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Thread: Testing 3,2,... (keywords: WinMLS, S2000, IB)

  1. #21
    Tester Extraordinaire ErinH's Avatar
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    Yep. They're incredibly easy to use.
    Your ears: The best tools you have... and they're free, too!

  2. #22
    Senior Member cvjoint's Avatar
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    Book 2: Making use of the soft top (continued)

    Abstract

    Adam raised the point that the soft top is a residual contributor to cabin gain. Here I test whether the windows are the main contributor.
    Results

    Figure 6


    There are 6 sweeps total in the figure, the pink green and light blue are samples with the window cracked about an inch and a half. The other 3 are with the window up. Top is up in both cases. It seems that the frequency response indeed rolls off much faster with the window open. There seems to be an offsetting effect in higher frequency where the output gets bumped up a little.

    Figure 7



    The window is down for the red sample. There seems to be quite a bit of rolloff from 55hz coming down in frequency. I then rolled the window up a bit in the blue sample, you can see the output flattens more. In the fully closed position -black- I get the usual frequency response with lots of output at 30hz.

    Thoughts

    I'm inclined to say that the window is a major contributor to cabin gain. I wouldn't say if fully accounts for it but it could very well be the majority of it. If I could convert the front windshield down all cabin gain would probably be lost. I find it odd that output seems to get bumped up at 55hz or so when the window is cracked or down. Overall I think Adam's theory that the vinyl top does little for constructive interference is probably true.

    Maybe I should do one top down with the windows up? For some reason I never drove like that, seems odd to me.

  3. #23
    Devil's Advocate Adam_MSS's Avatar
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    Quote Originally Posted by cvjoint View Post
    What's happening to the S2000? :stop:
    Baby on the way. Looking at some four door options.

    Quote Originally Posted by cvjoint View Post
    Maybe I should do one top down with the windows up? For some reason I never drove like that, seems odd to me.
    Seems like a logical way to wrap things up and eliminate the top as a variable. I've never driven like that either, but it certainly will help isolate the various impacts. Again, great testing thus far!
    You don't use science to show that you're right, you use science to become right. - R.Munroe

    The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. - W.L.Bragg



  4. #24
    Senior Member cvjoint's Avatar
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    Mazda RX8? It's just awful on gas, and a bit funky looking on the front.

  5. #25
    Senior Member cvjoint's Avatar
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    Book 3: BG Neo 8

    Abstract

    The BG Neo 8 stands in a category of its own. +-5db from 150hz to 15khz. This driver can span more than 6 octaves!

    Results

    Figure 8 Driver's Side Pillar Pod



    Legend
    Red 30 degrees off axis (between driver head and car top)
    Blue 20 degrees off axis (driver ear level)
    Black 10 degrees off axis (driver chest level)
    Green 0 degrees off axis (driver belly level)

    Testing done in car top up window up for the driver's side pillar pod. The Neo 8 is sealed in roughly 1.5l pillar pod. I used 1 inch thick closed cell foam 1/2" from the driver back in the pod to absorb rear wave.


    Figure 9 Passenger Side Pillar Pod



    Legend
    Red 25 degrees off axis (between driver head and car top)
    Blue 15 degrees off axis (driver ear level)
    Black 5 degrees off axis (driver chest level)
    Green 5 degrees off axis (driver belly level)

    I was able to aim the passenger pod a little higher. This results in different off axis angles for the same mic position.

    Figure 10 Vertical Off-axis Response of the Driver Pod



    Red 0 degrees off axis
    Blue 15 degrees off axis
    Black 30 degrees off axis
    Green 60 degrees off axis

    This was a test done to help out other Neo 8 users. Since the vertical dispersion is the most limited on this driver that is the one I checked. Results will vary a little from installation to installation but given the small baffle I have used on my planars, it can only get better than this!


    Thoughts
    The first two figures are geared towards figuring out my in-car response. I placed the mic in a variety of mic height locations in reference to my own ears. I chose to vary height as that is the weak point of these planars mounted in a vertical position. For reference, it's not unusual to get +- 5db variations in frequncy response in a car. However, I was never able to span over 6 octaves with so little variation before using a SINGLE driver. More importantly the sensitivity is 93db for these guys so there is a lot of output to boot as well. The important message to take here is that the Neo 8 seems to have an impressive high end extension even under severe deviations off axis in the vertical direction. This driver is very tractable!

    Some things I want to point out. High end extension:
    On-axis this speaker has a rising response and a huge peak at 12khz. This is apparent in the first and third figure where there is a measurement for 0 degrees. Because of this I find it useful to use the driver just slightly off axis to get rid of the peak and the rising response. Anywhere from 5 to 60 degrees seems to give a fairly flat response up to 13khz or more. If you mount them say 20-30 degrees off axis, you can move your head a foot up or a foot down and still get similar response. That's great! You can get even better performance using a wider/taller baffle. In a car I find this prohibitive but to each his own, it's great already imo. I have almost no baffle on the sides and only a few inches up and down.

    Low end extension:
    This depends entirely upon your sealed box (if any). I seem to get a bit of gain 300-500hz due to the box. I cross mine 800hz and up to maintain lots of output capability. If you are the type to sacrifice dynamics for soundstage you can cross these as low as 200hz it seems. Not sure how much output you'd get like that.
    Last edited by cvjoint; 04-05-2011 at 01:19 AM.

  6. #26
    Senior Member cvjoint's Avatar
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    Accompanying photos for the tests above:




    The pods are not wrapped in leather yet, i just sprayed them with whatever cans I could find around the garage. Two of the pictures are in the cabin ear level.

  7. #27
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    Damn impressive right there! Looking at the pics, it seems you could get that "in your face" sound from the driverside pillar. Is that the case?

  8. #28
    Senior Member cvjoint's Avatar
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    I have the driver's side pod 2db lower the the right. Without that adjustment it would be a screamer. There is no way around the tight confines of this car, the depth is what it is. It makes up for it by being a helluva driver's car.

  9. #29
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    Thanks for posting up some pics! You got me thinking again. Probably won't sleep too much tonight.

  10. #30
    Senior Member cvjoint's Avatar
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    Book 4: Vifa XT25 Ring Radiator

    Abstract

    They were not kidding when they said this one produces a narrow beam.

    Results

    Figure 11 Driver's Side Pillar Pod



    Legend
    Black 30 degrees off axis
    Blue 20 degrees off axis (driver ear level)
    Red 10 degrees off axis

    Testing done in car top up window up for the driver's side pillar pod.


    Figure 11 Passenger Side Pillar Pod



    Legend
    Black 25 degrees off axis
    Blue 15 degrees off axis (driver ear level)
    Red 5 degrees off axis





    Thoughts
    I guess the idea with these narrow dispersion designs is that you can get better staging and fewer reflections. Personally I think they are way to picky about being perfectly on axis. I prefer to have good dispersion up to 30 degrees at least.

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