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Discussion Starter · #1 ·
I'm building out four sealed subwoofers for dlbeck's The Savoy theater and thought I'd document it here and in his thread.

Drivers: 4 ohm Acoustic Elegance PB18H+


These are the same as the TD18H+ but with dust caps instead of the phase plug. You can read the thread here about the PB18H+ drivers.


Order date: November 15, 2013

Delivery date: January 31, 2014

10 week lead time

Boxes: 3.75 cubic ft sealed boxes 21" wide x 23" high x 19" deep

Materials: 13 ply 3/4" birch veneer with hardwood core from Menards, PL Premium, Green Glue, 18 gauge nails, Bondo, Duratex

Amplifiers: Two Behringer iNuke nu6000 amps, 1000-1200 watts RMS per channel with 2000 watts peak at 4 ohms


Here they are modeled all together in WinISD. I like to model for desired response (red) and maximum output (green) with the amps actually being used to see what can be expected. The red is with 1000 watts per sub and the green is with 8000 watts per sub. I used a Linkwitz Transform with an fp of around 32 Hz to match room gain. That will probably change with actual measurements. I'll also be using a special sealed subwoofer limiter that only starts limiting from 50 Hz and down. It allows for maximum headroom above 50 Hz while making sure you don't surpass excursion down low. It will keep the sub linear up to maximum excursion while allowing for massive midbass headroom. Instead of limiting lower bass levels, it allows higher midbass levels.







Most of the time these will hardly be using any power since they are so efficient:




Two weeks ago I spend Sunday afternoon at rkinmoval's shop along with dlbeck and his son. I made sure I brought along plenty of tools:



Rkinmoval has a nice shop with a table saw and outfeed tables so we didn't even use the track saw.

Cutting the plywood to length:



Prototype...making sure the cuts were accurate:



Cutting the holes for the driver:



Driver fits!



Gluing and nailing:



The front and back are double layers with Green Glue and PL Premium between the plywood:



Couple pictures of an SI 18" driver (right) and Acoustic Elegance PB18H+ 18" driver (left).




We only built out two of the boxes. This past weekend I finished the other two. Here is the cut plywood all stacked and ready to put together for two boxes:



I first attach the baffles to the sides. These are all cut exactly the same height.. If you use a circular saw to cut your boards you can use a flush cut router bit to make all baffles/sides the height of the shortest board. In this picture the box is rotated. Those are the sides and not the top/bottom.



I cut the top/bottom about 1/8" oversized which leaves about 1/16" all around. After they are attached, I trim the with a flush cut router bit. This ensures your edges match exactly and allows your assembly to be a little out of square. You can see the slight overlap in the red circle. I use a single clamp and PL Premium glue to assemble everything. While clamped, I use 18 gauge nails to hold it together.



After I flush cut the top/bottom, I then attach the second front/back baffle. This is also over sized and then flush cut. For these you don't even need to wipe off any excess glue. You can just let it dry and the flush cut bit will clean up excess glue. Now you have a box that has all the sides matching exactly. I then use a roundover bit on all corners.


Here are all boxes ready for Bondo.
 

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Very cool! I've got 3 of the PBH18s and need to finish up my boxes. I'm going 6 cubic feet tuned to 30hz as an option presented from antripodean. They're beefy drivers and probably weigh the same as the SIs.
 

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Discussion Starter · #3 ·

Quote:
Originally Posted by gpmbc  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4/0_100#post_24469486


They're beefy drivers and probably weigh the same as the SIs.
According to data-bass.com, the SI's weight 30 lbs each and the TD18H+'s weigh 45 lbs each. That is 50% more!
 

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Confused. SO 3.75liters is 3.75cuft per cabinet correct?


Your simulations were showing 15cuft. I assume you were looking at a box size of that size for four of the 18's. BUT not sure.
 

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Discussion Starter · #8 ·

Quote:
Originally Posted by chrapladm  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4/0_100#post_24470898


Confused. SO 3.75liters is 3.75cuft per cabinet correct?


Your simulations were showing 15cuft. I assume you were looking at a box size of that size for four of the 18's. BUT not sure.

Oops. Yes, I meant 3.75 cubic ft per cabinet.
 

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fantastic!


the only potential issue that I see is related to cone excursion on the low end. 500 watts seems fine, but with 2000 peak it looks like the driver could get into trouble. I forget how that driver performs out past xmax (i.e. if it is a soft bottom/no bottom type design or a hard bottomer).
 

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The TD 18 is a soft bottom. Surround, spider and BL limited. Hard bottom is past 40mm I was told. It will never get there. 30mm peak to peak is no problem.
 

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Discussion Starter · #11 ·

Quote:
Originally Posted by LTD02  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4/0_100#post_24470963


fantastic!


the only potential issue that I see is related to cone excursion on the low end. 500 watts seems fine, but with 2000 peak it looks like the driver could get into trouble. I forget how that driver performs out past xmax (i.e. if it is a soft bottom/no bottom type design or a hard bottomer).

The initial plan was to use these from 40 Hz up to 200Hz or even 250 Hz in order to help alleviate Speaker Boundary Interference Response (SBIR) or the Allision Effect. These would be MBM's and could be placed closer to the wall with different driver orientation. In this case, there obviously isn't a problem.


David (dlbeck) recently went with the addition of a screenwall which helps with SBIR and these will serve as speaker stands for the mains with another in the rear of the room for the surrounds. If the high pass is lowered to 150 Hz, then the excursion at lower frequencies shouldn't cause any issues with increased THD in the higher frequencies.


If these are run full range, then a limiter will be used. The driver is a soft bottom design per data-bass.com . I see Ricci answered this while I was typing.

Quote:
Originally Posted by desertdome in first post 

I'll also be using a special sealed subwoofer limiter that only starts limiting from 50 Hz and down. It allows for maximum headroom above 50 Hz while making sure you don't surpass excursion down low. It will keep the sub linear up to maximum excursion while allowing for massive midbass headroom. Instead of limiting lower bass levels, it allows higher midbass levels.


The following are options for their frequency range:

40Hz-200Hz with below 40 Hz routed to dual JTR Speakers Captivator S2's

0-150Hz with below 40-80 Hz copied to dual S2's

0-150Hz with below 40-80 Hz copied to dual S2's and the LFE routed back to the PB18H+'s

0-150Hz with no bass routing

0-150Hz with LFE routed back to the PB18H+'s


So, for sources for bass/midbass:

JTR Noesis 212HT-LP: 70Hz and up

AE PB18H+: up to 250Hz

JTR S2's: up to 100 Hz


The final implementation will depend on measurements and listening.
 

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This will be interesting to follow Desertdome.



For info: The PB18H+ you show in the picture has a new surround with 3 corrugations (previous surround 2). From a message I got from John at AE early december 2013: "The newer surrounds do have more overall travel, about 25mm one way vs 18-19mm one way so I figured it was best to wait "


( I am currently building boxes for 4 pcs PB18H+ myself. In the picture the non stained baffles are just "dry mounted" with some alumnium tape to check the fit vs the in wall cabinets.)

 

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Quote:
Originally Posted by desertdome  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4#post_24472211


The following are options for their frequency range:

40Hz-200Hz with below 40 Hz routed to dual JTR Speakers Captivator S2's

0-150Hz with below 40-80 Hz copied to dual S2's

0-150Hz with below 40-80 Hz copied to dual S2's and the LFE routed back to the PB18H+'s

0-150Hz with no bass routing

0-150Hz with LFE routed back to the PB18H+'s


So, for sources for bass/midbass:

JTR Noesis 212HT-LP: 70Hz and up

AE PB18H+: up to 250Hz

JTR S2's: up to 100 Hz

The final implementation will depend on measurements and listening.

+1

Quote:
Originally Posted by Scott Simonian  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4#post_24473041


Awesome.



I don't think you'll have any damage issues to worry about running these full range.


+1


If possible, I'd examine and pursue operating all the 18" drivers all the way down ... no high pass.

Then assure full, global, in phase summation and smooth FR with both time alignment and low pass filtering per group.


In essence, utilize all displacement possible, yet trim back upper range coverage as needed.

Which may be what you meant by; "final implementation will depend on measurements and listening"

 

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Discussion Starter · #15 ·
I free air tested the first two drivers. These make no noise until the excursion gets very high.








Then I made some connection wires up for the Speakons:




I drilled 15/16" holes on the left side corner for the Speakons and mounted them with #4 3/4" black screws. This way the subs can be pushed all the way up against the wall if necessary.




A finished pair!




Here is a single one with my LS-6 line source speaker for comparison:




Overlaid native response of each sub:




Oops! Looks like I need to reverse the wiring on a Speakon.


 
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Quote:
Originally Posted by FOH  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4#post_24474960



If possible, I'd examine and pursue operating all the 18" drivers all the way down ... no high pass.

Then assure full, global, in phase summation and smooth FR with both time alignment and low pass filtering per group.


In essence, utilize all displacement possible, yet trim back upper range coverage as needed.

Which may be what you meant by; "final implementation will depend on measurements and listening"


This is essentially what I am doing in my room.


I just need to work on the "phase summation and smooth FR" part.
 

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Discussion Starter · #19 ·

Quote:
Originally Posted by Face2  /t/1522095/acoustic-elegance-pb18h-sealed-build-x-4/0_100#post_24524306


How much stuffing do you have in the enclosure?
I am using Bonded Logic Ultratouch insulation that is 5.5" thick. I made the braces 5" apart to make it easy to install. I have the back section filled completely, the middle section only filled on the sides/top, and the front section only filled in the corners. I used 3M Super 77 adhesive to hold it to the walls in the middle/front sections. I estimate the weight to be about 3.7-4 lbs.



Quote:
Originally Posted by rkinmoval 

Very nice work DD!
Thanks!
 
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