# 3 commercial subs or an IB sub system



## trippigs (Apr 6, 2015)

Hello to all. My wife and I are building a new home which will have a dedicated home theater room. The dimensions are 18'x14'x10'. I would like to use as much of my equipment as possible. I have Definitive Technology speakers (ProMonitor 100 (2), ProCenter 100, BP-1x (2) and Powerfield 12). I also have two (2) Energy ES8 subs. Have a cheap Pioneer A/V receiver that I will replace with a Marantz SR 5008. Have a Hafler DH-200 amp. Now, I need advice from you Home Theater experts! 

Should I use my three subs OR build a IB Sub manifold system with two (2) Dayton Audio 15" drivers and my Hafler??? I am generally not too much into experimental audio but the IB stuff is intriguing and could be installed before home construction is completed. I basically can't decide if the IB concept is for real and represents a legimitate alternative to commercial subs. Just hard to imagine a simple homemade wood box with drivers can outpreform commercial subs with years of design and engineering. I am pumped either way but just have a decision to make.


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## tonyvdb (Sep 5, 2007)

The challenge with IB subs is you can't move them if placement becomes non ideal. Sub placement is crucial in a room and is impossible to predict how they will react once furniture is in place and walls are up. Generally it's better to have a sub that can be moved around. That said 4 subs placed with two up front and two in the rear can give great results so IB can work.


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## Talley (Dec 8, 2010)

and to my understanding you want to have subs in multiples of 2.

one sub, or two, or four, or eight, or sixteen.

not 3.


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## trippigs (Apr 6, 2015)

Didn't know three subs was problematic. I did know you need a even number of drivers in the IB system. I actually do have a fourth commercial sub (an old Yamaha) but didn't plan on using it). Thanks for the input.


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## tonyvdb (Sep 5, 2007)

The other issue is you have mixed matched subs, the issue with that is you can't blend them together without having peaks and nulls because each sub has a very different frequency response. I would start by picking two matching subs and see how that works. 4 is overkill in my opinion. 
There are many Comertial subs that sound fantastic. But my personal take is that getting them from Internet direct companies like SVS or HSU gives you far bigger bang for buck. 

Do you have a budget in mind?


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## trippigs (Apr 6, 2015)

Well I could build the IB sub system for ~$300...experimental and fun but inexpensive. I've not thought about, nor do I really want to, buying another commercial sub....kinda been there and done that feeling.


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## Insearchof (Oct 21, 2014)

tonyvdb said:


> There are many Comertial subs that sound fantastic. But my personal take is that getting them from Internet direct companies like SVS or HSU gives you far bigger bang for buck.


^^^Agree. If you've never heard any of the offerings from SVS, HSU, Rythmik or the some of the other ID sub companies, you owe it to yourself to at least audition them. 
They can be a step or 2 above anything box stores or even some high end audio stores will try to sell you. 
For what they can do and how they sound, many of the ID company's prices make the decision easy.


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## tonyvdb (Sep 5, 2007)

IB for $300 won't give you much in my opinion. But given your budget DIY is going to be your only option if you want anything decent.


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## trippigs (Apr 6, 2015)

$300 is approximate but it would buy four(4) Dayton Audio DC 380-8 drivers (15"). I already have the wood and the Hafler amp. The minimal cost is one thing that appeals to me. I am just leery of ending up with a poorly performing sub system...and more extra stereo stuff I don't need. I fully recognize that commercial subs cost considerable more.


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## Tonto (Jun 30, 2007)

Isn't that a 100 watt/ch stereo amp? I think you'll need a lot more power to drive them.


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## trippigs (Apr 6, 2015)

AAHHH...they are rated @ 100watts. I didn't know how to calculate watts to each if they share an amp. Thanks...this is good information.


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## willis7469 (Jan 31, 2014)

Fwiw, I have 3subs in my system, and while not perfect, my results are great. Yes it took a lot of tweaking, but was worth it. Also, if you feel like "been there,done that" with commercial subs, I think maybe you haven't tried the right one. As said above, you owe it to yourself to try. SVS for example. 45 in home trial, free shipping both ways, 5yr warranty. Agree with Tony, and tonto. 300 bucks in drivers, and an amp that's not powerful enough will surely leave you wanting more. Plus the pile of extra stereo equipment you didn't want, will possibly be junk. And you won't be able to move them around the room. IB is great, but it has to be done right.


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## trippigs (Apr 6, 2015)

Yes, the amp is rated @ 100wpc into 8 ohms.... some say the power was under rated. Is this math correct... 2 drivers in parallel is 200 wpc into 4 ohms. 4 drivers in parallel is 400 wpc into 2 ohms. I find little information about stability @ 2 ohms so I would not chance it.


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## trippigs (Apr 6, 2015)

I completely understand that there are much better commercial subwoofers than what I currently have.... and there will immediately be better ones out there if I were to buy the "best" one available right now! I am just testing the waters to decide if I should just use the commercial subs I already have or experiment with an IB sub system. Want to take advantage of new room construction if I go with IB sub. Your opinion.... would a single manifold with two (2) Dayton Audio drivers as referenced above possibly be adequate for the room as I have described?


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## Insearchof (Oct 21, 2014)

trippigs said:


> I completely understand that there are much better commercial subwoofers than what I currently have.... and there will immediately be better ones out there if I were to buy the "best" one available right now! I am just testing the waters to decide if I should just use the commercial subs I already have or experiment with an IB sub system. Want to take advantage of new room construction if I go with IB sub. Your opinion.... would a single manifold with two (2) Dayton Audio drivers as referenced above possibly be adequate for the room as I have described?


Using the Hafler amp to drive them? Probably not. Depends on your expectations. With a 100wpc @ 8 ohms and 2 of those drivers you mentioned earlier you'll probably be hard pressed to pressurize your 2500 cuft room with those.


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## trippigs (Apr 6, 2015)

OK. Would wiring the drivers in parallel make a meaningful difference?


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## tonyvdb (Sep 5, 2007)

If you do that you reduce the output to 50wats per channel so that would be way to little.


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## trippigs (Apr 6, 2015)

How about in series??


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## tonyvdb (Sep 5, 2007)

Ok sorry, let me clarify. If you run them in series you increase the ohms meaning you reduce the amount of power that the amp will supply to each speaker. So your 100 watt amp becomes only a 50 watt amp

When you wire in parallel you reduce the resistance and the lower you go the closer to a short you have. Anything below 4 ohms on most amps will cook it


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## trippigs (Apr 6, 2015)

Tonyvdb...I appreciate your help. Given that series wiring cuts power in half, is it correct that parallel wiring doubles the power? If so, does this mean my Hafler would deliver 200 watts to each driver. I am still learning!


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## tonyvdb (Sep 5, 2007)

In a sense yes, however if your Dayton Audio 15" drivers are the 4ohm ones you would then be down to 2ohms and that would cook that amp in only a few min. Even 200Watts is not enough for a sub. You would probably need at least 600 before you get even close to what they should be getting.


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## trippigs (Apr 6, 2015)

OK...that is very helpful. The IB experiment appeal was really based on intrigue, new construction and what I thought would be economical costs. Yall have helped me understand that this will involve all new equipment and more expense than I hoped. So, I am leaning toward just using my commercial subs for now. Of course, I still might try IB down the road sometime....never say never! Thanks so much for all the input.


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## tonyvdb (Sep 5, 2007)

A decent amp to drive subs is not expensive (less than $300), do you have a budget?


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## trippigs (Apr 6, 2015)

Not really but my house budget is ~$600,000 plus land so I am just not interested in much new stereo stuff. I hoped a couple of drivers, a manifold (which I can build @ minimal cost) and my Hafler would work. This is my retirement home so I will have plenty of time to consider an IB later on. Could experiment with commercial sub placement in the completed room which would be good for locating the IB manifold. It is all just a matter of priorities and balance!! Thanks again


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## tesseract (Aug 9, 2010)

Talley said:


> and to my understanding you want to have subs in multiples of 2.
> 
> one sub, or two, or four, or eight, or sixteen.
> 
> not 3.


Earl Geddes spent 40 years working on the problem of big bass in small rooms. 3 subs work great!

http://mehlau.net/audio/multisub_geddes/


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## trippigs (Apr 6, 2015)

Nice read which provides some good ideas on 3 subwoofer placement.....gotta start somewhere. Thanks for sharing this.


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## Nitrofreakman (Feb 18, 2013)

tesseract said:


> Earl Geddes spent 40 years working on the problem of big bass in small rooms. 3 subs work great!
> 
> http://mehlau.net/audio/multisub_geddes/


I COMPLETELY agree with you about Earl. I've been reading his posts for the last 15 months and it has completely changed the way I view audio. IMHO, if there ever was an all-around audio guru, it would be Earl Geddes. Following what he advocates completely transformed the sound of my system's bass quality and output. At first I bought 2 cheap subs on Kijiji to complement the two I already had ( all 4 subs were different brands and sizes BTW), I blew the 10" ported JBL a few month back, the other 3 are sealed ( which I prefer ), and I can't tell the 4th one is missing LOL..I only paid $75 bucks for it anyway.

I actually just received my 3 Nathan NN-10 speakers a week ago. I bought them from Earl on 'hope that what I'm reading is correct' lol. Well let me tell you, they far exceeded my expectations, and just keep getting better every day...my old music is all new music again, and they integrated with my multi-sub setup even better than the speakers they replaced. I will keeping these with NO plans to upgrade ( unless I can afford Summas one day )

Try 3 subs, you'll really like it, especially with a miniDSP, if 3 doesn't cut it, add more 3 is just the point of diminishing returns. I haven't even used my mic to setup the subs yet, but the sound is so good that I'm in no hurry.


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## trippigs (Apr 6, 2015)

Earl's writing style registered with me. It just made sense without being excessive or using too many subjective adjectives. Sometimes audio literature reads like a wine review! His has a bit of science to ground concepts but offers an understandable blend..


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## Nitrofreakman (Feb 18, 2013)

Yes, I agree. He truly uses a scientific approach and he designs his whole 'system', not focusing only on just a few aspects, but optimizing everything..I haven't even began to use my mic..partly because I'm not technical enough on that end..I have an idea what to do, but haven't applied it yet..I did follow his 'by ear' suggestions, and I'm more than happy with the results..this without any EQ on the subs ( only overlapping bandpass filters as suggested by Earl ) with the front speakers set to large, and NO EQ on any speakers either ( the only room correction I used was buying the correct speakers lol ) Keep the subs and front speakers as far apart as your room will allow.

The other reason I haven't gotten overly picky with my sub setup is because my whole HT room is in the mock-up phase, We bought a different( bigger ) house, one with a dedicated room for my HT addiction. I mocked up my system to figure out where everything will be mounted and setup, before I completely tear the room down and structurally damp it as per Earl's directions..my goal is to mimic his room design, if I can get close, I'll be happy..gotta sell our other house first though!

I hope you try it out, I'm sure you'll be quite please. It took some time to do by ear, I did it over the span of a few afternoons, spending 20 minutes here and there and tweaking the miniDSP's bandpass filters until it sounded great. My subs aren't huge either ( 12", and oval sub about 12.5"w/Passive Radiator, and an 8" ), but I have more/better bass than my friend who has 4-21" sealed subs in his room..there's no reason for it, but it's true. He refuses to read Earl's technique all the while remaining frustrated at why my bass is so much better. The bar has been raised in my neck of the woods, but I can't take credit. It's really hard to argue with Earl's results, even when I haven't followed them to a T:T I hope your results make you as happy as I am with mine.:bigsmile:


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## gdstupak (Jul 13, 2010)

Here is my IB sub experience:
most info is in posts #1,4,5.
http://www.hometheatershack.com/for...ild-projects/50657-glenns-ib-sub-2-fi18s.html

In short, there is a different experience between IB subs and normal box subs. 
With IB subs, the low frequency pressures are greatly felt but with very little physical shaking, the IB bass box and ceiling vibrate slightly. 
With normal box subs, the low frequency pressures are there but usually I am overwhelmed with physical shaking of the sub box which in turn shakes the flooring, the couch, the tables, the cabinets, etc.
I believe the physical shaking has more to do with the physical set up of sub drivers than whether the drivers are in a IB box, or in a standard closed box. My IB sub has 2 drivers facing each other, they probably cancel out big vibrations. My standard sub boxes contain 1 driver facing the floor, that 1 driver really shakes up and down with not much to stop it, it works much like a butt-kicker you place on a couch/chair.

Even though my IB sub plays frequencies as low as (or lower than) my standard closed box, I missed the physical shaking, so now I always use my IB subs with my standard box sub. I use outboard EQ's to match all frequencies between the subs.


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## gdstupak (Jul 13, 2010)

*A note on how many subs is overkill...*

1 normal sub woofer should be able to reproduce 50-70hz tones at the proper decibel level. Getting below 50hz, the decibel levels fall off. Yes, a good one can play 5-10hz, but not at the proper levels.

Multiple subs isn't about getting the bass louder than it should be, it is about being able to reproduce those 5-10hz signals properly and evenly with the 50-70hz tones.

More than 3 subs is necessary for proper ultra-low frequency response, it is nowhere near 'overkill.'


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## trippigs (Apr 6, 2015)

AAAHHHH...nice continued input. I have decided to got with my three commercial subs and see if I like it. If so...well that is good. If not....I will build an IB system.


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## willis7469 (Jan 31, 2014)

gdstupak said:


> A note on how many subs is overkill... 1 normal sub woofer should be able to reproduce 50-70hz tones at the proper decibel level. Getting below 50hz, the decibel levels fall off. Yes, a good one can play 5-10hz, but not at the proper ncy response, it is nowhere near 'overkill.'


 Glenn, I was wondering about the omission of the 10-50hz stuff. For example, my PCs can play flat down to about 17hz. Or Tony's ultra that goes even lower. Even my old PB12 was good down to 25. I may misunderstand where you're going,so just wondering if I missed it.


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## tonyvdb (Sep 5, 2007)

There are plenty of subs that can play down to 18-15Hz and at decent dbs. My room is 4000cu ft and my single pb13u fills in nicely although It would be nice to have one more.


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## gdstupak (Jul 13, 2010)

*willis7469,*

_omission of 10-50hz stuff_... I wasn't omitting this range for any reason, it's just most "normal" subs have a hump around the 50-70hz region and then the low point is 5-10hz.

_"normal" sub_... I wouldn't consider either of your subs "normal," they are much better than normal. And even as good as both of your subs are, they fall off rapidly below 17hz, you will not get proper 5-10hz reproduction without multiple subs. 
I am being specific here about reproducing a properly flat ultra low frequency response, not just being able to get decent output.
Also, more subs=less distortion.


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