Bang for the Buck

[cordes]

I would like to build an Infinite Baffle subwoofer as a project with my children so they can learn a little about making things themselves, and also for the performance gain vs. a traditional unit. That said, I am a huge bang for the buck type of person, and I live very, very much below my means. 

As a result, I'm wondering if I could beat out the performance of the Klipsch subwoofer which Costco has on sale fairly often? I have a commercial amp lying around which would probably do the job, so I'll just need some drivers and wood. 

Is this a feasible project, or should I just pick up a box sub from Costco the next time they're on sale?

[dan77]

I feel like a lot of info is missing here.

IB’s are built into the very frame of a home, is that opportunity present for you?

Also, most amps have built in roll off under a certain hz rating. Does your amp do that? I would think that such an amp would negate the benefits of a subwoofer capable of creating infrasonic levels of bass.

You don’t mention anything about the make/model of the traditional sub. But only elite or very high end subs can hope to compete with a properly installed IB setup. Traditional subs hoping to compete with an IB setup end up weighing in around 80 pounds or much more. And they can be quite large!

If this is a project meant for children, possibly go with an open baffle sub. Far quicker and easier to build. You can teach all the basics of physics with that just as well. And when done they can take it with them and have fun with it. No major investment (time or money) per se, so no harm done!

[cordes]

Thanks for the feedback. 

The room is relatively small, about 15x16x9. I have a hole in my floor above the basement which was most likely from an old cold air return for an octopus type coal burning furnace. It's approximately 15" square. 

I would have to get back to you regarding the specs on the amps which I have. They are from a sound system in a gymnasium which I pulled from a dumpster years ago. They should function just fine and are in great condition. I recall looking up the specs, and I believe that they can each produce up to 1000 watts depending on how they're configured and the impedance of the drivers. 


ETA: The subwoofer I'm referring to would be something like the following:
www.costco.com/klipsch-r-120swi-wireless-subwoofer.product.4000207198.html

I guess the real question I have is whether or not something I make for ~$500 would blow this thing out of the water, or whether it would not be that big of a difference in performance.

[dan77]

The traditional sub you have a link to is a very, very, very, entry level sub. I have over the counter subs with smaller swept areas (cone size) and smaller cabinets that go much lower than that sub at similar db ratings. And yes, I paid much more for them.

Almost all amps, expensive and cheap have ‘roll off’ protection built into them. It is why when building an IB setup amp choice is very important. I would not proceed with and IB installation until you have an amp that can go below 16hz.
For example, I have a mid line amp array for my HT setup. They are ‘Emotiva’. I emailed the manufacture directly and their answer was ‘yes’, there is a built in roll off at 16hz that is not defeateable. I will make the educated assertion that any commercial amp will have the same protection built in. It makes it safe for the amp and it makes it safe for the speaker being attached to it.
Let’s be honest, most people need such override protection so that they don’t blow out equipment by accident.

What I am trying to understand is what is your use case? Music? Home Theater (HT)?

If this is truly an educational exersice for children I think building a traditional sub would be more effective as a learning tool. Rhythmic sells sub kits that could be fun. I build 2 of their 15 inches sub kits. Took about a month of evenings, but I am very much into the details.

For the existing hole in the floor, this is a concern. If you are remotely serious about having really deep and immersive bass, then the sub determines where it should be located, not a pre-existing hole. If the sub woofer crawl excersice (explained in many articles) determines that the best location is where the hole currently exists, then that’s great. But you need to take the time to determine if that is true. This is truly one of the more fun parts of determing where a (any) sub would be located, meaning I would think the kids would enjoy this the most.

I am guessing you know this, but an IB array is considered an ‘exotic’ subwoofer implementation. These types of installations allow for some of the best bass that can be had. They exceed specs at any theater and elsewhere. They have requirements in areas of power (amp), space behind them, being opposed to each other (minimum of 2 cones in each manifold), speaker ‘F’ ratings, speaker ‘Q’ ratings, etc.

To answer your one question below… what can i do for 500 bucks. I would say it would be difficult to built an IB array for that. IB’s are built in pairs, so you need 2 speakers. Since IB speakers have very specific specifications to be able to work without a box, you have to get IB speakers. Cheapest I know of are about 250 a piece. Then you simply need a qualified amp. The cheapest I know of is around 300 to 350. So right there we are at 700 and you have not purchased the lumber yet.

Just know that if you do spend this ‘made up’ figure of 700, you will have a setup that will outmatch any $1,000 sub. You will also outmatch or at least have parity with the $4,000 and $6,000 subs out there. Harbottle comes to mind

Keep in mind that IB’s compete with the big boys. Like the king of subs, the Harbottle. You have admit that if I can built an IB setup for $1,300 (which is about what I spent) that sounds at least as good, but in my opinion 1000 times better than a boxed sub at $4,000 or $6,000 then that is a win.

But at this level of performance, no one with IB setups are trying to or needing to compete with traditional subs below $1,500 (or thereabouts, just a number I pulled out of my head). These are simply different weight classes (a wrestling metaphor). You don’t generally compare or compete heavyweight classes with lightweight classes.

Again, this is for a properly vetted and installed IB setup.

[ThomasW]

If the amps are up to the task yes you could build a dual 12" IB for roughly $500. Do you have a receiver that has a sub output?

[dan77]

Agreed, if going down to a 12 inch cone, there are savings to be had by doing that. My numbers were based on 15 inch speakers.

[cordes]

I'll attempt to answer some more questions.

This will be for movies at home, although I do listen to albums while we shoot pool in an adjacent room. I had planned on making the sub such that I could switch it on independently of the rest of the system, but that may not be necessary? 

I don't have a receiver with a sub output. I actually have a Kenwood integrated amp from the 70s. 

In regard to sub placement, the room unfortunately dictates that I'll have to put the sub right near the existing hole in the floor if I used a traditional sub, so I'm thinking that's pretty well a wash. 

I should state that I have better than average ability with a soldering iron and some basic electronics knowledge, though I don't expect that to be worth too much in this situation. That said, my father is a wealth of knowledge when it comes to electronics, and he may have various supplies lying around which may further the cause. 

If we could keep the price down with two twelves and make something which would blow away the super entry level sub while staying relatively within the budget for this project, I think that would really be worth looking into. 

[dan77]

I have had many subs in my life, garage sale subs, ones I built (several times), but never owned new.

Going DIY for anything takes time, interest and a willingness to do the necessary research. DIY provides a veritable gauntlet of challenges that you must overcome before the final product can be called a success.

All the knowledge you need for an IB install is on this forum. If you choose not to read a large portion of it, then gauntlet number one gets the better of you.

Here are some very basic questions that you must be motivated enough to address:

X) You must perform the ‘sub crawl’. I know you are limited in location, but just know that if you install an IB setup and it creates nulls in all the wrong places, you will just end up going to Costco and buying that $249 sub so that you can move it a few feet elsewhere. That is a waste of time and money.

X) No receiver with a sub output? Project is over before it starts. This is true for IB or trad. No bueno. Do not pass go. Just fold.

You know Craigs list has a wealth of used items. I would check there to see what subs you could find. Your average 12 inch sub (or larger please!) can produce very pleasant bass. In my area (Denver) I can find a used 10-15 inch sub for $75-175 all day long. In fact, in the last 7 years I have bought 4 used subs off Craigs list for about $100 each. One I put out in my back patio so as to help with the anemic outdoor speakers. Another one I placed in the workout room until I could afford a ‘better’ sub several years later (which was just a bigger sub I got off of Craigs list).

I just want you to know that I am happy to help. Know that all my responses are centered around someone wanting ‘serious’ bass. I have not seen any IB installs where the person was just looking for ‘better bass’. We are all trying to get stadium level bass into our little theater rooms. Do you really need 15 hz frequencies at 100db while playing pool? I am not trying to read into your responses, but I wonder if you would be happy with a trad sub. You can move it a little to obtain better null placement. And frankly, they can provide a pleasant amount of bass!

A successful IB install has very little to do with being able to solder. I did not use a solder once for my install. A successful IB install has to do with placement (location, location, location), proper amp power, and a desire to run the necessary DSP package afterwords. This might include Audessy, Dirac, etc. Most of us start out with REW as a minimum to see what DSP changes are being introduced. In the end, IB installs almost always require at least some amount of basic EQ (EQ is not to be confused with DSP of course).

Here is another idea!
90% of all used subs on Craigs list have ‘low power’ and ‘high power’ inputs. This is actually designed to work with a receiver such as what you already own. You run the speaker wire from your kenwood (left and right speakers wires) directly to the sub. Then run speaker wires from the sub to the speakers you already have. Wala! Done! You have a sub where you want, it is properly crossed over, if you need to move it you can, and you will have much improved bass. If you snag a 13 or 15 inch sub, then it may also be quality bass! Your out $100 and the hour to pick it up. Dare I point out that these used subs have the amp built into them already?

An IB setup does not lend itself to this kind of simplicity. There is no ‘high or low’ speaker input options on the back of some panel. Only XLR or RCA (depends on your amp - maybe post a pic?). So right off you will need to buy a different receiver or purchase some sort of splitter. Going this path will end up with you purchasing a passive cross over (solder alert!). This hack can work, but the audio quality will be so poor I am not sure what you would be chasing at that point. Let me repeat. With this approach, no cross over point control, very, very poor signal to noise ratio, very poor signal. This is an odd rabbit hole to visit much less consider.

Don’t get me wrong, I am all for IB’s. And I can tell that you have heard the quote: “IB setups are cheaper and better than any trad sub”. But the formula is not quite that simple.

Back to your children, I really think an open baffle project would be a lot of fun for them. Far more understandable than an IB build out. An awesome family project.

I hope that you keep us updated on your progress.

[ThomasW]

Some things to consider: an IB requires an electronic crossover, an equalizer, and power amplifier. Passive crossovers aren't practical because the inductors required need to be MASSIVE to do the job adequately, and those would cost more than an active unit.

To do this on the cheap used Behringer stuff for the crossover and EQ. There are analog units like the CX2310, or CX3400,or the electronic units dsp1100, dsp1124p,(note these can be used as Xovers or EQ). There are of course other brands of prosound equipment that will work Rane for example.

If you provide info regarding the power amps you have we'll try and figure out if they'll work.

[cordes]

Sorry to take too long in replying. Would either of these amps be sufficient for what I would need? If not, I may be out. If they'll work, then this might be a go. 


www.bogen-paging.com/catalog-product-hta250a.aspx


www.qsys.com/products-solutions/power-amplifiers/installed/non-network/multipurpose/isa-series/isa500ti/

[dan77]

The first link goes to an amp that does not seem to describe much at all. Not even a pic of the back. So no idea how to hook up to it. It runs 250 watts, that is enough for what you need

The second link goes to an amp that has selectable 50hz and 75hz high pass filters. No mention of defeating that.
So that means that you will buy a speaker that is capable of going down to 20hz or lower, and then provide power to that amp that feeds no signal below 50hz.

For casual listening either amp will work fine. I keep asking what your goals are.
If you are seeking a HT with exquisite bass, a different amp may serve you better. But if your goal is background music or just loud music, either amp will work just fine.

In any case, once you have completed the IB build and you decide you enjoy it, you can get any old amp/receiver at a garage sale and it won’t have such high high pass filters. Heck, you can get old receivers that can act as amps for about $20-$80. I know, I ran my HT off of 4 of them for about 6 months. They worked great!

On a whim, I looked on Craigs list for here in Denver. There are over a dozen for sale right now. This is an active listing. $35 bucks and it pumps out 150 watts for a single channel (which is all you need, a single channel):
denver.craigslist.org/ele/d/commerce-city-pioneer-vsx-605s-receiver/7713543884.html

There are 4 others currently listed as well. All below $60.

No matter what, you already have 2 amps that will work! Just buy the speakers and “git’r done”!  : )

[cordes]

Thanks for the confirmation that they will at least work. My goal is to have something better than the very entry level Klipsch unit which Costco sells and to not cost that much more. If I have to spend a few bucks, so be it. I would love to give this a try. 

Where should I be shopping for drivers? 

[dan77]

Sounds like you are going for a low cost solution. That is perfectly fine, but I feel compelled to say that 2 12 inch subs will be fun for sure, but again, without knowing what you will be using it for I have no idea if you will be happy.
You say you want a sub better than at Costco, but that does not tell me much. Sorry : (
Lots of used subs on Craigs list you can get for 200 that are way better than the Costco sub

Do you listen to radio/phonograph/CD’s/movies?
Do you listen to rock/EDM/classical/punk?
Do you listen at loud volumes?
Are you a bass head (like me)?
Are frequencies below 30hz while watching movies required to make you happy?
Do you even watch movies?
If so, is it a dedicated movie watching area?
Are 2 separate subs required for sub listening enjoyment (like me)?
Etc, etc.

Here is the cheapest sub I can find in a 12 inch size. You will need 2 of them minimum:
www.parts-express.com/Dayton-Audio-UM12-22-12-Ultimax-DVC-Subwoofer-2-ohms-Per-Co-295-512?quantity=1&irclickid=RVuU2LXHIxyIRDjz-8Si0zyFUkH1j9UF03Uc2k0&utm_source=Impact&utm_medium=Impact&utm_campaign=Impact&irgwc=1

Honestly if you want something with some real kick, then you need two 15 inch subs like these
www.parts-express.com/Dayton-Audio-UM15-22-15-Ultimax-DVC-Subwoofer-2-ohms-Per-Co-295-514?quantity=1

If you want to go with a speaker actually built for IB installs, then you step up to this bad boy:
aespeakers.com/shop/ibau-woofers/ib15au

And then there is the IB3 series. Highly referred to in many forums and what I own:
www.oneaudiousa.com/product-page/ib3

Here is my final and best recommendation. This company does not make 12 inch subs, but they do make cheap and well built 18 inch Infinite Baffle subs.
You can get 2 of these cheaper than all of the speakers above (per speaker) and truly have a sub that ALL of your friends will be impressed by.
Again, you need 2 of them:
stereointegrity.com/product/ht-18-v3