |
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Post by chrisbee on Dec 5, 2008 13:53:03 GMT -7
I'd love to be there when you fire up those 8 x IB18s. Except that you might as well use fewer drivers if you don't seriously think about the consequences of using 8 x 18": Try and remember that at this level of performance that it's all about radiating area. Displacement hardly enters into the picture with so much headroom. The incredible Xmax of the IB18 is just insurance against hitting the end stops on heavy transients with fewer drivers. Not about continuously high levels. If you ever call on maximum power into 8 x 18" drivers the room itself will probably be the limiting factor rather than the amplifier. Provided you give the amp an easy load. 4 Ohms per channel is kind and maximises output. 2 Ohms is too much like hard work and 8 Ohms per channel throwing away power and output. So 4 x 4 Ohms in series-parallel per channel looks good. Brick or concrete walls would be a good idea to avoid flexing and generating unwanted and irritating structural noise. It also helps to ensure you get maximum benefit from cyclic VLF compression effects in the room. If the room surfaces flex you have lost vital information in the input signal. So you might just as well have used fewer drivers. (just as Thomas has already suggested) If you ever see any serious cone movement I'd be very surprised. That's the beauty of having so much radiating area. It will go seriously loud without dynamic droop. (acoustic compression) All those motors holding a tight grip on the cones will rock your world. Dynamic range to die for. Distortion so low you can't measure it . The perfect (transducer) subwoofer. Unless, that is, you go for 16 x IB15s? You'll ideally need 10 x total Vas in your enclosure to avoid compression effects and unwanted changes in driver performance. Otherwise you might as well stick to and enjoy 4 x 18s" or 8 x IB15s. There is a limit to maximum average enjoyable SPLs or the dialogue will sound very exaggerated. Everyday experience suggests that normal conversation takes place at quite a low level of 60-65dB(C) against a quiet background. It is often surprising how load a film dialogue sounds when you leave the room and and come back in. This has its limits though. When the dialogue gets too loud it begins to sound like your deaf old granny's TV. Small incidental sounds become irritating because they sound so unnaturally loud. It all becomes too exhausting to enjoy and you really want to turn down the master volume. The secret to film soundtrack excitement is huge dynamic range and low distortion. BAM! Silence. BAM! Inky silence. It is the contrast in loudness which excites the listener. The difference between constant high levels and real musical contrast is the difference between Motorhead and Metallica. Which is why Metallica rules the world and nobody has heard of the also-rans who can only do loud. You'll need a lot of cross bracing to keep the walls of such a long manifold from flexing. Reaction force cancellation assumes rigid coupling between opposing walls of the manifold. That, or the drivers will flop around like two arrays facing each other. If you can't avoid flexure then you might as well use fewer drives in a really rigid manifold. You'll also need speakers to match the IB or the subwoofer will easily dominate. That incredible potential dynamic range in the bass will need to be matched all the way up the frequency scale. Not continuous power handling but the ability to go suddenly very loud when necessary. That takes a lot of radiating area too. Probably need another pro power amp and lots of 6-8-10" bass/mid drivers and plenty of tweeters to do it well. That will have to include the centre speaker too. Not just the mains. You don't want to deafen yourselves at foolishly high levels. You just want to seriously frighten yourselves at quite normal listening levels.  Otherwise you might as well use fewer IB drivers and make do with ordinary, large, floor standing speakers. It's all about balance. |
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Post by smithski on Dec 5, 2008 17:10:14 GMT -7
I want my new sub to go as low and be as authoritative as my current sub. Funny dilemma you have here! Just to remind you, you are comparing your 8 Dayton 15's w/ about 19 liters of Vd to roughly 58 liters of Vd with 8 FI 18's....the latter setup would be more than just a bit more authoritave than the former.  I went through the same mental wrestling match last week. I knew that 4 FI 18's would be enough for my room...but I wanted 8.  As Chrisbee talked about, balancing out the bass with everything else should really not be overlooked. I finally came to my senses and settled for 4; they should be here early next week. My room is only 2000-2200 cu. ft. though (depending on how I end up configuring it). The QSC amp driving them will push them right to xmax at 10 Hz w/o the need for a subsonic filter and will have more than enough output to get the job done. My room is over the garage like yours and I'm expecting simply awesome bass impact due to the fact that this room is basically 'floating' over the garage and really lends itself to tactile sensations. I was going to run 8 TC 15's, but sold 2 to Eric Eash on here so he could add 2 to his other 2 to make a quad pack. It's all about helping a brother out.  |
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Post by titch on Dec 5, 2008 17:11:21 GMT -7
Have you ordered your subs yet? Ive been trying to get ahold of them by email for a week now, with no response.  |
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Post by smithski on Dec 5, 2008 17:32:28 GMT -7
Have you ordered your subs yet? Ive been trying to get ahold of them by email for a week now, with no response. Odd, I've found Scott to be quite prompt in regards to email. I had 7 or 8 exchanges with him last week...even when he was on vacation for 4 days. Maybe it's because you're Canadian. ;D J/K, I'm 1/2 Canuck (Mom's from Alberta) and over 90% of my family lives there and BC. |
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Post by Todzilla on Dec 5, 2008 19:35:08 GMT -7
First off, thanks to everyone for their input...
I'm going from about 2,000 cubic feet in my media room to close to 5,000 cubic feet in my media room... I guess I'll find out, but I have strong faith that my DefTechs will handle the job of keeping up with the sub. I may have to feed them more power than the Pioneer Elite's 130 watts per channel, but the CLR3000 center and the BP2000TL mains should hold their own. I fully agree that it is about being overwhelmed at normal listening levels, but although a lot of people thought I was overkilling the sub in my old media room, the sub and sound experience in the room is phenomenal at normal listening levels...
Thanks Chrisbee, for the response... and to answer a few questions:
I'll be running a 4 ohm load.
Do you really think a 20.5' x 19.5' x 12' room is going to flex from this sub?
Not sure what you mean by enclosure size for the sub... it won't have one.
There will be plenty of bracing... my current mainfold isn't that much smaller than the one i'm planning...
I guess I'll ask this because it sounds like this is what you are saying... Are the eight 18" drivers I'm considering too much for this room?
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Post by ThomasW on Dec 5, 2008 19:45:38 GMT -7
Instead of one huge manifold how about this.... Since there's no additional discount after buying 4 drivers start with 4. Do one smaller manifold and give a listen. If it's not enough you know what to do... |
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Post by chrisbee on Dec 5, 2008 23:12:54 GMT -7
The point I was trying to get across is that a subwoofer's output has to be balanced with the speakers. The speakers in turn don't want to be too loud of you'll end up deaf or totally exhausted after watching a film. There is a strict limit to how loud any system wants to go before it literally become dangerous to your hearing. Perhaps you enjoy watching a film while wearing industrial ear defenders? That sounds like a joke and it does conjure up a rather funny image. In industry you would not be allowed to expose yourself to such high sound levels for very long without ear protection becoming mandatory. Or self discipline coming into play. It's not about being butch or hairy chested. Noise is a serious concern. It doesn't matter if you are an eight hundred pound Hell's Angel on a noisy Harley or an HT wimp. If both of you are deaf you are both handicapped. So if you suffer from tinnitus after a film that's just your body's way of warning you to stop doing something very dangerous. Long term tinnitus is nasty. Lying in bed at night listening to a scythe being sharpened on a grinding wheel is downright unpleasant. You can't put your fingers in your ears to stop the racket. You're stuck with it! All IBs have an enclosure/back space except when they exhaust straight into the great outdoors. If your enclosure volume isn't large enough to cope with your intended total Vas then you may as well use fewer drivers. One can always turn down a huge subwoofer to match the speakers but then the sub won't ever get stretched. So again fewer drivers will do. A huge IB may literally have far more headroom than you will ever use. It's rather like running a blown 7 litre V8 where there's a 55mph national speed limit. You have the bragging rights but can never put your foot down without serious consequences. |
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