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Thread: Altec 802-8G fs

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    Junior Hostboard Member Mercury3's Avatar
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    Altec 802-8G fs

    Can someone tell me if this curve on the 802-8G with no horn attached looks normal? I'm just surprised the FS is about 700hz. I have two and both look the same. In FS wouldn't go lower with a horn attached right?

    If it's really that high I think this would explain why some recommend an 800hz crossover frequency even on the 511B (Just reading around)

    Thanks

    802-8G.jpg

    - - - Updated - - -

    Sorry looks like my image came through looking fuzzy.

    802-8G2.jpg

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Altec 802-8G fs

    I thought 802G were only used down to 1200hz and 802D and earlier were used down to 500hz in factory systems? Maybe I?m getting the 802G confused with the 902 usage though

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    Junior Hostboard Member Mercury3's Avatar
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    Re: Altec 802-8G fs

    Quote Originally Posted by Elitopus1 View Post
    I thought 802G were only used down to 1200hz and 802D and earlier were used down to 500hz in factory systems? Maybe I’m getting the 802G confused with the 902 usage though
    Oh rats really?

    I bought these a while back and one had a bad coil so I sent them in to GPA and had new diaphragms and recharged.

    GPA lists their 802-8G to 500hz so wouldn't mine be the same with their diaphragms? Or are they stretching the specifications on that driver?

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Altec 802-8G fs

    Like I said, I might be getting the 802G and 902 confused. Bowtie or someone else knows for sure.

    I know that while GPA lists the freq response of the 802-8G as 500-20khz, the crossover they recommend is a 1200hz unit.

    https://greatplainsaudio.com/wp-cont...Spec-Sheet.pdf

    My own opinion is the 802D and 802G sound best crossed over at or above 800hz. Even on a 500hz horn like the 511b.
    Last edited by Elitopus1; February 5th, 2020 at 02:01 PM.

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    Altec 802-8G fs


    Old Guy's Avatar
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    Re: Altec 802-8G fs

    Absolutely no reason the 802G can't be used like any other 802. Tangerine phase plugs do not need a higher crossover.

    Bear in mind the mass of air in the horn. That mass will load the driver, and yes, fs will drop. GM likely would be better at explaining.

    That air load is why drivers blow when operated below horn cutoff. The diaphragm isn't adequately loaded.

    Small format Altecs IMHO sound better at 800 or 1200. If I wanted to go to 500 I would use a 288.
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    Junior Hostboard Member Mercury3's Avatar
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    Re: Altec 802-8G fs

    Quote Originally Posted by Old Guy View Post
    Absolutely no reason the 802G can't be used like any other 802. Tangerine phase plugs do not need a higher crossover.

    Bear in mind the mass of air in the horn. That mass will load the driver, and yes, fs will drop. GM likely would be better at explaining.

    That air load is why drivers blow when operated below horn cutoff. The diaphragm isn't adequately loaded.

    Small format Altecs IMHO sound better at 800 or 1200. If I wanted to go to 500 I would use a 288.
    Great thanks!

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    Senior Hostboard Member Elitopus1's Avatar
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    Re: Altec 802-8G fs

    I would be interested what the Fs is with the driver attached to a horn. If you test it pls post the results

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    Junior Hostboard Member Mercury3's Avatar
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    Re: Altec 802-8G fs

    Quote Originally Posted by Elitopus1 View Post
    I would be interested what the Fs is with the driver attached to a horn. If you test it pls post the results
    Yep I'll be happy to do that as I'd like to know too.

    It will be a while as I haven't obtained the 511-b's yet.

    FYI I wanted to buy some nice wooden horns but damn they are just to expensive.

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    Senior Hostboard Member GM's Avatar
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    Re: Altec 802-8G fs

    Quote Originally Posted by Mercury3 View Post
    Can someone tell me if this curve on the 802-8G with no horn attached looks normal? I'm just surprised the FS is about 700hz. I have two and both look the same.
    Can't read the scale, but yes and frankly, was expecting a 707+ Hz Fs for a 500 Hz XO point, i.e. a very good ROT is to tune a 4th order band-pass [BP4] alignment 1/2 octave above desired tuning, though having never known actual specs, not sure what to think since BP4 alignments I've designed using point source drivers has been within a Hz or two accurate. Ditto a bunch of DIYers.

    GM

    edit: After looking at some other's measurements, it appears the 1/2 octave ROT is still intact as the 0.707x 686.4 = ~485 Hz tuning clearly shows up here: Altec 511B horn compared to the GPA MR931
    Last edited by GM; February 6th, 2020 at 04:55 AM.
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    Junior Hostboard Member Mercury3's Avatar
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    Re: Altec 802-8G fs

    Quote Originally Posted by GM View Post
    Can't read the scale, but yes and frankly, was expecting a 707+ Hz Fs for a 500 Hz XO point, i.e. a very good ROT is to tune a 4th order band-pass [BP4] alignment 1/2 octave above desired tuning, though having never known actual specs, not sure what to think since BP4 alignments I've designed using point source drivers has been within a Hz or two accurate. Ditto a bunch of DIYers.

    GM

    edit: After looking at some other's measurements, it appears the 1/2 octave ROT is still intact as the 0.707x 686.4 = ~485 Hz tuning clearly shows up here: Altec 511B horn compared to the GPA MR931
    Interesting I didn't know that.

    If that horn / driver combo will do 500hz that would be great. I don't like running those large woofers to high. I'll have to experiment but assume I'll compromise as best I can between the woofers / drivers - I'd planed to go active and I have a Pass Labs XVR-1 which is very flexible.

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