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post #1 of 37 Old 03-27-2008, 08:01 PM - Thread Starter
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I have been looking at all of your awesome DIY subs and I am wanting to make my own. I have a little bit of woodworking skills and my neighbor has a wood shop in his garage so I have most of the tools I will need. My space is quite limited so I was thinking of making a sealed box roughly 20" cubed. If my math is right it will be about 130 litres or 4.6 cubic feet. I think sealed would be better for me because I would like to keep it small and simple. For the driver I was thinking of using a sound splinter RL-P15 because it looks so good and their website says the optimal sealed enclosure for home use is 4.6 cubic feet. For the amp I want to get a Behringer EP1500 or something else for about $300-$400.

So now I have a few questions I want to ask. First of all does this combo work well together? I will use it about 80% for music and 20% for movies. My volume levels don't get too crazy usually. I put in the t/s parameter for the RL-P15 into winISD but I am not sure what I am looking for. WinISD say I will hit xmax at about 15 Hz, but I still not sure what to put in the series resistance box. Also it says my -3 dB will be at 54 Hz, that can't be right. I think it has to do with the series resistance because changing that makes a HUGE difference. Is there a better amp I should be looking at? What are the benefits of using a plate amp over an external amp? I also don't know what the differences between the dual 2 ohm driver and the dual 4 ohm driver are. The dual 2 ohm runs at 4 ohms and the dual 4 ohm runs at 8 ohms right?

My next questions are where can I get more information on building subwoofers? What books are best to read? Is there any websites with lot's of good info and tutorials? I have been reading through a bunch of stuff all over the internet and a lot of it is either too complicated or irrelevant. I would like to know what kind of a high pass filter I would need, if any, and what not. Sorry for all the questions and I appreciate any input.
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post #2 of 37 Old 03-27-2008, 08:50 PM
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Assuming 3/4 mdf for the walls and Dual layer for the baffle-a must with this driver you will have an internal volume of 4 cuft without driver and bracing, After considering driver volume and minimal bracing you should be left with an internal volume of about 100L or 3.5 cu ft. The recommended volume by Q is only 38L so your box will yield some greater lower end extension. Your F3 value is correct considering no EQ. Don't worry about xmax-the frequency is low and output is minimal at that Hz. Your driver should be able to handle short bursts at max SPL without a problem. I would suggest an amp with parametric EQ and highpass filter or a behringer feedback destroyer to flatten your response curve a bit. The Parts Express HPSA 1000watt plate amp or a crown XTI 1000 with onboard DSP would be good choices, the least expensive being the PE amp, then the Crown and most $$ the ep1500 and feedback destroyer which would offer you the most EQ and driver protection. Hope this helps and good luck
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post #3 of 37 Old 03-27-2008, 09:05 PM - Thread Starter
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So how low do you think a sub this size would go? If it's only going to go down to 50Hz I think I might have to rethink this a bit...
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post #4 of 37 Old 03-27-2008, 09:15 PM
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With Eq and room gain it will go much lower than that. At max system output it will probobly chase your family out of the house and nearby neighbors knocking on your door. I say go for it. You won't get flat output like a ported system but for mostly music and some HT it should be outstanding. If you could go a little bigger lets say 24" cube then you could go ported with a 15" driver and achieve substantial output below 20hz. Hope this helps.
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post #5 of 37 Old 03-27-2008, 11:11 PM
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If you have a well sealed smaller room ( IE: cement basement with corner placement of sub... ) you will have PLENTY of deep bass with the room gain.

If you have a lossy room ( open archways to other areas ) or say main-level or upstairs room... you will experience not as much bass, still you will have good output to at least 20 hz.

If you can spring for some sort of EQ or buy an amp with built-in EQ ( such as the Crown XTI ) this will help tame some room modes.

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post #6 of 37 Old 03-28-2008, 05:16 PM - Thread Starter
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Ok thanks guys that makes me feel much better. All I need now is to order some parts Will have to wait until payday though
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post #7 of 37 Old 03-29-2008, 10:18 PM - Thread Starter
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OK, so today I was farting around in google sketch-up and made a model of the enclosure I want to build. I still haven't decided yet which amp to get though. Now I think I am leaning towards the Dayton 500 watt from PE, even though it will take even more internal volume from cabinet. I might make it a few inches taller I think. I also don't know what kind of binding posts I am going to need. Do I use one like this or like this or like this?
LL
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post #8 of 37 Old 03-30-2008, 04:46 AM
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Nice enclosure design with good bracing. Yields about 3.6 cuft after driver volume. Should work nicely for a sealed driver. Did you choose a driver yet? The Pe amp would be a good choice with Parametric eq for sealed. I wouldn't worry about volume decrease-many drivers can work in that volume sealed with decent low end extension.
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post #9 of 37 Old 03-30-2008, 05:05 AM
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The internal volume of a 20 inch cube is 3.6 cubic feet. Minus the sub and bracing, you'll have a little over 3 cubic feet net volume. Definitely not optimal for a RL-P15.
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post #10 of 37 Old 03-30-2008, 06:19 AM
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19.25x19.25x19.25/1728=???
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post #11 of 37 Old 03-30-2008, 09:36 AM - Thread Starter
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Uklit I think you mean 4.6 cubic feet and just over 4 cubic net volume.... Either way I decided to make my box 24" tall so I think I will be a little under 4.5 cubic feet net volume. As for the driver I am still gonna use a RL-P15.
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post #12 of 37 Old 03-30-2008, 06:03 PM
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mayhem13, a 20 inch cube is 18.5 internal, not 19.25.

Canadian_Dude, if you increase the height to 24 inches then your net volume is 4.2 cubic feet after deductions for the sub and bracing. Close enough for the RL-P15.
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post #13 of 37 Old 03-30-2008, 09:11 PM - Thread Starter
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I have a semi-unrelated question. If I were to use a passive radiator would I need to use the same size box and tuning as for a normal ported enclosure or would it be ok in a smaller sealed size enclosure?
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post #14 of 37 Old 03-30-2008, 09:53 PM
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If you go with PR's this sub at 110L would be a beast. It would require 2 opposing 18"ers. I modeled it with 2 18's at 4.2hz 1600 grams each. This system will play 118db down to 26hz with an F3 of 24.5hz with 700watts. At 1kw 120db with maximum excursion at 19.2hz. If you use the HPSA1000 from PE you could easilly control sub 20hz. If you can afford this then go for it. The PR's are $118 each though.
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post #15 of 37 Old 03-31-2008, 10:50 AM
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C_D, since this is your first build and have 80/20 use, I think you'd be better off forgetting about PR's this time and start thinking about multiple sealed subs powered by a pro amp...there's lots of reasons why multiples are so much better. Can you afford two RL-P15's? If not, we can make some suggestions.

You were asking about terminal cups - These are what I suggest:
http://www.partsexpress.com/pe/showd...number=260-311

Warmon -
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post #16 of 37 Old 03-31-2008, 04:54 PM - Thread Starter
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Lack of space means I only have room for 1 sub and I barely have room for it. And mayhem, what brand passive radiator's are you talking about?
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post #17 of 37 Old 03-31-2008, 08:50 PM - Thread Starter
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Well I was bored this evening and discovered how much fun Google sketchup is and how my whole evening disappeared instantly. I modeled a RL-P15 and put it in my box sketch.
LL
LL
LL
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post #18 of 37 Old 04-06-2008, 01:14 PM - Thread Starter
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After spending forever modeling different drivers and different enclosures I decided, hopefully final decision, to go with a CSS SDX15 driver with 2 CSS PR1816 passives. The Creative driver is slightly cheaper than the Sound Splinter, and it's a Canadian company so I should save a lot on shipping too.

Here is how the two setups modeled:
Red is the creative driver and yellow is the sound splinter.


And here is the new box design:
I still havn't modeled a SDX15 yet so I might have to change my brace a bit.


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post #19 of 37 Old 04-06-2008, 03:57 PM
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CSS's SDX 15 driver is a monster in its price range. Linear motor,30mm Xmax and high Xmech. With the dual PR's CSS you can get high SPL ~20Hz.

The beauty of the SDX15 is it performs great in sealed and vented.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #20 of 37 Old 05-17-2008, 03:26 PM - Thread Starter
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Ok, so now I have my mdf cut and ready to go and my sdx15 and pr1816's are on order. Pretty much all that's left to buy is the amp and some cables. After seeing the test on the xti1000 I originally planned on getting, I am having second thoughts. Now I am wondering if I should get the ep2500 and the dsp1124 instead. I really liked the crown because it wasn't as ugly as the ep2500 and it had the built-in dsp. Any suggestions?

I also had some questions on building the box. First, since I was planning on using screws instead of clamps, I was wondering if it was better to glue and nail the panels together then pre-drilll and screw them. Also, if I nailed the panels first should I wait till the glue dries to screw them or do it while the glue is still wet? Secondly, is it worth all the extra work or am I okay to just pre-drill then glue and screw the panels together? Lastly, I have a big box of screws leftover from when we had out deck built, and the screws are 7 x 2" and have a special coating on them. Are these screws long enough for 1.5" of panel thickness? And are the the right thickness at just under 3/16" or 4mm?
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post #21 of 37 Old 05-17-2008, 07:06 PM
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You're okay to pre-drill, glue and screw. No nails; you can tack most fiber board but MDF loves to split, so always pre-drill. I never really needed long clamps.. just a few small c-clamps for gluing the double baffle together and drilling. Screws = your clamps. You could even remove them after, but I'd leave them and fill the holes for a nice finish.

the screws, hold them up to the wood and look. Do they go through two thicknesses of whatever MDF you are using? Screws are cheap, I recommend using the square bit ("R1", 2, etc) and loose threads (you already drilled holes at this point with a smaller drillbit) type from HD. Use lots of glue, let it ooze out and wipe off the rest. I like to seal my corners with liquid nails for added strength. I also use it for gluing the braces to take up small gaps. Use wood glue on the rest, I like Gorilla brand, also from HD.
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post #22 of 37 Old 05-17-2008, 09:25 PM - Thread Starter
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I picked up a bunch of glue from the store I bought the mdf from, it's the regular titebond stuff. I think I will just grab a few extra-long screws for the double baffles then and use these everywhere else because they are never gonna get used otherwise.
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post #23 of 37 Old 05-17-2008, 11:54 PM
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I have found that even with pre-drilling screws have a tendency to push apart the layers of paper forming the MDF.... not so bad to mount a driver or port, but into the edge will cause splitting. If you can glue and clamp, you really don't need any more mechanical clamping, unless you start to get into very high displacement drivers.

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post #24 of 37 Old 05-18-2008, 09:16 AM - Thread Starter
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The problem with clamps is that I have none and I am worried they will get expensive quick. I do get a discount at Canadian Tire though, so I might just do that. I will check out the prices on clamps maybe today and if they aren't ridiculously expensive I will just clamp and glue it together. I have another question also; whats the best way to laminate two sheets together? I have a bunch of landscaping bricks that I was thinking I could just put on top but I am worried the panels will move too much.... Should I be worried about that?
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post #25 of 37 Old 05-18-2008, 10:22 AM
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You can drill and put in dowel rods, screws or clamps along the outside of your sheets clamped in the middle of the two layers. That should keep things from shifting around. As for gluing the layers together, just put a thin layer spread across the entire gluing surface and then start stacking hundreds of pounds of blocks, weights, car tires, ect.. on top of it. The more weight the better! A couple dumb bells wont cut it, get the entire weight set on top of it. :-)

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post #26 of 37 Old 05-18-2008, 10:53 AM
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Put the house on top of it.
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post #27 of 37 Old 05-20-2008, 05:58 PM - Thread Starter
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Since I don't want to make a new thread I will just use this thread to show you guys my build progress. Today was like my birthday, but better, that's because my new toys arrived in big boxes I knew these would be big but when I took them out I was thinking, "wow what have I got myself into?" and "I'm glad I didn't go crazy and get a 18 incher" then "I'm gonna want that 18 incher next...".

First picture here is my wood stack cut and ready to go. I will hopefully get to laminating the 6 pieces that will be my 3 baffles this week.


The next two are my new babies.


and

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post #28 of 37 Old 05-20-2008, 06:55 PM
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Good family picture.

These strange round air pumps improve anyone's birthday ! The SDX15 is one heck of a great driver,built like a tank too.

Ask yourself mortal , do you have as much displacement as me ? The answer is no unless you have a Windmere fan sub.
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post #29 of 37 Old 05-20-2008, 07:23 PM - Thread Starter
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How much power do you think these can take? In my modeling program I can put 1400 watts into it and hit xmax around 17 Hz I think it was, with a tune at 18ish Hz I think this is just right. As for the PR's I am hoping they can handle the 28mm travel. I am still having trouble deciding on an amp though.... I was wanting the xti1000 and now I am waiting to see what crown says over on their forums, if nothing happens I need to pick a different amp and maybe some sort of eq.
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post #30 of 37 Old 05-20-2008, 07:37 PM
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The PR's are good up until 38mm of travel so you should be more than safe running them at 28 mm peak.
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