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sexterra

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Posts posted by sexterra


  1. Looking good, get some bracing in there and she will be stout.

    Going brace with 2" dowels and still have to cut and place corner braces. Still debating on running a full port divider down middle or a partial. Made the box a little bigger than design. 50" X 20" X 38".

    Looks good man! I think you'll be happy with the birch decision.

    I probably would try to avoid putting a brace in the port as it'll increase turbulence in there. Maybe just double up the side walls of the port and round over the ends.


  2. well this sucks. the more i look/ask around the more i hear thats wrong, dont do that. it seems that all info floating around is either misconception or just plain false.

    is there any one that can either help me design a proper ported box or link me to some actual reliable resource so i can figure out how to do it myself?

    That's why I don't ask questions on here. People are plenty happy to shoot ideas down without offering anything constructive. It's never gotten me anywhere.

    Check out the speaker cook book. It's got good stuff in it but I think it's a little more than what you are looking for at this point in time. I read a little of it. It's pretty good. I think most of what Quentin was talking about was trying to get a perfectly flat response.

    You would be fine with a 6" aeroport IMO.


  3. Also if you can, try to get 9 or 13 ply birch. It's stronger than 5, and if there are any voids they would be much less significant.

    There a big difference from baltic birch ply and shop birch (11 or 13) for this kind of application.
    The more plys, the more directions the grain can be angled in, the stronger. So it is more rigid. It's what most of the guys I know who build boxes use.

  4. The area of the port isn't the issue. Any driver with at least 20mm of coil overhang utalizing proper port area will need a port in excess of 30 inches long.

    I know how to go about creating nearly unlimited port length with a round port without using elbows or bends but the average Joe or even these so called box designers don't know how to.

    And FYI if a so called designer wants to build you a octagon shaped port run far away as quick as possible. It's either tuned to 50 hertz or it's only about 25 percent of the nessecary port area needed for the system. There is no way a 30 to 50 inch long port of that nature will fit in typical box. Unless they know what I know and even if they do they would be impeding on proprietary patented information.

     

    Wow, interesting. Alot of this is pretty crazy to me since it basically means everyone is doing it wrong. 

     

    Are there any articles/literature I could read to understand how this all works? 

     

    And I'm assuming that means that my hopes of getting an explanation on how to do that are unreasonable? 


  5. The size or port surface area has nothing to do with "what you are trying to do". There are only three things that dictate port area

    1. Driver sd

    2. Driver Xmax

    3. Enclosure tuning

    Number 1 and 3 are easy. Good luck with 2. No one gives a Xmax rating that is associated with Richard Small's minimum port area formula. Xmax is defined as coil overhang, not the rating published by most.

    99.999% PVC ports won't work unless you are tuning incredibly high or you are using no where enough port area.

     

    Learn something new everyday. What I mean by what hes trying to do is that people who are all about spl generally go for a ridiculous amount of port.

     

    Id be interested to see how my port area will be for my box, I could probably get the actual xmax spec from PSI for my subs.

     

    If the pvc ones arent big enough, there are always the concrete tubes, or you can build an octoport.


  6. Why no flares? They make the port even more efficient, can reduce chuffing etc.

    if you don't want to pay for the precision port kit, I would grab a router and make wood flares, basically just router out a ring and rabbet the inside edge so that the PVC fits into it and then epoxy it or fiberglass it on and hit it with a roundover bit on the inside and outsides. . A wooden flare would also make it possible to brace the port just by screwing the flare to the box.

    The size of port you want to use depends on your goals, the woofer and the size of the enclosure. If I was you, I'd go for a 5" or 6". I'll find the tuning formula for aeros.


  7. I'd make the box a bit larger, and would make the port a bit wider than 1.75, the less ratio of h:w the better. You could also give an aeroport a shot, it'll be a bit more costly than building a slot, but much easier since all you have to do is cut a hole in the box. It'd be pretty easy to do it side firing as long as you have clearance, or firing out of the baffle if you used an elbow piece. It would also be a good deal easier to calculate tuning.

    For reference, I'll be running a 4" aero in my build for 2 8s (slightly more cone area than 1 10") on 1.5k in about 1.75cubes


  8. Baltic birch would still be ply, it's just a higher grade. The recommendation for a lumber yard is a great one, that will save a good bit of $, and get you higher quality wood most likely.

    Mdf dust sucks. I can't imagine that I would use Mdf again.

    You only need one side finished, so if you can save $ there also. Only one side needs to be pretty haha

    I really want to see this thing stained up nice when it's done.


  9. Yes, the baffle will be triple stack. So the first two will be mdf with the third one will be birch. Top, bottom, back and sides being belined. Now I was talking about make a replacement midgate trim piece from birch or fiberglass. Front baffle and midgate being lacquered. But you say that lacquer will be a better choice for the birch but what about for the mdf. Sorry, typing from phone.

    I guess you could seal the Mdf with lacquer. It may take a bit mor lawyer though.

    I'm just not really sure why you're so hung up on using Mdf? It would cost you maybe 80$ more to do birch ove mdf, and you already have a good bit invested. I probably see more people use birch than Mdf, and it sounds great. And in your application just seems like a much better choice since it's more resilient to moisture, as well as stiffer than Mdf.

    I'd also be willing to bet that stain and lacquer is gonna be a good bit cheaper than herculiner.


  10. Sexterra, I rolled mines. Did you rolled it or sprayed it. But it do leave a texture. Might have to see if lacquer will do well far as look and water resistant.

     

    Yeah, I rolled it. Tried to use a fuzzy roller at first. big mistake, all the fuzz came off into the liner, so i used a foam one. Much better. Wound up getting some of it on my hands though, boy was that fun to get off 

     

    The lacquer would probably be your best bet for waterproofing. and would look awesome over a stain.


  11. Sexterra, I was thinking about the final baffle to be birch while the rest will mdf(hurcliner) with a birch trim plate (lacquer).

     

    Im not sure I understand what youre getting at?

     

    Are you saying build the box from mdf, but the second baffle will be birch, and then bedline the mdf portion with herculiner. And make panels of birch to cover the bedlined mdf portion?


  12. Looking forward to seeing this build, Ive got a symphony 1500 Im waiting to hear as well. Thing is crazy tiny! 

    Curious to see how you like the 800.4 as well, been thinking about grabbing one so I can get my pwx8s on a seperate amp channel from my 6s for more power.


  13. I also painted a box and amprack with herculiner, looks great but will probably never use that shit again. Such a pain in the ass to work with and clean up. Also has a bit too much texture for my liking. Ill be using the rustoleum rattle can for my box I'm working on, much easier and less messy although much less durable and waterproof etc.

    This was my herculiner result...

    IMG_0448.jpg

    IMG_1600.jpg


  14. Sexterra and Leedoggs you both have valid points. Sexterra I was leaning more towards SQ with low tuning and use wood dowels like you said. Also, do you think that pocket hole jig will be better than staples? Leedogg, I did used Herculiner before on mdf. Came out good with two coats. I really didn't know if that Baltic Birch would swell, but was going just paint (oil based) it if I went that route.

    Sorry man but 2 2500 watt rms 18s ported is not SQ just bc Its tuned low. SQ= aiming for completely flat frequency response through the entire system. Your objective is clean ground pounding, Im just stating this before the real SQ nazis come out on here haha

    The baltic birch will handle moisture best out of the 3, and would look amazing with a nice stain, and a good layer of laquer would seal it up really nice. You could also double up the entire thing and do mdf insides, birch outer layer and stain and laquer if youre really set on mdf. But with the volume youll be reaching and equipment youre running, I highly doubt youd notice any "SQ" difference.


  15. Mdf is heavy but after doing some reading to find out that Baltic Birch 13 ply is about 10 lbs lighter and less dense than mdf. HD or Lowes birch ply will have voids in it. So which is the worst of the two evils. Baltic Birch ~$52.00 for 5'x5', mdf ~35.00 for 4'x8', or birch or maple ply ~48 for 4'x8'. Just thinking that the main factor will be bracing. With it being in the bed of an a Avalanche makes it hard because they are water resistant and not water proof (in the bed).

    If its not absolutely waterproof, your biggest con to mdf is that any moisture will make it swell and eventually make it fall apart and thats not something I would risk.

    Id go with the 4x8 birch ply, thats what most people use in larger builds. I highly doubt you will notice a difference as this is not a SQ install. My last box for a pair of crossfire xsv2 15s on a bc5500 was built from it and it was awesome. Had a sweet window brace in it also.

    For extra piece of mind, go for the baltic birch.

    Id also say whatever you do, paint the outside or seal it in some way.

    Main factor wont be bracing, a couple stout dowels and youll be fine. Just make sure you make good clean straight cuts, and get a good bond when you glue.


  16. I have the baffle triple stack and might look at going mdf after comparing the pros and cons and just use bedliner to coat the box. Also going do a trim plate to replace the midgate.

    With the steel tubes, are you talking about 1/2" pipe with floor flanges? I am also going used T - nuts for the subs and debating about using staples or pocket hole screws to hold the box together while glue is curing.

     

    gotcha, triple baffle will stiffen it up alot. 

    What are your pros and cons of MDF to Birch? MDF is cheaper but heavy as crap. Birch is stronger, lighter but more $. Id personally go birch.

     

    yeah, like this...

    ED788A38-A857-4674-910B-B93F742D411F-248

    Easiest way would probably be some wooden dowels though.

    Pocket hole screws would be better than staples,but alot more time consuming.

    If you go staples, make sure you get them all the way in and in good.


  17. Damn that thing is awesome! Ive never seen a hole saw that size. Kinda pricey but sweet. Looks like itd make speaker rings a breeze, no more multiple passes with a router, just cut a bunch of circles out, then size it down and cut out the centers for rings. 

    You wouldn't be able to do a flushmount ring though.


  18. i have also been looking at dual subs in my system and have read many places that separate chambers are preferred. I believe the reasons for this are 2 fold: one is that if one sub fails then you are not immediately over loading the remaining sub due to lack of back pressure and second is that a split box allowed for a full front to back brace down the center of the box. i have never seen a prefab box with shared chambers (outside of ebay) and assume this is the reason. I do not believe there would be any output difference between shared or separate - all else being equal.

     

    The one sub failure would be the only reason to not do a shared chamber. I wouldn't base and box I was building on any prefab box ever, theres a reason they all suck. 

     

    It looks like you are on the right path, threaded rod is great for bracing. You can also use steel tubing with a base plate and a cross connector for bracing if you dont want the ends of the rod and bolts sticking out of the box.

    Id also recommend a double baffle, cant tell if you had one on that sketch.

     

    Also make sure to seal it off so that all the pressure is focused into the cab.

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