Dual 18cf ported UM-18 Build Thread - Page 3 - AVS Forum | Home Theater Discussions And Reviews
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post #61 of 137 Old 12-18-2016, 12:30 PM - Thread Starter
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Thanks, notnyt. The mattress toppers are your usual cheapo, yellow, open-celled foam with an eggcrate pattern/texture. My 1PR is 153Hz. I would've preferred higher, but I struggled for hours with cab/port size just to get it up to 153Hz.

I have that Boxnotes program, which IIRC calculates resonances. I'll see what it says. I will be using a miniDSP for EQ duties for the subs and I will be running REW. I bought the USB umik to go along with it. Never used REW before. The last time I had a real HT was a very long time ago, back before AVRs came with measurement/tuning mics and auto-programming/tuning. Spent many hours with my Ratshack analog SPL meter tuning things ye olde fashioned way. /bang head against wall
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post #62 of 137 Old 12-18-2016, 12:38 PM
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Originally Posted by michaelddd View Post
Thanks, notnyt. The mattress toppers are your usual cheapo, yellow, open-celled foam with an eggcrate pattern/texture. My 1PR is 153Hz. I would've preferred higher, but I struggled for hours with cab/port size just to get it up to 153Hz.

I have that Boxnotes program, which IIRC calculates resonances. I'll see what it says. I will be using a miniDSP for EQ duties for the subs and I will be running REW. I bought the USB umik to go along with it. Never used REW before. The last time I had a real HT was a very long time ago, back before AVRs came with measurement/tuning mics and auto-programming/tuning. Spent many hours with my Ratshack analog SPL meter tuning things ye olde fashioned way. /bang head against wall
I wouldn't worry about a port resonance at 153hz, the one I have there at 108hz is inaudible. 153hz is totally good. I went with a larger port and lower resonance to keep compression/velocity down. Everything is a tradeoff, but I was happy with this one.

I don 't think you'll have any enclosure resonances below 200hz...
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post #63 of 137 Old 12-18-2016, 12:52 PM
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Also, re your bracing, I braced an enclosure like that, but when moving it flexed and popped one of the braces off the side which made an awful noise. I switched to first affixing blocks to the side with brad nails and glue, then attaching the bracing to both the side and the blocks. It made it a good bit more secure, and I haven't had any issues like that since. It also made it a bit easier to position the bracing and keep it in place when working.

http://i.imgur.com/99gtHLC.jpg

http://i.imgur.com/2piBLJo.jpg
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post #64 of 137 Old 12-18-2016, 01:49 PM - Thread Starter
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Thanks for the tips on the bracing and the pics. Those are some nice-looking cabs you built. But, I can only imagine the fun you had moving them. It's fun enough for me just to flip them over and slide them around the assembly table.

For bracing, I'm using .75 x 1.50" strips in hopes of having that much more surface area where the end of the brace meets the cab panel. I'm also using 23-gauge pins toenailed into the brace ends/cab panels in hopes of preventing brace ends coming loose and giving the PL that much more purchase. Additionally, I'm doing the "PL finger filet thing" with all the brace ends and glopping it on there. PL is cheap, my time is not. So...there's a little mountain of dried PL around the end of each brace. Would be very difficult to get blocks in there at this point.

I've never done bracing like this before and I'll be pretty ticked if one comes loose....I'm doing everything I can to prevent that. Worst-case scenario: I pull the driver and screw/nail/glue/remove whatever winds up rattling. Pretty easy to do with a 16 5/8" driver cutout. But let's hope it doesn't come to that.

Good to know that 200Hz or so is my resonance ceiling...I can certainly live with that.
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post #65 of 137 Old 12-18-2016, 07:22 PM - Thread Starter
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Part II of BraceFest 2016 is complete. That would mean the X and Y axis' of all four cabs have now been braced.

In an ideal world, every brace would be attached to multiple braces. When using stick bracing, it's almost impossible to accomplish that unless you somehow assembled the bracing outside the cab first and glued it in as a unit...or built the cab around the bracing. I'm attaching brace-to-brace when able. By the time bracing is done, every brace will be attached to at least one other brace as well as two panels of the cab.

Pics of all four cabs and where bracing stands as of tonight.






Lots of shorter bracing for the Z axis (back panel to front baffle).




And finally, from the "It's not DIY until you bleed on it" department...I'd like to give a special shout-out to this Irwin clamp.



It was in place doing it's thing and I had to get my head in the cab to nail from the back of the braces...and you can guess what happened. That cut is only about 1.5" long and didn't hurt too bad but it bled like I got shot. Scalp wounds are always dramatic.



Save the comments about my thinning hair...I'm quite aware of the lack of vegetation up there. I can hear that clamp laughing from here...

More tomorrow. Thanks for looking.
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post #66 of 137 Old 12-18-2016, 07:46 PM
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Boxes and bracing looks great, didn't realize they were that thick from the previous pics.

As for the brace... yeah they all seem to know that trick. I must have done that half a dozen times.. think I would have learned by now. That looks far worse than any hits I've taken. Though, the front panel from the enclosure I pasted a pic of, when standing up on a bench, rolled off and I tried to save it with my foot. I saved it, but I think it also fractured my foot. Not one of my brightest moments

Ah this hobby is fun.
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post #67 of 137 Old 12-19-2016, 09:38 AM
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Lots of progress, Michael, great work. And thanks for the detail on your assembly table, I love the T-track and the flexibility that would give. Are you on the Garage Journal board by any chance? That table would go over very well with that crowd. Some fun similar projects and great ideas there.
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post #68 of 137 Old 12-19-2016, 02:02 PM - Thread Starter
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Thanks for the kind words, OJ Bartley. I'm not a member of that forum but may check it out.

I'm off to the garage to finish the bracing. Will be glad to get the bracing done and then let the PL cure for a few days before stapling in the mattress topper. Don't want to be bumping/leaning on the braces just yet.
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post #69 of 137 Old 12-19-2016, 09:37 PM - Thread Starter
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Well, I won't say I'm done with bracing, but I'm darn close. Most probably I'll say this is "good enough" and go with it. But I reserve the right to contradict myself at a later time.

Quick pics of all four cabs. All cabs are now braced on the X, Y & Z axis'.






I learned some lessons over the past few nights.

First: I should've gone with a simple slot port at the bottom of the cab. This would have enabled me to use window bracing instead of this fiddly stick bracing. My cab panels are 100% square b/c I used right-angle clamps when assembling. My stick bracing is not square as it was done by eye/hand. So, as you try and add braces that cross others at 90-degrees, one brace being 1/2" higher than the other throws things off, necessitating trimming braces one at a time as you go. Frustrating and time-consuming.

Second: Your nifty brad nailer might not fit in between all those braces. I'm glad I also own a pin-nailer that's about 2/3rds the size of the brad nailer. Still, toenailing (trying to) the braces was a hit or miss affair, with lots of brads ricocheting off the brace and into my hand or face (I always wear safety goggles when dealing with any power tool). It was very time-consuming but every end of every brace and where braces cross has at least two brad nails in it in addition to the PL. Cheap insurance.

Third: PL takes forever to dry once the ambient temp drops below 60F. I have a small space heater in my garage that keeps the temp around 55F but it's not what PL likes.

I'm pretty confident that the braces that run from front baffle to rear panel are short enough to allow for a dollop of PL and not interfere with the fit of the baffle. But I'll double check each cab and brace with a metal straightedge before buttoning up the cab. This goes back to "First" above. Window bracing on a square cab would eliminate this issue.

So the bracing will have a few days to cure as I've got a lot going on this week and wont' have much time to work on the cabs. That's a good thing...the PL curing, not me having no free time.

Next steps: Drill recessed mounting hole for Speakon on real panel. Check length of front-to-back braces. Button up cabs!
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post #70 of 137 Old 12-20-2016, 07:40 PM - Thread Starter
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Managed to get a small but sometimes overlooked detail taken care of tonight; drilling for the terminal cup/Speakon.

Tools of the trade: 2" Forstner bit for recessing (not necessary, purely cosmetic), 15/16" spade bit for the body of the Speakon (this is the size you need), 1/16" drill bit for drilling pilot holes for mounting screws. True: You could drill the pilot holes later...but do you want to? Easy to take care of now and makes mounting that Speakon a very simple affair later on.



Counter-bored holes drilled.



Now with pilot holes for mounting screws! *ooooooh! ahhhhh!*



Now, isn't that pretty? If these were PA subs that got moved every day I'd have recessed it further so the entire Speakon body was flush or recessed into the back panel. Keeps from snapping connectors off or damaging them while moving through doorways or loading into a truck. These will be (hopefully) placed once and never moved again. Recessed them purely for my knowledge that I did so.



Speakon mounts done on all four cabs. And that's it for tonight. Having to account for brace and port placement required a little thinking, so this simple task took more than an hour for all four cabs. I am not rushing Jack Schitt at this point! Got too much sweat equity in these cabs at this point.

Additionally, though it warmed up to the low 60's in my garage today, it was low 50's last night. The PL for the braces isn't as cured as I would prefer to see before moving cabs around. The next step is lining them with mattress topper....which I'm pretty sure I'm going to go ahead with and do. There's much debate about lining ported cabs. I've always done it and never thought about it. Sometimes you can research and research and wind up with "Paralysis by analysis." If I think the cabs totally suck (doubtful) I can always remove the driver and rip the foam out.

Thanks for looking.
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post #71 of 137 Old 12-20-2016, 08:26 PM
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Those cabs could survive a trip over Niagara Falls.

They have to be incredibly heavy already without the driver installed. Once that driver is in, they aint moving without a lot of help.
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post #72 of 137 Old 12-20-2016, 09:38 PM - Thread Starter
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Those cabs could survive a trip over Niagara Falls.

They have to be incredibly heavy already without the driver installed. Once that driver is in, they aint moving without a lot of help.
You have no idea how right you are on the "incredibly heavy" part. I've been moving these suckers from working table height to "move it around on the floor" height and back for a couple of weeks.

I suck at math, but there are many formulas out there for calculating the weight of MDF. Generally, it's accepted that although the weight varies depending upon manufacturer, a 4'x8' sheet of 3/4" MDF weighs an average of 95 pounds. Sometimes 90, sometimes 100+, but generally 95 pounds.

I estimate that assembled, with bracing and without the driver, 3 of 4 cabs weigh 175 pounds each. The fourth cab I'll rate at 200 pounds due to the 1/2" thicker front baffle (for driver recess). Believe me, it feels like a lot more when you're trying to lift them from the floor onto a table that is 38" high. I'll add that those weight estimates are conservative b/c each cab has a 4x12x40" port made of 3/4" MDF inside. Each port must weigh 20 pounds or so. So take my weight estimates with a conservative grain of salt. Look, I'm 6'1"/220 pounds and no weakling and these things are freaking heavy for me! Interpret that how you may.

The UM-18's weigh 40 pounds each, IIRC. I won't be installing them before the cabs are hauled upstairs. The cones are actually pretty sturdy, so I'm not worried about random fingers going through the cones. I'm worried that 40 pounds is 40 pounds, and when the cabs weigh around 200 pounds, every pound matters. Especially when your "moving crew" is a bunch of 50-something guys who have all seen better days. LOL! :d

As we all know: "It's not that it's 200 pounds, it's that it's so small and hard to get a grip on!!!" Sound familiar? We're all in the same boat, brothers! Ever pushed/lifted a car that was stuck in the snow? You probably exerted around 200 pounds of force...but that's "different" than a dead-lift and carry of the same weight but essentially concentrated into a space about an arm's-width apart.
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post #73 of 137 Old 12-21-2016, 06:10 AM
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You have no idea how right you are on the "incredibly heavy" part. I've been moving these suckers from working table height to "move it around on the floor" height and back for a couple of weeks.

I suck at math, but there are many formulas out there for calculating the weight of MDF. Generally, it's accepted that although the weight varies depending upon manufacturer, a 4'x8' sheet of 3/4" MDF weighs an average of 95 pounds. Sometimes 90, sometimes 100+, but generally 95 pounds.

I estimate that assembled, with bracing and without the driver, 3 of 4 cabs weigh 175 pounds each. The fourth cab I'll rate at 200 pounds due to the 1/2" thicker front baffle (for driver recess). Believe me, it feels like a lot more when you're trying to lift them from the floor onto a table that is 38" high. I'll add that those weight estimates are conservative b/c each cab has a 4x12x40" port made of 3/4" MDF inside. Each port must weigh 20 pounds or so. So take my weight estimates with a conservative grain of salt. Look, I'm 6'1"/220 pounds and no weakling and these things are freaking heavy for me! Interpret that how you may.

The UM-18's weigh 40 pounds each, IIRC. I won't be installing them before the cabs are hauled upstairs. The cones are actually pretty sturdy, so I'm not worried about random fingers going through the cones. I'm worried that 40 pounds is 40 pounds, and when the cabs weigh around 200 pounds, every pound matters. Especially when your "moving crew" is a bunch of 50-something guys who have all seen better days. LOL! :d

As we all know: "It's not that it's 200 pounds, it's that it's so small and hard to get a grip on!!!" Sound familiar? We're all in the same boat, brothers! Ever pushed/lifted a car that was stuck in the snow? You probably exerted around 200 pounds of force...but that's "different" than a dead-lift and carry of the same weight but essentially concentrated into a space about an arm's-width apart.
Lol, the new boxes I'm making are close to the same size, so I was wondering this exact same thing! I'm torn b/w assembling them in the garage then lugging them downstairs, or cutting in the garage and assembling downstairs. I was also on the fence about assembling on the table and getting them down to the floor, vs. assembling on the floor. Your post didn't clear any of it up for me (b/c your shop is so beautiful you'd be crazy to assemble anywhere else), but helped me feel better about my manhood after being concerned!


What it *did* do was help me clear up the driver hole dimensions tho, thanks!!


(Cabinets look great BTW!!)
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post #74 of 137 Old 12-21-2016, 06:40 AM
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As we all know: "It's not that it's 200 pounds, it's that it's so small and hard to get a grip on!!!" Sound familiar? We're all in the same boat, brothers! Ever pushed/lifted a car that was stuck in the snow? You probably exerted around 200 pounds of force...but that's "different" than a dead-lift and carry of the same weight but essentially concentrated into a space about an arm's-width apart.
I hear you loud and clear! Moving my speakers just sucks, and now I am changing waveguides/compression drivers I have to re-do the recess for the waveguide. Somehow I have to get them back outside without damaging the finish (or router in the house while the wife is gone and vacuum/dust like crazy).

Perhaps I can talk @DougUSMC to come out to assist a fellow Department of the Navy brother.

Still, these are fantastic subs you are building!!!!!!!!!!

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post #75 of 137 Old 12-21-2016, 07:10 AM
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I hear you loud and clear! Moving my speakers just sucks, and now I am changing waveguides/compression drivers I have to re-do the recess for the waveguide. Somehow I have to get them back outside without damaging the finish (or router in the house while the wife is gone and vacuum/dust like crazy).

Perhaps I can talk @DougUSMC to come out to assist a fellow Department of the Navy brother.

Still, these are fantastic subs you are building!!!!!!!!!!

Sure, let me know. I'm on the FAR west side of Ellicott City (5. mi from Glen Elg), so you're probably not that far from me. I'd guess ~30 mi down 70...
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post #76 of 137 Old 12-21-2016, 07:36 AM
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It's time to cut the driver mounting hole in your carefully-glued-up double baffle...so much work and material...you can't screw this up...so you...

Check the manuf's mounting info...four times:



Then you triple-check the instructions for your circle cutting jig b/c you're using a larger bit than specified in the instructions:



As shown in the screen shot above, PE specifies the baffle cutout for the UM-18 at 16.75. I can tell you that is way too large. There was a lot of "play" b/t the driver and a 16.75" cutout in my first test cut. I reduced the cutout by 1/16" in the second test cut. Still a lot of play. I reduced it by another 1/16" for a final cut out of 16-5/8", which is a much better fit. A smaller cutout than that MIGHT work, but I didn't test it b/c I ran out of scrap large enough to use for a 3rd test cut. Does that smaller cutout matter? I think it does. It leaves that much more material in the "mounting circle" for the t-nuts to bite into. Mass is always good when it comes to speaker cabs....moving them, non withstanding!
Hey Mike, this post (and the couple after, where you verify the interior cutout) helped me a lot as I prep for my first cutout. I was looking @ the Jasper jig specs, and it looks like it only goes to 18 3/16, how did you get that 18.25" hole? Did you go with a 1/2" bit and dial back to the 18 1/4 pin hole?


BTW, I'm planning to use an UM-18 too.
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post #77 of 137 Old 12-21-2016, 07:58 AM
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Hey Mike, this post (and the couple after, where you verify the interior cutout) helped me a lot as I prep for my first cutout. I was looking @ the Jasper jig specs, and it looks like it only goes to 18 3/16, how did you get that 18.25" hole? Did you go with a 1/2" bit and dial back to the 18 1/4 pin hole?


BTW, I'm planning to use an UM-18 too.
For my jasper jig i projected out to where the right size hole should be and drilled one with an 1/8-in drill bit. Not sure what others have done.
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Sure, let me know. I'm on the FAR west side of Ellicott City (5. mi from Glen Elg), so you're probably not that far from me. I'd guess ~30 mi down 70...
That sounds great! The CD's are on backorder so it may be awhile.

To bad @michaelddd lives so far away, would love to hear his setup. Perhaps when I am in his neck of the woods.
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post #79 of 137 Old 12-21-2016, 03:18 PM - Thread Starter
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Sorry for the delayed response: The forums are blocked at work.

To cut out the required 18.25" circle for the driver recess, I used a 1/2" bit and the formula from Jasper.

As per the formula on the Jasper website: Pilot hole value = Cutout diameter - Bit diameter + .25. So in my case that's 18.25 - .50 + .25 = 18.0. So I used the 18" setting on the Jasper jig, which is pretty close to the 18 3/16 limit. FYI: You can always drill additional holes in the 18" line to get larger circles; just be sure to line them up properly. I did that on my older Jasper jig (I have two...old one is cracked but usable) and it works great.

@NWCgrad : If you're ever down in San Antonio, you have a standing invite for a demo, lots of tech talk and the beverages of your choosing! Lots of joint operations and conferences happen here, so you may wind up TDY here one day.

And at this point, I'm also looking forward to hearing my system! I may have to install one driver in a sub and set an 88 Special on top of it in the garage just to hear the combo, finally. I can't wait until the room's complete to do that...that would be silly. LOL!
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post #80 of 137 Old 12-21-2016, 03:34 PM - Thread Starter
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Lol, the new boxes I'm making are close to the same size, so I was wondering this exact same thing! I'm torn b/w assembling them in the garage then lugging them downstairs, or cutting in the garage and assembling downstairs. I was also on the fence about assembling on the table and getting them down to the floor, vs. assembling on the floor. Your post didn't clear any of it up for me (b/c your shop is so beautiful you'd be crazy to assemble anywhere else), but helped me feel better about my manhood after being concerned!


What it *did* do was help me clear up the driver hole dimensions tho, thanks!!


(Cabinets look great BTW!!)

Thank you, @DougUSMC . I actually built that table specifically for this project. Now, b/t when I built it and when I started these cabs I used the table for a lot of other things, but it's original mission was this project. Having worked on a piece of plywood across plastic folding saw horses ON MY 4' x 8' APARTMENT BALCONY for many years, I really do appreciate the shop I have now. And that balcony didn't have an electric outlet either. Had to run an extension cord through the living room. Lots of fun!
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post #81 of 137 Old 12-21-2016, 03:38 PM
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Thank you, @DougUSMC . I actually built that table specifically for this project. Now, b/t when I built it and when I started these cabs I used the table for a lot of other things, but it's original mission was this project. Having worked on a piece of plywood across plastic folding saw horses ON MY 4' x 8' APARTMENT BALCONY for many years, I really do appreciate the shop I have now. And that balcony didn't have an electric outlet either. Had to run an extension cord through the living room. Lots of fun!
Lol, I think of all the crazy ***** we did when we were younger, and I'm sometimes surprised we're all alive!
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post #82 of 137 Old 12-21-2016, 03:45 PM - Thread Starter
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I can tell you that b/c of the small dimensions of the balcony, I had to hang a 4x8 sheet of MDF over the railing in order to cut it up. And I was on the 3rd (top) floor. And one time it slipped and a full sheet of 3/4" MDF fell a good 30 feet into the bushes below. Thankfully as it hit the ground it flipped forward, away from the building and not backwards, into the row of windows for the first-floor apartment.

So, me being the young man with things to accomplish that I was, I threw the extension cord off the balcony down to the ground, took my circular saw down there and cut the salvageable pieces out of the busted sheet right there on the grass. Neighbors were not pleased. I was embarrassed but I had a cab to build! Ain't got no time for embarrassment...or finding another work location!

Ah, the good old days were...not really that good. LOL!
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post #83 of 137 Old 12-21-2016, 07:12 PM - Thread Starter
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Got one cab lined tonight. This mattress topper is particularly thin (befitting what I paid for them...) so I'm not worried about any negative effects from using it. Like I said a few posts up, I've always done my ported cabs this way, so why mess with tradition? Besides, sitting 12-14 feet away from four 18's, I don't think I'm going to miss 1db of cab efficiency, should I even lose any.

So here's the mattress topper. Bought these four back in Jan 2016. Been in the closet since then.



How I fasten the topper in the cab. LOVE my electric stapler. It can be tiring to use though b/c you still have to press downwards while firing, else the staple doesn't penetrate the MDF. I probably have 300 staples just in this cab.



And one cab is done. Used about 80% of one King size mattress topper. It is a Class A PITA cutting the foam to go around the stick bracing. But, do it once and do it right and you don't have to do it again.



Just realized there is an empty square in the lower left-hand corner. I have no idea what happened there. LOL! I don't think it matters if that little patch is unlined...but my OCD will get the better of me, I know.


Blurry shot but you can see the port area is completely clear.


I didn't do the middle bottom of the cab b/c the driver sits very low in the cab. Didn't want foam there. Appreciate any thoughts you may have on the lining.

Last edited by michaelddd; 12-21-2016 at 07:16 PM.
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post #84 of 137 Old 12-21-2016, 07:24 PM
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Just skimmed through the thread, looking good my friend!

That first simulated graph drew me right in, should definitely kick in the lower registers...

Actually, I love tube amps..
I play guitars through them.
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post #85 of 137 Old 12-22-2016, 05:40 AM
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Overall build looks amazing!

Will that thin foam have *any* actual effect at bass frequencies?
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post #86 of 137 Old 12-22-2016, 01:45 PM - Thread Starter
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Quote:
Originally Posted by wreckingball View Post
Just skimmed through the thread, looking good my friend!

That first simulated graph drew me right in, should definitely kick in the lower registers...
Thanks, it's been a lot of work so far but the end is in sight. I certainly hope chasing those last few Hz turns out to be worth it. The last real sub I had was an SVS PB2-Plus in a much smaller room. It went down to 16Hz, but always seemed to struggle with output. I wanted lower and I wanted a lot more of it. This should be just the ticket.

Quote:
Originally Posted by KevinG View Post
Overall build looks amazing!

Will that thin foam have *any* actual effect at bass frequencies?
Not sure, TBH. I've always lined my ported subs with mattress topper and I've been happy with them. Also, to be totally unscientific here; there's something comforting about yelling into a large box and getting almost no echo/slapback. Dead is good when it comes to speaker cabinets. That comment will probably get me tarred and feathered but hey, it's DIY and I am.
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post #87 of 137 Old 12-22-2016, 05:41 PM
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Originally Posted by michaelddd View Post
Also, to be totally unscientific here; there's something comforting about yelling into a large box and getting almost no echo/slapback.
Well, sure...but when you can yell at < 30Hz to do the same test, let us all know.
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post #88 of 137 Old 12-22-2016, 07:54 PM - Thread Starter
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Point taken, KevinG. I'm sticking with what I know; good, bad or otherwise.

As I was looking at the cabs today I realized that I've started lining them, but yet I haven't rounded-over the ports yet. That machining operation generates a ton of dust, as you know. Not exactly what you want for your "finished cabs". MDF dust would stick to the mattress topper like glue...I'd never get it clean.

So, I covered up that first cab as best I could and rounded over the port. Took care of the other 3 cabs as well. I used a 1" roundover bit. Turned out well, IMO. Pics of all four cabs' ports.






I have also finished lining all four cabs. Took roughly 3.5 King size mattress toppers. There was a bit of waste as I cut off probably 6 square feet per roll of topper that was so compressed, it wasn't open cell foam any more...it was like....I don't know. Dried PL? It was obvious to me those parts weren't passing air, so I cut them off and discarded them.

Pics of the three cabs I lined tonight.





I look at it this way: Should I decide to remove the lining due to measurements or what I hear or both, I can easily remove it all. Trying to staple it in there after the fact would be near-impossible.

All that is left for the cabs is attaching the baffles...but not before ensuring all the front-to-back braces are short enough, then truing up the baffle with the rest of the cab, rounding the edges and finishing. Only one cab is getting Duratexed; the other three are getting a slathering of Mouse Ears (flat black) and that's it.

As temps in the garage aren't ideal for PL curing, I am planning on allowing 72 hours for the PL on the baffles to cure before I move the cabs. So basically, I should start attaching baffles tomorrow, then whenever adequate time has elapsed, I'll proceed with the rest of the operations.

This thread, while a large project unto itself is really just a smaller part of my HT build (link in sig). It's all coming together.
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post #89 of 137 Old 12-24-2016, 08:07 PM - Thread Starter
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Merry Christmas and Happy Holidays to you all!

With BraceFest and TopperFest 2016 done and over with, it was time to seal up the cabs. There's always that moment of trepidation where you're about to put the first line of PL down and you say "Wait...I must have forgotten SOMETHING..." and you put the PL down, shut off the compressor and stare into the cabs like some clueless guy on the side of the road with the hood of the car up, staring at the engine compartment like he can will the motor to work fine again.

So yeah, I did that for about 10 minutes...couldn't find anything wrong and consoled myself that "Tomorrow, when I see what I missed I should be able to fix it through an almost 17" diameter driver cutout." Well, it's now tomorrow and I've not found anything I missed. Yet. Ignorance is bliss.

As I have four large cabs to close up, I really wanted to get them all done in one shot. But I didn't have even close to enough clamps. So Harbor Freight was really happy to see me yesterday. I bought another 24, 36-inch clamps. I really only needed the 30" clamps, but the 36" were a dollar apiece more. Better to just buy the bigger ones and have that extra capability going forward. I really didn't want to buy so many clamps that I'll probably not use too often, but I didn't want this baffle glue up to drag on for a week while I did one cab, wait a day, remove clamps, do another cab and on and on.

Here is a pile of forty, 36 and 30-inch clamps.



But before we get to the baffle glue-up, we have to ensure that the front-to-back braces won't interfere with the baffle. They need to be just a hair short so the baffle will sit flush. The PL will easily fill a 1/16" gap. To accomplish this task I used my old fence rail from my tablesaw. Basically, it's a bigass, 1/8" thick piece of angle iron. Who keeps crap like this around? This guy and for reasons just like this.

Set it on top of the cab like this:



And check for distance b/t it and the braces like this:





About a fourth of my front-to-back braces needed minor sanding. OK, that's done. Now to get to glue-up. I've got all those clamps and now I have to make sure I can use them. Laid down some 2x4's to elevate the cabs off the floor so I could get a clamp on the back panel, like so:



Assembly line is ready.


Thus began glue up. I used five tubes of PL to glue the baffles onto these four cabs. I put down a bead about 1/2" x 1/2". Total waste of PL but you HAVE TO do it at this step. That cabs' got to be sealed. All the work I did so far? PFFT! Squeeze that crap on there! BTW, in total, I used 14 tubes of PL on these cabs. PL Premium: Making up for your sloppy-ass woodworking for 10 years and counting!

I was pretty concerned with those braces...wanted to ensure everything worked as I thought it would, and it did. Interior shots of braces against the baffle. Happy to report they all look like this.





Lovely squeeze-out.



Shot of one cab with a roll of paper towels for size comparision.



Bracing through driver cutout.


And all four cabs glued up. You can see the sqeezeout. I'm confident these things are sealed tight.




BTW, STILL ran out of clamps and wound up using this old trick twice.


And then some Christmas magic happened! I went into the garage this morning and the Christmas ELVES had scraped all the PL off for me!!!




Well, OK, it wasn't Christmas Elves...it was the Christmas Chimney Gnomes.

Even though is 70F in the garage, I'm leaving the clamps on there for 48 hours...maybe more. As the PL is already scraped off, once the clamps come off I'll true up the baffle with the cab sides and roundover all the edges. Then it's painting time! Flat black primer on all four, Duratex on just one (the one that will be out in the room vs. behind the screen wall.)

Thanks for looking.
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Last edited by michaelddd; 12-24-2016 at 09:11 PM.
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post #90 of 137 Old 12-25-2016, 09:03 PM
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