upcoming home theater room, advice needed.

Discussion in 'Home Theater Projects' started by john_q, Jun 5, 2004.

  1. john_q

    john_q Auditioning

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    Hi to everyone here.... I'm gathering up info and most importantly, suggestions for a completely DIY 5.1 speaker setup for a basement that is going to (eventually) be turned into a HT/rec room situation.

    So where do I start with my questions? This is the sort of thing where I think I know what I want, but have some questions I haven't seen many answers to in my browsing.

    So here goes with some facts about the planned environment. The room will be 24' x 13' when finished, and has 7' ceilings currently (though some will be lost once a ceiling is put in place). The reciever that will be running the speakers, right now at least, is a Sony STR-V444ES. In the future, I'd consider upgrading, or just getting a 5.1 power amp and use the Sony as a pre-amp only.

    My initial considerations for speakers hasn't even gotten to the "which brand?" stage yet... but here are my initial ideas:

    Main fronts: Sealed towers, 2 8" drivers, 1 4", 1 ribbon tweeter per side. This room will be used for music listening as well as movie viewing, so I'd like to have an option of front's that can be run full range reasonably without demanding a subwoofers help.

    Center: Sealed MTM configuration

    Rears: Sealed 6" and ribbon tweeter bookshelf setup

    Sub: Sealed 15" Titanic Mk III with a PE 500 watt plate amplifier, crossed over at something like 60-70hz

    I'm pretty set on the idea of sealed cabinets for everything... limitations on cabinet size is not an issue for this project, and I enjoy quick accurate bass that is not overbearing or "saturating".

    My questions however:

    -is all this "too much" for the size of this room?

    -crossover options seem fairly daunting to me... I see a lot of people designing thier own crossovers, so what am I losing out on buying an already built 2 or 3 way crossover from PE, for example?

    -what else do I have to think about aside from matching the crossover up with the posted frequency response of each driver?


    Any advice would be extremely helpful... and of course, thanks in advance [​IMG]
     
  2. GrahamT

    GrahamT Supporting Actor

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    In my opinion,

    Dont buy a pre-built crossover. I dont think it is possible to do it right. You dont just have to look at the nominal impedance(8,6 or 4ohms) and frequency response but also the efficiency of the drivers in the area of the crossover and the actual impedance for the enclosure size at the crossover point. Also even if you added components to compensate, even then you may not have a flat response. I think you have to do as much research as possible, then build, then test and tweak. You have to consider phase issues from the crossover order and driver placement etc

    or

    just buy a tried a tested kit from www.adireaudio.com www.partsexpress.com www.creativesound.com etc or use a design by some else like Tony G http://home.hetnet.nl/%7Egeenius/ There are plenty of excellent choices out there. Take your time and do as much research as possible.
     
  3. John E Janowitz

    John E Janowitz Second Unit

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    john_q,

    Couple basic suggestions. One, keep the speakers the same all the way around. Matching the tone with the same drivers will help things to sound much better in the room. Two, a sideways MTM is about the worst possible configuration for a center channel. If you can stand it up vertically then it would work well. If at all possible keep at least the front 3 all the same.

    If you want to go fullrange on the front speakers you could always do the same speakers all across the front but do vented towers for L & R and a smaller sealed center cabinet.

    John
     
  4. john_q

    john_q Auditioning

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    Thanks for the replies. I can see how unmatched surrounds would throw off HT listening... oh well, maybe a pair of full ranges in a second room for listening then .... line array!! [​IMG]

    As for crossovers, I'll just dig in and try to learn about things.. it will only help in the long run.



    Why do you say this? I'm not trying to be arguementative, but I cannot recall seeing a center channel that wasn't setup in this configuration...is this just what is considered mainstream due to ease of positioning the speaker itself?
     
  5. John E Janowitz

    John E Janowitz Second Unit

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    An MTM is designed to minimize early reflections off the floor and ceiling. It does this by creating almost a vertical beam. Listen to an MTM right at ear level and then move up or down and the sound drastically changes. If you take a pair of 6.5" drivers with a tweeter between them, figure the closest the centers could be is 9.5" or so.

    Measuring and moving up from the middle of the tweeter to above the mid you will notice a rather large dip at about 1200hz, followed by dips every octave above there. Unless you have a tweeter that can play down to 600hz your response off axis vertically is horrible.

    Now take that and turn the same speaker sideways on top of a TV. If you're sitting directly in front of the TV you're fine. Move off to the left or right and your vocals and everything else below the xover point sound horrible.

    The reason for the sideways MTM is simply marketing. It looks nicer laying down on a TV than it does standing up. If you want to go with something sideways, then go with a 3way system. Add a 3" mid below the tweeter in the center that you can take down to 300-400hz. That way your woofers don't play up high enough where you get into any kinds of cancelations off axis.

    John
     
  6. Dean-P

    Dean-P Stunt Coordinator

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    You could go full range using this:USB speakers
    Then you could make all the same speakers across the front. They are kinda like the Adire Audio's 10:1.
    If you e-mail him, he is very quick to respond and will answer all your questions.
     
  7. John E Janowitz

    John E Janowitz Second Unit

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    Yep, those would work well. Very similar to the Center Points I have now. Full details on the design and some finished pictures in curly maple are up here:

    http://forum.stryke.com/viewtopic.php?t=134

    He uses the other version of the SEAS coax with the clear cone. His enclosure does seem to be rather large for that driver though. I see that he tunes to 47hz. I tuned to around 65hz. My intent was to use them with a subwoofer crossed at 80hz. Trying to get them to play much lower than 60hz severely limited the output capability.

    John
     
  8. john_q

    john_q Auditioning

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    Very interesting idea.... John, are the DIY kits for the centerpoints still going to be available? (the Stryke link says only through 2003)
     

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