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Dual AE AV15-X sealed subwoofers DIY Build

Discussion in 'DIY Subwoofer Build' started by Member 96948, Sep 24, 2009.

  1. Member 96948

    Member 96948 Active Member

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    I thought I would start my own build thread, although there will be obvious similarities with at least two other adventurous (fool hardy?) builders on here....

    The plan is to build a 75L sealed subwoofer around an Acoustic Elegance AE15-X driver, that will take the place of an Ikea Lack occasional coffee table and look much the same as if it had a box built under it. The main difference will be rounded edges, a real oak veneer and solid oak legs will be used. The end result (veneer colours excepted) should look much like this:

    [​IMG]

    and here's another view:

    [​IMG]

    For those sad enough, here's the full Google Sketchup to spin to your hearts content. For those even sadder, here's proof it can be cut from one sheet of 25mm MDF.

    [​IMG]

    The whole shebang will be powered from a Behringher EP4000 PA amplifier which will deliver about 1200w into 4Ohms. The originally planned EP2500 would (according to WinISD) result in the driver reaching Xmax at 800w@10Hz. Xmech is higher still but with 1200w on tap, I will still have to keep an eye on bottoming the drivers, but based on 800w this should result in 103dB(SPL) at 20Hz, before you factor in 6-12dB of room gain. Factor in the additional 3-6dB of running two subs, destruction should only happen if I'm actually trying to kill them.

    I may yet downsize to a 65L box to give a bit more driver protection, with the added bonus that effective box size and system Q can then be adjusted by adding fibre fill - a trick that does not work in reverse with too large a box to start with.

    Just for a comparison against the predicted figures for a single AE AV15-X, the forum favourite SVS PB-13U when run in sealed mode is 'only' producing 99dB @ 20Hz and doesn't produce similar SPLs unless running the 15Hz tune, below which it rolls off twice as steeply as the proposed sealed box.

    The Behringer has been bought at £244. The six drivers (two each) got us a quantity discount and resulted in much cheaper shipping, so each driver weighs in at about £181 each which is frankly, staggering. The Govenment will of course ruin this pleasant surprise with import tax and VAT, but even still, this is good stuff.

    Any thoughts or input welcome, especially from anyone into DIY subs, speakers or furniture.:)

    18/10/09
    -----------


    Pesky Homebase.:mad:

    I got their wood cutting service to dice me up panels for the second 106L box; the first is 65L. I had a Google Sketchup of the panels to show how they were to be cut from a single sheet of MDF. All of the dimensions were displayed to make it easy. There's one row of 550mm panels and another of 514mm. Unfortunately, the second row was cut at 509mm thus leaving 5mm gaps all over the shop. Grrr!

    It's a shame, because all of the cuts are absolutely square and the rest of them millimetre perfect, so when offering up the panels to each other, the fit is extremely tight with nice clean edges. At £28 for the 18mm MDF sheet, plus 50p per cut after the first two, it's pretty good value and takes the heat off getting one of the most critical stages of construction right.

    I guess that's a trip back to HB during the week as I'm hopeful the drivers will turn up this week and would like to have both of the boxes ready for next weekend. Which reminds me; I must get the Neutrik connectors and appropriate cables sorted.

    I've decided to go speakON rather than traditional 4mm/5-way binding posts because they're a rock solid connector that cannot vibrate loose like spades or banana plugs. They're cheap too at £1.99 for the plug (4 required) and £1.74 for the chassis connector, plus gaskets at £2.90.

    I'm guessing the the de rigure Van Damme Studio Series Blue 2.5mm cable should suffice. I'm going to make a pair of 10m cables (although I'll need one of 4m and another of 7m) to future proof the cables for any other 'smart' ideas I have. Any better suggestions gratefully accepted.:)

    21/10/09
    -----------


    The drivers have arrived.:eek:

    The pictures can't convey the loveliness, or the fact that each one weighs as much as a bag of cement.

    Some teasers:

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Me? I'm unnaturally excited by metal in a way that hasn't happened since I last owned an Italian Motorbike.;)

    21/10/09
    ----------


    They are quite large. About 7" across, but heres some more [-]porn[/-] pictures to illustrate:

    [​IMG]

    [​IMG]

    For you Sir? Of course:

    [​IMG]

    [​IMG]

    Russell
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    Last edited: May 16, 2010
  2. micb3rd

    micb3rd Member

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    I am looking forward to hearing this !
  3. gperkins1973

    gperkins1973 New Member

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    Russel

    Is that all the PB13 produced. Very surprised at that especially as mine will be chucking out 120db without room gain.

    Good luck with your build. That 2D drawing showing the cuts, is that an add on in sketchup cos I couldn't get mine to do that.

    cheers graham
  4. AngelEyes

    AngelEyes Active Member

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    As you know and true to form I still haven't decided which route to take.:clown:

    My room is a pain so 2 subs should give me more options. I suspect I will build 3 cabinets and see which works best. One set like yours, probably at the smaller end of the scale and a single larger (130L) one similar to below, although I will probably be finishing in Walnut to match my speakers.

    [​IMG][​IMG]

    I am interested in how you will be joining the corners/legs? I am considering a few options but I think I will try cutting a rectangular section from each leg that the 'box' will sit in. This will involve some chiselling to finish off but it should fairly straightforward using a bench saw to do the main cuts.

    The reason I am favouring this approach is that if my 65L test box doesn't work then I can use the legs on the bigger box as they won't be integral to the construction. That is the idea anyway, I am pretty new to this stuff. :suicide:

    Adam
  5. Member 96948

    Member 96948 Active Member

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    That's exactly what I was thinking for the legs. It would also neatly side-step rough joins in the veneers, or rough cuts on the upright corners.

    As a result of chatting on the Acoustic Elegance board, I'd also changed my mind to go with front firing for two reasons:

    1. Driver sag - Big drivers don't much like hanging on the suspension as it reduces travel in the downward direction and eventually results in needing the suspension replaced. AE are certain this won't be an issue with their drivers, but why tempt fate?

    2. If the driver is on a vertical face then, given the 55x55x45cm (WxDxH) dimensions of the sub the driver can effectively be moved from against the wall to 55cm from it and 55cm up or down the room, simply by turning the sub on the spot.

    To do this I would make the legs stand out an extra 30mm on the driver face, and insert a grill fixed with magnets hidden behind the veneer.

    Russell
  6. Member 96948

    Member 96948 Active Member

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    So am I.

    Mic, can you post that link to that glue you mentioned. IIRC this was a glue that rather than expanding to fill gaps, it gripped and contracted to pull surfaces closer together.

    Russell
  7. Member 639844

    Member 639844 Former Advertiser

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    Looking good guys. Ive been pondering starting my own thread, but Ive no camera at present, couldnt be bothered to invest much time on google sketch up so Ive nothing really to put in such a thread a present.

    One thing which may interest you though Russell, Ive decided to build 2 cabinets so I can test 2 designs to hopefully find which is the best of the 2. Murphy's law will probably dictate both have pro's and con's, and I'll end up being forced between the 2 though :suicide:

    @ Angel, out of interest how did you come about the 65 litres per driver figure. Its a touch smaller than Russ and I were looking into, so are you perhaps thinking of using more wadding? I ask because I was only intending on using it to re-coup a bit of lost performance due to lost volume due to driver and brace displacement, bu it loks as if you may be taking that one a step further, I dont know?

    I have also been pondering if I should pad out the inside of the cabinet with foam to improve things a little, but remain undecided. Thoughts?
    Last edited by a moderator: Sep 26, 2009
  8. AngelEyes

    AngelEyes Active Member

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    I think winISD suggested my twin driver enclosure be 134 litres and as I am keen to keep things as small as possible the use of wadding seems ideal. What concerned me a little is when I ran simulations of EQ to boost the bottom end a little it had a dramatic effect on how easy it is to exeed the driver excursion, so I thought a slightly smaller box might protect the drivers more.

    When you introduce EQ it really becomes a balancing act with Group Delay, -3dB point and Cone Excursion. I still have a lot to learn in this area so won't be making any snap decisions.

    There are so many parameters, I will probably opt for a 'safe' design and then tweak in-room with wadding and EQ if necessary.

    Adam :)

    EDIT: The interesting thing about EQ is the effect it has on the group delay. For instance although it dramatically raises the GD at the frequency you add the boost it reduces is at lower frequencies. Maybe this is a bit of a reach but it may be possible an EQ of say +4dB at 25hz reduces the group delay in the more musical end of the spectrum? It also improves the -3dB point by 10 hz. As I said, loads to think about...
    Last edited: Sep 26, 2009
  9. Member 639844

    Member 639844 Former Advertiser

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    I see where you going, and I guess if your trying to keep size down then thats the route you'll be forced down.

    Ive been trying to keep things as simple as possible (despite a push pull design), so have accepted a larger box to try keep this simplicity. Ive basically pushed the box to its limit size wise to get max performance but keep within xmax. I did notice a few things, like how much you can actually reduce box size and power without dramatic performance reduction.

    Be interesting to see if your smaller box is just as good as my larger one, or perhaps better, it'll show the value of putting in a little extra effort with some in built eq.
    Last edited by a moderator: Sep 26, 2009
  10. micb3rd

    micb3rd Member

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    This is what I use.

    Polyurethane Glue

    Bear in mind it has a 1 year shelf life so does not last forever.
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  11. Member 96948

    Member 96948 Active Member

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    Thanks Mic. Moonfly has sent Adam and I a skeleton gun cartridge of an adhesive he uses at works and that's Polyurethane too, so we're all working along similar lines.

    I still seem to remember someone send me a link to an MDF adhesive that penetrated the hard MDF surface and then pulled the surfaces together to create an air tight seal, rather than expand to fill the gap. Mmm....I shall have to Google to make sure I didn't dream it.:confused:

    Russell
  12. gregmcquaid

    gregmcquaid Member

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    Gripfill by any chance?

    Gripfill 350ml - Screwfix.com, Where the Trade Buys

    Regards,
    Greg
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  13. gperkins1973

    gperkins1973 New Member

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    That's what I got in the end. Gripfill.

    cheers

    Graham
  14. AngelEyes

    AngelEyes Active Member

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  15. gujuboy

    gujuboy Member

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    :thumbsup:

    Keeping myself updated on this thread...
  16. Member 639844

    Member 639844 Former Advertiser

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    Its worth bearing in mind that I intend to use screws on my cabinets with the glue. The saBesto stuff is designed to bond surfaces and create an air tight seal, but its designed to last a very long time and resist vibration. As such it retains a certain amount of flexibility (although not obviously soft) so I'm not sure if its use is as appropriate for a non screwed cabinet.
  17. IronGiant

    IronGiant Moderator

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    Good point :thumbsup:

    Dave
  18. AngelEyes

    AngelEyes Active Member

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    I was thinking the same thing, it should be good for glueing the interior beading to reduce leaks though.

    Adam
  19. Member 639844

    Member 639844 Former Advertiser

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    I cant think of anything better to create an air tight cabinet. I would use it to seal the box inside even if you dont use it as a bonding, this stuff will hold an incredible amount of air pressure its that good. Its main use for me is to ensure ventilation systems are airtight so as not to lose pressure, and those systems can run hundreds of meters. Its even used on high pressure systems, and we use it outside as its totally weather proof.

    I would say test it though, with any 2 materials. Leave it overnight and try separate the 2 materials the day after. We use self drilling tek screws to fix ductwork together, but once this stuff goes off you dont need them and the system remains solid, so it may well work very well for a non screwed cabinet. It cures like hard tire rubber.
    Last edited by a moderator: Sep 30, 2009
  20. leedude03

    leedude03 Member

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    i use a non acidic silicon sealer like the bathroom sealant stuff to seal all the internal joints on the cabs i build, seals almost anything air tight.
    Just run a bead around all joints then drag your wet finger end over it to smooth into position, works for me,
    i do not use internal beading on the joints as i find if you have enough bracing in the correct places there is no need although it wouldnt harm in doing so.
    The glue i use on mdf is just the plain old resin w have been using it for years and had no probs, this of course would depend on how close of a fit your joints are.
    Hope this is of use.
  21. IronGiant

    IronGiant Moderator

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    I just used good old fashioned PVA wood glue with biscuits (and screws to hold it together while the glue dried) on my last MDF box. Makes the MDF go black for some strange reason.
    Dave
  22. gperkins1973

    gperkins1973 New Member

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    Dan,

    How much is the stuff your talking about and where can you buy it?

    cheers

    Graham
  23. AngelEyes

    AngelEyes Active Member

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    Anything to report Russell? ;)
  24. Member 639844

    Member 639844 Former Advertiser

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    Its not that cheap, PM your address and I can send a couple tudes.
  25. AngelEyes

    AngelEyes Active Member

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    Just be aware 'Bond & Seal' is minging stuff to work with, very much like oldschool mastic. Gloves and some parafin might be useful but don't use the parafin to clean the MDF unless you like stains!

    I am just about set on using biscuit joints (thanks Dave), you need to be careful that you make accurate cuts but they will make locating the various pieces much easier than glueing and screwing IMO.

    Adam
  26. Member 639844

    Member 639844 Former Advertiser

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    You certainly need something to protect your hands if you dont want to get them dirty, but its not that bad. Good to see you tried it then Adam :D, what do you thin of it?
  27. AngelEyes

    AngelEyes Active Member

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    I am not sure really, it doesn't set as hard as I thought it would, any bits squeezed out are very stretchy which gives the impression it could be pulled apart (if you are he-man strong like me :D) but as it is not my box I am not about to try :rolleyes:

    I think the real test will be when the driver is inserted and it gets a good pressure test.

    I would say though it doesn't seem that suitable for sanding and painting over but I haven't tried it of course.

    Adam
  28. gperkins1973

    gperkins1973 New Member

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    Dan

    Did you get my PM ok with my address.

    cheers

    Graham
  29. Member 639844

    Member 639844 Former Advertiser

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    You can pull it apart with a fair bit of brute force, and holding it down with your feet. That flexibility is key though IMO, it will ensure a very long lasting and airtight seal. Nothing you bond with it will ever fall apart, but like I say, I'm not as interested in its bonding ability as its sealing ability. I will be using it in conjunction with screws, and together they will be very strong indeed, dare I say it, stronger than jointed boxes :rolleyes:

    Personally I dont trust the route of not using any screws on such a substantially sized sub with so much power, and the saBesto will remain impervious to cabinet vibrations/resonance pretty much indefinitely IMO.

    No doubt when we finish our boxes I'll travel down for a shoot out with you guys and we can see if there are any merits to any particular method, if your up for it that is.
  30. Member 639844

    Member 639844 Former Advertiser

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    Yeah got that mate, I'll send it off as soon as I get chance :smashin:
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