# Dual SDX-15 6.6 cu ft tuned to 19hz



## dougc

And so it begins...

This is my build of the two enclosures for my Creative Sound Solutions SDX-15" subs for my home theater neighbor-haters. I will use a Behringer EP4000 and a yet-to-be-determined device for crossover and filtering. Most likely the DCX. These will be front firing, side ported, and side-by-side directly under my screen. 

I am using glue only to attach the slotted panels and silicon to seal the seams on the interior. Mineral wool for deadening - single layer on the walls and double on the back wall.


On with the pics:

Using the Dado blade set at 0.25"









Panels cut









The dry fit


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## dougc

This Image Dynamics 8" looks so cute on there


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## dougc

I have glued the bottom, sides, and bracing together. Now I have to track down some mineral wool to line the interior. I am planning to use some Gorrila glue for the ports, then round them over on the ends. CSS is supposed to ship one of the subs today and then I can double check the sizing for the front baffle pieces, glue them together, make holes for the hurricane nuts, and glue on the top. I am contemplating adding some additional bracing. My original thought was that the tight-fitting ports glued to the bracing would be good enough for lateral bracing.


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## gxstress

Lookin good Doug. Thats some nice work!


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## Binary

Coming together niceley. Great woodworking. I need some tools...


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## dougc

Thanks! I glued the ports in with some Gorilla Glue so that they would double as internal bracing and have rouned off the corners with the router. Paypal deducted $2300 out of my bank account a few days ago from an ebay scammer - all is well and I have it back, so now I can order some rock wool, connections, and put it together for a listen before I finish the outside with oak. Still trying to figure out if I need a B2 or BFD.


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## dougc

I bought a beat up EP2500 from another Shackster and received that and my sub today. I dropped the sub into an old enclosure for a 13w7 and it sounds great for a 15 minute throw-together. It has a constant hum though...

edit: after reading a million threads on this hum, I must have a ground loop issue somewhere since the only hum is in the sub. It hums in any outlet I plug the amp in to (different ciurcuits) so I will have to start one piece at a time starting with the cable connection.

I have decided to just leave the ghetto enclosure hooked up so that I can take my time on the finish work on the good enclosure. I got that "look" from my wife, you know the one, that it was time to turn the music off, stop jacking with the EQ, and turn the Runway Model show on for her.

Source for finding the Hum source:
http://www.audioholics.com/tweaks/c...ground-loops-eliminating-system-hum-and-buzz/


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## dougc

Stapled in the insulation









Adding the spacer to the front for the top trim piece. Routed guides for the grill.









Prep for the port openings









1st of 2 coats of the rattle-can bed liner 









"clamping" down the first piece of oak panel. 18" tile is wicked heavy.


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## dougc

I have finished installing the oak to the enclosure, adding the wire terminal to the back, and installing the sub. Now I have to pick out some stain and finish it with a couple of coats of sanding sealer and poly.


Some little feet for easy sliding. We plan to hard wood the floor when we remodel the room, so these will be fitted with some felt then.









The Creative Sound Solutions SDX 15









The DVC wired in series


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## dougc

I am most happy with how the port openings came out



























You can get an idea of the less than ideal acoustics I'm dealing with in here. The plan is to mount the LCD on the wall after I rip the paneling out, rewire the electric and install 7.1 in the walls. My last DIY build is the set of mains on the walls. They blend nicely with the sub.


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## dougc

I have had it up for a couple of days now and am happy with how it sounds for movies, but not so much with music. I need to get a subsonic filter for it for sure since I had some distortion on louder low end tones. It digs DEEP for the low end in the explosions and machine gun fire when I watched Heat last night, and blends well with my mains. 

In music, it lacks the punch and sheer volume of bass that the sub produced when I had it in the temporary small slot ported spec box made for an old 13w7 (16.5x17x25 with 22" x 2" slot port). I actually am much happier with the overall sound it produces in that box for all music. I am considering using an identical design of that box with the exterior to match this build if I can get the subs to blend. I'll open a discussion in another thread.


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## Mike P.

Great looking sub, well done! We'll try and figure out what the issue is in your "Troubleshooting" thread.


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## gxstress

I had a ground loop hum as well. The culprit was the coax cable coming into my hd box. (my hd box is connected to my avr via a hdmi cord). So I ran the coax cable through my surge protector/line conditioner and then back out to my hd box. That fixed the problem for me.


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## dougc

I forgot that I posted that I had the issue: it just went away with me doing nothing. It could come back when I move everything during my remodel, so I will throw that fix in my toolbox. Thanks!


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## dougc

Sub #2 on the way!


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## dougc

I have the 2nd sub now and the B-2. I am considering tuning the 2nd enclosure at 31 or 34hz for music. I listen to music every minute I am home, so I should cater to that. The size will be the same. I'm still playing with stain color and will post some pics of the finish when I finish.


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## dougc

I have both of the subs finished now. I am VERY happy with them - two subs tuned the same sounds better than the different tuned subs, IMO. 

I bought an inexpensive coax line conditioner for my incoming cable line which killed the miniature chainsaw noise out of my subs. I also acquired a new noise when I hooked up to my pc to listen to music. I killed this noise by simply moving the plug to a different outlet - one without an amp on it. The finish on one is a little darker than the other since I applied the finish almost a month apart. A little sanding, more stain, more poly and I'll be finished. I noticed a major catastrophy in the top panel finish: the veneer released from the ply and there is a 1' x2" bubble going through the middle. My guess is that I was a little wet with the stain and it melted the glue. I dunno. I guess I will deal with it since I am the only person that notices. This area might be right under where the centerchannel sits until I have a chance to remodel the room and fix the center to the wall. I'll try and get some pics up tomorrow.


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## gxstress

Glad to hear you got both subs finished and that you fixed the ground loop hum!
Lookin forward to the pics:sn:


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## Mike P.

Glad to hear you're happy with them. I take it both subs are 6.6 cu.ft and not the smaller size.


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## dougc

The final was 6.6 cu ft with a 19hz tune. 

I need to find some test tones. I listened to "how Low" by Ludacris, which I would guess to be about 20hz, it is very low. I was at 108 on the SPL meter for the sub only. This is a few db below some rattles at higher volumes, so I'll say 108 is a comfortable guestimate without a test tone generator. Pictures fall off the wall and the windows vibrate violently and rattle at this volume. I only listen at this volume normally when people ask how they sound.

edit: after listening to raw tones, I think the track mentioned above hits at around 30-35+ hz. Still lower than most of the bass from rap which is closer to 40-50hz, sometimes 60.


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## dougc

I ran some tests:
50hz 118db
40hz 116
30hz 112
20hz 94 I can't really hear much sound at this level - the house rattles louder
10hz ?


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## Mike P.

You can get test tones down to 1 hz here:

http://realmofexcursion.com/index.php?pageid=audio_downloads


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## dougc

Thanks Mike!

Here are some pics. I still need to stain the mains, finish the center, remove the oak panel from the wall, rewire, re-rock it, and finish. Maybe by next winter. Tile for the kitchen and a new fridge is next.







The temporary cover


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## Mike P.

Wow, they're looking really good! Now it's time for you to enjoy them. :T


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## sub_junkie

That is a nice build. Very clean looking. Do you keep the glass door shut while the amps are on, and are watching movies? I know my EP2500 puts quite a bit of hot air when watching content that has a lot of bass in it, especially really low bass. That will make the fan on the amps sing :bigsmile:


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## dougc

Thanks! We leave the door open, have 5" behind the amps to the wall, and almost always have the ceiling fan going. Both fans were running mach 10 when I was doing the frequency tests. The EP4000 runs less than the 2500, the fans aren't too noticeable when we are watching movies unless there is alot of bass followed by a few minutes of silence. I might do the fan mod if it starts bugging us


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## gxstress

Lookin sexy! Looks like you have a very relaxing living space as well. :T


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## dougc

Thanks, gxstress. I spend quite a bit of time unwinding from my 24 hour shifts at the FD, lounging on the couch sippin coffee and watching the sun come up, listening to the Zero 7 station on Pandora. Then again, I relax on the other end of the day with the same tunes sippin on a Guinness.


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## Ricci

Very nice finish work on the cabinets. Enjoy.


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## dougc

Thx Ricci!

I have made some measurements with an Aperion Audio analog SPL meter on loan from a friend and the pure tones found on Realmofexcursion.com. These were made 3' off the floor, 8' in front of the subs. There is a 3-5db increase if I measure at the corner next to my amps 6' from the floor, not my listening position though.

100hz 111db
79hz 117db
70hz 121db
50hz 108db
45hz 108db
40hz 110db
36hz 107db
33hz 104db
30hz 103db
20hz 101db
18hz 96db
16hz 94db
14hz 92db
12hz 91db
10hz 90db

The measurements are much more flat than the estimations. It doesn't get up to 124db as predicted on the higher tones (40-100) and keeps alot more db all the way down to 10hz, which I didn't expect. It will get a bit louder, but not without distortion shortly after - not willing to get there for show-and-tell! The breaker tripped on the 45hz tone and the fans were screaming at this point. My wife mentioned again that she likes this bass test as much as bamboo under the fingernails or being mauled by a wild dog.


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## Mike P.

Did you apply any correction to the measured results?


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## dougc

I have 12+ boost at 30-40hz and the Subsonic frequency set to about 16 on the Reckhorn B2. I'm guessing those figures since there is no precise way to tell on the knobs. This is just from tweaking over the last month listening to music. I have a Y coming out of the B2 to split to the amps. Do I have it set up right?


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## Mike P.

I meant correction to the SPL numbers you got. These meters are not accurate at low frequencies and if they are tested it can be found out how far out they are. For an example the meter could be 20 db out at 10 hz. You measured 90 db so you would add 20 db to that.


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## dougc

I did not use any correction to the values posted. I didn't see anything in the manual about it.


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## Mike P.

Then your measurments are not accurate. What's the model number of the SPL meter?


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## dougc

Here's the model # and link - thanks Mike

ASM-1 (In the accessories menu if the link won't get you direct)

http://www.aperionaudio.com/product/Aperion-Audio-Sound-Level-Meter,43,48,146.aspx


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## Mike P.

I can't find a file for it. It was said the ASM-1 was bench marked against the RS analogue meter although they didn't say which one. Here are the corrections for one of the RS analogue meters. You can add these to your measurements to get a basic ball park idea. If you really want to be accurate you should consider getting a SPL meter that there is a file for.

10Hz +20.5
12.5Hz +16.5
16Hz +11.5
20Hz +7.5
25Hz +5
31.5Hz +3
40Hz +2.5
50Hz +1.5
63Hz +1.5
80Hz +1.5
100Hz +2


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## dougc

Thanks again Mike - If I ever get ahold of some better equipment, I will post more accurate results. This meter was a cheapy, but available. 

Here are the value-corrected SPL ratings from the Aperion ASM-1 analog SPL meter

100hz 113db
79hz 118.5db
70hz 122.5db
50hz 109.5db
45hz 110db
40hz 112.5db
36hz 109.5db
33hz 107db
30hz 107db
20hz 108.5db
18hz 105.5db
16hz 105.5db
14hz 106db
12hz 107.5db
10hz 110.5db


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## Mike P.

When you measured did you use "C Weighting - Slow"?


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## dougc

I used the fast response on each tone and the needle didn't bounce around at all with the solid tone


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## Mike P.

But did you use C Weighting?


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## dougc

No, I used the A setting. It yielded the same result with the tones, just faster to get there with the A setting.


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