I need some 3-way design help. . .

Discussion in 'Home Theater Projects' started by Ron D Core, May 19, 2003.

  1. Ron D Core

    Ron D Core Stunt Coordinator

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    I'm currently helping a friend put together a set of full range towers for his home. He well be using them for 75% music (techno, punk, metal, ambient, rock) and the rest for movies.

    I was hoping for some feedback on this driver selection, and, if it seems they will work well with one another, I need some serious crossover help since I have never setup a 3-way crossover. Last year I found alot of good people here to help me with my last 2 way MTM project (which turned out awsome) and I figure this would be the best place to turn with this one.

    The plan so far is to do one tweeter, two mids and two woofers per cabinet. He will be running two Dayton DVC 15" sonosubs (tuned to 17Hz) off a couple PE250 plate amps.

    Here are the drivers I was thinking of. . .

    One of these
    http://www.partsexpress.com/pe/pshow...64-555&scqty=2

    Two of these in an MTM configuration
    http://www.partsexpress.com/pe/pshow...97-302&scqty=4

    And two of these on the bottom
    http://www.partsexpress.com/pe/pshow...97-450&scqty=4

    I will most likely do it all in sealed enclosures since the dual sonosubs will take over under 50Hz anyway.

    The rough crossover points I'm considering are 300Hz for the woofers, 300-3500 or 4000Hz for the mid and then the tweeter from there. I would like to keep the x-overs 1st or 2nd order to keep the cost down.

    That's all I have for a plan at the moment, I hope you guys can help me fill in the rest of the blanks, especially with the x-over since I don't know if I should trust the program I have (x-over pro from PE)

    Thanks,
    John T.
     
  2. Ron D Core

    Ron D Core Stunt Coordinator

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    Anyone with lspCAD willing to whip up a x-over for me? Thanks!
     
  3. Dave Milne

    Dave Milne Supporting Actor

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    John,
    It sounds like a great project, but recognize that "doing it right" is going to be a lot of work. A 3-way, 5-driver speaker is not for the faint of heart. Perhaps that's why no one has chimed in yet.

    I think to get responses from the gurus that frequent this forum, you'll need to take it as far as you can and then ask specific questions. Start with XoverPro and see what sort of response you get... post the sims and ask for tips on fine-tuning.

    I'll try to help along the way, but there are others with much more experience on this sort of thing than I. I'd start with 300/3500 1st order and see how it models. When you're in the final tweaking stage, my Schlumberger response analyzer (actually borrowed from work) and measurement mic might come in handy.

    Incidentally, were you thinking WMTMW, WWMTM, side-firing woofers, or some other variation? With woofers mounted near the bottom, a tapered (pyramidal?) shape might help reduce diffraction and raise the baffle step compensation frequency. On the other hand, Dynaudio, Dunlavy, Focal/JM lab, and others have used the WMTMW approach to good effect.

    Finally, are you going to tantalize us with some of your spectatular 3-d renderings before you fire up the table saw? [​IMG]
     
  4. Ron D Core

    Ron D Core Stunt Coordinator

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    Haha, you remember those renderings from way back? That's great. People liked them before, so I probably will put up some renders of the concept enclosure.

    Ok, I will mess with x-over pro and try to come up with something. We are determined to build soemthing of monolithic proportions (WWMTM all on one baffle) and are willing to go through with the painstaking x-over design process to achieve our ultimate goal. One thing I don't have are some frequency response plots in x-over pro to base my initial response estimation.

    Quick questions

    1. Should we build the box first, then test the speakers accordingly?

    2. Could those drivers work well with one another? I don't want to end up finding that they simply cannot blend or have some other wierd issue.

    Thanks,
    John T.
     
  5. scott besancon

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    I just completed a custom center speaker project that is a 3 way design. I am using 2-Klipsch KV1089 10" woofers, T35 horn tweeter, and a K52 midrange horn with the 90°x60° Tractrix® Horn. Crossover is a 3-way, 2nd order (12dB) crossover with a 3 octave spread between crossover points. Metallized polypropylene capacitors are used in critical midrange and tweeter signal paths. 18 gauge inductors are used to keep DC resistance to a minimum. crossover points are 700/5600.
    The cabinet is 42"w x 13,5"h x 15"d. Also has 2 4" ports in the rear. Cabinet is made out of 3/4" oak plywood with complete internal bracing and wired with 12 gauge monster cable. Can't wait till she gets a little broken in but she sounds soo smooth now. I am very pleased with the results.

    Al that I can say is take your time and do lots of research before jumping in. I have built many speaker projects but this one was a great challenge. I am very please of the sound qulity I was able to achieve.

    hope this helps and Good Luck on your project! Click on my web site to see pics.

    http://www.geocities.com/scooterb4u/ScootersHT.html
     
  6. Todd Shore

    Todd Shore Stunt Coordinator

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    I wonder about that choice of drivers just a little. Not saying if won't sound good, but... to play devils advocate…

    What kind of padding will it take to match efficiencies?

    I think the Vifa XT tweeters like to be crossed high enough that you won't get the best the P13 has to offer. To me, the P13 sounds best under 2K and I've heard that to get the XT tweet crossed over that low (unless going 3rd or 4th order) that you might have to add a notch filter to the tweet. There was just some talk about this over on the MAD board.

    But hey, it is all about compromises.

    What crossover points were you going for?
     
  7. Ron D Core

    Ron D Core Stunt Coordinator

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    I was thinking of going with 300 and 3000 or 4000Hz for the x-over points, after much concideration, we may actually be going with the same setup I built a year or so ago (2 Hi-Vi M8a's and an XT25 in an MTM). I have my homemade circle jigs already setup for them and a crossover designed, so it would be much easier to go that route and we already know what the outcome should be.

    The x-over I used for that one was a 3rd order at about 2000Hz. That tweeter has an Fs of 500Hz, so it doesn't seem to mind being crossed over low, and I can't hear much distortion from it either. They turned out great except for a spike in the response at about 3000Hz that needs equalization. You talked about a notch filter for the tweeter, do you happen to have the specs on that? I might try it out. Thanks for the replies.
     

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