Newbie Sub building pain

[foamfan]

Hello folks, I got referred here and have been reading about some threads on DIY subs over the past few weeks. I'd like to build something good and hopefully under $1000 and with a maximum height of 3 feet or 6.75 cubic feet exterior dimensions due to home decor restrictions
This is going to be my first sub and am not looking for extreme performance in the less that 20 hertz range (old & cant hear it). I've read --k--(Ryans first twins build) and it is probably close to what I want to accomplish but need help on how to get this thing started since there are a few more choices now in terms of equipment used and more important; not screw it up.

Thanks

[joecarrow]

For $1000 and such a reasonable enclosure size, i'm certain that you'l be able to find extreme bass.

A few things that will help people help you-

-How large is the listening room? Is it open to other spaces?
-Is it just home theater?
-What is the desired crossover point to your main speakers?
-What are your main speakers?

These are just some preliminary things that should help us get an idea of how much power you need to keep up with the main speakers, and how the bass is likely to fill the room.

Also, sub-20hz bass is something that you're likely to experience and enjoy (as far as I know) until long after you are deaf. A large number of movies on DVD contain bass down into the teens.

If I had to guess what the gurus would set you up with, I'd say the "standard" is pretty close. It's about like this-

1) Soundsplinter RL-P 15" woofer, one or two in the largest vented box you can handle. There should be some help to be had with picking port size and getting the port flare right. These are about $280 each.

2) Behringer EP1500 for power. This is around $250.

3) Behringer Feedback Destroyer Pro for room equalization. This is about $100.


The total cost before wood is around $750 with shipping and tax. I'd say you could go just a touch over your budget and get two woofers, but I don't know if your box is large enough to accommodate two.

Anyway, that's my two cents- I read the forum a lot, but haven't built the kind of sub you're talking about yet.

[Gir]

Two RL-P15's are probably a bit overkill for what you need, unless your room is really big.

Also, like Joe said, subsonic really is an experience. You don't hear it, you feel it!


-Tyler

[ThomasW]

The basic info needed is 1) size of the room, 2) distance from the location of the subs to the listening position, 3) how loud you want the sub/subs to play? 4)do you want one larger and very heavy box, or 2 smaller lighter ones?

[foamfan]

Everybody, Thanks for your interest in my project and your willingness to help.

Here is the rest of the information:

1. The room is about 4300-4500 cubic feet. The bad news is it has one large opening to the rest of the house (approx another extra 12000 cubic feet) used exclusively for HT.
2. The listening position right now is 10 feet away from the sub.
3. We listen at moderate loudness levels.
4. My ideal enclosure size is no taller than 3 ft or 6.75 cubic feet exterior dimensions but I'm open to the idea of 2 smaller boxes if this is the best solution.
5. Will probably be ordering these speakers without amp & controller: http://nhthifi.com/2006/ht-s-classicfour.html unless there is a better DIY alternative :T

Thanks

[ThomasW]

If you're talking about only one 6.75 cu ft box containing 2 drivers, you can't go ported the box is simply too small.

Making a pair of boxes each 3-4 cu ft (internal dimensions) is about the smallest one can go. And we actually have several build threads with projects just like this using the RL-p15"s.

I'll post a couple of links when I get a chance

[foamfan]

If you're talking about only one 6.75 cu ft box containing 2 drivers, you can't go ported the box is simply too small.

Making a pair of boxes each 3-4 cu ft (internal dimensions) is about the smallest one can go. And we actually have several build threads with projects just like this using the RL-p15"s.

I'll post a couple of links when I get a chance

Would it be feasible to try to put 2 drivers in a single 6.75 cu ft box or cylinder ala LLT without giving up too much in sound quality? This is certainly appealing since ported designs seem to be bulkier

Similar to this:



Thanks

[joecarrow]

Careful, the "LLT" is what some people are calling a certain configuration of ported box- what other people call an EBS (extended bass shelf). Basically, this is a large box with a low port tuning that causes the output to decrease at about the same rate room gain causes it to increase. This allows fairly flat bass to very low levels without much EQ required.

If you meant to say "LT" as in Linkwitz Transform, then yes- it's feasible to put two drivers in such a box and correct the bass response electronically with a linkwitz transform. I don't think it would be a stretch to do so, but it can greatly increase the power requirement for a given SPL. It also reduces the overall possible SPL. I think that if you did the math you'd find that for a box of the size you're talking about you would have similar max SPL with two drivers in a LT and one driver in a ported box. The single woofer is cheaper, and requires less amp power.

There are other benefits of a sub with linkwitz transform, but I think that in order to do it right and get good performance it would exceed your $1000 budget.

[ThomasW]

The LLT is nothing more than a standard EBS (extended bass shelf) design. This design has been around for decades.

If you want to build an EBS alignment that's fine, but you're not going to be able to do that with 2 drivers sharing a 6.75 cu ft box.

Just so you understand, there are no performance differences between box subs and tube subs. Tubes are just cheaper, easier to build, and lighter weight.

[foamfan]

....snip.....If you want to build an EBS alignment that's fine, but you're not going to be able to do that with 2 drivers sharing a 6.75 cu ft box....snip....

Okay, Please correct me if I'm wrong but I guess the way to go is build 2 individual enclosures for 2 individual drivers using sealed enclosures to keep them as small as possible or make a ported single driver sub staying with a 3 foot 6.75 cubic foot enclosure. Is this a correct interpretation?

Joe, Thanks for pointing that out, in that scenario it definitely makes more sense to go with just one if ported can be made to work within the set limitations.

[ThomasW]

make a ported single driver sub staying with a 3 foot 6.75 cubic foot enclosure. Is this a correct interpretation?.

You'd need a ported enclosure ~8 cu ft (net internal volume) for a single driver to get a 18Hz tuning.

[foamfan]

Just throwing some ideas...but, What if an 18" driver is used instead of a 15"?

Is 18Hz the "magic number" to achieve for a sub to be considered pretty good?

Thanks

[ThomasW]

Just throwing some ideas...but, What if an 18" driver is used instead of a 15"?

Generally that means a bigger box

Is 18Hz the "magic number" to achieve for a sub to be considered pretty good?

It's an example to show how big the box must be.

[foamfan]

Thanks again for everybody's insight on this.
I'm sure that beginners like myself get to be oftentimes irritating but I'm a big believer in learning from someone who has "wisdom gained from experience".
I could play with the modeling software all I want but it would never give me the real-life results that enthusiasts like a lot of participants in this forum have gained over a long period of time so please pardon me if I come across as too naive ops:

I've read a few construction threads on builds similar to this and it all seems like it all comes back to an enclosed 15" driver as a possible solution or probably 2 enclosed 15" drivers as the solution with the least compromises using powerful amps and a BFD.

The thoughts in my mind are; do 1 enclosed driver now but keeping in mind that 2 is the ultimate goal. Can equipment selection be made based on this scenario? or a committment to doing 2 at the same time is absolute?

[---k---]

It sounds like to me, from what you've said that you would do well with one or two corner loaded sealed 15" subs. Ported subs just get really big, really fast. With you're 3' height limit, I think you've ruled out ported subs.

I think my twins thread and SteveNN's sealed threads are excent places to start.

As far as new drivers go, I think the RL-p15 is still postioned very well. I haven't spent any time calculating displacement/$$ numbers, but I think it will do well and git your budget. Amp prices have gone up, but the EP2500 is still the way to go in terms of power/$$. With going sealed, consider a Berhinger DEQ2496 over the FBQ. You can even go without at first, depending on your room (we lived for years without PEQs afterall).

And, you can certainly build one now and one later. I think this is a great way to get your feet wet. It will cost a little more, because SoundSplinter gives discounts for buying 2 ata time, but it isn't much.

Don't spend to much time researching or you'll miss out on time you could be enjoying you're new sub.

[joecarrow]

If you build one sealed 15" sub with a high quality, long excursion sub- say the soundsplinter- then if you get a reasonably large amplifier you will have everything you need to add a second sub at a later time. If you get the Behringer EP2500 instead of EP1500, then you should have enough wattage leftover to add a second sub and give one stereo channel of the amp (same mono signal) to each sub.

Don't build the sealed box any smaller than you have to, or you're just increasing the amplifier requirements, adding thermal compression, and increasing distortion.

I forget, is infinite baffle even a remote possibility? This would allow you to get by with a smaller amplifier, have reduced distortion, and have no visible enclosure in the room. You would just have the question, "Where is all that bass coming from??".

I hope, some day when I buy a house, to be able to build an infinite baffle sub. I doubt that my girlfriend would understand or let me do it, but I've been wrong before.

[ThomasW]

These are threads to reference, some you've already seen, some you haven't.....

https://www.htguide.com/forum/showpost.php?p=228946&postcount=1

https://www.htguide.com/forum/showpost.php?p=233970&postcount=14

https://www.htguide.com/forum/showpost.php?p=278542&postcount=35

https://www.htguide.com/forum/showthread.php?t=19391

[foamfan]

Thomas, Thanks for the links and your guidance behind the scenes.

Ryan, I've followed your twins and dual builds inspiring me to consider this undertaking

Joe, IB isn't possible for my application. Thanks for the tips on what stuff use.