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Post by jefflam79 on Dec 27, 2006 19:08:38 GMT -7
I have a question regarding placement of the drivers. First, would using the wide open outdoors as the rear wave space work? I'm thinking no... but it didn't say specifically in the FAQ's. Also what about a closet that is on a patio that shares a wall to the main listening room. The closet can be mostly sealed off from the outside with the door closed. And would a small closet like this be enough space for an IB to function properly? I measured it and it's almost exactly 100 cubic feet of space but I do have some things stored inside.
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Post by ThomasW on Dec 27, 2006 20:13:17 GMT -7
Yes over the years several people have built IB's that vent outside, they work just fine.
The closet is to small to function as an IB. If you remove everything from inside the closet and line it with fiberglass, it will function as a large sealed box sub.
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Post by PeterW on Dec 27, 2006 20:18:14 GMT -7
Hi Jeff  In theory, using the outdoors as your rearwavespace is feasible. The logistics become the issue in practice. How far away are your neighbors? Venting your IB will mean that you will be having unmuted bass directed outside at the rest of the world. I remember that a guy named William Cowan in Australia has an exterior vented IB, he said that: "Since the sub only operates below 50Hz, the output off the back of the drivers is not offensive, and so far has not been responsible for any neighbour complaint." Here is a link to his info on this project: diy.cowanaudio.com/index.htmlI'm thinking that you would need some drivers suited to outdoor humidity and temperatures. You would need some type of manifold that would protect from rain and such. William Cowan is on this forum under the tag of "cowanaudio" As for if your 100 cubic foot or 2804 liter closet will work, just find the combined vas of the drivers of your choice and see if there is more than four times that volume in your closet. If there is more than four times the combined vas of the drivers in the closet, then it will work as an IB. Any more volume over 4 times vas is good. Anything over ten times vas is ideal. If the stuff in the closet is soft, (furniture,clothes, sound dampening foam,) then it it is desirable to have it in there as it will increase the closet's perceived volume as seen by the drivers. Hope this answers your questions accurately.. ;D |
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Post by jefflam79 on Dec 28, 2006 10:51:26 GMT -7
Thanks for the input guys. I failed to realize the bass would be wide open to the outdoors while thinking about an outside vented IB... That wont work as I live in a condo complex.
I could work it out to use the closet as an IB if I get a lot of the junk I have in there out and line it with some poly batting or something similar. The issue I have now would be driver selection. I'm thinking about using 2 15" drivers as I have only a small listening room to fill. Can you recommend good IB drivers with preferably a small Vas to accommodate my 100 cubic foot closet?
Also, how much bass would you expect to hear from just outside the closet on the patio outside if it was sealed off? I do want to be conscious of the neighbors.
Edit: Would you guys think I may be able to get away with a single 15" or 18" driver? The listening room is only 12' by 18'. My entire condo is only 950 square feet with 8 foot ceilings
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Post by PeterW on Dec 28, 2006 18:44:06 GMT -7
The audile bass outside should be minimall especially if you cross the sub low.
Low vas drivers, i am about to go somewhere right now but there are a bunch to consider in north america>(That is where you are right now?)
soundsplinter, adire audio, ascendant audio, mach 5 audio, FI car audio, tc sounds.
those are some companies i can think of off the top of my head..
As for the single 15 or 18. I would not advise it as you will need lots of excursion for low frequencies.
My opinion is to get a pair of the mach 5 audio MJ_18's they might work.
Hope it
goes well ..
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Post by jefflam79 on Dec 28, 2006 18:49:31 GMT -7
Im in California. Not sure what the shipping is on the Mach 18's but I may check them out. Would my space be enough for two of those? I only have the 100ft^3 remember...
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Post by ThomasW on Dec 28, 2006 19:31:03 GMT -7
What's the budget for this project?
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Post by PeterW on Dec 28, 2006 19:45:13 GMT -7
The vas of an mj-18 is 243.8L per driver. (mach 5 website)
Multiply this by two for two drivers.
Divide by 28.038 which is the conversion from liters to cubic feet.
This is the vas of two mj-18's in cubic feet.(17.39)
Divide 100 cubic feet by 17.39 to find how many times vas there is.
5.75
There is an estimated 5.75 times vas for two mj-18's in your closet.
Since the accepted minimum is 4 times vas, there is enough rearspace.
The question is, will there be enough dicplacement from two mach 5 mj-18's.
(They are endowed with a short 12mm xmax.)
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Post by jefflam79 on Dec 28, 2006 21:04:06 GMT -7
One thing I need to add is I have limited width on the closet. The width is only 27" so I'm not sure how deep the drivers are but if I go with a manifold style, the manifold and the mounting depth of the drivers can't be more than about 20" taking account room for the driver to breath... Unless I do a top and bottom mount manifold.
I also want to go with a pair of drivers that don't require a ton of power. I would like to use the APEX SR that I already have to drive these if possible.
My budget for the 2 drivers is about $500. I can add more if needed and the driver's cost can be justified. I don't want to pay double the money for 10% performance increase if you know what I mean. I'm looking for the best value driver that will fit my requirements.
A small Vas would certainly help as would a large Xmax with low power requirements. Does such a driver exist?
Are you sure a single 15 or 18 wouldn't be enough? I'm only looking for 100-110dB from ~16Hz on up in my small room...
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Post by ThomasW on Dec 28, 2006 21:41:39 GMT -7
A small Vas would certainly help as would a large Xmax with low power requirements. Does such a driver exist? Nope that would violate Hoffman's Iron law Positive Only?......Well, I hope you have really tolerant neighbors. You can buy 2 SoundSplinter RL-p15"s for $500+ shipping. Or you can get 2 Fi Car Audio .Q18"s for $480 including shipping. |
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Post by jefflam79 on Dec 28, 2006 22:04:19 GMT -7
A small Vas would certainly help as would a large Xmax with low power requirements. Does such a driver exist? Nope that would violate Hoffman's Iron law Positive Only?......Well, I hope you have really tolerant neighbors. You can buy 2 SoundSplinter RL-p15"s for $500+ shipping. Or you can get 2 Fi Car Audio .Q18"s for $480 including shipping. What about Chris White's IB? He said he had to work extra hard to get his IB down to ref levels. I assume his listening space is quite bigger then mine and he only used two Dayton IB 15's and the PE 250Watt amp... white.hometheatertalk.com/tips/ib.htmKeep in mind my living room is only 12 feet by 14 feet with openings into the very small kitchen and very small dining area. My entire condo is only 950 square feet. |
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Post by ThomasW on Dec 28, 2006 22:28:52 GMT -7
What Chris White fails to tell people is that he's running a separate box sub behind the listening position. Also I guarantee he's not getting 100-110dB at 16Hz from those 2 drivers.
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Post by jefflam79 on Dec 28, 2006 22:33:28 GMT -7
So it looks like I may end up looking seriously at 2 SoundSplinter RL-p15's. These are over 2x the price of the Mach 5 18's. Will they offer me that much more and will they be ok being driven by my APEX SR?
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Post by PeterW on Dec 28, 2006 22:35:17 GMT -7
In his review of his IB on the link you posted, Chris states that
"At 16hz, the sub was still putting out well over 75 db with ease. "
I would not think that this small IB would provide even close to 110 db at the stated "16hz and up"
With the halving of frequencey (32-16Hz), you must quadruple the amount of air dicplaced to keep the same spl. Dicplacement becomes more and more critical as the frequencey goes lower.
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Post by ThomasW on Dec 28, 2006 23:01:10 GMT -7
So it looks like I may end up looking seriously at 2 SoundSplinter RL-p15's. These are over 2x the price of the Mach 5 18's. Will they offer me that much more The Mach5 18"s don't displace anymore air than Parts Express' DVC 15"s. Looking at the driver comparison hyperlink will show how various drivers compare. Nope not even close. Look at the BK amp or the Behringer EP1500 |
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Post by jefflam79 on Dec 29, 2006 10:41:49 GMT -7
So it looks like I may end up looking seriously at 2 SoundSplinter RL-p15's. These are over 2x the price of the Mach 5 18's. Will they offer me that much more The Mach5 18"s don't displace anymore air than Parts Express' DVC 15"s. Looking at the driver comparison hyperlink will show how various drivers compare. Nope not even close. Look at the BK amp or the Behringer EP1500 That set up will put me way over what I wanted to spend on this project. I'll have to sacrifice something... I would be willing to sacrifice output down in the 16Hz range... I really want to use the APEX Sr if I can, which will save me at least $200-$300 on a new amp. If I can get 100dB from 20Hz on up with my budget I would be happy. I never listen at reference levels anyway, the additional power down low would only be for bragging rights and showing off to friends that come over. |
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