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Thread: Unadultered Crossover Points

  1. #21
    Member Highly's Avatar
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    Quote Originally Posted by Whiterabbit View Post
    Are you sure you need the metal mesh? There was NOTHING in the xA, and it was a curved stretch too for the grille cloth. I'm sure you can remove that stuff and just let the grillecloth float if you wanted. It won't change the finished look, just the durability.

    Other than that, Are you able to change the baffle design? I ask because the xA designer mentioned he had to try a few configurations before getting it how he liked it. Subtracting extra midbasses, tweaking tweeter position if I recall, etc.

    This car is daily driven. From the simple aspect of maintenance; how would you possibly clean a floating fabric dashboard? Could you ever set something on it? What possible benefit would there be to NOT making the most absurdly durable creation possible? And what judge (assuming this was a competition vehicle) would not deduct points for having your speakers covered by a hammock? Or was that a selling point...

    No, I think I'm rather pleased at the solid surface. You can bounce a basketball off of that thing. It's isolation mounted on rubber feet, and doesn't make a sound when driving over the roughest roads (unlike the REST of the car!). Personally I have a propensity for building for war. Here's what I mean: one midbass enclosure (drivers' side)...

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    Most people don't build like this. That's OK. I do. I hate having my s4 fall apart on me with daily use. That doesn't happen with my car, and it gets USED. Daily.

    Don't get me wrong; I am not saying that would be an easy way out, I just prefer not to take them if I have the choice.

    As for the baffles, the mids have a 90 degree vertical and 120 degree horizontal range of motion (azimuth) for left, right, and center. They are pretty well locked in their physical locations however.

    -Todd
    Team MSE/JL Audio
    2010 MECA OK State Champion Modified SQ and Install
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  2. #22
    Senior Member cvjoint's Avatar
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    Quote Originally Posted by Highly View Post

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    That's you dash?? Whoa, that's a lot of modding. So you are going with the route of sacrificing bottom ITD, and long PLDs. In return you get to have a unflinching stage, height and no xover on the top end of the vocal range. Nicely done. Unlike most people that do this with small cones you will have lots of output which is a major selling point as it inevitably translates into lower distortion at a given SPL. Props for keeping the vent holes at 3/4 SD, that's something I found out the hard way with 8" in the kicks.

  3. #23
    Tester Extraordinaire ErinH's Avatar
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    Todd, you seriously stepped up your game this year. I feel like you're at a different level than most other competitors not only on the build but the true UNDERSTANDING of why you did things the way you did. props, dude.
    Your ears: The best tools you have... and they're free, too!

  4. #24
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    Erin:
    You know I was a member of DIYMA for nearly three years reading and searching and absorbing before I made my first post? It took me that long to learn enough to ask a question that I couldn't already find an answer to. I don't have big post counts anywhere because I spend most of my time trying to sort out the truth from the 'other' stuff. Let there be absolutely no doubt, however... I jumped into the deep end of the pool with this years' build. I was sure that I was capable of doing each of the little bits and pieces that make the build up, but every time I stepped back and looked at the big picture I blanched. This is, after all, my daily driver and only my second real build. Ever. That picture is what it looks like sitting out in the parking lot right now. Thanks for the props!


    CVJoint:
    The PLDs at the midrange's current locations are within an inch of the PLD to the deepest part of the footwell. The only way I could get the pathlengths closer would be to mount the mids in the fenders somewhere... and believe me I looked at what it would take to do it! As it is they get their own special little airspace in the water-resistant cowl. Testing before I cut proved that this was a low pressure area (could you imagine sucking the cones of the drivers out through their holes at 80MPH one day?). The thought occurred to me...

    I am hoping for some extreme dynamicism with this build. To that end, there will be 2.6KW of power backing up the system. Only 750 of that is on the sub. I am sure that's enough power to all but eviscerate the car itself. I want the judge to go to crank the knob and get scared and wuss out before they get it 'all the way up'. I know I will never ever take it there!

    Here's to hoping it works out as planned!

    -Todd
    Team MSE/JL Audio
    2010 MECA OK State Champion Modified SQ and Install
    2011 MECA OK State Champion Extreme SQ, SQ BOS
    2011 MECA World Champion Extreme SQ
    2012 MECA OK State Champion Extreme SQ, SQ BOS

  5. #25
    Founding Member OSN's Avatar
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    Quote Originally Posted by Highly View Post
    This car is daily driven. From the simple aspect of maintenance; how would you possibly clean a floating fabric dashboard? Could you ever set something on it? What possible benefit would there be to NOT making the most absurdly durable creation possible? And what judge (assuming this was a competition vehicle) would not deduct points for having your speakers covered by a hammock? Or was that a selling point...

    No, I think I'm rather pleased at the solid surface. You can bounce a basketball off of that thing. It's isolation mounted on rubber feet, and doesn't make a sound when driving over the roughest roads (unlike the REST of the car!). Personally I have a propensity for building for war. Here's what I mean: one midbass enclosure (drivers' side)...

    Name:  DSC00129Small.jpg
Views: 84
Size:  35.8 KB

    Most people don't build like this. That's OK. I do. I hate having my s4 fall apart on me with daily use. That doesn't happen with my car, and it gets USED. Daily.

    Don't get me wrong; I am not saying that would be an easy way out, I just prefer not to take them if I have the choice.

    As for the baffles, the mids have a 90 degree vertical and 120 degree horizontal range of motion (azimuth) for left, right, and center. They are pretty well locked in their physical locations however.

    -Todd
    Todd, I can't speak for the reason Whiterabbit was suggesting the floating fabric idea, or similar, but I'll ask my question- is having your drivers behind a sheet of metal mesh an acoustical concern to you? I am guessing not, but I'd like to know the rationale.

  6. #26
    Senior Member cvjoint's Avatar
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    Fair point. In installs where the dash drivers are mounted as close as possible to the windshield the PLD are very close to kick mount, in fact it may be simply a matter of how tall the listener is. With short listener it may even be reversed, with the dash drivers farthest!

    I'm a gearhead as much as I'm an audiophile so I'm not cutting any metal in this car otherwise I think this solution makes very good tradeoffs and little at that.
    Last edited by cvjoint; 04-11-2011 at 04:33 PM.

  7. #27
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    Quote Originally Posted by OSN View Post
    Todd, I can't speak for the reason Whiterabbit was suggesting the floating fabric idea, or similar, but I'll ask my question- is having your drivers behind a sheet of metal mesh an acoustical concern to you? I am guessing not, but I'd like to know the rationale.
    That was a concern of mine until I thought about it rationally. My head says 'look at all those edges that sound will be diffracting off of!'. Then I pick up a tweeter like the L1Pro. Which of the two likely has the higher ratio of open area to metal...this 1/2" expanded steel mesh or the tiny freaking pinholes on the front of that tweet? And the higher frequencies would be worse, no? Longer wavelengths won't even see the mesh there. Heck, by the time you get down into the hundreds of hertz you can cover the speaker in carpet and not tell the difference. I think in the scheme of things it really doesn't make a difference if the movement of the grille (vibration) isn't adding anything to the sound (twaaaaang!). I welded every tine on that grille, and it's silent when you whack it.

    I will be taking measurements with and without the grille. I'm willing to bet at 1/24 octave you can't see the difference on the RTA. I mean...



    that's got more edges per inch, right?
    Team MSE/JL Audio
    2010 MECA OK State Champion Modified SQ and Install
    2011 MECA OK State Champion Extreme SQ, SQ BOS
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    2012 MECA OK State Champion Extreme SQ, SQ BOS

  8. #28
    Tester Extraordinaire ErinH's Avatar
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    it seems I recall reading a 'rule' that as long as the distance between holes in the mesh was no shorter than 1/4 wavelength of X frequency, you were fine.

    So, as long as the distance is no smaller than 0.16", you're good out to 20khz:
    13500/20000/4 = 0.169 (rounded).


    I believe the bigger issue would be the driver frame/grille interface, depending on how you have them connected.
    Last edited by ErinH; 04-11-2011 at 05:14 PM.
    Your ears: The best tools you have... and they're free, too!

  9. #29
    Senior Member cvjoint's Avatar
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    I wouldn't be too concerned about it. Very few tweeters have grille that shows up in measurements, let alone a mid. I suppose you could fabricate one that is restrictive but we're talking about mesh. I can't recall a single review where this mattered.

  10. #30
    Senior Member cvjoint's Avatar
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    Quote Originally Posted by ErinH View Post

    I believe the bigger issue would be the driver frame/grille interface, depending on how you have them connected.
    Bingo! I've noticed my TBW3 and Scan Classics have a lot of coating filling up the gap between the surround and cone for minimal difraction at high frequencies. This suggests the surround profile can make things fuzzy, and I suspect the grille ring could too.

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