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Thread: Altec 511B horn compared to the GPA MR931

  1. #31
    Senior Hostboard Member GM's Avatar
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    Re: Altec 511B horn compared to the GPA MR931

    Actually, it looks like the driver didn't have a good seal on either horn since neither load down to ~1200 Hz more than the little 931. That, or the driver 'died'.

    GM
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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    Senior Hostboard Member Panomaniac's Avatar
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    Re: Altec 511B horn compared to the GPA MR931

    Good call, GM. The graphs don't look anything like what I've measured - but I don't have a 902.

  3. #33
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    Re: Altec 511B horn compared to the GPA MR931

    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  4. #34
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    Altec 511B horn compared to the GPA MR931


    Alien_Shore's Avatar
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    Re: Altec 511B horn compared to the GPA MR931

    Thanks for the analysis and comments. This evening, I tested the same three horns on a brand new B&C DE250:

    de250horncomparison

    I made sure to have the driver good and snug on the horn. I did notice that using the highpass settings in Holm were creating some weird issues (causing severe rolloff at 6k), so I turned that off and things returned to normal. It is odd that the 511b creates that spike at 950 in opposition to droop there for the other two horns. What would cause that? (perhaps the ringing? I'll try that horn again with some dampening on it and verify...)
    Last edited by Alien_Shore; September 6th, 2012 at 09:54 AM.
    - Mike

  5. #35
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    Altec 511B horn compared to the GPA MR931


    Alien_Shore's Avatar
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    Re: Altec 511B horn compared to the GPA MR931

    Veellllyy intelllessstink!
    I dampened the 511b with sand bags and some foam pipe insulation:

    horncomparison5

    Now the resonance of the 811b is standing out. Cool! I'm learning a lot here as I go.
    - Mike

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    Re: Altec 511B horn compared to the GPA MR931

    Nice work, thanks. The 811 looks very nice, except for the little dip circa 1900Hz.
    I may ask you for the HOLM zip file, for a closer look.

  7. #37
    Senior Hostboard Member Earl K's Avatar
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    Re: Altec 511B horn compared to the GPA MR931

    Mike ( Alien_Shore ),

    Your ancient picture links are broken.

    Any chance of restoring them ( or re-posting the latest measurements )

    Thanks <> EarlK

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