Nearfield Behind Sofa Sub Build

Discussion in 'DIY Speaker & Subwoofer Building' started by markymiles, Jul 5, 2015.

  1. markymiles

    markymiles
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    Haven't even got my 18's yet for my main subs build, but new elec recliner coming Tue and have just been measuring and due to the width it's going to have to be moved further forward than the current sofa (shame). That's going to leave a whole new space to explore, and I'm thinking of making one big enclosure the width of the sofa (2m) approx 35cm deep and 80 cm high.

    Needless to say it couldn't just be that easy, there is a radiator to incorporate, so it will have to fit round and on top of that. It is in the middle of the sofa at least, so each side of the radiator will have the deepest bits and I was thinking to have one driver in each facing the sofa back. I can turn off the radiator if necessary.

    I will have a play on sketchup, I can make it one internal volume or section it internally to maybe make one enclosure each side per driver.

    I have no experience of drivers suitable for nearfield, obviously the depth is the main issue, with only 35cm external they need to be fairly shallow drivers.

    I'll start calculating internal volumes when I get a min.
     
    Last edited: Jul 5, 2015
  2. markymiles

    markymiles
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    OK so very rough calcs, with lets say two SI HT18's mounted either side of the radiator, using 1" mdf all round, not including bracing or radiator volume gets me around 400 litres. The depth will fit in too.

    Radiator I reckon with a quick measure around 40 Litres. I dunno, bracing lets say another 10 litres. Giving me 350 litres or so. This is all quite rough, not allowing for skirting boards etc, the height can be adjusted when the time comes to hit a figure if I have one in mind.

    Anything obvious I'm missing? From reading around the closer the better for nearfield. I think this should add some nice tactile sensation to the mix. I didn't really get used to buttkickers, wondering if this will be similar. Reckon two 18" subs very close to the back of the sofa should add something. Could go with another inuke6000, or even try a 3000 and get D4 subs. Hmmm. I'm probably going to build the box anyway as it'll be handy to put drinks on behind the sofa so time to start counting the pennies.
     
    Last edited: Jul 5, 2015
  3. markymiles

    markymiles
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    Brain going into overdrive :)

    I am getting two subs. Why not try one of those, DOH!!!

    Deffo going to give it a go, only going to cost me a bit of speaker cable and another box.

    I imagine one in my favoured position and one nearfield will be awesome. Even more excited now.
     
  4. mojogoes

    mojogoes
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    Mark you've lost me somewhat! Are you building a twin enclosure for the two ht18s and then another for a nearfield sub behind the sofa.
     
  5. markymiles

    markymiles
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    I've still got my two sub enclosures sat here waiting for the UXL-18's. I only mentioned the ht18s as a possible idea for near field as they were the cheapest option I could think of. But I can just try out one of the UXL's when they arrive behind the sofa.
     
  6. mojogoes

    mojogoes
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    Ok gotcha!! I spec's x2 ht18s in 300L at 13" deep! And they sound very good;)
     
  7. mattkhan

    mattkhan
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    sounds like an interesting experiment :smashin:

    couple of quick thoughts... firstly that's a big space for a single UXL-18, would you go ported or sealed? secondly I wonder whether you *need* big drivers for near field, certainly in SPL terms you're that much closer so you don't need so much output but then the Q is whether it is SPL or something else (particle velocity is one suggestion) that delivers tactility.
     
  8. mojogoes

    mojogoes
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    I'd personally opt for a tactile transducer or two but i guess because of the sofa being spanking new is probably out!
     
  9. markymiles

    markymiles
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    Yep totally new to this idea, so not sure exactly what I need. I like the effect you get from a suspended floor so looking to try and replicate that.

    I'm sure using the UXL as nearfield is a bit overkill but obviously would be available for a test. Enclosure wise I can make it whatever size I need. Doesn't have to be one unit, could do a box either side of the radiator hidden under a full width shelf and aim for around 90-100l sealed. I might screw the box to the wall to keep it secure, does that pose any obvious problems?

    Tactile transducer is out, no way the boss would permit that.

    No one seems to do nearfield over here just curious why that is? I could in theory have both nearfield and nothing else although don't think that will be optimal.

    Will wait for sofa tomorrow then start thinking about measurements. I've got time as I think the UXL's will be a bit longer due to CNC Machine problems :(
     
  10. mattkhan

    mattkhan
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    I don't think many in the US do either. There are a few vocal posters but not so many systems using the approach as far as I have seen. You need a fair bit of space to make it work and the extra challenge of integrating it into the system.
     
  11. markymiles

    markymiles
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    We'll see, it's only going to cost around £100 to try so figure why not.

    Integrating it will be the interesting bit ;)
     
  12. markymiles

    markymiles
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    So this has ground to a halt in two days flat.
    Sofa actually fits so no space behind it :facepalm:

    Guess I'll have to make do with two 18's lol.
     
  13. mojogoes

    mojogoes
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    Who is it that did the measuring?
     
  14. markymiles

    markymiles
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    Haha, I think mine was faulty :p
     
  15. mojogoes

    mojogoes
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    We must have bought our tapes from the same place!! As when i measure things with it its always an inch or three out:p:D
     
  16. MemX

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    *must not make inappropriate comments about judging size*






    :p




    Although the size of Mo, we must all look like ants to him ;) lol :laugh:
     
  17. markymiles

    markymiles
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    Well looks like this is back on.

    Thanks to @mattkhan suggesting some cheap drivers that would work I am going to try 2 x Infinity 1260W.

    Using everything I have lying around to keep costs down, so have had to change my planned dimensions a little as didn't quite have enough mdf.

    Box will be 50cm W x 80cm H x 25cm D and situated behind me on the sofa. Nearer the better for nearfield they should work out 30-50cm from my ears. MDF was cut this morning and the drivers were ordered and should be with me by Monday.

    I don't own a router and not going to buy one so I'll do my best to do the driver cutouts with a jigsaw.

    Will be powered by one channel of my inuke 6000 that's sat there idle since January.

    There is an option to buy another two for behind the other end of the sofa should I decide to. Not quite sure how they would play together though so for now this is it.

    Very interested to see what nearfield is all about.........
     
  18. thomasjohnflynn

    thomasjohnflynn
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    Is the logic of using near field subs to get as much tactile response as possible? just intrigued. Thanks
     
  19. markymiles

    markymiles
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    Hopefully a bit of that and also should be less/no room influences. Minimal dips/peaks so will be nice and smooth and easy to eq.
     
  20. markymiles

    markymiles
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    Ok so all the mdf cut and at least one decision to make. The center brace is currently a full size piece. Do I leave it as is and then have two separate chambers for the drivers. Or do I make it a window shape and have the two drivers effectively in one big box? Not quite sure what difference it will make.

    Secondly just checking my wiring. I think I have a couple of binding post plates in the loft. If I wire each driver up to a separate set, I'm thinking that it would mean that I don't need to remove the drivers to change from series to parallel? Just change how the binding posts are wired ie run a cable from one left binding post to the other plates right for series. Should be the same as internal wiring?
     
    Last edited: Aug 22, 2015
  21. mattkhan

    mattkhan
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    Only difference I can think of is that a full size piece will marginally reduce volume and will also push any standing wave higher in frequency.

    Wiring internally or externally makes no difference.
     
  22. markymiles

    markymiles
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    Finally got it all made and quickly chucked it next to the inuke to test. I don't have time to do much other than check it all works which it does. Phew.

    I think we can call it functional lol.

    Waiting for a long run of speaker cable to arrive so I can chuck it behind the sofa. Looks taller than I imagined, hope I haven't had a tape measure failure.

    IMG_0256.JPG
     
  23. mojogoes

    mojogoes
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    That files isn't working for me
     
  24. markymiles

    markymiles
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    Strange, works on my desktop and iPad.

    Minor disaster at 01:30am woken up by all mighty crash downstairs. Walked into the lounge and the PJ screen had fallen down taking out one of the speakers on the way down. Landed on the new sub as well, luckily no damage to that. Guess we will blame my DIY skills.

    Luckily only scratches to speaker and dents to screen casing but annoying all the same. Don't know if you can make an insurance claim for scratches and dents?
     
  25. mojogoes

    mojogoes
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    Yeah iPad here too although I can seè the pic now:smashin:
     
  26. MemX

    MemX
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    It's usually the case that you can try and claim for anything you want, but whether they pay out is another matter... lol
     
  27. markymiles

    markymiles
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    Yeah agreed. Given that I bought everything 2nd hand and don't have receipts it'll give them all the ammo they need to say no. Don't think I'll bother.
     
  28. markymiles

    markymiles
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    Cable arrived today, squeezed it behind the sofa and had about 15 mins to play with REW.

    1st impressions are very favourable. Adds a bit of tactile sensation but not too much. I only have these at the moment no ordinary subs. I imagine they will be brilliant once set up to either fill in some gaps in FR and/or add a bit of feel to proceedings.

    Couple of graphs for matt :)

    RAW from MLP.jpg Raw response at MLP
    After EQ.jpg MLP after EQ
    Waterfall after EQ.jpg Waterfall at MLP after EQ
    L+ Sub.jpg L+ Sub
     
    Last edited: Aug 26, 2015
  29. markymiles

    markymiles
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    Almost considering building another pair, putting down the other end of the sofa and not worrying about anything else.

    I am really surprised how good these sound. Only thing missing is the ULF
     
  30. markymiles

    markymiles
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    Do I risk boosting a bit at 20hz. No idea how far I can go without killing the drivers. They don't have much xmax.
     

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