# SDX 15 in 12.5ft3



## ace27 (Feb 24, 2008)

Hi I am a first time builder and I am looking to build, after port, driver & brace loss, a 12.6 ft 3 LLT tuned to 15hz. After running what I think is the right numbers in WinIsd I end up with a port velocity around 47m/s. Is that a high number or an accepted number. I am going to run it off an EP-2500 and put in a number of 850 watts. One last thing is it better to use the SDX 15 or move up to an IXL 18.4. Not too much to pick from here in Canada.Thanks in advance!!!


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## Mike P. (Apr 6, 2007)

Comparing the two subs, the ouput is similar. The SDX15 in 12.6 cu.ft. tuned to 15 hz would take 1000 watts to reach Xmax. An 8 inch diameter port 41.75 inches long will keep the port air speed to a maximum of 28 m/s at 13.5 hz.


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## Canadian_Dude (Jan 24, 2008)

I just checked and the SDX-15 actually has more displacement the IXL because of the extra 8mm xmax. I like the looks of the SDX better and I own one so it gets my vote.


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## ace27 (Feb 24, 2008)

Thanks for the reply. I was reading another post on a build of a Mach 5 in a 350l box at 15hz and a few of the posts on it were concerened about the port not being the diameter of the port away from the wall. This may cause an unefficient port. Would I run into this with a 8in port, or would have a bigger issue with the port turbulence with the 6in?


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## Canadian_Dude (Jan 24, 2008)

An 8 " port would probably need a bend, as Mike p. said the port is 41.75" long. You could also do a slot port too, or my favorite option would be to spend a few more dollars and get 2 18" passive radiators from CSS. PR's don't have any of the problems as ports, the only downside is the cost. You can also make a smaller box for the same tune with PR's.


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## Canadian_Dude (Jan 24, 2008)

An 8" port would need to be 41.75" long as Mike P. said, so it might need a bend, or you could use a slot port, or my favorite option is using 2 18" passive radiators from CSS. PR's don't have any of the flaws that ports have, the only downside is the extra cost. PR's can also tune lower in smaller boxes. Here is an example of a SDX-15 in 8 cubic feet with 2 PR's in blue and a SDX-15 in 12.6 cubic feet tunes to 15 Hz with a port in yellow:










Not a huge difference in the FR and both can handle an EP2500 bridged, plus the box is much more manageable.


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## Mike P. (Apr 6, 2007)

An 8 inch diameter port 41.75 inches long will keep the port air speed to a maximum of 28 m/s at 13.5 hz. Ideally the port should be one diameter away from any wall. If it were only 4 inches away from a wall, I personally don't think it would be a big deal. As with many other things, less then optimum conditions still provides good performance.


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## ace27 (Feb 24, 2008)

I think I will upsize my port to a 8" one. Looks like this will be a good change over from the six. What length do you think I should have to get a 15HZ tune. With a box like this will there be any need for a subsonic filter. I was thinking of the Reckhorn B-1 to go with the Ep-2500.


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## Mike P. (Apr 6, 2007)

An 8 inch port would need to be 42 inches long. With a 1000 watts input you exceed Xmax at 13.5 hz. Try the sub with the EP2500 first and see if you need the Reckhorn B1. No sense buying it until you know you need it.


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## ace27 (Feb 24, 2008)

Mike P. said:


> An 8 inch port would need to be 42 inches long. With a 1000 watts input you exceed Xmax at 13.5 hz. Try the sub with the EP2500 first and see if you need the Reckhorn B1. No sense buying it until you know you need it.



Good point mike, Good to see another Sask. boy, I'm from Swift Current.


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## Mike P. (Apr 6, 2007)

Howdy, "neighbor"! :bigsmile: Will you be starting your sub build soon?


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## ace27 (Feb 24, 2008)

I sure would like to get started on the box soon. Called around the other day to see who will cut the wood I want, and found a place that will. I want to do as much of this as I can however I only have a small table saw and think the 24" cuts will be hard to do on it. Is it best to go with the 8" port, I was wanting to stay with the 6" but if it will cause to much port noise I will change my plans. I see the SDX-15 has two 2ohm vc's. Would you run the EP-2500 bridged @ 4ohms or one side to a single 2 ohm vc? Thanks,


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## Mike P. (Apr 6, 2007)

The air speed of a 6 inch port would be 50 m/s, which is way beyond port noise. An 8 inch port is the right size, with the air speed being 28 m/s. Wire the sub for 4 ohms and run the EP2500 bridged.


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## ace27 (Feb 24, 2008)

Thanks mike, I will go with the 8"er.


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## ace27 (Feb 24, 2008)

I ordered my sub on Sat. from CSS. Hope to get it later this week, plan on cutting up some MDF on friday and get working on it on the weekend!!!!!


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## Mike P. (Apr 6, 2007)

Sounds good. Looking forward to the build pics!


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## beolson (Jan 16, 2009)

I recently bought a SDX-15 and am very pleased with its low end performance. I am pushing it with my Behringer EP2500. I think you will be delighted with the quality of the SDX series. My box is approximately a 27.5" cube with an 8"X5" square port. Not sure if that is the best tuning but it does work really well for low end. Good luck


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## ace27 (Feb 24, 2008)

Thats good to hear that the SDX and the Ep-2500 work well together. Sub should be here today and goin to get MDF around 2:00 pm. Hope to make some headway this weekend!!!!!


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## beolson (Jan 16, 2009)

Good luck. Hopefully you have more tools than I did. I actually ended up paying a place $60 to make all my cuts. I am a college student and my selection of tools does not include a table saw. More like a circular saw and a drill. Have fun and I hope it works out well for ya.


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## ace27 (Feb 24, 2008)

Well I got the box made up and had a chance to listen to the sub untill both vc's went. Not too sure why they went. I was running one vc(2 ohms) to the ep-2500 and the the sub quit working so I pulled it out and the vc had 0 resistance. So I checked the wiring and the amp. All looked good. Within about 15min of a movie the other went as well. Now I am out. Big box ,no sub till I can get another. The settings on the EP-2500 are 1 on, 2 off, 3 on, 4 off, 5 off, 6 off, 7 off, 8 on, 9 off, 10 on. Line in on Input 1, Sub connected to Output 1. Any help would be great. Dont want to get another and have the same happen...:explode:


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## Mike P. (Apr 6, 2007)

Sounds like it was over driven. How hard were you pushing it?


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## ace27 (Feb 24, 2008)

It was on a few gunshots that it went out on.....It was drove pretty hard. In WinIsd it seemed that the sdx could handle the Ep-2500. Guess Im gonna have to tone it down a bit next time. For the time it lasted however it was a great sub. It even rumbled the projector on the roof. Anyone know the max wattage on this sub?


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## Mike P. (Apr 6, 2007)

It's rated at 1000 watts. You should consider the Reckhorn B1 for a high pass filter to ensure the sub doesn't exceed it's rated Xmax at low frequencies. The $100 price is worth the piece of mind in my opinion.


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## ace27 (Feb 24, 2008)

Well with top notch service and a few quick E-mails back and forth with Bob over at Creative Sound Solutions I should have a sub by the weekend. And with some advice from Mike P a reckhorn B-1 as well !!!!


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## bassman_soundking (Nov 4, 2008)

I was reading along and was going to ask how well the sdx could handle the ep2500. I guess it cant. I am planning on running a sdx to a crest CD2000, and wanted to know the safety.


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## Mike P. (Apr 6, 2007)

> I was reading along and was going to ask how well the sdx could handle the ep2500. I guess it cant.


As long as you control the input power and don't exceed the recommended power handling it'll handle it just fine. That applies to the Ep2500 and the Crest SD2000 as well. Both amps have enough power to over power the sub. It's all about moderation.


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## Ricci (May 23, 2007)

Ace27,

This may be a dumb question, but it sounded like you were running the driver off of one VC at a time in an earlier post. Is that true? Did you hear any sounds of bottoming or clanking during the movie? Do you know if the amplifier was clipping? What movie was it?


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## bassman_soundking (Nov 4, 2008)

Ricci said:


> Ace27,
> 
> This may be a dumb question, but it sounded like you were running the driver off of one VC at a time in an earlier post. Is that true? Did you hear any sounds of bottoming or clanking during the movie? Do you know if the amplifier was clipping? What movie was it?


X2


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## ace27 (Feb 24, 2008)

Yes it was on one VC giving the amp a 2 0hm load. The movie was Ratatoille, near the begining with the shogun shots. I had the pre-amp and amp both set way to high. The sub must have bottomed out during the shots and Im pretty sure it clipped the amp. As a first timer and a bass lover I had to over do it of course. The projector on the roof was shaking!!! I have a new one on its way with a Rechorn B-1. This time I will be a little bit lighter on the gain. I will be sure to post when the new one arrives!!


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## bassman_soundking (Nov 4, 2008)

Always remember when using a dual voice coil driver that both coils must be used at all times. I believe that ep 2500 puts out like 2400 watts at 4 ohms bridged. If you ran it at 2 ohms it was pushing more, and probably clipping pretty hard too. Also one voice coil can only handle half of the rated power that the sub handles with both coils combined.


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## bassman_soundking (Nov 4, 2008)

Also wire the coils in series to get a 4 ohm load. If you wire them is parallel you will get 1 ohm or lower. That would be even worse that before. If you are not sure how to wire the sub in series look here.

http://pinq.wordpress.com/2007/05/11/wiring-your-subs-dual-voice-coils/

Look at the example and picture your ep2500 instead of a jl amp. The 3rd spec about series relates to you 2+2=4 ohm in series


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## ace27 (Feb 24, 2008)

I was running one coil off of one side of the EP. Never knew to run both all the time!!!! So for the next time do I run both coils in a 4 ohm config on one side of the EP or bridged on the EP????


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## SturmMD (Dec 30, 2008)

Yeah, running 1 coil at 2ohms off one channel of the EP is definitely what did it considering that's up to 1200 watts if you go by the specs. More than double what one coil is rated.

Run them in series for 4 ohms then you can play it safe and just use 1 channel (about 700 watts). In bridged you're should be careful with material with constant tones because it can put out about 2000W. In bridged you'll have the same speaker blowing capability as when you were at 2ohms off 1 channel except it will be 3dB louder


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## ace27 (Feb 24, 2008)

Hey guys, thanks for all the help so far along the way. This is some great information. Another question for ya, Does a guy need to put a little stuffing inside the speaker box.


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## bassman_soundking (Nov 4, 2008)

ace27 said:


> Hey guys, thanks for all the help so far along the way. This is some great information. Another question for ya, Does a guy need to put a little stuffing inside the speaker box.


I use stuffing to make up size for undersized boxes. In this case with that large of a box, I would just line the walls, and not stuff the box. Alot of stuffing will lower sensitivity and lower tuning frequency.


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## ace27 (Feb 24, 2008)

Well I recieved the sub and the B-1 the other day and found some time to get it all installed and playing. Now that hook-up has been cleared up I have it hooked to one side of the EP. The sub sounds great! Fills the room up with bass. I am happy with the way it turned out. I posted a few pics under home theater set-up section.http://www.hometheatershack.com/forums/home-theater-equipment/17326-ace27s-home-theater.htmlThanks for all the help.


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## bassman_soundking (Nov 4, 2008)

You are running one channel of the ep2500 to the sdx, so about 600 watts going to the sub? I am just wondering real world power handling in that sized enclosure. I've havent measured power from my amp to my sub, but I would guess I have pushed over 1300 watts to my sdx so far without problems. I dont do it for long periods of time, and I dont turn it all the way up to even close to clipping either.


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## looneybomber (Sep 20, 2006)

Ouch, burnt the coils on an SDX? I've clipped my EP2500 (one channel per coil) on a 40'ish hz sine wave and didn't burn my SDX. Granted I shut it down pretty quick when I realized my input signal was way too high, but if quick gun shots took yours out, then a short sine wave should have taken mine out too.

...Hmm

And since you're only using one channel of your EP, maybe build a 2nd SDX? That will give you a lot higher level of safety.


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## Binary (Nov 23, 2009)

I was gonna say, i've got my SDX on a QSC RMX2450 bridged in 4 ohm, i've clipped it a few times, but never had any complaint from the driver. i'd put it 100% to the fact that you werent using both coils. the ep is pretty similar to the rmx, you would have fed that single coil roughly 2x what it should have seen by itself. the power handling halves with only one coil running. Its definitely not necessary to run both coils, as long as you short the other, and halve the power you'll be fine.


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