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Thread: Peerless SLS 6.5" vs. quad Tympany LAT250 Midbass Testing

  1. #11
    Senior Member cvjoint's Avatar
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    Had some fun with this one, got WT2 TS parameters for each half of the LAT independent, then both working together for two units to see consistency:
    Single motor in the LAT250 (5 cones/10 opertational) no push-pull:

    Single motor 2 in the LAT250 (5 cones/10 opertational) no push-pull:

    Both motors (entire LAT) unit 1:

    LAT unit 2:


    It looks like the impedance peak goes down a bit in push-pull mode but not nearly as low as in Zaphs measurements. However, it is much lower than the average 7" which is what I feel a LAT250 is comparable to. It is also fairly low inductance. There is resonance at 900hz, by the rule of thumb this limits the LAT to a 450hz LP.
    Last edited by cvjoint; 06-20-2012 at 03:13 AM.

  2. #12
    Senior Member cvjoint's Avatar
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    Can someone verify if my plan is solid? 1/2 cube using 1/4" MDF baffles for 4 LAT250s per side. The box filled with poly lightly (10% increase in box size?), and an aperiodic vent per box. 5.25" aperiodic memberane constructed as follows:
    5.25" speaker grilles from PE choped up and pressed one into the other.
    Between them 3/4" fiberglass stuffing from Home Depot.
    Tune it to reduce impedance peak.
    Aperiodic vent right behind driver venting up into the dash. LATs downfiring into the floor.
    10% improvement in box size again, for .6 cubic feet total effective size.


  3. #13
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    IIRC you need 1lb poly per CF, heavy stuffing for "increase in box volume"

  4. #14
    Senior Member cvjoint's Avatar
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    I've been looking at that dash. It's a monstrous undertaking to make sealed midbass or for that matter AP. Full MDF construction would give an insanely small box volume. Fiberglass is necessary to allow enough leg clearance afterwards and to make use of the tiny airspace. Instead I think I'm going to try dipole/IB. Since I don't have a lot of time on my hands I think I'm just going to:

    1. slap 4 LATS per side on 16" by 17" baffles - this will be dipole
    2. as time allows I plan on fiberglassing the sides of the board so that it meshes with the floorpan and dash and separates the front and rear wave that way - this will be IB
    3. fiberglassing the bottom of the dash on both sides could create the 4th piece and seal the midbasses/ allow AP orientation.

    I can do the dipole easy, IB sometime in the fall next year..., sealed probably never.

  5. #15
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    Sounds like a plan. Curious how dipole will work in the car.


    Running into the same problems with my midbass. Just not enough room for anything by IB. I'll have something built to test by the next time I come down.

  6. #16
    Senior Member cvjoint's Avatar
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    Ok, dipole on a flimsy 1/4" MDF board that's hardly large did not work out. There was still way too much cancellation on the sides, I didn't have to put the mic on it to know it. The output was slightly under that of the SLS 6.5" despite using 4 LATs. I've also misjudged the series parallel final impedance, it's not 4ohms it's 2ohms which makes powering these suckers tough with a KS 300.4. The other realization is that the baffle still has to be really dead and strong despite the force cancellation. I used on existing dash screw point and 2 zip ties to mount the baffle and there was lots of resonance and such.

    They need to go in a properly sealed dash or box, and a half decent baffle. But, for a couple of hours of work I sure got a good idea of what it takes to make these babies sing.

    Pics, this is the part that protrudes out from underneath the dash. Note how small my underdash is, I barely fit them. One is at an angle to clear the protruding A/C compressor in the dash. BTW, does anybody know if the A/C compressor needs to breathe? Can I even seal up the underdash or does it need the cabin air to function?



    This is the underside, it bolts like this, going up to connect to the dash. I'll need to fiberglass the sides to seal up the sides to the footwells. I'll probably use 3/4 MDF too. Wiring took forever with 8 motors.


  7. #17
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    Is it the compressor under the dash, or just the fan. Usually its just the fan. If so, and if you don't mind not having the recirculate feature, you can completely seal up the dash.

  8. #18
    Senior Member cvjoint's Avatar
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    ohhh, yeah I guess the compressor is in the engine bay. I guess it's a fan, filter and housing. So it does have an air inlet then somewhere around there?

  9. #19
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    It should have a flap that opens and closes when you switch between recirculate and outside air. It usually pulls air from the cowl when in fresh air mode, and then the flap closes that hole off and draws air from the firewall area inside the dash when its set to recirculate.

  10. #20
    Senior Member cvjoint's Avatar
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    Gotta find that flap.
    2001 Honda S2000
    Head: Pioneer P99 + Samsung Galaxy S3
    Amplifiers: 3,000w+ Zeff class G/H power
    4 way: Aurum Cantus AST2560 Air Motion Transformers, BG Neo8-s Planar transducers, Peerless XLS 10" MAC midbass woofers, Tympany LAT700 x2

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