DIY in a concrete cubby: thomasw and any others...

[ttraynor]

i have a natural concrete enclosure under my waist high fireplace. Dimensions are 22"D x 25"H x 33"W with a 30" wide opening up front. What would be a good driver/amp combo for this space?

Room is 6000+ cu.ft. allowing for openings to other room/hallways. I listen to 95% music. I will be adding a good sub (600-1,100 bucks) for the other end of the room as well--probabaly from one of the mail-order companys.

Suggestions?

[cjd]

[QUOTE=ttraynor]i have a natural concrete enclosure /QUOTE]

This just cracks me up... Natural concrete enclosure, eh? As opposed to human-made? :P

The volume sounds good for one of the high excursion 15" drivers out there, sealed.

What kinds of music? What kind of performance do you want to get out of this system? Include in that any additions ( you mention another sub for the other side of teh room?)

Also... does this space under the fireplace happen to have the ability to lead into, say, an open basement or something?

C

[ThomasW]

Hi,

And thanks for moving the thread here, it will be much easier to answer your questions on this forum.

I'll get everyone up to speed. The cubby is 5 sided enclosure below a elevated fire place. It was probably intended to store wood. It can't be used for a pure IB so the options are a ported or sealed.

The room is fairly large and he wants high output.

The idea is to simply fabricate a removable baffle board that screws to frame attached to the concrete.

Since the box is pretty big it maybe possible to use a pair of 15"s mounted diagonally.

We're hoping to get a picture for reference. He doesn't have a digital camera so he's trying to get some to shoot a pic for him....

[cjd]

A pair would be slick. There enough volume in there for that? I would guess sealed would be the only option at that point, but a good amp and some EQ and it'll be producing thunderous bass.

Hopefully there are no issues with vibration in the structure itself - firebrick is usually laid up dry. . .

As to the IB thought, unless it's on a slab or an upper storey, sawzalls work wonders. :P

C

[ThomasW]

If you want really high output the current best buy would be a pair of the RL-p 15"s from

http://www.soundsplinter.com/rlp_premium_series_12_and_15_inch_subwoofer.html

Next in line would be the 15" TC2+ from oaudio

http://www.oaudio.com/TC2_PLUS.html

Both these driver are made by TC-Sounds. When Adire, Ascendent and AE get up to speed on their new drivers there will be many more options. But right now options are limited.

[Drewbert]

If you want really high output the current best buy would be a pair of the RL-p 15"s from

http://www.soundsplinter.com/rlp_premium_series_12_and_15_inch_subwoofer.html

Next in line would be the 15" TC2+ from oaudio

http://www.oaudio.com/TC2_PLUS.html

Both these driver are made by TC-Sounds. When Adire, Ascendent and AE get up to speed on their new drivers there will be many more options. But right now options are limited.

whenever they do get up to speed, what sub would potentially be the best?
For me that RLp is looking really nice

[ttraynor]

Do these drivers "match" the space? How does one know? What amp(s) with them? from who? Does 2-12's" "beat" one 15"? How much monkeying around with equalization will be needed?

As much as this a DIY, I'd like it to be "plug-and-play". Also, I want musicality...thinking about HSU's new HO sub up front, Axiom, Rocket, etc...about 800 bucks on the up-front and hopefully only this much for the DIY.

Thanks.

[ThomasW]

To be honest I don't know anything about retail subs, I've never owned one. Any design we create should pretty much lay waste to a retail design costing $800.

The cubby space is ideal for a single 15". If you want more output we can go with a pair of 15"s, and use EQ to boost the bottom end.

You might want to save a few bucks and duplicate your rear sub in a premade box from Part Express. That would give you virtually identical performance and save money.

[ttraynor]

What's involve in EQuing the set-up/ How much? Amp(s) cost, anything else? I might as well get going on this and "need the info" as Austin Powers would say....

[MDJones]

To EQ the sub you would need something like the Behringer Feedback Destroyer. It's about $100, and you can follow Sonnie Parker's guide here for a good tutorial. Amplification ultimately depends on what drivers/how many you choose, but you should definitely get a pro sound amp. If you want good bang for buck, get something like the Behringer EP1500 (~$250) or EP2500, but just be aware that it does produce noise from the fans. If fan noise is an issue (and you can't place the amp in another room), then you might want something like a crown K1 or K2, but these are a lot more pricey (>$1000 new).

[ThomasW]

Here's what you could do. The BFD and the power amps are stereo. You only need, one mono channel for the front and one for the back.

So buy one big amp like the EP-2500 ($300) and one Behringer BFD ($99) and that's takes care power and EQ for both the front and back subs.

As Marcus said the EP-2500 is a fan cooled amp, if you can't live with the fan noise then you need a Crown K2, a K1 is to small for a pair of these. K2's are ~$1200 new, and usually 1/2 that on eBay

People are finding Sonnie's guide to be a bit over the top these days so I've written a much simplified version HERE

As with any sub you'll need a Rat Shack meter and Excel to plot the curves. I've made a updated and simplified spreadsheet, you can download it and read more about EQ and placement HERE

[ThomasW]

Drew,

whenever they do get up to speed, what sub would potentially be the best?

A single RL-p 15 does fine with a EP-1500 for most people. Chris at SoundSplinter is running one RL-p 15" with a EP-2500, but he gets his drivers fixed free if he blows one up ...

[ttraynor]

I'm confused. The Soundsplinter site says 2.1 cu. ft. is recommended with 15" driver. I have just over 10 cu. ft.--probably just under allowing for driver displacement. To me then, it points to at least two drivers + amp (fan noise--still don't know how much noise amp puts out--can it be mounted ON the baffle board--that's a little further away from my main listening site, but not much, so maybe not good idea), + BDF thingy.

So, now this thing is pushing 2000 bucks with a silent amp and baffle board construction (no--I don't own a router, plus I probably want some furniture grade wood)....and you guys say it WILL sound musical--not just fat, flaccid, low frequency--guaranteed? It has to because I have no money in budget to disperse/support bass output sound with a front end ready-built sub.

My concern is with so many engineered subwoofers sounding so different to reviewers at seemingly similiar specs/price points, how do I KNOW my home-made thing-a-ma-bob will hit the musical sweet-spot for what I am going for (I really don't give a hoot about movies--STEREO music is the priority)? At least with those mail order type subs--I can order from a couple manufacturers and return one for full refund minus shipping--and NO blood, sweat and tears.

Thanks all.

[Paul H]

There's a certain irony in someone you don't know posting to tell you 'don't worry - trust them' but I'll do that anyway, particularly for this forums moderators.

A couple of years ago I had the same thoughts about spending good sums of money on designs I knew nothing about, designs from people (on this forum) I knew nothing about. I'm glad I decided to take their advice and jump into some projects.

The vast majority of so-called professional reviews you're reading on various subs are confusing and biased. Good subwoofers have decent large drivers to move lots of air, powered by large amps in properly sized boxes that may or may not have ports.

If you're going to build a subwoofer youself, download unibox and put in the parameters for various drivers. The resulting frequency response curves, etc will give you an indication of how they will perform.

If I were you, I'd buy a single 15" driver, a behringer feedback destroyer for equalization and a used pro amp.

Then if you don't like the results, you can sell the works for little to no loss - I'd bet that you won't want to sell ...

Paul

[Paul W]

I'd put 2 drivers in that cubby...or build it so you could easily add another anytime you want more output or lower distortion.

The space may be larger than listed on the Soundsplinter site, but a larger space will just relax the response curve and improve transient response. Considering room gain, the "relaxed" curve may actually be a better match for your room...less boom with your music. Anytime you want deeper/stronger bass, just dial in a little EQ. Go for it!

[SteveCallas]

Regarding the fan noise, I think what is important is if your room is carpeted, has furniture, few windows, a sofa, is of decent size, etc., or if it is relatively empty, has hardwood floors, many windows, is small, and things like that. In the first room type mentioned, an pro amp with variable speed fans shouldn't be a problem - in the second room type, the fans may very well be bothersome.

[ThomasW]

Tom,

You need to understand how the retail audio market operates. With the exception of internet companies (SVS for example) the markup for good home audio gear is no less than 100%. And as per standard practice for any product sold at retail the cost of marketing is 40%.

Good subs are heavy, so freight adds quite a bit to the cost. Mfgr's usually underbuilt their cabinets to save weight.

Despite marketing claims there's nothing magic regarding the design of any subwoofer on the market. Some companies add circuits to limit distortion (Velodyne servo for example). Doing this allows them to use a smaller box, and that's basically all it does.

If you want a finished wood from you can buy hardwoood veneered 3/4" ply for ~$40 a sheet from any home center store.

I built speakers for 15yrs using only a hand held circular saw, a jig saw, and an electric drill.

SoundSplinter primarily sells to car audio people. So they design and recommend small enclosures. A bigger enclosure means the sub is more efficient and plays lower.

You have a foolproof situation, since the rear box is built. All you need to do is attach 2"X2"s to the concrete and install a board to hold the drivers (aka a baffle).

Since this is a rear sub you many not need 2 drivers. That depends on what you use for the front sub.

It's pretty easy to make a front sub using the same driver/drivers by getting a premade box from Parts Express. All you do with them is make the cutout for the driver and glue in a bit more wood to stiffen the box.

This is the $150 box (currently no charge for shipping) from PE (Part Number 302-820 ).



One or two of these using the same RL-p 15"s driven off the other channel of the amp, would be a pretty good front sub for a fraction the cost of anything comparable at retail.