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"The Shadow of the Beast"...Adventures in Closet-Sized Subwoofers - Page 4

post #91 of 236
I know I'm late to the party, but subbed! I gotta give you a call soon to catch up. biggrin.gif
post #92 of 236
Thread Starter 
Quote:
Originally Posted by Gorilla83 View Post

I know I'm late to the party, but subbed! I gotta give you a call soon to catch up. biggrin.gif

Yes you do sir!!!! Hope baby Rilla and Mom are doing well still biggrin.gif

So some progress for the night:






Man, I love dropbox, I don't know how I didn't discover it earlier but snapping photos on the phone and uploading them is a sinch with it!!! Anyways. As you can see in the photos, I have the first baffle mounted and drying. The test pipe is actually the 5 inch ports I cut for the rear chamber and just used them to measure and test fit. I still have to cut the front box's port tubes but walking around with a tiny 5 inch port is way easier than a 30" one biggrin.gif Front baffle should be dry tomorrow and be able to mount the ports using PL and then hopefully a test fit/mount before the weekend. That gives me the possibility to start working on the OSB in the front chamber if I can get the truck sooner rather than later.

I have guests coming into town this weekend and a fantastic "BrewGrass Festival" with copious amounts of craft brews Saturday so I can promise no work this weekend as I imagine I will be a little fuzzy Sunday as well. :priorities:

I will basically be happy if I can finish sealing up the room, insulating the rest of it, and getting the front port mounted and sealed up. The wall is ready for it, so that shouldn't be a huge deal. The biggest task will be building out the "woofer wall" and sealing that up. I am tossing the idea around whether or not I want to mess with OSBing the stair treads or not. Once I get the wall up, there really is no turning back so I have to cover all the bases now.
post #93 of 236
Thread Starter 
Just noticed too, in that last pic, you can see the XXX peeking through the hole in the back.... Haha!!!!
post #94 of 236
sounds great. looks great.

i wonder if there is some way to attach the ports semi-permanently in order to get some measurements and confirm that they are doing what is anticipated before gluing them in permanently.
post #95 of 236
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

sounds great. looks great.

i wonder if there is some way to attach the ports semi-permanently in order to get some measurements and confirm that they are doing what is anticipated before gluing them in permanently.

As far as port baffles go, I am planning on just putting them in with some closed-cell foam and screws so the entire baffle can be removed and replaced if needed.. on both. The actual 12" ports will be PL'd to the baffle, but a quick deconstruction/reconstruction is feasable. inside the front chamber will be tough, but not impossible. I hope to have a decent sized access hole that I can at least fit through, svelte as I am, I certainly am not a gymnast... Those girls that fit in 12x12 boxes amaze me, but i am young and still limber enough to squeeze into a tight space. fluffy insulation just makes it that much more fun...A hazmat suit probably won't be accompanying me if adjustments are needed.

Also, cut the other port/baffle hole. I also realized that for the dual opposed the drivers are going to HAVE to be vertical. Not enough width for both and a box. Not a problem, actually makes it a little easier on me as the RE's vent to the sides, not out of the back so I will be placing something under the bottom woofer to supplement the weight of both drivers on top of each other.
post #96 of 236
Thread Starter 
Looked at the TS specs and they are what RE has on their website, but I don't know if that is the new overhung version or not. Ricci has TS specs on both and my non-overhung split coil version's numbers are all off from the ones RE has on their site. Take a look

http://www.data-bass.com/data?page=driver&id=6
post #97 of 236
Quote:
Originally Posted by beastaudio View Post

Just noticed too, in that last pic, you can see the XXX peeking through the hole in the back.... Haha!!!!

Lol!

post #98 of 236
sorry beast, i didn't follow that. which driver do you have, the t/s on the top (a), or the bottom (b), or completely different?

set A:


set B:


the good news is that it may only make a little difference (at least between these two sets).


Edited by LTD02 - 9/19/13 at 5:51pm
post #99 of 236
Thread Starter 
Seems that Josh's specs are different than both:

http://www.data-bass.com/data?page=driver&id=6

But if I had to pick, I am closer to the cms on option A. The thiele parameters are off a little on both according to Ricci's test tho.
post #100 of 236
so is the driver that you have the same as the one that ricci tested? if so, i can plop those specs in no problem.
post #101 of 236
using these specs:
i entered the green parameters and winisd calculates the blue based on various formulas. if they are a hair different than ricci's measurments, that will have no impact. if something is very different, it will matter.



gives this:
blue is ricci measurements
red is what we were using before
looks like about 1db difference, negligible.



that is with cone excursion like this:






.
Edited by LTD02 - 9/19/13 at 8:17pm
post #102 of 236
Thread Starter 
Is that with the 30hz top end tuning? If so, I think we could drop it down a shade to get it a little more smooth. If you are down for that. I have not cut the sono yet, but I do have both port baffles ready so I need to get those going tomorrow. Looks ok on that last one, but taking a little off the top end SHOULD smooth it out a shade. Just tell me where to cut the 12" ports with a smooth graph and we should be good to go. Also, the last one you put in was still with a 32 cuft front chamber and I am around 40 now like the original. Thanks bro!!!!!! This is coming together NICELY!!!
post #103 of 236
Thread Starter 
and yes, the one that Ricci tested is the same one I have, not the overhung version, but the link I posted is the correct version
post #104 of 236
23hz tuning on blue



24hz:
post #105 of 236
personally, i'd keep the extra sensitivity of the 25hz model and just put a little -1.5db eq (q=2.0, f=25hz) on it like this:

post #106 of 236
Thread Starter 
Sounds good to me. Port length for both chambers? assuming two 12" diameter ports for each? Bed time, but will cut tomorrow and have them setting and ready for paint/install by Sunday
post #107 of 236
doesn't change.

for dual 12" ports, winisd shows: 5.08" for the rears and 21.57" for the fronts



assuming these sizes for the rear and front chambers.

post #108 of 236
Why doesn't winisd let you model down to 5hz?
post #109 of 236
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

doesn't change.

for dual 12" ports, winisd shows: 5.08" for the rears and 21.57" for the fronts



assuming these sizes for the rear and front chambers.


Front chamber still shows at 32 cuft. I will be at 40 where the wall is now. I recall that actually making a bigger difference than the port length.
post #110 of 236
Quote:
Originally Posted by mtg90 View Post

I think it means an acoustic suspension, 4th order bandpass, front loaded horn, etc. only use one side of a driver's acoustic stroke while both sides can contribute in a bass reflex, 6th order bandpass, tapped horn...

Quote:
Originally Posted by noah katz View Post

I thought it might be that, which sounds like what I think is a false belief that ported boxes are more efficient because they use both sides of the diaphragm.

This may be true for dipole designs where the midrange reflections add to the overall SPL, but not in the bass; in ported designs the increase in bass efficency is from resonance.

The only case where using both sides may be true is in a labyrinth that's half a wavelength long that puts the radiation from both sides in phase, but that may be due to pipe resonance.

Just inquiring about two separate aspects; the overall alignment/design clarification, and secondarily room response integration with the existing sub system.

Having never really built, or employed anything outside the sealed alignment in my primary system (let alone a 6th order band-pass), I'm not familiar with anything other than the typical mixed alignment anecdotal warnings. Maybe these caveats don't have merit. Hence my "I'll sit over here and be quiet".




Additionally, I've no idea if this applies, but here's my take. As a general room/system subwoofer approach in normal, modestly sized HTs, one nice technique could utilize one mega-sub for the deep stuff, and a distributed-multiple sub config for the remaining spectrum upward. Since there's no advantage (to distributed subs) in the so called "pressure region", the mega-sub could address the region around the first resonance downward, and the (smaller, placement friendly) distributed set addresses the modal region above.

Again, no idea if this would even apply here, but as I understand it we can't fully delineate phase or time alignment down low. It's my understanding it takes approximately 40-50ms. for the brain to sense and discern a tone down around 50hz. However, taking this into the realm of hands on blending and optimizing a multi-sub system (of mixed alignments or otherwise), the effects of phase can enter the equation wrt acoustic summation of disparate sources, and the final FR across the listening positions.

All this was the genesis of my initial comments. In the hands of someone as capable as Beast, perhaps this can be an ideal test case in actual use. This is fascinating work, above both my armchair, or hands on DIY chops for sure.

Thanks

edited for clarity, italics
Edited by FOH - 9/20/13 at 1:26pm
post #111 of 236
Thread Starter 
Yes sir, I am thinking along the same lines and thus, wasn't too worried about where the ports exited to the room as we are below that modal region with the whole build. Whilst blending this "sub" in with the rest of the system, I will certainly be documenting the process front to back.
post #112 of 236
Has anybody achieved 140db in room at 11hz before? Can your equipment measure that loud/low, beast? What if you open a worm hole?
post #113 of 236
I could not be in a room that loud! Too much pressure.
post #114 of 236
John,

No way in hell the XXX has an mms of 450 grams. It is closer to 550-600. BL is very close to factory spec on the split coil. LE should be entered as about 6 for winisd. The OVH version has a much higher BL check DB specs and the LE should be around 10 for winisd modeling.
post #115 of 236
Quote:
Originally Posted by Stumbo View Post

Has anybody achieved 140db in room at 11hz before? Can your equipment measure that loud/low, beast? What if you open a worm hole?

OMG I could not imagine. 130db @ 20hz can kick my heart out of it's natural rhythm. I got AFIB once when I was about 21... from (4) 12" subs I had in my 1996 Camaro (man I was so lame). Well that was back in the late 1990's- I got into car audio before it really got going. I remember that feeling I got- It was not cool. A few clips of test is fine, but extended listening at those levels and frequencies messes you up.

I could not imagine 11hz at 140db. That would seriously be very bad for your heart and lungs and natural body functions. I think you could die from prolonged exposure.

Do you even have an idea of what it would take to get that volume in a room ?
post #116 of 236
Quote:
Originally Posted by Mfusick View Post

OMG I could not imagine. 130db @ 20hz can kick my heart out of it's natural rhythm. I got AFIB once when I was about 21... from (4) 12" subs I had in my 1996 Camaro (man I was so lame). Well that was back in the late 1990's- I got into car audio before it really got going. I remember that feeling I got- It was not cool. A few clips of test is fine, but extended listening at those levels and frequencies messes you up.

I could not imagine 11hz at 140db. That would seriously be very bad for your heart and lungs and natural body functions. I think you could die from prolonged exposure.

Do you even have an idea of what it would take to get that volume in a room ?

Huh? Late 90's?
post #117 of 236
"John,
No way in hell the XXX has an mms of 450 grams. It is closer to 550-600."

don't shoot me man!

that is what winisd autocalculates from the t/s equations using the fs, vas, and sd (the source for those inputs was probably a resonant engineering manual or the company website, so about as good as one could be expected to do without actually measuring the driver).

but, we are ok, as post #101 has your numbers and it turns out not to make much difference anyway, and...thanks for keeping an eye on things.


.
Edited by LTD02 - 9/20/13 at 12:32pm
post #118 of 236
Thread Starter 
John, will you confirm port lengths with the proper front chamber size of 40cuft, instead of 32 in your calcs you posted on post 107? Thanks dood smile.gif
post #119 of 236
"...here's my take. As a general room/system subwoofer approach in normal, modestly sized HTs, one nice technique could utilize one mega-sub for the deep stuff, and a distributed-multiple sub config for the remaining spectrum upward. Since there's no advantage in the so called "pressure region", the mega-sub could address the region around the first resonance downward, and the distributed set addresses the modal region above."

and building on that idea, size tends to be the primary culprit with respect to placement, so to the extent that a giant built-in could handle say 10-20hz or so, that could reduce the size requirements for the other subs which increases the placement possibilities.

btw, "built in" refrigerators, such as the subzero, have been all the rage for the past decade or so. it is a huge status symbol thing. so if anybody asks, just say its like the subzero is to refrigerators...top of the line, custom, built-in. :-)~
post #120 of 236
for dual 12" ports, winisd shows: 5.08" for the rears and 15.50" for the fronts





going to the 40 on the front bumps up that peak by another hair.

this is the eq that i have running in the background. high pass at 10hz and 1 band of parametric on the first peak.





.
Edited by LTD02 - 9/20/13 at 12:55pm
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