Getting started with IB project...

**Sonnie** · **06-29-06, 11:37 PM**

Okay... let's get this thang on the planning block and see what we can come up with. I'll probably post some of this over at the CULT but obviously want to keep track of it here too.

First off I scoped out the potential mounting locations and did some measurements. ALL BY MYSELF I lifted one of my PB12-Plus/2's up into the recliner and let it relax for a few minutes...

Here are some shots of my attic... the red line is about where my front wall is in the HT room...

It looks like I might have to work around the truss system or move it... where you see that center red line is a 3" pipe running to my projector.

Here's the layers of material from HT ceiling to attic...

Here's an inside shot of the proposed location... those red blocks really need to be spaced further apart since I will probably want to stay with each cutout inside the 16" OC area.

Here's a construction pic before the wall and ceiling sheetrock was installed...

So this is pretty much what I've got to work with.

**Sonnie** · **06-29-06, 11:48 PM**

Now on to the measurements... with the sub reclining and me with one hand holding the mic taped to a broom stick and my other hand working the computer.

I basically checked all across that front ceiling and got the same response down low all the way across about every two feet. I did not go all the way in the corner because there's no way I could mount it on the outside wall with the roof being so low in the attic. I'm gonna have to stay close to center.

Here's five different spots across the ceiling...

I went ahead and tossed in a few filters and remeasured just off center....

**Sonnie** · **06-30-06, 12:00 AM**

From what I'm gathering it takes a lot more drivers and a lot of power to get the same impact from IB as I get from my SVS's. Obviously the IB's will be playing lower and cleaner but just not as fast maybe?

Anyway... if I'm gonna try it then I'm gonna try it. This means 8 drivers and possibly two amps. I can buy the Behringers at cost so a couple of EP2500's (2 x 1200 watts @ 2ohms or 2400 watts bridged @ 4ohms).

My tentative plan is to run two manifolds with 4 drivers each. I'll run from my sub pre-out on my receiver to the BFD and split out from the BFD to the two amps. Everything will be mono. The manifolds will be symmetrically located so hopefully I can use one channel of the BFD to eq both manifolds at the same time. This has worked very well for me on the SVS subs.

Drivers... right now I'm undecided for sure. I'm favoring the SoundSplinters for their xmax ratings and power handling. I'm not sure there's anything else out there quite comparable... but I haven't looked at everything yet.

**Exocer** · **06-30-06, 12:40 AM**

Sonnie, this is very exciting!
I do have a question however. In most cases, doesn't an IB allignment have lesser Xmax utilization than typical sealed or vented allignment due to the relatively low stress on each driver? You'll have so much cone area with 15" subs and effeciency due to large Vb of an IB enclosure that you'll probably barely use all 23.4mm of Xmax the SS Rl-p 15 has to offer in theory? I could be completely wrong but this is my current understanding of IB,nor do I know if the RL-P 15 is considered a low Qts driver. Also with the low Q associated with IB you'll probably not get slow bass at all! You'll be in for a treat indeed.

Edit: look how flat you've gotten your Fr with just a few filters...you're a pro indeed

**Sonnie** · **06-30-06, 01:31 AM**

Actually Darren and I were discussing the SS RL-p15 earlier. He stated ThomasW had recommended the dual 4ohm version due to its higher Qts of 0.447... which is indeed higher than everything else I've been looking at. Of course I have no idea how that figure comes into play. I don't understand all the TS parameters and their various explanations/uses, etc.

As far as xmax... I'm going by what I've been reading about some of the lower xmax drivers being pushed to their limits fairly easily. I may not need the full amount offered by these drivers but I've not seen anything around the minimum of probably 18-20mm that I would at least like to have. I'm still looking though. $2000 for 8 drivers is pretty stout.

**Darren** · **06-30-06, 08:45 AM**

For IB Higher XMAX is a very desireable trait...nothing less than 12 or 14 should really be attempted. If you are into high DB bass you'll be glad you bought drivers with the higher XMAX. In your room with 8 of these drivers I'll be surprised if you can see straight sitting in the room. Because these drivers are in an infinite baffle they will be utilizing much of the rated xmax on the sub 20Hz frequencies. There is little to no back pressure... we'll use up the mechanical xmax and never reach the thermal rating. Anything under 12mm will be destroyed in short order

when played at reference volumes.

I think you may have misunderstood the more drivers needing more power thing too. Actually the opposite is true... I believe ThomasW touched on that in the cult post. You actually need less power.

Oh and yes, a Qts. of .50 is ideal and the .447 of the dual 4ohm is **** close.

Dang, I wish I could hear your system after you get those SoundSplinters rockin'. You might want to have an aid car standing by if you can.

**Mark Seaton** · **06-30-06, 09:38 AM**

Sonnie,

An IB is very efficient down low, which means that it doesn't take nearly as much power to reach the same output down low as in a small sealed box. In a sealed/IB system, excursion is output. You don't have one without the other, and 2x the excursion yeilds 6dB more output at a given frequency. I haven't modeled the drivers up yet, but I doubt you would need two of the EP2500's. Your money is typically much better spent on drivers than amps here.

**Darren** · **06-30-06, 09:41 AM**

Hey Mark,

I asked this of Thomas over at the cult but you seem to know a bit about the power required for these drivers as well. Do you feel 300 watts is enough to see their full potential? Because of the reduced power requirements I'd think it is close if not adequate. I think Sonnie is like me in that I like to ensure I have a decent amount of overhead. I like to have a bit of reserve.

**Sonnie** · **06-30-06, 09:42 AM**

Right now I'm sittin' on 300 watts per driver running an 8ohm load. But I can get up and let 150 watts go and sit back down on 150 watts per driver. I did post this thread over at the CULT and maybe ThomasW will chime in and advise on the power needed.

I do not want to get nausea from this project... I'm not good with that. Skippin' a heart beat or two might be okay, but nausea... no-no.

**FlashJim** · **06-30-06, 09:54 AM**

Woohoo! I'll be living vicariously through you, Sonnie. I put my IB project on indefinite hold and decided to go with a single sealed RL-P15. I got a dual 4ohm just in case I decide to pick up that IB project again.

Keep the great pics coming!!

**Darren** · **06-30-06, 09:58 AM**

Quote:

Right now I'm sittin' on 300 watts per driver running an 8ohm load. But I can get up and let 150 watts go and sit back down on 150 watts per driver. I did post this thread over at the CULT and maybe ThomasW will chime in and advise on the power needed.

I think the EP2500 supplying 300 watts per driver will end up being sufficient. You can run all 8 at 4ohms bridged mono to get the 2,400 watts from the single amp. Thomas recommened I get that amplifier if I decided to go with the RL-P15 Dual 4ohm. As I said to you before, I like your thinking when it comes to bass

This setup should give you exactly what you are after with the ability to drive yourself right out of the room if you desire. Do you have industrial hearing protection? You may find out if the "brown tone" really does exist.

I'm hoping we get some confirmation from Thomas and the rest of the more knowledgable guys here and there.

Oh, and we do require the "head" shot just as soon as you can.

**Exocer** · **06-30-06, 10:24 AM**

Quote:

Sonnie wrote:

Actually Darren and I were discussing the SS RL-p15 earlier. He stated ThomasW had recommended the dual 4ohm version due to its higher Qts of 0.447... which is indeed higher than everything else I've been looking at. Of course I have no idea how that figure comes into play. I don't understand all the TS parameters and their various explanations/uses, etc.

As far as xmax... I'm going by what I've been reading about some of the lower xmax drivers being pushed to their limits fairly easily. I may not need the full amount offered by these drivers but I've not seen anything around the minimum of probably 18-20mm that I would at least like to have. I'm still looking though. $2000 for 8 drivers is pretty stout.

Ah, so as far as Xmax utilization is concerned (and just about everything else) you should be fine!. Wasn't sure if this was the 2ohm version or 4ohm version of the driver you planned to use. And yes, I can see why some fairly high xmax drivers are easily being pushed to their limits, IB is very efficient. You lucky dog you...how did you convince the wife to okay this one?? hehe

**FlashJim** · **06-30-06, 10:37 AM**

Quote:

Exocer wrote:

how did you convince the wife to okay this one?? hehe

Use my method ... don't tell her.

**SteveCallas** · **06-30-06, 11:44 AM**

Sounds like a great plan! At first I was worried you might under-woof (new word) this project, but eight RLp15s drivers will beat out the four 12" drivers in every single way. Your response with the filters in place looks good too, so that spot should work out fine. Expect to see that respone stay flat much lower when it's done

**Darren** · **06-30-06, 11:54 AM**

He he, the 4 drivers he's considering will kill the 4 12's as well... Sonnie is going way overkill. I like it.

**Sonnie** · **06-30-06, 12:27 PM**

Yeah... the wife ain't gonna know until she thinks we are literally in the middle of an earthquake or finally gets to missing me and wonders out to the HT room and finds me lying on the floor bleeding from the ears.

I'm not sure what I was thinkin' on that power per driver Darren. If I'm now thinkin' correctly, I'll get just as much power per driver with one amp as I will with two.

**Darren** · **06-30-06, 12:29 PM**

Yeah, it can get confusing dealing with dual 2ohm, dual 4ohm, bridge, stereo... I was thinking backwards on a few of my decisions as well when I was calculating. Saves you some cash though!

**SteveCallas** · **07-01-06, 08:48 PM**

Given any consideration to using the TC Sounds 2000 15" SVC instead? I don't know how big of an issue the high QTC is, but they have more xmax and a lower Fs for not much more $, and I'd have to imagine you could get some discount pricing when ordering 8.

**kingkip** · **07-02-06, 12:17 AM**

Sounds like it will be great Sonnie. I can't wait to see some pics. Also I found you don't need a ton of power. Mostly just enough to get the drivers to move full excursion, in fact it seems that too much power is almost more dangerous to the drivers. Just from my limited experience.

**Sonnie** · **07-02-06, 01:08 AM**

Quote:

SteveCallas wrote:

Given any consideration to using the TC Sounds 2000 15" SVC instead? I don't know how big of an issue the high QTC is, but they have more xmax and a lower Fs for not much more $, and I'd have to imagine you could get some discount pricing when ordering 8.

Yes... I've looked closely at the TC Sounds drivers. I'm not sure how a 3 or 6 ohm load would work.

ThomasW likes the higher Qts of the SoundSplinter dual 4 ohm. I don't really understand all the T/S Parameters... I guess it's better response time, which might be important in an IB setup.

I'm gonna move our two posts here in Sub locations to my IB thread.

**Sonnie** · **07-02-06, 02:08 AM**

Quote:

kingkip wrote:

Sounds like it will be great Sonnie. I can't wait to see some pics. Also I found you don't need a ton of power. Mostly just enough to get the drivers to move full excursion, in fact it seems that too much power is almost more dangerous to the drivers. Just from my limited experience.

Hey kingkip... not sure how I missed your post there but I'm just now seeing it... lol. Gotta get my eyes checked.

Yeah... I was originally planning on two amps and culled that back to one. If I go with the SoundSplinters then Mike at SS has suggested the 300 watts per channel should be just right for those.

Looks like you got all done huh? Nice work... I did ask you a few questions you see in your thread.

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