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The Berstuck Box: 2xUM18-22 in 25 Cubic Feet at 16Hz

18K views 237 replies 28 participants last post by  berstuck 
#1 · (Edited)
So @berstuck was looking for a build for his theater with a budget of $2000. I put this together, which should absolutely pound, consisting of two of these enclosures and two iNuke 6000's. The enclosure is designed to take 2x UM18-22 and is tuned to 16hz. Box volume excluding port and speakers is about 25 cubic feet. A 14Hz Butterwith highpass filter is required to keep excursion in check. Using two of these enclosures with 4 UM18-22 models out to 130db @ 1m ground plane.

The beauty of this build is that all long edges are 48", so all the cuts except the bracing are just across the sheet of plywood. Doesn't get much simpler. Takes 3 sheets and there should be enough left for a good bit of bracing.

Anyway, WinISD project, sketchup, and cut lists attached here.

The enclosure:


Box size:


Vent info:


Filter info:


SPL with 3000 watts to the enclosure:


Excursion with 3000 watts:


Port velocity with 3000 watts:


Super simple cut list:




 

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#142 ·
Ok the sub is assembled now. I'm a little disappointed because after everything going so well, the top was not square. In the end though, it's my first attempt at a speaker build, or any woodworking at all. And after it's done no one will know the difference. I need to flush trim the front and spackle the back. Either way sometime this week this unit will be playing and as soon as I can borrow a truck again I'll start on number 2.
 

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#145 ·
It's back to work all week so I have to work on finishing it at night. Probably sand and flush trim tomorrow night. Along with spackle the back. Then take a couple night's to paint. So probably Thursday. I need to borrow my dad's furniture dolly. Haul it in the driveway to measure and them it'll go inside. Quick question for you on the minidsp. I set the highpass as you instructed. Should I set a lowpass as well or let the avr handle it?
 
#148 ·
I got all my flush trimming done. That bit is pure magic. Did a fair bit of sanding as well. 2 of the ports stuck out around an 1/8th of an inch more than the front baffle. Sanded them down flush. I need to buy some solder and a smaller putty knife than what I have now from Lowe's tomorrow. Came inside after sanding and my hair is now the exact color of mdf. That was a lot of dust.
 
#151 ·
OK first coat of black paint on. Once it dries I'll flip it on the side and finish the bottom. After that it'll be time for Duratex. Hopeful I'll have a sub tonight. It's raining outside right now though, so I might not get to do ground plane measurements tonight.
 

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#158 ·
Ok, one sub is completely done! Got my Duratex in, while I was at work yesterday. Put in some more bracing, swapped out the grey weatherstipping for black. Painted the cab black Duratex. Swapped out the brass wood screws for black. Looks pretty professional for my first sub, I was quite proud. My preliminary measurements the other day showed me response down to 12hz! Not bad at all. It drops like a rock after though. Considering I didn't want to spend the money chasing 5hz I'm very satisfied. I get terrible response in my room from any single location on the front wall, so for now I am using double bass on the Onkyo to even things out. I am hopeful that changes with the second sub being inserted. It's night so my pictures are relatively poor, plus it's a cell phone camera.



 

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#164 ·
I have to move it by myself. Getting it in the house was a pain in the ass, getting it back out would be worse. I'm going to do a ground plane measurement on the second box before I bring it in the house. We leave on vacation in a couple days, and when I get back I should have 2 or 3 days with my wife around to watch the kids where I can get some work done. I don't imagine the second sub will take more than 2 or 3 days total to complete. Once I have ground plane measures I'll post them up. I'll start posting my rew sweeps of both subs once it's in the house. I'll probably need some advice anyways to smooth everything out. As far as impact yeah it's nuts. My 6 year old son told me today that it makes everything sound real. He thinks it's cool that the couch shakes like crazy when stuff blows up on screen.
 
#160 ·
with the sub right next to the mains like that, getting them in phase at the crossover frequency is very important to impactful midbass. the mains likely need to be moved back in time slightly (delayed) to be time aligned with the subs. with six drivers punching at you, it should hit pretty hard.
 
#166 ·
The midbass on the jbl's is pretty damned awesome. It's my second favorite thing about the speakers, the dynamics being their best feature. Thanks for the tip though, I've lost some of that midbass slam since switching this sub in, but I haven't had much opportunity to get everything dialed in. I played with the sub phase enough to get decent low bass response, and quit at that since the other sub will be going in soon. Right now my low end is just nuts though. I had to turn the volume down when doing sweeps and even start running them at 20hz up, because it was shaking the kitchen cabinets and pissing off my wife =)
 
#172 ·
I have an Onkyo with xt32, it doesn't have the multi sub eq stuff, but I can figure it out with minidsp.

"Will Audyssey correct this?"


in theory it should, but iirc the optimization routines are not public information, so who knows what the heck it is actually doing.
Dunno if poor integration with mains is causing my current lack of slam anyways. The sub is currently in the less ideal position. Where the psa is at is a better spot for most seats. But I chose to use the other spot first because it makes it easier to wire in the second sub later, plus I didn't have to move the psa sub out first. Realistically I think that slam that I'm missing is just boosted response in one corner. I've never measured though. Either way in my wife's chair now it sounds better than ever. And in every seat the really low bass stuff is the best I've ever heard.
 
#174 ·
Honestly, audyssey likely will botch it up even worse. You must do the "sub distance tweak" afterwards to get the integration right.

One way I like to do it is to flip polarity on the sub and mess with distance until I see the maximum suckout at the crossover frequency. At this point your subs and mains are perfectly out of phase. Flip polarity back and you are superbly integrated at this point...
 
#176 ·
Sorry for the long delay in posting. We had a nice vacation taking the kids to disneyland. Didn't get the time I wanted to while on vacation to work on the sub though as too much stuff to do. Today was my son's seventh birthday and while he was playing with his cousins I snuck into the garage and cut the panels for the second sub. I'll get started gluing it up later tonight or tomorrow and hope to have this one finished on Sunday. I'll get this one out to do ground plane though once finished.

I have some impressions of the first sub though. I moved it back to though other side where the psa sub was located. It fixed all my problems I had with response in my seat. My wife's seat doesn't sound as good now though. It will be nice to get the other in and even response out. This thing is ridiculously capable. I can't really play it to what's it capable of because of vibrations in the house. The biggest culprit right now are the 6 hollow core doors in the hallway. I've tried weatherstripping but it's not a great solution, I may have to replace all of them with solid doors. Outside of that I've started rattle proofing picture frames and mirrors.

I watched Edge of Tomorrow before reading the "warning thread", that sweep at about 5db over reference is obscenely loud. The sub didn't break a sweat though. No funny sounds, no chuffing, no bottoming out. Just a ****load of bass. Pretty damn satisfied so far. I've had to change some settings in the avr because of it's massive sub 20hz output. Like dynamic eq just pisses my wife off, because every volume level shakes the house. So that's been turned off now. To be honest it's no longer needed anyways. \

I'll post some updates and pictures as this second sub goes together. It's already going much smoother than the first, I only have 2 panels out of square by maybe a 1/16th or less. The last sub had most panels out of square by that much or more. Going to put it together the way Notnyt recommended as well so it should be a smoother process.
 
#178 ·
Already had enough power with the avr, but adding a pair of crown dsi 1000 from chopshop's sale. Why the hell not, my dad bought my psa sub, and I'm giving him my old veritas speakers. After this project I may have to build a pair of bedroom subs, and possibly a nearfield/end table sub. This is definitely never ending.



This is all I got tonight. The brads at the bottom of one panel weren't holding well enough, so I just left some clamps on the bottom. I'll get the side on tomorrow along with the vent braces. I'll start the front baffle tomorrow too. This time I think I'll route the speaker cutouts before gluing it up. I wasn't pleased with how the front baffle turned out last time. It glued up with some gaps in the middle.
 

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#180 ·
Great work, nice job!

You will be loving life when you get the second one done and in place. :cool:

Those UM18s are bad ass looking too!

Congrats!
 
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