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Ack's DIY Subwoofer Build Idea Thread - Newbie Alert! - Page 3

post #61 of 203
11/29/12 at 8:32am
Thread Starter 
Quote:
Originally Posted by krakhen View Post

Amazon seems to have the Behringer NU3000DSP iNuke for $345 and 15% off right now.
http://www.amazon.com/Behringer-NU3000DSP-Ultra-Lightweight-High-Density-3000-Watt/dp/B005EHINAS

Ordered... That is a great deal. No tax and I am Prime... Thanks!
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post #62 of 203
11/29/12 at 8:54am
Quote:
Originally Posted by krakhen View Post

Amazon seems to have the Behringer NU3000DSP iNuke for $345 and 15% off right now.
http://www.amazon.com/Behringer-NU3000DSP-Ultra-Lightweight-High-Density-3000-Watt/dp/B005EHINAS

NU6000DSP is also on sale with 15% off. Total comes to $397.94. Heck of a deal. They're not currently in stock but you can still order it.
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post #63 of 203
11/29/12 at 8:58am
Glad I could be of some help, even if it's just bargain hunting. The rest of the help you are getting here is invaluable in my opinion!

Your project is very interesting. Suscribed!
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post #64 of 203
11/29/12 at 9:30am
I scanned through this thread quickly, so my apologies if I missed previous discussions about quantity and placement.
Quote:
Originally Posted by ack_bk View Post

A little about the room... It is a large basement media room with a 125" screen, projector, etc. Main room is 4992 cubic sq ft and there is another room that is 1300 cubic square feet that is open to it. So slightly over 5100 cubic sq ft. The room is actually well insulated (all walls, and ceiling) and there is a lot of heavy drapes, carpet (this is a basement) and sofas/chairs.

If this is a typical basement - all boundaries made of concrete - then it will have strong modes because the boundaries are so rigid. Being large will help, but it's not large enough to push the modes below the audible range. So I think probably the single most important thing is to run a multisub configuration, even more important than driver build quality or cabinet type or construction. Not that those aren't real important too, but the distribution of bass sound sources is going to be the single highest factor for quality.

I'd suggest flanking subs to smooth the self-interference from the nearest boundaries and a more distant sub or two to smooth the lower frequency modes. I'd expect the lowest frequency modes to be fairly strong, so I'd probably rather go with a pair of distant subs. Nobody ever made things worse with too many distributed subs. They provide diminishing returns when you get past four, but four gives more placement options than three and makes it less critical where they are placed. With four, you can almost put them anywhere as long as they aren't all grouped together.

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post #65 of 203
11/30/12 at 12:18pm
Thread Starter 
Okay have been doing some measuring and modeling and what do you guys think about a ported box that is 36" tall, 23" wide, and 26" deep? I know I was thinking slotted port, but am also open to rounded flared ports as well (PE sells some nice plastic flared ports). From some of my readings, rounded ports are more efficient then slotted ports (rounded ports have less internal surface volume and should have more efficiency due to less air friction)?

With bracing and adding the ports (but not adding the driver volume as I don't know that):

If I go slot port, I am getting a calculation of 3" height, 21.5" wide, and 43.86" long assuming 8.76 cubic ft enclosure which takes into account the slotted port and the bracing (not the driver, as I don't know the volume).

If I go rounded, I am getting 2x 4" diameter ports that are 20-21.38" long, but I notice the volume of the enclosure increases to 10 cubic ft?

So would rounded ports be preferred?

I have also entered in the DVC385-88 driver parameters into Winisd Pro and have been playing around with different models. It seems two of these 36x23x26 subs are going to be potent with dual drivers and 880 watts each....
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post #66 of 203
11/30/12 at 1:00pm
Quote:
Originally Posted by ack_bk View Post

Okay have been doing some measuring and modeling and what do you guys think about a ported box that is 36" tall, 23" wide, and 26" deep? I know I was thinking slotted port, but am also open to rounded flared ports as well (PE sells some nice plastic flared ports). From some of my readings, rounded ports are more efficient then slotted ports (rounded ports have less internal surface volume and should have more efficiency due to less air friction)?
With bracing and adding the ports (but not adding the driver volume as I don't know that):
If I go slot port, I am getting a calculation of 3" height, 21.5" wide, and 43.86" long assuming 8.76 cubic ft enclosure which takes into account the slotted port and the bracing (not the driver, as I don't know the volume).
If I go rounded, I am getting 2x 4" diameter ports that are 20-21.38" long, but I notice the volume of the enclosure increases to 10 cubic ft?
So would rounded ports be preferred?
I have also entered in the DVC385-88 driver parameters into Winisd Pro and have been playing around with different models. It seems two of these 36x23x26 subs are going to be potent with dual drivers and 880 watts each....

You need at least four 4" di ports for a dual 15. Actually that's still too small, but it's close. You could do 5, but it would look odd. You could do 2 x 6" and be fine.

I don't know what internal surface volume is supposed to mean. A round port will have less internal surface area than a square for a given port mouth area. However, a slot port--which is a type of square port--of a given mouth area ends up being shorter in length than a tube port of the same port area thus the slot port has less internal surface area. This is due to the slot port sharing 3 walls with the cabinet + some physics that I've forgotten.

PE's flares don't seem to work w/ PVC pipe and they don't sell tube for the flares in long enough lengths. Just glue the PVC to the baffle and use a round over bit to make your flare.
Edited by nograveconcern - 11/30/12 at 1:31pm
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post #67 of 203
11/30/12 at 1:11pm
I'm probably a little late to the party, but what about a low profile THT? This one is from Brad's Pimp My LP THT. You could place it under your screen.

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post #68 of 203
11/30/12 at 1:48pm
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

You need at least four 4" di ports for a dual 15. Actually that's still too small, but it's close. You could do 5, but it would look odd. You could do 2 x 6" and be fine.
I don't know what internal surface volume is supposed to mean. A round port will have less internal surface area than a square for a given port mouth area. However, a slot port--which is a type of square port--of a given mouth area ends up being shorter in length than a tube port of the same port area thus the slot port has less internal surface area. This is due to the slot port sharing 3 walls with the cabinet + some physics that I've forgotten.
PE's flares don't seem to work w/ PVC pipe and they don't sell tube for the flares in long enough lengths. Just glue the PVC to the baffle and use a round over bit to make your flare.

Ahhh... I definitely don't like the idea of 4-5 4" ports, I was clearly doing the math on on two 4" ports based on a single driver forgot to double them... I think I could do 2 6" ports, but I really do like the look of the slotted port more, and it seems pretty straight forward. Does a slot port of 3" height, 21.5" wide, and 43.86" L sound right to you for a 36"H x 23" W x 26" L box with dual 15" front firing woofers?
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post #69 of 203
12/2/12 at 2:11pm
Thread Starter 
Well, I have been doing more reading today and I think with my room, more sources will be better. So instead of two larger boxes, I am thinking 4 smaller (5 cubic square feet) ported 20hz tuned subwoofers spread throughout the room. Looking at my room I can fit:

Three of these subwoofers along the front wall under the screen. One of these subwoofers on the side wall behind the couch, and then the VTF-15H in the back of the room with 2 ports open for maximum SPL. That would be five similarly sized ported 15" subwoofers . I am liking this idea more and more.

I have also really been debating building four smaller sealed boxes (3-4 cubic ft) and then selling the VTF-15H and building a few more (6 total) . Sealed seems easier to build, but I don't know if my iNuke 3K can power 4 sealed 15" subs adequately.

Thoughts?
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post #70 of 203
12/2/12 at 3:32pm
Quote:
Originally Posted by ack_bk View Post

Well, I have been doing more reading today and I think with my room, more sources will be better. So instead of two larger boxes, I am thinking 4 smaller (5 cubic square feet) ported 20hz tuned subwoofers spread throughout the room. Looking at my room I can fit:
Three of these subwoofers along the front wall under the screen. One of these subwoofers on the side wall behind the couch, and then the VTF-15H in the back of the room with 2 ports open for maximum SPL. That would be five similarly sized ported 15" subwoofers . I am liking this idea more and more.
I have also really been debating building four smaller sealed boxes (3-4 cubic ft) and then selling the VTF-15H and building a few more (6 total) . Sealed seems easier to build, but I don't know if my iNuke 3K can power 4 sealed 15" subs adequately.
Thoughts?

The 3k has will easily drive 4 sealed DVC's to their linear travel limits since that happens around 300w ea, but in your room I am unsure you will have the displacement limited headroom to reach reference level w/ 4 dvc's sealed.
Edited by nograveconcern - 12/2/12 at 5:54pm
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post #71 of 203
12/3/12 at 8:09am
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

The 3k has will easily drive 4 sealed DVC's to their linear travel limits since that happens around 300w ea, but in your room I am unsure you will have the displacement limited headroom to reach reference level w/ 4 dvc's sealed.


I think I would have to build 4, then sell the VTF-15H and build at least 2 more sealed 4cubic ft DVC's. I could easily fit 6 of them in my room if the boxes are 4 cubic ft or so. I gotta think 6 sealed 4 cubic ft subs with 15" drivers would be enough to fill my room?

I am doing some more modeling with 5 cubic ft enclosures tuned to 18-20hz. I think I can make it work, but they are really pushing it in the size department if they are to go in front of the screen. I do think going ported would allow me to integrate the existing 15H much easier into the room.

I will say that I am learning a ton thanks to folks like you and LTD02, etc. I am probably starting to overthink everything, but I don't want to spend the time and resources building 4 boxes if I have not done the work upfront.
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post #72 of 203
12/3/12 at 8:36am
Thread Starter 
For a ported 5 cubic ft box tuned to 18hz I am getting a port length (round) of just under 18" in Winisd Pro and via another site... This just does not seem right...

Edit, never mind if I change the diameter to 6" I get a length of 42.46"

I am thinking 2 4" ports with a length of about 39" will be easiest in a 5 cubic ft box.. For a 20hz tune in a 5 cubic ft box using these drivers I am getting 30" for the port length.
Edited by ack_bk - 12/3/12 at 8:46am
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post #73 of 203
12/3/12 at 9:40am
Quote:
Originally Posted by ack_bk View Post

I am thinking 2 4" ports with a length of about 39" will be easiest in a 5 cubic ft box.. For a 20hz tune in a 5 cubic ft box using these drivers I am getting 30" for the port length.

You are going back and forth between 2 different design goals. A 20hz tune means usable frequency response to about 16-17hz. A sealed alignemnt is the way to go if you want to get down to single digits but don't mind, or have the displacement make moot, giving up about 6db of spl around the ported box's tuning. So, do you want 16hz or 6hz?

Going from 4 sealed 15's to 6 is only adding 3 db or so of headroom and only if you run the extra 2 on a second amp. You will need to go to 8 and the iNuke 6k to get back to the 20hz sensitivity of 4 ported 15's and an iNuke 3k.

That's not to say you shouldn't go sealed. 4 dvc's sealed will give you a lot of output. I simply don't think it is realistic to expect this to produce 115-120db at the listening position at 15-20hz in your large basement room.

If you do decide to build sealed a 3-3.5 cu ft enclosure is a good size.
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post #74 of 203
12/3/12 at 12:35pm
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

You are going back and forth between 2 different design goals. A 20hz tune means usable frequency response to about 16-17hz. A sealed alignemnt is the way to go if you want to get down to single digits but don't mind, or have the displacement make moot, giving up about 6db of spl around the ported box's tuning. So, do you want 16hz or 6hz?

Too be honest, I would rather focus on higher SPL into the mid to high teens than trying to play clean to 5hz. I was thinking sealed mainly due to the smaller enclosures and WAF factor, and it is still something I am considering, but am mostly leaning towards ported, because as you have mentioned, my room is so large. It is just really helpful to talk all these decisions through with the experts who know more than me, and for that I am very grateful for all your advice and assistance smile.gif
Quote:
Going from 4 sealed 15's to 6 is only adding 3 db or so of headroom and only if you run the extra 2 on a second amp. You will need to go to 8 and the iNuke 6k to get back to the 20hz sensitivity of 4 ported 15's and an iNuke 3k.
That's not to say you shouldn't go sealed. 4 dvc's sealed will give you a lot of output. I simply don't think it is realistic to expect this to produce 115-120db at the listening position at 15-20hz in your large basement room.
If you do decide to build sealed a 3-3.5 cu ft enclosure is a good size.

Thanks for your feedback throughout this thread, I did some models and here is a 5 cu ft ported sub tuned at 20hz vs a 3.5 cu ft sealed enclosure using the Dayton driver. I am 99% convinced on going ported now smile.gif

Yellow line is sealed, grey line is ported. Both are modeled using 440 watts and this is just 1 box smile.gif 4 boxes should give me what, another 3db or so each across the board? Even more if they are collocated and this is not accounting for room gain?

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post #75 of 203
12/3/12 at 5:37pm
You are looking at the wrong graph. Look at max spl (I have PE set closer to peak so I can see excursion limits).

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post #76 of 203
12/3/12 at 6:45pm
Quote:
Originally Posted by nograveconcern View Post

Ported is being recommended because you have 5100 cu ft to fill. The bigger the room the more displacement you need. A ported alignment adds sensitivity and excursion control at and above the tuning frequency which results in about 6db more max SPL. So, you would need double the subs w/ double the power to get the same output in a sealed configuration compared to what we have recommended in ported subs.
The advantage of sealed is being able to produce output below the tuning frequency of a given ported alignment. The cost is more long throw subs and more power to produce the same SPL....

You forgot to mention that an oversized sealed box (Q>.707) will typically be significantly smaller than a ported box tuned that low. Enough so that you might actually get two drivers and cabinets in the same volume. If room placement trumps efficiency (expressed in $ for dirvers and amps) sealed may be a better choice.

You can always test the same drivers and amps in multiple boxes and locations. Boxes are cheap. It's the labor to finish to high WAF that's expensive (time or $). Even the drivers look not very expensive if you're paying someone else for a professional finish.

I prefer sealed. I've built ported bass and sub-bass, but I come back to sealed.
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post #77 of 203
12/3/12 at 7:07pm
"Too be honest, I would rather focus on higher SPL into the mid to high teens than trying to play clean to 5hz."

yeah, get that right first. that is where most of the fun is.

---

also, thanks for the kind words.
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post #78 of 203
12/4/12 at 3:04pm
Thread Starter 
Here is what 4 ported 5 cu ft subs on the iNuke look like compared to one ported 5 cu ft box:



And this is four ported 5 cu ft boxes with a 20hz tune (grey) vs 4 sealed 3.5 cu ft boxes (yellow) look like:




I don't really see any reason not to go ported at this point...

Can't wait.. This is not even factoring in the Hsu VTF-15H in max extension mode which should yield another 3db+ easy.
Edited by ack_bk - 12/4/12 at 3:10pm
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post #79 of 203
12/4/12 at 6:32pm
if you can go a little larger and tune it a little lower, it might be a little better.
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post #80 of 203
12/4/12 at 9:30pm
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

if you can go a little larger and tune it a little lower, it might be a little better.

That is the kicker huh? I might be able to stretch to 5.5 or 6 cu ft and an 18hz tune. But that is about as big as I can go and as low as I really need with five subs in the room.
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post #81 of 203
12/4/12 at 9:36pm
yeah, its just a little tradeoff.
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post #82 of 203
12/4/12 at 9:51pm
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

yeah, its just a little tradeoff.

I am modeling all different types of sizes and tuning points, and I think 5 to 5.5 cu ft and a 19hz tune look pretty good. Modeling different drivers, the Dayton DVC385-88 holds up pretty well until about 18hz and then you can see where the superior TC Sounds driver can go lower.

Winisd Pro is rather addictive smile.gif
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post #83 of 203
12/5/12 at 6:30am
Ported boxes are all going to unload at a few hz below tuning, so it doesn't matter what driver you use. The TC just looks like it does better because of the high excursion but it is still unloading. The 20hz hpf on the iNuke will work fine to protect from that. -3 will end up being around 17 or so and you can adjust the hpf lower by boosting 20hz if you need to.

You won't be able to hear a difference in 1 or 2 hz of tuning or less than 1/2 cu ft though. I think you have a good plan and if you are at your limit then that's fine. These designs are often a compromise. But, if you could squeeze in 6 cu ft @ 17 hz instead of 5 cu ft at 20 hz then it would be worthwhile. Just make the box an inch or so deeper and you should be there. wink.gif
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post #84 of 203
12/5/12 at 6:58am
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

Ported boxes are all going to unload at a few hz below tuning, so it doesn't matter what driver you use. The TC just looks like it does better because of the high excursion but it is still unloading. The 20hz hpf on the iNuke will work fine to protect from that. -3 will end up being around 17 or so and you can adjust the hpf lower by boosting 20hz if you need to.
You won't be able to hear a difference in 1 or 2 hz of tuning or less than 1/2 cu ft though. I think you have a good plan and if you are at your limit then that's fine. These designs are often a compromise. But, if you could squeeze in 6 cu ft @ 17 hz instead of 5 cu ft at 20 hz then it would be worthwhile. Just make the box an inch or so deeper and you should be there. wink.gif

7 is probably not going to pass the WAF test if I build 4 of them and stick 2-3 of them in the front of the room. I could easily build 2 larger boxes (8-9 cu ft) that have dual drivers. Modeling in Winisd, I think 4 smaller boxes tuned a little higher is a better fit for my really large room, and more sources seems to be a good thing in such a large space. I will do a few more models, but should be cutting wood sometime next week. Drivers and iNuke sub all arrived, and I will be making my own Speakon cables this weekend.

And just to be clear, when you guys are talking enclosure volume, you are talking interior enclosure volume after factoring in bracing, ports, etc. Because when I say 5 cu ft, I mean 5 cu ft interior volume after subtracting bracing, ports, drivers, etc and the material thickness.
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post #85 of 203
12/5/12 at 7:05am
Yes, net volume.
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post #86 of 203
12/10/12 at 12:47pm
Thread Starter 
As the woofer turns.....

After doing some cardboard mockups, I don't think I can sell the wife on 4 x 5cu ft boxes plus the HSU in the room (they are much bigger in person with the mockups that on paper and with a measuring tape in the room). Since this is a shared family space, going sealed with 4 x3.5 cu ft (internal) boxes will be much easier to implement into the room. I can do four of them now and possibly add more as I need to, but to be honest, I think 4 are probably overkill anyway. I am coming from one Hsu VTF-15H so keep that in mind (and I am 80% happy with that as it is). I can probably keep the HSU as well with the four sealed 15's, but I will need to measure and EQ I am sure to get everything to play nice. I could probably get away with 2 7.5-8 cu ft ported boxes in the room (one in the front corner, one in the rear corner) and sell the Hsu.

But I think I would be happier with more sources in such a large room, and sealed seems easier to build and easier to place. With four sealed 15" boxes I would get useful extension well into the low teens I suspect.

Another option is to build 2 dual opposed sealed boxes (could go 4cu ft internal), sell the Hsu, and build 2 more dual opposed after buying 4 more drivers and another iNuke.
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post #87 of 203
12/10/12 at 4:52pm
WAF strikes again.

I think you are throwing away output if you go smaller than 3 cu ft per driver sealed. I do get a bunch of movement out of my sealed dvc though and am considering a dual opposed in the near future. The other option is to do down firing boxes so that you don't get a back and forth rocking type loss of energy.
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post #88 of 203
12/11/12 at 7:29am
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

WAF strikes again.
I think you are throwing away output if you go smaller than 3 cu ft per driver sealed. I do get a bunch of movement out of my sealed dvc though and am considering a dual opposed in the near future. The other option is to do down firing boxes so that you don't get a back and forth rocking type loss of energy.

Thanks, I will stick with 4 x 3.5 cu ft sealed subs and that number might creep up a little closer to 3.75 cu ft or so. If I go down firing (which I am not opposed to), these are on some petty thick carpet, and I would imagine I would need to raise them off the ground a few inches?

I have also been doing some reading on measurement tools/analysis and am really leaning towards Omnimic V2. REW, to me, seems like it could be difficult to install and get going and in some ways is not much cheaper by the time you buy a calibrated mic, preamp, etc. But I am curious on opinions of what people use and recommend.

I know the only way I will ever get my system where I need it is with measuring, EQ, measuring again, moving subs, etc. Probably be Jan/Feb before I buy it, but am trying to start learning now.
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post #89 of 203
12/11/12 at 7:42am
With 4 subs you shouldn't have to move much.

Minidsp has a new usb mic that is a good price. The dayton calibrated mic is cheap too.
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post #90 of 203
12/11/12 at 7:52am
Thread Starter 
Quote:
Originally Posted by nograveconcern View Post

With 4 subs you shouldn't have to move much.
Minidsp has a new usb mic that is a good price. The dayton calibrated mic is cheap too.

Yeah, I was looking into both of those. With the new mics, is this as simply as plugging into your laptop and running REW? Like Omnimic is today? I realize these are not released yet, but if that is the case, I might lean towards getting one of these with REW.
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