4 15" Sealed Subs

[---k---]

I'm at work, so I can't model it up. Did you make sure you hit used the pull down menu to "Heavy Fill". That can make a big differance. Maybe not the differance between 200L and 900L though.

Also, iirc, the D4 version wants more volumn than the D2. But, again, not probably the differance between 200L and 900L.

Based on what I remember, I think you should be in the 150L - 200L range.

Hit the print screen key, and then paste into MS Paint or something, and post the screen shots.

[InPhase]

Brian, why should I shoot for .6-.65? Is that a "happy meduim"? I thought someone told me earlier that .5 was optimal. Sorry for all the questions. I just don't want to screw this up.

--k--, I'm at work as well, but I will post my Unibox model when I get home.

Should I try to make the volume as close as possible to the Q I'm targeting or should I just try to make the boxes as large as possible?

Thanks for all the help everyone! ;x(

[InPhase]

Btw, I'm on the fence about whether to do each of the 4 RP-L15's in their own boxes, or doing 2 per box. Can you guys help push me one way or the other? I can fit both options in my theater. TIA!

[engr_dave]

whether to do each of the 4 RP-L15's in their own boxes, or doing 2 per box

I struggled with that very decision (I'm using four RSS390HOs). The big plus for individual boxes is ease of mobility. The big plus for 2-per-box is opposite-face mounting which provides force cancellation (less wasted energy and no tendency to walk across the room).

I had actually thought of trying to get the best of both worlds by building individual boxes in such a way that they could be latched or bolted back to back. But I couldn't think of any mechanism that would a) be strong enough to prevent buzzing or rattling, b) pose no risk of damaging the speakers (MDF has poor compression strength and doesn't hold fasteners well) c) not overly complicated or expensive and d) aesthetically acceptable (this ruled out four big bar clamps).

So in the end I went with the 2-per-box approach. I just cut the pieces this morning and I'll start assembly tonight.

[ThomasW]

Brian, why should I shoot for .6-.65? Is that a "happy meduim"? I thought someone told me earlier that .5 was optimal.

The "Q" will determine the size of the box. Higher "Q" = smaller box.

0.5 = critically damped alignment, IMO = best sound. There are 2 ways to get that "Q", big box, or with a smaller box assisted by a Linkwitz Transform circuit

[InPhase]

Dave, I'm looking forward to seeing your progress.

The "Q" will determine the size of the box. Higher "Q" = smaller box.

0.5 = critically damped alignment, IMO = best sound. There are 2 ways to get that "Q", big box, or with a smaller box assisted by a Linkwitz Transform circuit

So if I have a LT (I have the DEQ2496) what Q should I aim for? .6-.65 and then stuff it and LT it, will I be close to the critically damped alignment?


--k--, The Unibox models are attached. I reentered all the numbers and the box volume came out slightly different, but Q=.5 is still too large a box. Any hints on the box volume I should go after since I have the LT for it?

Thanks.
Dual RP-L15's Q=.5:

Image not available

Dual RP-L15's Q=.6:

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[ThomasW]

Model a Qtc of 0.707.

Or just choose the largest box you want to live with and go from there.

[Bent]

smaller box with an LT will give you the system Q, but at the expense of some output
bigger box - most output that the selected Q will allow.

if given a choice ahead of time, and knowing you can fit/build a larger box, why not?

[---k---]

First, I'm confused. You're using the SS RL-P15 D4, correct? Your models show a RP-L15. I think our dyslexias isn't in sync today.

Okay, moving on. I modeled the RL-P15 D4, it looks like I'm using the same parameters as your models. WOW! Huge differance between the D2 version and the D4 version. For the D4 version to get a Qtc=0.6, needs 300L while the D2 version needs 118L. About half. I didn't realize there was such a big difference between these drivers.

For the price you paid, they were still a great deal. I think you need to mock up in your room what 300L looks like and the other options, and see what you can live with. 300L is quite large.

Thomas must know how big Qtc=0.5 is going to be and therefore isn't pushing this option. So I must agree with him, build as big of a box as you can live with. Because, at the end of the day, I think you are going to want the same frequency response, and whether you get there with physical box size or by EQ, it doesn't matter. But, imho, the less EQ you need, the better, and less amp required.

Also, have you considered tubes? Thomas has a project on his website where he put a driver in the top and bottom of a sealed tube.

[InPhase]

Ryan,
Thanks for checking my numbers. I haven't considered tubes, but I might. Right now my plan is to build 2 boxes that are ~26"x24"x19".

Does anyone know the volume that the SoundSplinters take up? Also, should I glue the wood together (In order to double my thickness) before making my cuts?

[---k---]

Use 0.21 cu ft for each driver.

I think you'll want to cut the wood first and then double up. Working with double thickness will be near impossible due to the weight.

Those dimensions only give me ~131L effective. Can you live with bigger boxes? Like 2x as big?

[InPhase]

Thanks for the information Ryan.

I can live with a bigger box to make these work. If I use Birch or some other wood instead of MDF, can I get away with not doubling up the walls to keep the weight down? Any recommedations on a strong light wood to use so I don't have to double up?

I'm plan to buy the wood tomorrow, so any help will be appreciated. Thanks!

[ThomasW]

With a pair of drivers per box, it's a good idea to use double walls.

[InPhase]

Okay, I'll double up then. If I decided to make a tube sub, is there any issues with the distance between the drivers and resonances?

[engr_dave]

Okay, I'll double up then.

Probably a good idea. However, in the interest of weight, I decided to double up only the baffle and just brace the crap out of everything else. :B Maybe I should have gone with Baltic birch? Oh well, too late now! :blink:

any issues with the distance between the drivers and resonances?

The wavelengths of any sub frequencies are so much longer than box dimensions that it shouldn't matter. Some lining/damping will absorb any higher frequency stuff.

I think I'm just ahead of you in the build process. I started sawing up MDF yesterday. In one long day, I got all the way to mostly-assebled boxes. I'll start a build thread to avoid hijacking yours. Good luck! :T

[ThomasW]

Okay, I'll double up then. If I decided to make a tube sub, is there any issues with the distance between the drivers and resonances?

Not unless the boxes/tubes are significantly longer than what you're building.

[InPhase]

Project is on hold till next weekend because the guy who has the tool shop is not available. Looks like I have all week to finalize my design and see how Dave's project is coming along.

[InPhase]

Did I just make a big mistake? I went to purchase the wood at the local builder's store and they had normal MDF and Ultralight MDF. A asked a couple of employees about the strength of each and they all agreed that they were equal. I went with the Ultralight because of how large and heavy I expect my boxes to be. I even paid a few extra dollars for the Ultralight over the normal stuff. But when I to cutting it, I noticed it is very soft and easy to damage. Is this stuff strong enough for speaker building? Is normal MDF soft?

[ThomasW]

Normal MDF has no strength.

Don't have a clue about "lightweight" MDF since I didn't know such a thing existed.

[kingpin]

Image not available

Hope this helps.

Mike

[InPhase]

Should I use it then? It seems to be slightly less dense than normal MDF. Thanks!

[---k---]

If you can afford to buy more, probably should use the heavier MDF. Heavier is always better.

Differnt people across the internet argue differnt things about how much thickness and bracking is needed. I think around these parts, the typical recommendations are at the extreme conservitive end. So, I guess it all comes down to your goals. If your not willing to sacrifce sound quality, then get the heavier stuff. I'm not sure anyone will be able to tell you how much SQ you might give up with the lighter stuff.

If you're doubling the thickness, maybe you can use the lighter for an inner layer and bracing.

[Mark Seaton]

If the drivers are on opposing faces to cancel any rocking forces, weight doesn't matter. Bracing does. As can be seen above, nominal "MDF" comes in all sorts of variations. You are probably just fine, but it probably won't withstand a ding on the corner as well as some of the more dense boards.

[InPhase]

My first inclination was to go buy the heavier (normal) MDF and use it for the outside layer, like Ryan suggested. But since my design will have opposing drivers, I'll go with what I have and add some braces. Thanks for the help Mark! You just saved me $100. ;x( I really think it's great that you are willing to give advice like this, even with your own business and your designs being used by Mark Shifter.

Construction pictures to follow... :T

[InPhase]

We made a lot of progress on the the two boxes today. Just to recap: each box will be (outside dimensions) 35"x19"x34" with a RL-P15 (4 Ohms) on each side, wired for each box to be 4Ohms. Each box will be powered by a bridged EP2500 and both will be LT'ed with a channel on the DEQ2496.

As my design evolved to using two 15"s in an opposing configuration I am not sure floor spikes are needed. Do you guys recommend floor spikes for this design? If the forces cancel for the most part due the the configuration, I wonder if spikes are necessary. Also, do you glue insulation in or just lay it in there? Thanks!

Baffles (only 2 layers, third layer remaining):

Images not available


Baffle next to internal brace:

Images not available

[ThomasW]

Attach the insulation to the walls with hot glue. Lay in any additional insulation needed.

Spikes are nice but not necessary.

[InPhase]

Tomorrow we will be placing the 2nd layer on the boxes. Here is the progress so far. Please feel free to comment or make suggestions. Thanks!

More progress:

Images not available

[kgveteran]

Beautiful things happen when people dream.They look great.No doubt they will sound great!

Post the final pics and your results.

KG

[InPhase]

Okay. Here are some photos. I haven't had anytime to actually listen to them yet :roll: , except running some low volume sine waves and program material through the line out on my laptop, so I will hold judgement on sound quality till later.


Images not available


Oh... Is it just me, or are the Behringer manuals FUBAR? I could not get the EP2500's to work in bridged mono until I found this sequence (LRRLLRRRRL) for the DIP switches online.

[ThomasW]

The Behringer manuals are translated from German so they're frequently weird.

[InPhase]

I've created a monster! :E

I listened to scenes in War of the Worlds, Titan AE, Matrix Revolutions, and some Stealy Dan last night and I am extremely happy with this project. I have both subs in the front of my theater (the only place they will fit) and the EP2500's sensitivity are set at about 9 o'clock. I have not put the DEQ2496 into the mix yet to boost the low end as I need to pick up a cable - oops. But listening to them straight from my Denon 3806 was an experience.

They have that quality of an IB in which they don't seem to be making sound, but there is a foundation to the sound and my room is crying Uncle! My girlfriend said that it didn't seem too loud except that it felt like a lot of pressure on her ears. It is extremely clean sounding. No coloration to my ears. (That and the fact that the door to the room was starting to rattle obscenely; something that my SVS PB2+ never did.)

I placed my hand the top of them during the scene with the machine coming out of the ground in WotW, and it doesn't feel like they are even on. I'm talking NO vibration. The opposing drivers was a fantastic idea.

I'm still not exactly sure how to properly make the DEQ2496 act like a LT. Right now my plan is to just put in a low pass shelving filter, measure it with REQW then make adjustments to the filter from there. Anyone have more specific instructions than that? Thanks! I have REQW and the EMC8000 and will be graphing them this weekend.

[ssabripo]

gaddam that looks good!!! :T

awesome Job man.....they look like Mark Seaton's SUBmerssive's....and that's saying a lot. If they sound like them, once you get the DEQ going, you indeed will have monsters!! ;x(

keep'm coming

[ThomasW]

I've created a monster! :E

Wasn't that the point?.... :B

I'm still not exactly sure how to properly make the DEQ2496 act like a LT. Right now my plan is to just put in a low pass shelving filter, measure it with REQW then make adjustments to the filter from there. Anyone have more specific instructions than that? Thanks! I have REQW and the EMC8000 and will graphing them this weekend.

This will get you started

http://home.comcast.net/~thomasw-2/SubwooferSetupandEQpageDEQ2496-LT.html

[InPhase]

Thanks ssabripo! I don't know what the Submersive sounds like, but if it is anything like this then it must be fantastic. Oh and its probably nice that the Submersive only weighs about 110lbs, whereas these weigh (just a guess) ~300lbs. Luckily, I won't be moving them much.

Thanks for the link, Thomas. I had read that before, but couldn't remember where it was.

[ssabripo]

This will get you started
http://home.comcast.net/~thomasw-2/S...EQ2496-LT.html

this brotha knows EVERYTHING it seems!! :E ;x( :B :T

[ThomasW]

this brotha knows EVERYTHING it seems!! :E ;x( :B :T

Nope, credit for that goes to DennisH. I just uploaded it to the website.

[ssabripo]

Nope, credit for that goes to DennisH. I just uploaded it to the website.

I was gonna say man....how many Holiday-inns did you stay at!!! :rofl: :B

[kgveteran]

Inphase,
Those look great.The EP2500 is quite an amp.Great job.

[kingpin]

Man those look awesome. :T
They almost weigh as much as my ongoing project. :W

Pet peeve time though.
Would you mind taking a pic with not so much zoom. This way we can actually get a better idea of the size of them. I enjoy seeing pics up close for detail, but pics taken from further back give me a better idea of their actual size. :T

This goes for the rest of you DIY'ers also. :B

Mike

[InPhase]

The two of these in this small room are strong down to single digits. I was watching WotW, and the Ice Field scene in Titan AE, and the SPL Meter was hitting just under 120! This is after I employed the shelving filter on the DEQ2496. I'll post some REQ plots later. My ears and the room can not take any more! I have got to weatherstrip the theater entrance door because it is flapping increadibly loudly during these scenes. Also, I went out in front of my house and it sounded like a train in the distance. You wouldn't be able to tell where it was coming from except the garage door (the big one) was vibrating. :rofl:

Just for kingpin:

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That is an 8' wide 2.35:1 DIY screen.

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Even after about 5 hours of calibrating today, the EP2500's were not even slightly warm!

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[kingpin]

Just for kingpin:

Thanks man.
That second pic is perfect.
Look how small your rack and components look compared to those subs.

[---k---]

You forgot the feet photo!

The original and some imitators:

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