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My 15/6 cab I'm building... (pics)

#22
lo-freq said:
Curious about Duratex.
Can a person make it more durable by using 2 or 3 coats?
Is it pretty easy to touch-up if the finish is damaged?

Thanks in advance!
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More coats will make it more durable, but it will never be as durable as a 2-part system of any kind no matter how many coats you apply. Yes it's very easy to touch up, which is one of it's advantages
 
#23
Not the pretties layout or solder job, but should work regardless (never claimed to be an expert, after all :D )

100_3538.jpg


The midrange wires are already in the box so they are not present in this photo. Should have the last side on tomorrow and will be putting some sound to the ground soon enough!
 
#24
+1 for Duratex. It was easy to apply, and I did use a couple coats. If and when I get annoyed with it getting scuffed up, I can easily re-touch it. Something to ask is how much abuse the speaker will actually get. I only use mine for local gigging in relatively tame environments, so it really doesn't get knocked around a lot. If it did, I would simply maintain it.
 
#25
fdeck said:
+1 for Duratex. It was easy to apply, and I did use a couple coats. If and when I get annoyed with it getting scuffed up, I can easily re-touch it. Something to ask is how much abuse the speaker will actually get. I only use mine for local gigging in relatively tame environments, so it really doesn't get knocked around a lot. If it did, I would simply maintain it.
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+1 -- that's what I'm thinking about for my situation.

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I know in some bands some bandmates can be really rough and careless with other peoples equipment (or even their own), for those the bedliner type stuff is probably a better option if they have the funds for it.

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DSFDF, yada yada, etc...
 
#26
redstaraudio said:
Hey great job! You put a lot of three-dimensional thought into that design and it shows - impressive work without the benefit of a cnc machine!

That looks like import (chinese) birch you used... the delamination is a real problem. In case you're not familiar with this, if you shoot the box with rhino (or any other) bedliner product you will need to seriously prime it with an high-quality oil or polyester primer, 2-3 coats is better. The moisture in the wood will vent and blister the coating and you'll get a lot of pinholes, craters, etc when it snap cures. Again, you may already know this, but if you didn't, please don't skip this or you'll be crying later.

We have a lot of experience with Duratex and if you have access to someone that can spray the rhino liner, and you are ok with cost difference, we'd recommend you go that route. Duratex is a fine product but there is really no comparing the two systems.

Again - great job!
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Just curious, is there any specific brand or type of primer to use? Outside of primer you do on a car/fiberglass box/etc and latex primer for a house, I'm not sure what would be the right stuff to use (when you say oil, I think of the oil you use on a fretboard type of oil?)
 
#27
If you're just doing one or two cabs, you should consider 2-3 coats of Kilz. Make sure it is well shaken when you buy it and you should use within 2 days if possible, otherwise take it back and have them shake it again.

When we used our previous coating system we had the cabs sprayed with a high-build polyester primer. If you use an automotive type primer it has to be very good quality stuff, but the results are great.

FYI - if you use Duratex you do NOT want to prime, the Duratex is self-priming. You only need to prime if you're going to shoot a high-pressure, high-temperature system like Rhino or LineX. Low-pressure systems (i.e. the stuff shot from a texture or bin gun) does not need priming either.
 
#29
yeah just make sure it's not the water-based kind, it needs to be oil-based. 2-3 coats are adequate. Just so you know, it's almost impossible to completely stop pinholes or blisters with this method, but you'll come really close. Do a knock-down sanding on the final coat with about 100 grit.

If your baffle is recessed, like almost all of them are in the world of cabs, consider painting the baffle and inner edges near the front of the cab with flat black spray paint. The reason is that the high-pressure guns dump a lot of product, around 15lbs per minute if I remember correctly. When they try to spray into the interior edges on the front, you get buildup and roll-over (looks like a frozen waterfall) on the front edges. Tell the operator not to worry about trying to coat the interior edges and baffle and you'll have less cosmetic issues. You'll still have some rollover but you can usually trim it off with a razor blade and it's barely noticable.

One more thing... the coating won't hide blemishes or cracks as much as you think it would. Think about doing a quick skim of Bondo on the joints, edges, etc before priming and coating. It will make big difference in finished quality.

If you do this you'll have the same finish quality as roughly 75% of the cab makers that advertise bedliner finishes. It will outlast anything else on the market, and will look as good except for the proprietary systems that don't use bedliner mixes.
 
#30
Awesome to know. Will bondo hold up on larger openings, such as where the dado cuts went to the outter edges?

Also, here is an update...
100_3540.jpg


With Xover in and everything set to go... I slapped it to my amp. Within 10 seconds of playing it, I went "wow...."... kinda of speachless. It sounded absolutely amazing. EXACTLY what I was wanting after just a hair of EQ tweeks (probably no more than going from 12-o-clock to 1 or 2 o-clock in degrees on a few settings). I just can't find the words. On or off axis, its just a beautiful sound that I only dreamed I could have. But the tone... oh man. The midrange cuts through a lot better than I thought. It doesnt have the sizzling highs a horn would offer, but really, I don't think that it would be noticed much with my style of playing, especially once you get a band in front of me. It came out very well balanced, too. I can hit the open note at dropped G# on one bass, or go to my 6 string and play with the highest on the high-C string... it comes out even and clear.

I gotta say, I didn't expect it to be THIS good. I'm very pleased. Kinda want to build a 2nd one now :D But first, I must finish this one. Make it beautiful and durable enough to last 1200 years.
 
#31
if it's the grooves showing in the picture, that's too big, primarily because bondo will shrink a little.

Your best option is to fill it with a strip of wood then bondo to fill the cracks. second best option would be some epoxy with microspheres or very finely milled fibers. the expoxy will gap-fill much better than Bondo, but is a lot harder to sand. In fact, fast-set (5 min) epoxy with a little microspheres will be your best friend for the screw holes/screw heads.

Good Luck, and again that's a very nice looking cab and you should be proud of your work!

Redstar Audio
 
#32
That is nice! I wish I could get those kind of results. Every box I have built has buzzed in the lower register. Of course every box I have built(all 3 of them were out of cheap plywood). Where did you get your plywood?
 
#33
redstar's wood strip and bondo thing will be needed on the dado grooves. I've found bondo to work just fine for covering screwheads and other small/shallow blemishes like where the veneer has chipped away from cutting. If you're doing a bedliner type finish, make sure to allow yourself a good bit of extra time and elbow grease to do filling and prep sanding. That stuff makes a great finish but it will allow blemishes to show through instead of hiding them like a carpet or tolex wrap will. If you like the sound you're getting with only a minor eq tweak or 2 you've got yourself a nice cab there. Your construction method, woofer choice and the fact that is has a mid-driver, any mid-driver already puts it way ahead of anything on the sales floor of your local music store, now just make it pretty.:)
 
#34
Thanx gang!

I have done plenty of "body work" on custom fiberglass boxes, so I hear you on filling every little crack! I did fill in a few with cuts of the same wood, but was hoping there was an easier way... oh well, not THAT big of a deal :D

Z6e9n - I wouldn't call this high grade plywood... its from Home Depot, the 18mm 13ply birch they sell. The type of wood definitely has an effect, but not as much as the overall build and design of it. The nicest wood put together horribly will not sound as good as midgrade wood put together perfectly (IMO).

Some notes to make sure it is going to sound as good as it gets!
-Clampzilla. Don't be afraid to go borrow clamps from all your neighbors. I borrowed 12 long ones from a friend, plus 2 long ones I already have and ~5 mid-short sized ones. As you can see in my pics. Snug em up good!
-Seal it up. Even a pinhole can make a difference in sound.
-Bracing! Obviously I did it here, but even putting triangles to each corner helps.
-Round that port out! The port should be rounded off inside and out. You might even round off anything around the port as I did, just to be sure. The sound of air against a sharp edge, especially in the lower realms where air is REALLY moving, is not a pretty one.
-Make the baffle strong! Wherever you drivers mount to is THE most important spot to have strong. Use either thicker wood, bracing, or preferably, both. But with more bracing and thicker wood comes more weight... so chose carefully.
-Keep components inside cab secure. Lose wire stapled or glued down, crossover securely mounted, etc.
-Acoustic fill. I have heard some boxes that had some pretty bad standing waves and just overall strange sounds because they didn't use something. Polyfill is cheap and located just about everywhere.

Just a few things from my experiences... hope that helps!

Also, the box w/ only the drivers mounting holes cut out and the rear jack plate cut out (no hardware AT ALL yet) was just over 40lbs. Sounds heavy, but really, even without handles in it yet, feels a lot lighter then a lot of commercial cabs I have picked up, especially my Carvin 4x10. Next box, i will probably be NOT so cheap and do the 3/4" front baffle and 1/2" for everything else (and will probably be a 2x15 and 2x6... but ill finish this one up first before starting yet another project!)

AND... if anybody wants, I can take a little audio clip of me playing around w/ one of my mics at any requested position. I have an SM57, SM58, and Rode NT-1. I would definitely love to hear everybody else's opinion, as its simply my opinion that this cab sounds absolutely amazing (so far) :D
 
#35
Just a couple notes; hope you don't mind.

nodestiny said:
Round that port out! The port should be rounded off inside and out.
Click to expand...

I found that if you have a lot of entry area and exit area - especially on floor-level shelf style, that this is a small consideration. It matters a lot more when you are using ports that chuff a lot earlier because they have a less generous cross-section. I'm into ports that don't reach high chuffing velocity until right about the point xmax is reached. Those will be big ports and then, under non-sine musical signals, will never be in the zone where velocities even reach that.

EDIT: also, bracing on the baffle nearer the woofer substitutes very well for needing a thicker baffle.

Bracing! Obviously I did it here, but even putting triangles to each corner helps.
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The corners are the place where really no bracing is needed, due to the panels meeting there the rigidity is already about as high as can be... I think of bracing as performing two functions: adding rigidity further out from the edges and more centrally, while also applying damping to various otherwise open subsections.

Next box, i will probably be NOT so cheap and do the 3/4" front baffle and 1/2" for everything else (and will probably be a 2x15 and 2x6... but ill finish this one up first before starting yet another project!)
Click to expand...

If you are concerned about weight you might try Baltic Birch multi-ply 12mm baffle, with a lighter 12mm choice for panels. With smart bracing that works very well. And one sensitive midrange driver instead of two weak ones ; }
 
#36
nodestiny said:
100_3538.jpg
Click to expand...

I meant to ask you about your crossover topology, acoustic and electrical crossover points and general slopes, all that. Also, wondering if both of those are iron-core inductors or that's a spool that can also be had in air coil, and whose?

EDIT: finally saw part of the answer earlier in the thread...
 
#37
Port size is going to make a big diff on how important it is to have those corners rounded, no doubt. As a general rule of thumb, I always do it, just to be safe.

The reason I mentioned corner bracing was because its better than nothing. The most flex is going to be dead center of any panel of course.

What midrange would one recommend over this one (or two of this one?)

As for weight, this cab came out way lighter than anything I have made with MDF! So it was surprising. With doing a larger cab, I would still use a thicker front baffle with bracing, just because, obviously from this project, im all for overkill. Even the thought of doubling up this setup is overkill! :D

Xover goes as follows:
Zobel on woofer
12db/oct butterworth on subwoofer, lowpass, 8ohm, 650Hz
18db/oct butterworth on midrange, highpass, 9.2ohm, 650Hz

Oh yeah, "P-core" inducers from partsexpress (ironcore, if you will)
[Invalid or Expired Link Removed] (as an example)

I can post a full xover parts list if you want. I didn't use a program, but just general calculators and just my brain. Probably not the best Xover design possible, but I would take it any day over a pre-built generic one! :D
 
#39
^^^ thanx for the info, ill check em out!

An update... been tough to find time to work on this stuff, but here it is...
100_3561.jpg

100_3562.jpg


3 layers of oil based Kilz. This stuff is much different from latex based! Never used the oil based stuff... hard to get off your hands :D

I decided to cheap out on the truck bed coating. I bought a can of rustoleum truckbed coating. It was $17. Its either gonna work decent and I made good with my money, or its gonna be a worthless investment and will cost me time to remove it and put on some good stuff. I know my friend used that Hurculiner stuff back yonder on his truck bed and it was pretty good, figured this stuff is probably similar. Either way, figured it would be worth the try.
 

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