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Discussion Starter #1
I am planning our future theater room as our home is being built as we speak. I have the mains and rears taken care of thanks to DIYSG and now I am on to the subs. I have an L shaped rec room that is roughly 35'x22' with a bar around the corner. Ceilings are 9' in the basement so it's a fairly large room. It's over 8500 cf

If I am sitting at the LP the wall to my left is shared with the mechanical room. I want to build an IB manifold on the side wall about 16" from where the two walls meet. It will almost be in the corner. I have no way of measuring or experimenting at this point as it is just framed.

Am I making a mistake to commit to having an IB in that spot without experimenting first? This is not a room I can place subs out in the open so my thought was to get the most without taking up real estate I should do an IB.

Budget is around $1000 for subs and an amp. I would like to get 4 SI HT 18's with an Inuke 3000dsp. That puts me very close to the budget. Do these work well in IB? I know FI IB3's are probably better, but are they worth the extra $400 I would spend for 4?

Thoughts??
 

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I don't know much about IB, but I do have a room around 8000cf, and currently have two si18's in large ported boxes.. I have two more, just haven't built the boxes yet. I do think are on the right track by looking at doing four, but I think you might be better served with an inuke6000dsp to get the extra power, and also do four separate enclosures so that you can spread the subs out.. that way it will take care of more room modes and null spots. That's going to be a challenge in a room that size
 

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Discussion Starter #3
I don't think they can handle that kind of power in an IB configuration. I will probably have to set a filter even with the 3000 to keep the low frequencies from bottoming them.

I would love to build 4 enclosures or 2 dual opposed enclosures and spread them throughout the room but that's not gonna happen since this is our family room, bar as well. I was hoping that 4 of these in an IB would have sufficient output for the size of space I have??
 

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I was just suggesting four enclosures spread out, because that is a very large area to cover, and I think having all the subs in one spot is going to make for pretty uneven response / nulls all over the room. Having them spread out fills that all in much better, and will usually give a much more even response
 

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Discussion Starter #5
Well, if I didn't have the other half to worry about then I would in a heartbeat! I just can't think of any other options that would allow that many subs in that room without having boxes all over. If I do put an enclosure in the room I would probably be limited to 1

Surely the IB would outperform a single 18 or 2 in a dual opposed box, right?
 

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The IB318 seems to be the gold standard for IB speakers. You are forgetting the $80 off for ordering 4.
You could up the budget a little and get 4 of them for $1000.


Another option would be to use these:
http://www.sonicelectronix.com/item_13863_JBL-GTO1514D.html
At $75ea you could get 8x 15's for $600. I think this deal is the $/displacement leader right now. 1000W total for all 8 will get them to xmax.
For about $1549 you could get 16 of them and an INUKE6000DSP. They might be cheaper if you call up to order, just ask for a quantity discount.


REMEMBER, you have a huge room to fill and displacement is what makes bass.


SUB / $ per sub / $ per Liter of displacement
IB318 $250 $36
SIHT 18 $179 $32
1260W $54 $30
GTO1514 $75 $26


read up about IB here:
http://ibsubwoofers.proboards.com/thread/1713/upgrade


You will want to do dual opposed (DO) manifolds to keep the shaking and rattling down. Basically a 5 sided box mounted to the studs on the back side of your wall with the 6th side open and touching a cut out in the drywall. About a 14.25" wide x 16" tall x 19.5" deep box for each pair of 15's with the drivers mounted facing each other on the left and right walls. This cancels out the force of the cones moving. Don't just put a piece of plywood on the wall and mount them with the cones facing into the room.


As far as determining a good location, get a umik microphone from minidsp and if you have even a little sub now, or one you can borrow, put it in the location that the ib will be and take some measurements. EVERY ROOM IS DIFFERENT If you can't get a sub to measure first, order your subs and build 2 cheap and easy sealed boxes with them and measure that. Since you will end up with 2 channels of dsp it probably makes sense to have 2 different locations to even out the response, front corner and mid wall maybe.
 

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Discussion Starter #8
Funny you mentioned the drywall that happens to be what I do for a living. I run the largest residential drywall company in the area. If we were staying in this house I would really do the room up right with closed cell foam, rc channel, and sound board!

On the wall I want to put the manifold I only have one stud cavity to use. I guess eight 15's would work just fine. Would 8 of the jbl subs outgun 4 SI 18's?
 

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Funny you mentioned the drywall that happens to be what I do for a living. I run the largest residential drywall company in the area. If we were staying in this house I would really do the room up right with closed cell foam, rc channel, and sound board!

On the wall I want to put the manifold I only have one stud cavity to use. I guess eight 15's would work just fine. Would 8 of the jbl subs outgun 4 SI 18's?

The JBL's should do better, it's close.
Neither of these are specifically IB drivers, but the SIHT has a very soft suspension making it easy to bottom out without a box.
I have the little brother to the JBL...the 12" 1260W, and they held up nicely in some free air testing. You will get more xmax than is stated, like 17-18mm instead of the 14.5mm listed. The suspension is much tighter than the SIHT and it gets progressively stiffer with excursion so it's harder to get the coil to bottom out, if it will at all. As a bonus the subs are kinda gaudy but will be hidden.


A front corner is a good blind guess as to where to put a big sub, you may end up wanting to put 1 or 2 single 15's in little boxes on a little amp in specific spots in your room to fix the frequency response if needed or if you care.
 

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Discussion Starter #10
Thanks for your advice. I have read quite a bit about IB subs over at the cult and bottoming the subs is one of my concerns. The only experience I have with DIY subs so far is a ported Shiva 12" tuned to 20hz. It seemed like that sub would bottom pretty easy so I always had my hand on the volume knob just in case and I didn't like that at all!

I am hoping that either way I go with the IB it will have enough headroom to not worry about maxing them out. I was probably expecting way too much out of the single shiva and that's why I pushed it to the limit.

A couple of years ago my company did the drywall work for an individual finishing a theater room under his garage (concrete bunker) and we got to talking about speakers and subs and I recommended he learn about IB subs. Well, he ended up with 2 FI IB 15's and placed them in a manifold in the front corner similar to where I would put mine. I did get a quick demo from him when he was done and it sounded pretty good to me and he was very pleased with it. Granted that room was a bunker and a third of the size of mine.

We are almost ready for drywall. Once it's sheetrocked I could take my shiva over there and hook up my amps to get measurements. I have absolutely no experience or measuring equipment. Do you have link to the equipment you referenced for taking measurements?
 

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From what I see, the max performance of 8x GTO1514D is essentially the same as 4x HT18D2 in an IB. The 4xHT18 can hit xmax with a little less power, around 400W vs 600W for the GTOs. You could probably run them off of half of an NU3000DSP.

Remember, IB gets you the same total amount of low-end performance as a regular sealed sub does. It just does it with a fraction of the power, and it gets smoother, flatter rolloff over the frequency range since you aren't pumping as much energy into the mid/upper bass.

Could you enclose the backside of the baffle wall in the mechanical room and make it into an LLT ported sub? An 8' by 8' by 2' box tuned to 10 Hz or so would give you a ton of extra output above 10 Hz.
 

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Thanks for your advice. I have read quite a bit about IB subs over at the cult and bottoming the subs is one of my concerns. The only experience I have with DIY subs so far is a ported Shiva 12" tuned to 20hz. It seemed like that sub would bottom pretty easy so I always had my hand on the volume knob just in case and I didn't like that at all!

I am hoping that either way I go with the IB it will have enough headroom to not worry about maxing them out. I was probably expecting way too much out of the single shiva and that's why I pushed it to the limit.

A couple of years ago my company did the drywall work for an individual finishing a theater room under his garage (concrete bunker) and we got to talking about speakers and subs and I recommended he learn about IB subs. Well, he ended up with 2 FI IB 15's and placed them in a manifold in the front corner similar to where I would put mine. I did get a quick demo from him when he was done and it sounded pretty good to me and he was very pleased with it. Granted that room was a bunker and a third of the size of mine.

We are almost ready for drywall. Once it's sheetrocked I could take my shiva over there and hook up my amps to get measurements. I have absolutely no experience or measuring equipment. Do you have link to the equipment you referenced for taking measurements?

This is the diy measuring standard:
http://www.minidsp.com/products/acoustic-measurement/umik-1
Used with this free software
http://www.roomeqwizard.com/


Since you have 1 IB option, and wouldn't have more than 1 box in the room, I would just get 8 of the JBL 1514d's for $600 from here before the sale is over or they are sold out:
http://www.sonicelectronix.com/item_13863_JBL-GTO1514D.html
If you call and ask for a quantity discount, they may be cheaper. My subs were.


I have been thinking of what to do for an amp...
I would get a inuke6000dsp and run all 8 on one channel of it. (more than you need at the moment, but only ~$75 more) You said you could put 1 sub out in the room. I would reserve the other channel to do that with, to smooth the frequency response in the room...build a sealed 18 down the road if needed.
People have been getting that amp for $350ish by calling sellers or making an offer on ebay.


If you wanted to, with 9 foot ceilings, you could fit 12x 15's in that one stud gap and still run them on one channel of the 6000 without using the voltage limiter. That's $250 over budget, not sure how firm that 1K is.


Here is a spl graph from 1 meter away.
top blue line is 12x 15's,
bottom blue line is 8x 15's
red line is 4x IB318
green line is 4x SIHT


 

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From what I see, the max performance of 8x GTO1514D is essentially the same as 4x HT18D2 in an IB. The 4xHT18 can hit xmax with a little less power, around 400W vs 600W for the GTOs. You could probably run them off of half of an NU3000DSP.

Could you enclose the backside of the baffle wall in the mechanical room and make it into an LLT ported sub? An 8' by 8' by 2' box tuned to 10 Hz or so would give you a ton of extra output above 10 Hz.
I think the suspension on the SI is just too soft to do IB well, and excursion starts to spike at sub 10hz. I could see them doing fine till Irene or the WOW Pod scene beats the crap out of them. I can push mine down till it bottoms with 1 hand. I can shove my 1260w's by hand till they get to about 12mm, no more. I think that and the price sways the choice to the JBL's.


As to the LLT, that's a good idea if he has the room, and wants a more complex build with more output.
 

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Discussion Starter #14
That's a good idea but I don't think I could make that work. The storage room is on the small side as it is and that's the only storage we have in the house so I better not take up any more space than I have to.

If they are close to the same on output I would choose the 18's because it would look less cluttered. I am not opposed to upping the budget a little and getting the FI IB 18's if the output is worth it.

I guess what I am getting at is that I am going to this from a single 12. If the SI subs in IB will be substantially better than my ported 12 in my space then I would probably be more than satisfied. If there is a question on whether it would be enough then I would rather just up the ante and get the more expensive subs to begin with. My gut is telling me I would be fine with the SI subs??
 

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Discussion Starter #15
Thanks for taking the time and entering those in winsd. I had that downloaded at one time but since have a new computer. I will get it downloaded again.

From looking at the graph it seems the 8x15 option makes the most sense for me. It betters the SI's till the single digits which is enough to convince me to go that route. Just for kicks what do you think the spl of a single shiva 12" in 6cf tuned to 19hz would look like on that graph in comparison?

If I went with 8 do you still think the 6000 would be the way to go on the amp? Also, I am not opposed to crossing them over if that means I can get more spl above 10hz. I know with my space and constraints it would be pointless to chase the ultra low stuff anyway. I will save that for when I have a dedicated space.

So, above 10 or 15hz if crossed over would the 8x15 still outgun the SI's?
 

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If crossed over?
Not sure what that means.
 

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Thanks for taking the time and entering those in winsd. I had that downloaded at one time but since have a new computer. I will get it downloaded again.

From looking at the graph it seems the 8x15 option makes the most sense for me. It betters the SI's till the single digits which is enough to convince me to go that route. Just for kicks what do you think the spl of a single shiva 12" in 6cf tuned to 19hz would look like on that graph in comparison?

If I went with 8 do you still think the 6000 would be the way to go on the amp? Also, I am not opposed to crossing them over if that means I can get more spl above 10hz. I know with my space and constraints it would be pointless to chase the ultra low stuff anyway. I will save that for when I have a dedicated space.

So, above 10 or 15hz if crossed over would the 8x15 still outgun the SI's?

From some random shiva thread:
Based on the the Shiva SPl data chart for the 4.3 cubic ft box this should produce nearly 115 db at 30 and 40 htz, 112 db at 20 htz and still has plenty to give at 105db at 15 htz. The SPl shart shows that it is producing 90 db at 10 htz so I believe I will be very pleased with the results after it is finished.


I would still get the 6000DSP. I have a feeling that you are going to want a sealed 18 sitting behind your couch, or somewhere in the room to fill in room modes. And with the extra power on the IB channel, you can boost everything from 20hz and up by 3db if you want. It's ~$75...even if you don't use channel 2, you have it for later. You can't put all 8 on one channel of a 3000dsp and it's 275 extra if you need another for an 18.


Adding a HPF will let you add about 3-4db of gain across the board. But with the PEQ's/shelf filters in the DSP you could just boost/cut and have your cake and eat it too, no high pass needed. Add 3db where you want it. You can get more than that if wired differently on more amps.


More cone area, and more displacement...JBL wins.
 

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Discussion Starter #19
From some random shiva thread:
Based on the the Shiva SPl data chart for the 4.3 cubic ft box this should produce nearly 115 db at 30 and 40 htz, 112 db at 20 htz and still has plenty to give at 105db at 15 htz. The SPl shart shows that it is producing 90 db at 10 htz so I believe I will be very pleased with the results after it is finished.


I would still get the 6000DSP. I have a feeling that you are going to want a sealed 18 sitting behind your couch, or somewhere in the room to fill in room modes. And with the extra power on the IB channel, you can boost everything from 20hz and up by 3db if you want. It's ~$75...even if you don't use channel 2, you have it for later. You can't put all 8 on one channel of a 3000dsp and it's 275 extra if you need another for an 18.


Adding a HPF will let you add about 3-4db of gain across the board. But with the PEQ's/shelf filters in the DSP you could just boost/cut and have your cake and eat it too, no high pass needed. Add 3db where you want it. You can get more than that if wired differently on more amps.


More cone area, and more displacement...JBL wins.
I sure appreciate you taking the time to research and help me out on this. It really makes sense what you are saying with the amp. Now, you are talking about the 2 channel inuke 6000, not the 4 channel one, right?

It will be a priceless WTF moment when the ups guy shows up with 8-15" subs!
 

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The 6000 is 4 channel, the 3000 is 2 channel.
Edit; The NU46000 is 4 channel, the NU6000 is just 2 channel.
 
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