Structurally simplest DIY with a large number of subwoofers? - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 107 Old 03-30-2014, 08:14 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Lets say you were building a theater but you didn't have a lot of construction skills or all the fancy modeling software and whatnot...

What could be achieved with a best guess approach with around 4-8 very high quality drivers positioned around the room (lets say 4 in the front of a room and 4 in the back).

for the sake of the discussion, lets do 22'x19'x13' dimensions (around 5400 cu ft).

What drivers would you guys use and would you go for an infinite baffle? We will assume that any peaks are tamed by EQ. Nulls can be tamed by sheer number of subs which allows adjustment of the main listening position. Lets presume good performance in the 10hz to 60hz range...

Is my discussion pure insanity or would arbitrarily just mounting drivers here and there (guessing) result in reasonable bass response? I would be willing to compensate for complex enclosures with simply using more drivers if this would help in some way...

Blazar!
blazar is online now  
Sponsored Links
Advertisement
 
post #2 of 107 Old 03-30-2014, 08:25 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266

Doesn't get much easier than this

http://www.parts-express.com/dayton-audio-18-reference-series-ho-subwoofer-and-cabinet-package--300-7094

Mrkazador is online now  
post #3 of 107 Old 04-01-2014, 05:36 AM
AVS Special Member
 
Martycool007's Avatar
 
Join Date: Jun 2011
Posts: 3,692
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 280 Post(s)
Liked: 172
There would be no point in just adding random drivers at random areas around a 5400cu/ft room because of the fact that it is so cheap to do measurements! You can purchase a UMM-6 for around $75, and then download REW, and start measuring!
Mfusick likes this.
Martycool007 is offline  
post #4 of 107 Old 04-01-2014, 07:23 AM
AVS Special Member
 
HopefulFred's Avatar
 
Join Date: Mar 2007
Location: Atlanta, GA
Posts: 2,918
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 199 Post(s)
Liked: 223
If you want down to 10Hz, and eight cabs is cool, sealed makes sense to me. The good news is that you can't really go wrong with those kits, and with more than 5 or so, you can't really go too wrong with placement if you just spread them around.
HopefulFred is offline  
post #5 of 107 Old 04-01-2014, 01:32 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Can you measure the sub response without actually fully mounting it in a box in the wall? There are finite places i can put these subs.

I could easily do 2-3 drivers per bay which is 72" high, 22" wide, and about 9"max depth. It's really my depth that is the constraint.

The 4 spaces I have are midway up a 12ft wall and in the 4 corners of the room.

I just dont know how to "measure" it without actually putting them in and checking the results.

I want to max out driver size and number so this is a one-time adventure. i will make custom boxes and build them into the space with 3/4" MDF or other hard wood.

I think sealed with 3 drivers each bay for a total of 12 drivers seems very doable. The drivers will almost form a mini-array in each corner, especially if I go to 16 drivers...

The boxes would each have about 5-6cuft of space and sealed. Not sure how that would turn out.

Unfortunately the only things I can "choose" are driver type/brand.

If all this goes well I want to sell my pair of JL AUDIO F212 subs. JL audio drivers looks really pricey and I'm thinking are overkill when I will have like 12-16 drivers in the room.

Blazar!
blazar is online now  
post #6 of 107 Old 04-01-2014, 02:00 PM
Senior Member
 
WVSyd's Avatar
 
Join Date: Feb 2013
Posts: 333
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 42
The T/S parameters can be used to simulate a "theoretical" response.

"Beware of Salesmen: They are the modern Svengali, immune to Science and Reality"
WVSyd is offline  
post #7 of 107 Old 04-01-2014, 02:09 PM
AVS Special Member
 
HopefulFred's Avatar
 
Join Date: Mar 2007
Location: Atlanta, GA
Posts: 2,918
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 199 Post(s)
Liked: 223
I see... I didn't realize in-wall was a restriction.

If you've got four locations for 6cuft enclosures, you're going to need sealed designs to keep volume down. (As well as for the deep extension.)

I'd say you want eight drivers that are good in 3cuft each, like the ultimax 15s. And plenty of power.

I'm building 4 3cuft boxes with UM-22 15s for use in four corners of my 3200cuft room, and it should be good for reference down to 20hz or below, depending on room gain. Eight should get you pretty close, and squeezing more drivers into the same enclosure volume won't help.
HopefulFred is offline  
post #8 of 107 Old 04-01-2014, 02:19 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Great thanks, i figured too many drivers may not add much since they will be fighting the same vacuum in the box...

Any role for a passive radiator?

What about sound qubed products?

Blazar!
blazar is online now  
post #9 of 107 Old 04-01-2014, 02:19 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266

9" depth is going to be a problem...Are you going to build a enclosure in the bay? If so, that will decrease the depth too.

 

Dayton 18 HO = 9" depth

Dayton 15 Ultimax = 8" depth

Dayton 15 HF = 7" depth

 

Dayton 12 Ultimax = 6.22" depth, this can work well in a large ported enclosure.

Mrkazador is online now  
post #10 of 107 Old 04-01-2014, 03:03 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Yes i think i definitely need an enclosure in the bay. I may be able to build the enclosure into an odd shape to go deeper a few inches.

Are shallow drivers a really bad thing for performance?

Blazar!
blazar is online now  
post #11 of 107 Old 04-02-2014, 05:16 AM
AVS Special Member
 
Martycool007's Avatar
 
Join Date: Jun 2011
Posts: 3,692
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 280 Post(s)
Liked: 172
It's not that shallow drivers are bad performers, per se, it's just that most 15" and especially 18" drivers are not that shallow, and unfortunately, if you want shallow subs, you are stuck with 12" and 10" drivers.

Are you definitely opposed to having the enclosures out in the room? Are you stuck with having only in-wall enclosures?

You could do some nice looking end table subs, make them really pretty and I am sure no one would know that those end tables are actually subwoofers. For that matter, you can build all kinds of nice subwoofer enclosures disguised as furniture! I am sure some of us could help with the design ideas, and you could likely end up with a room full of nice 18" subs and no one would have a clue they are there! If you did eight of the Dayton HO18's or perhaps four of the UXL-18's then those would likely give quite the upgrade in performance compared to the JL-Audio F212!
Martycool007 is offline  
post #12 of 107 Old 04-02-2014, 07:10 AM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
In wall is a major option because the wiring and other stuff is designed already in the room for it. Its not a regular wall, its actually a cavitity that is built up with woodwork and stuff already.

Theoretically i could also do a near field sub behind my couch as some kind of console table but it would only look good if it was narrow.

The more options and drivers, the better, so i can fine tune the response more evenly.

I dont need extreme volume, reference +5db is more than enough. Just need as perfect of a response as possible.

Blazar!
blazar is online now  
post #13 of 107 Old 04-02-2014, 07:28 AM
Member
 
gworrel's Avatar
 
Join Date: Dec 2005
Location: Detroit
Posts: 64
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 18
You mentioned infinite baffle. What is behind these wall spaces and can the enclosure be open to the next room? If so, then definitely 18" drivers in an infinite baffle. Most bang for the buck are the FI IB318s.
gworrel is online now  
post #14 of 107 Old 04-06-2014, 09:35 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
As a refresher, I have cavities in the wall for 4 subs (one in each corner of the room) for a 5500 cu ft room.

There is room in the wall for me to build a sealed enclosure with these INTERNAL dimensions:

7.5"x73.5"x20" = 6.38 cu ft.

About 3 Cu Ft is recommended for each Dayton Ultimax 15" subwoofer driver. My space is just right for 2 drivers in series (8 ohms) on one channel of a pro amplifier (like crown XLS).

Questions:
1. Is it best to wire two 2+2 subs in series to get 8ohms or is there a better way to do this?
2. Is there any difference between impedances in the final result assuming your amp can handle down to 2ohm loads?
3. How much space is usually needed behind the sub driver for ventilation of the driver with a Dayton Ultimax?
4. For my cubic footage, are 15" drivers even needed or will 2x12" drivers per enclosure already provide crazy bass for a 5500 cu ft room? (goal is multi-seat smooth response at reference volumes, not earth shattering competition bass)
5. Is MDF the best material, or is there other routine hardwood that would be even more rigid and vibrate less?

Soon as I get these questions answered, I can order my drivers with confidence! Any help is appreciated!

Blazar!
blazar is online now  
post #15 of 107 Old 04-06-2014, 10:06 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266
Quote:
 1. Is it best to wire two 2+2 subs in series to get 8ohms or is there a better way to do this?

 

For a single sub, you can wire it as 4 ohms or 1 ohm.  If your amp can't do 2 ohms then you want to wire both drivers (4 ohm) in series for 8 ohms. 

 

Quote:
 3. How much space is usually needed behind the sub driver for ventilation of the driver with a Dayton Ultimax?

 

If the pole vent is 1" in diameter then 1" behind the driver should be alright.

 

Quote:
 4. For my cubic footage, are 15" drivers even needed or will 2x12" drivers per enclosure already provide crazy bass for a 5500 cu ft room? (goal is multi-seat smooth response at reference volumes, not earth shattering competition bass)

 

Go BIG, you'll regret it later :D You are going to need a decent amount of subs to reach reference volume in a 5500 cu ft room. I don't know if I would go with 2x12" sealed subs, I would go ported and tuned to 20hz. Multiple ported subs tuned to 20hz will go loud.

 

Here is a comparison of two sealed ultimax 15 with 1500w and two ported infinity 1260w tuned to 20hz, 800w.

 

 

Quote:
 5. Is MDF the best material, or is there other routine hardwood that would be even more rigid and vibrate less?

 

MDF is cheap, straight, heavy and dusty when cut. Plywood like Arauco is also cheap, light in weight but can warp. Birch is nice to work with but expensive. If you don't mind the dust, I would go with MDF.

 

 

 

You can always go crazy and get 16 infinity 1260w at $55 each... 4 sealed in each corner.

http://www.sonicelectronix.com/item_18916_Infinity-Reference-1260W.html

Mrkazador is online now  
post #16 of 107 Old 04-06-2014, 10:47 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Damn those infinity reference speakers are cheap, are they as good as the daytons? I actually do have room for 4 of those if you think that would be a better option....

I realized I have enough room between studs to actually extend back of my box and make room for the speaker magnets and extra space for keeping the speaker cool.


using Crown XLS amps, does it really make a difference if the final speaker load is 2 ohm or 8 ohm in terms of sound quality maximum SPL? I am assuming it does not make a difference...?

Blazar!
blazar is online now  
post #17 of 107 Old 04-06-2014, 11:24 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266

The crown xls can do stereo 2ohm so you can get more power if you wire the drivers as 2ohms. Eight Dayton 15" Ultimax is going to be amazing if you have the power to push them to their potential. If you want to save some cash and get almost the same spl then go with sixteen 1260w. 

 

 

 

Eight Dayton 15" ultimax with 4000w and Sixteen 1260w with 4000w. Both are pretty much the same BUT the infinity drivers are at its excursion limit. The Daytons could be pushed further with 8000w which will give you another 3db.

Mrkazador is online now  
post #18 of 107 Old 04-07-2014, 07:14 AM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Quote:
Originally Posted by Mrkazador View Post

The crown xls can do stereo 2ohm so you can get more power if you wire the drivers as 2ohms. Eight Dayton 15" Ultimax is going to be amazing if you have the power to push them to their potential. If you want to save some cash and get almost the same spl then go with sixteen 1260w. 





Eight Dayton 15" ultimax with 4000w and Sixteen 1260w with 4000w. Both are pretty much the same BUT the infinity drivers are at its excursion limit. The Daytons could be pushed further with 8000w which will give you another 3db.

Awesome, thanks for the great info!

I ordered the dayton 15" and I'll wire them to have a 2 ohm impedance per box. That should give me very decent power per driver.

I won't be driving them anywhere near max power/excursion requirements so we should be all good I think.

I can always pick up a behringer to try if absolutely needed. Is fan noise and reliability of the Behringer Inuke series an issue?

Blazar!
blazar is online now  
post #19 of 107 Old 04-07-2014, 08:19 AM
Senior Member
 
WVSyd's Avatar
 
Join Date: Feb 2013
Posts: 333
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 42
Quote:
Originally Posted by blazar View Post

...using Crown XLS amps, does it really make a difference if the final speaker load is 2 ohm or 8 ohm in terms of sound quality maximum SPL? I am assuming it does not make a difference...?
Don't want to cloud the water here, but don't make that assumption.
To truly evaluate amplifier performance - all the criteria ( qualifiers ) have to be examined.
Crown has to compete in a market where large wattage numbers sell.
So it lists power under a variety of signal and load conditions.
IF you listen to 1khz signal @.5% distortion ( doubtful ) than that rating is meaningful
Otherwise expect less power with a larger bandwidth and for lower distortion
http://www.crownaudio.com/media/pdf/legacy/133465-6.pdf

Note on page 20: Power draw and Thermal Dissipation
It's easy to see that with an increase of duty cycle or a reduced impedance load - the current draw and amount of heat generated increase substantially.
Cooler amps last longer.

"Beware of Salesmen: They are the modern Svengali, immune to Science and Reality"
WVSyd is offline  
post #20 of 107 Old 04-16-2014, 06:12 AM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Ok so here is the update:

I can actually build my boxes to about 7cu ft and can cut into some studs a bit and achieve the depth I need.

Ordered 8x15" dayton ultimax, waiting for next shipment.

Ordered a Lab Gruppen PLM 10000Q off of ebay and I will likely wire the speakers for 8ohms or put in a 30amp power line so i can wire them for 2ohm... The 10000Q can defintely do 2-4ohm (in fact that is the standard operating range).

I placed a my JL fathom f212 sub at my sitting position and did a "sub crawl" and discovered something useful. The subwoofer locations in my wall are in fact the "hottest" spots in the room. Higher up on the wall was even better... Since this will be a dual driver setup, one of my drivers will be near the hottest spot in each of the 4 corners of the room.

This should get me maximum "room gain" correct? Will this typically help all bass frequencies or just some of them?

The fathom 212 (dual 12") sealed with "sine wave" sweeps was straining pretty hard to reach high SPL and was making some driver "flapping" noise at the low end 20-25hz.

Hopefully 8x15" drivers will do a much more impressive job....

Blazar!
blazar is online now  
post #21 of 107 Old 04-16-2014, 07:45 AM
Senior Member
 
WVSyd's Avatar
 
Join Date: Feb 2013
Posts: 333
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 42
Quote:
Originally Posted by blazar View Post

... Will this typically help all bass frequencies or just some of them?....
Sweep the frequency and make note if it's uniform or nodal.

"Beware of Salesmen: They are the modern Svengali, immune to Science and Reality"
WVSyd is offline  
post #22 of 107 Old 04-16-2014, 10:36 AM
FOH
AVS Special Member
 
FOH's Avatar
 
Join Date: Apr 2010
Location: Midwest
Posts: 4,749
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 18 Post(s)
Liked: 213
Quote:
Originally Posted by blazar View Post

30amp power line so i can wire them for 2ohm

Although even a 20a circuit can pass huge amounts of current for short periods*, with that monster amp and 2ohm operation, I'd go ahead and get the 30a circuit.

*(A 20 amp circuit can pass 7-8 times the rated 20amp trip amount, .. for up to a second or more. It will allow up to 3x the rated amount for up to 10sec or so. And most importantly, the same 20amp circuit, can allow up to 1.5-2times the rated amount for a period extending as long as 30 seconds. That's over 100amps for around 1-2 seconds, about 60amps for around 10 seconds, and the circuit will allow 30-40amps for as long as 30 seconds! All from a 20a breaker.)


As of late, there's well documented cases of soundtracks that possess sustained LF/ULF effects that are quite demanding of all elements involved.

Quote:
Originally Posted by blazar View Post

The subwoofer locations in my wall are in fact the "hottest" spots in the room. Higher up on the wall was even better...

This is typical in every room. You're experiencing high pressure region that exists along each boundary in the room. And as you found higher up nearer the ceiling, the boundary effects are even more significant.

Quote:
Originally Posted by blazar View Post

This should get me maximum "room gain" correct? Will this typically help all bass frequencies or just some of them?

The spatial boundary loading effect you're experiencing, will impact all low frequencies. Also, flush mounting up front most often minimizes SBIR (an acoustic distortion in the front part of the room causing destructive interference dips). However, flush mounting drivers in the front wall, maximizes the need for rear wall acoustic treatment.

Quote:
Originally Posted by blazar View Post

The fathom 212 (dual 12") sealed with "sine wave" sweeps was straining pretty hard to reach high SPL and was making some driver "flapping" noise at the low end 20-25hz.

Hopefully 8x15" drivers will do a much more impressive job....

The JL offerings are fine products, but they can't compete with a well executed diy effort.



Good luck with this, you'll have the firepower. It just will need to be harnessed and blended properly to the space and remaining system.

------------------------------------
Flat, Deep, Clean, Linear, and Loud
------------------------------------
Active 16.8kw, 7.3 system
(3)Seaton Cat12C up front, (4)QSC K8 sides/rears
(2)Seaton SubM-HP, (4)18" IB
FOH is offline  
post #23 of 107 Old 04-16-2014, 11:41 AM
Member
 
Peterc613's Avatar
 
Join Date: Apr 2011
Location: Van Nuys, CA
Posts: 194
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Liked: 77

"The JL offerings are fine products, but they can't compete with a well executed diy effort."

 

---------------------------

 

I'm looking for two more subs for my system. They need to fit behind my sofa and integrate with an existing DTS-10 in the front corner of a theater area that opens to a large great room/kitchen/patio/den (10,000 ft3 total). Basically I've narrowed my choice down to either finding two used JTR passive Captivators or build two DIY subs with UXL-18's when they become available. Either way I'd drive them with a Peavy 7500 or QSC 5050:
 
QSC 5050     2-channel:   1,100/8ohm    1,800/4ohm    2,500/2ohm  
Peavy 7500   2-channel:   1,250/8ohm    2,020/4ohm    3,750/2ohm
 
I like the design of the Marty Cube at 24x24x24 or Eric H's "stonehenge" cabinet, probably at 30x30x15 (5 ft3) or build my own at 21" deep (7ft3), since I have the clearance behind my sofa. I do not have the room for anything larger, so some of the truly awesome DIY builds on AVS are out of my consideration. 

 

The DIY route is certainly less expensive, and I have already built a DTS-10 so it's within my skill set to assemble a flatpack. I have a standard table saw, but would need to buy more clamps to build my own and definitely some help to model it. I've downloaded WinISD Pro to my Mac desktop running OS X 10.7.5 and tried it in Windows XP through VM Fusionware, but it runs so slow as to be basically unusable.

 

I'd like to have both subs matching since they're visible in my living room and would have to find two used Captivators at approx $1,000/ea or a used one and a new one for $1,699 + $250 shipping (JTR wants $3,450 for two 2014 passive Captivators delivered). For the DIY option I'm figuring Eric's flat packs at about $170/ea (or $260/ea if I cut my own out of 3/4" Teak veneered ply) + $540/ea for UXL-18's + misc parts/clamps. That would be:

 

$3,450 two new Captivators

$2,950 One new/one used

$2,000 two used (If I could find two locally)

$1,800 two DIY dubs with UXL-18's

 

Maybe I'm comparing apples and oranges between a manufactured sub and DIY. I've read on AVS that the Captivators are legendary for Home theater, and I've also read that the UXL-18/MartyCube is an AVS DIY favorite. I'm assuming that AVS members that do DIY started with commercial subs and wanted more, or wanted the same performance for less expense. 

 

For around $2,000, I'm just trying to figure out which would work better for my situation. If the captivator is really that much better, them maybe it's worth saving up for the more expensive purchase. But if the performance for two subs is relatively comparable in a 10,000 ft3 room, then DIY UXL-18's are definitely the way to go. I've spent long periods saving up for audio or video purchases for my system over a many years so patience and delayed gratification have become a virtue. But it doesn't make any sense to save up for something that's comparable or better than what you can build now. Besides, I need to start saving up for other priorities like a decent amp to drive the subs or a new preamp. 

 

Do you guys really think that JTR Captivators "are fine products, but they can't compete with a well executed diy effort."?

Peterc613 is offline  
post #24 of 107 Old 04-16-2014, 11:46 AM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Quote:
Originally Posted by FOH View Post

Although even a 20a circuit can pass huge amounts of current for short periods*, with that monster amp and 2ohm operation, I'd go ahead and get the 30a circuit.

*(A 20 amp circuit can pass 7-8 times the rated 20amp trip amount, .. for up to a second or more. It will allow up to 3x the rated amount for up to 10sec or so. And most importantly, the same 20amp circuit, can allow up to 1.5-2times the rated amount for a period extending as long as 30 seconds. That's over 100amps for around 1-2 seconds, about 60amps for around 10 seconds, and the circuit will allow 30-40amps for as long as 30 seconds! All from a 20a breaker.)


As of late, there's well documented cases of soundtracks that possess sustained LF/ULF effects that are quite demanding of all elements involved.
This is typical in every room. You're experiencing high pressure region that exists along each boundary in the room. And as you found higher up nearer the ceiling, the boundary effects are even more significant.
The spatial boundary loading effect you're experiencing, will impact all low frequencies. Also, flush mounting up front most often minimizes SBIR (an acoustic distortion in the front part of the room causing destructive interference dips). However, flush mounting drivers in the front wall, maximizes the need for rear wall acoustic treatment.
The JL offerings are fine products, but they can't compete with a well executed diy effort.



Good luck with this, you'll have the firepower. It just will need to be harnessed and blended properly to the space and remaining system.

Awesome details, thx. Ill go ahead with 30 amps like you said then to make sure i get clean transients and go 2ohm wiring.

Blazar!
blazar is online now  
post #25 of 107 Old 04-17-2014, 05:56 AM
AVS Special Member
 
Martycool007's Avatar
 
Join Date: Jun 2011
Posts: 3,692
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 280 Post(s)
Liked: 172
Quote:
Originally Posted by Peterc613 View Post

"The JL offerings are fine products, but they can't compete with a well executed diy effort."


I'm looking for two more subs for my system. They need to fit behind my sofa and integrate with an existing DTS-10 in the front corner of a theater area that opens to a large great room/kitchen/patio/den (10,000 ft3 total). Basically I've narrowed my choice down to either finding two used JTR passive Captivators or build two DIY subs with UXL-18's when they become available. Either way I'd drive them with a Peavy 7500 or QSC 5050:

 

QSC 5050     2-channel:   1,100/8ohm    1,800/4ohm    2,500/2ohm  

Peavy 7500   2-channel:   1,250/8ohm    2,020/4ohm    3,750/2ohm

 

I like the design of the Marty Cube at 24x24x24 or Eric H's "stonehenge" cabinet, probably at 30x30x15 (5 ft3) or build my own at 21" deep (7ft3), since I have the clearance behind my sofa. I do not have the room for anything larger, so some of the truly awesome DIY builds on AVS are out of my consideration. 

The DIY route is certainly less expensive, and I have already built a DTS-10 so it's within my skill set to assemble a flatpack. I have a standard table saw, but would need to buy more clamps to build my own and definitely some help to model it. I've downloaded WinISD Pro to my Mac desktop running OS X 10.7.5 and tried it in Windows XP through VM Fusionware, but it runs so slow as to be basically unusable.

I'd like to have both subs matching since they're visible in my living room and would have to find two used Captivators at approx $1,000/ea or a used one and a new one for $1,699 + $250 shipping (JTR wants $3,450 for two 2014 passive Captivators delivered). For the DIY option I'm figuring Eric's flat packs at about $170/ea (or $260/ea if I cut my own out of 3/4" Teak veneered ply) + $540/ea for UXL-18's + misc parts/clamps. That would be:

$3,450 two new Captivators
$2,950 One new/one used
$2,000 two used (If I could find two locally)
$1,800 two DIY dubs with UXL-18's

Maybe I'm comparing apples and oranges between a manufactured sub and DIY. I've read on AVS that the Captivators are legendary for Home theater, and I've also read that the UXL-18/MartyCube is an AVS DIY favorite. I'm assuming that AVS members that do DIY started with commercial subs and wanted more, or wanted the same performance for less expense. 

For around $2,000, I'm just trying to figure out which would work better for my situation. If the captivator is really that much better, them maybe it's worth saving up for the more expensive purchase. But if the performance for two subs is relatively comparable in a 10,000 ft3 room, then DIY UXL-18's are definitely the way to go. I've spent long periods saving up for audio or video purchases for my system over a many years so patience and delayed gratification have become a virtue. But it doesn't make any sense to save up for something that's comparable or better than what you can build now. Besides, I need to start saving up for other priorities like a decent amp to drive the subs or a new preamp. 

Do you guys really think that JTR Captivators "are fine products, but they can't compete with a well executed diy effort."?

The JTR cap will not be able to match two UXL-18's in a large low tuned enclosure, if you drive them with a good amp. If it were me,I would pick up two UXL-18's and use a Behringer iNuke6000dsp through Sweetwater for under $360. That would give you more performance compared to the JTR, and cost considerably less!
Martycool007 is offline  
post #26 of 107 Old 04-17-2014, 06:58 AM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Should i use Acoustistuff from parts express or what? I have owens corning 703 panels leftover from making bass traps also...

Blazar!
blazar is online now  
post #27 of 107 Old 04-17-2014, 07:25 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Besides the acoustistuff question, would baltic birch be a reasonable way to go?

Blazar!
blazar is online now  
post #28 of 107 Old 04-17-2014, 07:29 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266
OC 703 and Baltic birch is alright to use.
Mrkazador is online now  
post #29 of 107 Old 04-18-2014, 02:35 PM - Thread Starter
AVS Special Member
 
blazar's Avatar
 
Join Date: Oct 2004
Location: USA
Posts: 2,307
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 72 Post(s)
Liked: 266
Ok got some big sheets of "b2" birch ply which is very flat. There is very little knotting inside of it. Got 6 big 3/4x4x8 pieces for $50 a piece. 1.5 inch wood screws.

How much smaller should a pilot hole be compared to a wood screw? Also, Same depth as the actual screw?

Is it best to glue and clamp first, then do pilot holes, and then screws?

Blazar!
blazar is online now  
post #30 of 107 Old 04-18-2014, 02:39 PM
AVS Special Member
 
Mrkazador's Avatar
 
Join Date: Jun 2005
Posts: 3,882
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 266

The screws are only there to hold the wood together while the glue dries. If you got enough clamps then you can use clamps only so you don't have to predrill holes and fill them after. To make it a bit easier with the clamping, you can screw the corners in so its all squared up then clamp the middle.

Mrkazador is online now  
Reply DIY Speakers and Subs



Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off