Help me with my first build! DIY Dual-Opposed Infinty 1262W

Discussion in 'DIY Corner - Tips & Techniques' started by collegeaudio, Dec 16, 2012.

  1. collegeaudio Audioholic

    collegeaudio
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    Hey guys. As a preface: patience is a virtue with responses here. My knowledge of DIY speakers is essentially zero.

    After going back and fourth between buying an ID sub to replace my lackluster Polk 505 and building my own, I decided to take the more cost effective and fun route and build my own. I need to pressurize a big room. Roughly 15x15x10, but open to kitchen and dining room.

    There seems to be a lot of love for this driver, so I'm planning on using Infinity 1260's and going to go off of Jinjuku's dual-opposed design, with an iNuke. My first question, is an iNuke 1000DSP enough or do you need the 3000 for headroom? Is there a most cost-effective option?

    http://forums.audioholics.com/forum...es/78575-modeled-infinty-reference-1260w.html

    This is what I need to order, correct?:

    2x Infinity Drivers: Amazon.com: Infinity Reference 1260w 12-Inch 1200-watt High-Performance Subwoofer (Single Voice Coil): Car Electronics

    iNuke 1000DSP: Amazon.com: Behringer NU1000DSP iNuke Power Amplifier: Musical Instruments

    Or

    iNuke 3000DSP: Amazon.com: Behringer NU3000DSP iNuke Ultra-Lightweight, High-Density 3000-Watt Power Amplifier with DSP Control and USB Interface: Musical Instruments

    Cables:
    AVR to Amp: Amazon.com: C2G / Cables to Go 40047 M/M Pro-Audio Cable (6 Feet, Black): Musical Instruments

    Amp to Speakers: Amazon.com: Pyle-Pro PPSS30 30' Foot Professional Speaker Cable Male Compatible With Speakon Connector to Male Compatible With Speakon Connector: Musical Instruments

    Terminal cups (any recommendations for nice terminal cups here?)
    http://www.amazon.com/Recessed-Bana...qid=1355702134&sr=1-14&keywords=terminal+cups

    General questions:

    1) Is there any reason to make this a ported enclosure? What would be the impact on SQ? If so, would you need two ports, or does that just not make sense?

    2) For building the box, ply vs. mdf vs. birch? Is the ply used anything special? Could I go to home depot and pick up 3/4s ply and be in good shape, or is this something I need to get at a specialty lumber shop?

    3) Does the placement of bracing have an impact on SQ, assuming it is braced sufficiently?

    4) Do you need any rockwool internally? If so, how much?

    5) If I went with the iNuke 3000, does that single amp have enough juice to power two of these subs? For ~$150 in drivers and materials, I would be tempted to build another sub in a year or two, and the amp is clearly the most expensive part of this build.

    Thanks guys! Pretty excited about this, I have a feeling it will make my (now sold) polk sound like the woofer on my towers.
    Last edited: Dec 16, 2012
  2. lsiberian Audioholic Overlord

    lsiberian
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    Slow your roll.

    Do you have tools and know how to use them?

    I don't recommend the Infinity Driver. For a first build I suggest a small sealed sub based on the TC Sounds Epic 12" unless your budget allows for one of the better drivers. Sealed subs are much simpler to build.

    But before we get you buying drivers we need to count the real cost.

    I have built lots of speakers and a sub. My recommended setup is based on my own experience.

    Tools

    For ripping wood.
    I use a bosch cs10 circular saw with a forrest woodworker I blade(Do not cheap out on the blade.) You might look for a Makita as they tend to be really well liked for their circular saws.

    For routing and circle cutting. I use a Bosch 1617 router with a plunge base.

    You will need a spiral up cut bit and a flush trim bit. I recommend you get your bits from Holbren or Whiteside.(Do not cheap out on bits)

    If you get a jasper jig(A precision speaker hole cutter) you will need a 1/4" spiral cutting bit. I recommend a 1/2" double bearing flush trim router bit it is the most used bit I own.

    A plug in Drill(These are really cheap and really powerful.)

    Other tools
    (8) Corner clamps(these help you line up the boards for glue up)

    (6) Bar clamps long enough to fit around your maximum dimension(These apply pressure for gluing)

    (1) Pencil or cut line marker.

    (1) Emerson Self Clamping straight edge. All other approaches stink compared to this nifty tool.


    For materials
    I recommend 11 or 13-ply which are available at my local home depots, but not at my local lowes. If you have a car they normally offer precut 2' x 4' sheets I don't recommend getting them to cut it for you because I love sawing and they won't be as accurate typically.

    Ply is lighter, stiffer and more durable than MDF. I prefer ply especially in a sub which tends to be heavy as is. Of course MDF works fine and is a little cheaper. Make sure you get Dust collection attachments for your tools and the connectors too hook up a shop vac to them.


    Techniques I prefer.
    For making cuts into plywood I use a Dow blue styrofoam Sheet laying underneath the wood. This helps with tear out faster time between cuts and gives me a bit more control. It is a little tough on my knees though.

    For glue up I recommend you glue the top, bottom and sides together first. Then add the rear and front baffles. If you need help calculating cut sizes I do have a program that does that linked around here somewhere.

    Now make up a shopping list and you can see this isn't as cheap unless you already have the tools.

    For an introductory woodworking project I always recommend a shelf because its has a lot more margin than a speaker. Of course you can always do a better box down the line.
  3. collegeaudio Audioholic

    collegeaudio
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    Sorry, I definitely should have clarified.

    I have pretty extensive woodworking experience and quite the vast selection of tools (table saws to CNC milling machines, and everything in between). For my highschool senior project a few years back, I built a speargun - a good test of precision woodworking, when you're dealing with routing shaft tracks and mounting things such as trigger mechanisms and line releases. Building the enclosure should not be an issue at all... woodworking I can do, but my speaker design knowledge is much more limited. My apologies for not mentioning this earlier, as I can see why many people probably come on here without first considering the tool purchases they might need to make.

    Good to know about the ply. I didn't know if people special ordered (or visited "real" lumber yards) higher grade plywood.

    About the drivers, why don't you like them? I am more than willing to listen to alternative suggestions. My only thought process was that the old Infinity Kappa Perfect design has been recommended many times on this site, and while they are largely unavailable, this seemed like a worthy alternative. I liked the dual-opposed design due to the high potential output for the footprint.

    I'm looking for a sub that will pressurize a big room, size is not an issue (I'm willing to use 15+" drivers) and under $500 (including amp) in materials. Tool costs need not be factored in, as I have access to anything I would need (excluding VERY specialized bits, but I can't think of many I don't have access to, including dovetails etc)

    Thanks!
  4. adwilk Audioholic Ninja

    adwilk
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    I'd be curious to know the difference between two separate subs vs the dual opposed just in terms of output...

    BUT, if you're ordering two drivers, I'd build two separate enclosures to achieve a better overall in room response.
  5. adwilk Audioholic Ninja

    adwilk
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    Oh, and I should add that while the driver itself really isn't the absolute best in overall SQ, its sounds pretty darn good for the money and is very capable in terms of output. Based on your budget, you'd be hard-pressed to find something that would out perform it.
  6. collegeaudio Audioholic

    collegeaudio
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    I would be also very interested to see how it compares. I searched for awhile, but had trouble finding any solid comparison - only that more driver surface area produced significantly more output. More than two subwoofers? I doubt more - but if it's close, that's a different story.

    Although footprint is not an issue, I would prefer having one subwoofer if possible. In the room it'll be in for the next year and a half, it is going to be very hard to place two unless they are stacked. And, if performance is similar in dual-opposed vs. two enclosures, I would prefer just one. That was part of the reasoning.

    Budget is very important which is why I was so attracted to them. Although I would be happy to spend $100 or so more to get a noticeably better driver. This is not a build I want to be underwhelmed with.
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  7. adwilk Audioholic Ninja

    adwilk
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    In terms of sheer output- I'd imagine they would be close.... Although I do know for sure that response could be better controlled with two subs in different locations.... IF that isn't an option and a single sub system is needed, for the price of two of the Infinity drivers I'm sure theres a single sub driver that would likely perform better. lsiberians recommendation of a TC sounds driver would make sense.
  8. adwilk Audioholic Ninja

    adwilk
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    Nevermind.. at 66 bucks a piece or 132 total thats probably going to be tough to beat... Build that thing and let us know what you think...
  9. Bryceo Banned

    Bryceo
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    Set of JL audio subs are the go I did the DIY project it's the worst thing I could have done
  10. brianedm Audioholic General

    brianedm
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    I thought you liked your diy sub?
  11. Bryceo Banned

    Bryceo
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    I like them, yes but I'd not partiserpate in another DIY
  12. collegeaudio Audioholic

    collegeaudio
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    Thanks, but I really think I'll like this project. DIY-anything is something I really enjoy.
  13. Bryceo Banned

    Bryceo
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    I'm a builder by trade so nocking up a frame for my sub box was no hastle at all it was the covering the frame and carpeting it after I was done that was the trouble
  14. lsiberian Audioholic Overlord

    lsiberian
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    I've run the numbers on your infinity driver and we are talking a very small box as a sealed sub. I don't believe that's ideal for this driver. It's takes a 7" cube which is of course smaller than the driver and would severely limit your lower bass.

    Even a dual driver build is too small to fit in a ported alignment.

    I do not recommend this driver. I suppose some other formulas might give a more favorable response, but I don't see a good build option for this.

    Instead I recommend a single sealed Dayton Audio RS315HO

    You can use from a 12" cube to 17" cube depending on how tight you want it to sound.
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  15. Bryceo Banned

    Bryceo
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    Or build your infinity duals, dual is a hard build if you have to do the maths really well in order to get the perfect sound
  16. lsiberian Audioholic Overlord

    lsiberian
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    Even a dual build with these drivers would have problems from my modeling.
  17. Bryceo Banned

    Bryceo
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    Yes, I ran the numbers myself aswell, and I still havnt usked how low he wants it to sit
  18. collegeaudio Audioholic

    collegeaudio
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  19. lsiberian Audioholic Overlord

    lsiberian
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    The Infinity driver requires a low tuning to get a box large enough to be useful. A dual opposed build might work well, Just know it's going to be a tight fit.

    I suppose it will sound good even if it's not entirely ideal.
  20. panteragstk Audioholic Chief

    panteragstk
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    I can say from my build that it does sound good. I've only put 100w through it, and the box is 1.2 cu ft internal without compensating for the driver. It was just a test build, and for a $60 driver, nothing for the scrap MDF, I have to think that it was worth it. I'm coming from a cheap 8" kenwood passive sub so anything is an improvement. Once I build the second box and buy the xls1500 I should have a much better idea of real performance. I wish I had a way to measure, but I don't currently have an RTA mic.

    The good thing is that if the drivers don't work I'll have two decent 12's for my truck. :D Then I can get teh TC sounds LMS drivers I really want.

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