DIY Entertainment center w/ built in speakers

Discussion in 'DIY Corner - Tips & Techniques' started by FunkIncubator, Apr 3, 2009.

  1. FunkIncubator Audioholic Intern

    FunkIncubator
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    I would love the opinions of you DIY forum members about my design.

    I have offered to build a custom 5.1 setup for my wife's parents' living room. To meet the aesthetic demands of the Mrs., my father-in-law and I have decided to custom build a wall unit that will house the TV, LCR speakers (and perhaps the sub). I know this is probably not optimal, but there is no convincing her of adding a pair of floorstanding speakers and a 2'x2'x2' wooden cube to the furniture arrangement she has chosen. It also seemed that building the speakers into the shelves would yeild much better performance than just placing bookshelf speakers in the cabinet. My main idea is that this will be a 1-piece, 3-speaker enclosure that also holds the TV & electronics; not an entertainment center with speakers shoved in it.

    I was originally drawn to TLS Guy's "Recession buster" Audax design Audax 2.5 way, but when I started poking around his blog/website, I was also intrigued by the MTM using the Dayton RS drivers and the Beston Ribbon Tweeter. How do the two designs compare in terms of performance and ease of construction? (I posed this question to TLS Guy directly, but he's quite busy these days. I don't expect many of you have built/heard both designs, but maybe you have some ideas about the drivers or designs). The Dayton/Beston crossover appears simpler and cheaper at a glance, so I'm leaning toward that design.

    Would you recommend either design for my setup? What information do you need to make an informed recommendation? Here is my sketch of the wall unit. It won't be built until this summer, so I can make some adjustments if it will improve the sound performance. The red spaces are my intended locations for the LCR speakers; that is open for adjustment, however, the overall dimensions (10' wide, 60" TV directly centered) can't be changed. I'd estimate the total room volume to be about 4000 cu. ft. because it is a big great room that opens to the dining area and kitchen. The living room itself is about 2400 cu. ft.

    I'm reconsidering putting the sub in the EC--I originally conceived of a sealed sub built into the bottom-left compartment of the EC. Then I say a really nice end-table build on the rythmik website, so that might be an option.

    Anyway, your thoughts?

    Attached Files:

  2. lsiberian Audioholic Overlord

    lsiberian
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    I thought this was already discussed. IMO it depends on where you are sitting.

    If you are going to be 8 or 6 feet away from the tv. Then you would be fine most likely. Make sure you don't to the speakers in. And I suggest something capable of a lot of output just in case. I suggest you get separate speakers and actually just put them in the center. The reasons for this are very long. But it gives you flexibility. Any of TLS's, Zaphs, or any other speaker designers designs will sound great if implemented properly. You can't get perfect so just shoot for good enough. For subs I suggest you find a pair that you can also put in the entertainment center. But that may not work well in practice. Even the Kappa design can be modded to fit in a smaller box. Though you will lose extension. This is already a compromise design.

    Since you control the design. I suggest you make it tall enough to use a matching center bookshelf. I suggest you use a coaxial for the center. you can use a comparable tweeter on the LR. This is something TLS does.

    What is the depth of the cabinet?
    Last edited: Apr 3, 2009
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  3. FunkIncubator Audioholic Intern

    FunkIncubator
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    Yes, I asked it in another thread, but I think it was a little misplaced.

    The primary seats are about 10' from the tv & speakers. I know the horizontally-oriented center channel is not the best, but I don't know where to build in a 15" tall speaker above or below the TV.

    The cabinet is 24" deep (outer dimensions)
  4. lsiberian Audioholic Overlord

    lsiberian
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    Then you will probably ok. It's not ideal, but what in life is.

    Since you are building the speakers you can decide the dimensions. just use a coaxial and port it on axis for the center. If a coaxial is to expensive you can use a tweeter above a midrange driver.

    With that much depth you can probably put a modded Kappa design into it for the sub.

    See the top thread in this section.

    Keep the port folded and try to keep the volume similar. If you have to take out volume that's ok too. Just do the best you can. The driver is very good.
  5. WmAx Audioholic Samurai

    WmAx
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    On detail I should make clear in regard to sound quality of the speakers.

    You need to design them to be 'floating' in the cabinet system. That is, you could use a high grade high resilience foam like latex foam (do not use normal cushion foams; they do not have a long life), about 1" thickness, wrapped all the way around the speaker box and then insert that into the entertainment center in slots you designed to fit the cabinets. You can then use trim and close up the front of the gap, leaving about a 2mm open gap between the actual speaker cabinet and trim. Then use masking tape and silicone to seal the gap and provide for a non-rigid coupling.

    If you do not heed my suggestion above, the entire cabinet of the entertainment center will act a large panel radiator in response to the speaker vibrations, causing a very audible coloration that will cause substantial reduction of the mid-range clarity/resolution.

    -Chris
    WmAx,
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  6. TLS Guy Audioholic Overlord

    TLS Guy
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    I did that design for someone who was dead set on that tweeter. It does not look a very promising unit to me. It has some very nasty response irregularities. I think you would be much better off with the recession buster MTM.
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  7. FunkIncubator Audioholic Intern

    FunkIncubator
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    Thanks. I was thinking I might need to decouple the speaker from the EC, but I wasn't sure how. I thought I'd just have to make it fit really tight or leave a small space all the way around. Will my speakers built from 3/4" mdf and filled with rockwool or something really transfer that much energy to the outer panels?

    What about the bottom of my speaker cabinet? Should I just let it sit on the foam, or use spikes or rubber feet?

    Do you know of a source of said latex foam? I found one site, foamsource.com, they sell it to replace sofa cushions or make mattress toppers. Looks like it'd be about $150 for enough of the hi density stuff ($4/sq foot.) Seem reasonable? I haven't looked around too much yet.
  8. FunkIncubator Audioholic Intern

    FunkIncubator
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    Thank you. I think I'll do the 2.5 way for the mains and the MTM for the center. If my mains' baffles are 12" x 24", does that affect the diffraction compensation in the crossover design?
  9. lsiberian Audioholic Overlord

    lsiberian
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    Do as Wmax says. But that seems a bit much for foam. I think that stuff is used for memory pillows and stuff. It's very durable. I would at least check local sources. Look for contractor stores not bedding outlets.

    You can use rubber feet for some isolation. and I would probably do that to gain some isolation.

    I say go for the Recession Buster stuff for an MTM the deals are very good. I think parts-express has a Recession Destroyer kit that might be nice. But I'm not going to do the homework for you. look it up yourself. You will find that design has many thread on the tech talk forum. Which is more oriented towards DIY than our forum.
  10. WmAx Audioholic Samurai

    WmAx
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    Yes, it is VERY important. That price you quoted from that site for foam is absurd! That place must be a real rip off! :)

    I use http://www.foamonline.com for most of my foam needs.

    It takes 2-3 weeks to get any custom order you make, so keep that in mind.

    You can use 1" on the bottom of speaker, and 1/2" around sides and top.

    Use Latex, Extra Firm. This stuff keeps it's shape/strength for decades when not exposed to lite.

    -Chris
    WmAx,
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  11. FunkIncubator Audioholic Intern

    FunkIncubator
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    I appreciate your interest in my project, but no need to get snooty.

    I actually saw that recession destroyer kit just yesterday. That is an amazing deal.
  12. lsiberian Audioholic Overlord

    lsiberian
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    Not sure what snooty means:D But it wasn't intended that way. ;)

    It's a nice deal. I figured you could handle following that spec. I think we've given you a lot necessary information for you to run with.

    You should be able to build a very nice front sound stage with the information you've gleaned. Now we do have one requirement for our work here. And that is we want to see photos of the person's handy work. :D So we can enjoy the hard work others do. This project is very intriguing to me so I doubly hope you intend to document it for us. I have no problem helping you with the subs as i've become familiar with the Kappa Perfect and can crunch any volume for you.

    For the Destroyer I highly suggest you check out the tech talk forum. They have intimate knowledge of the design.

    This could make you want to have your own entertainment center if all goes well. :D
  13. FunkIncubator Audioholic Intern

    FunkIncubator
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    I will take lots of pictures and make this a build thread, definitely. This is a huge undertaking and hopefully something I will be proud to show off!

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