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Thread: Altec 817A interior volume? (SS-1120)

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    Member macsic's Avatar
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    Altec 817A interior volume? (SS-1120)

    Hello, I have a question and I can't find the answer....
    Anyone know the interior volume of an Altec 817A or Stanley Screamers SS-1120???
    Thx
    Music is emotion.

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    Senior Member RMC's Avatar
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    MAYBE i have something about this, need to check in my stuff, will be back later with a reply.

    Richard

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    Thanks in advance for research.
    Music is emotion.

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    Senior Member RMC's Avatar
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    Went through all my Altec cabs info and unfortunately i don't have a simple and straight answer for you. What i do have is the 817 box plans (no A). From these you would have to estimate the internal volume based on the dimensions shown on plans. Sorry, but this is the best i have. Let me know in case you need the box plans... Regards,

    Richard

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    Member macsic's Avatar
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    Thank you, I'm not surprised because I searched quite a bit. I have 817a's that I currently use with 416-16A's and I have those blueprints as well. Information on the 817a or SS-1120 instead indicates 515 or 421 woofers that are used for these speakers. The T&S settings are different for these woofers compared to the 416 so I was wondering what volume to base on.
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    Music is emotion.

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    Senior Member RMC's Avatar
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    Nice cab you shown on pic.

    On the two versions of 817 tech sheet i have (817A and 817A/B) i don't see the 421 driver but it doesn't matter.

    On 3/84 version of 817 sheet the 416 is there as well as the 515.

    On 11/86 version of 817 sheet the 416 is gone, only the 515 remains. The 416 disappearance is a little curious. Maybe the cab was modified making driver less suitable? or the 416 has changed? or it was discontinued? Have no clue.

    Richard


    817A cab 1984 tech sheet version

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    817A/B cab 1986 tech sheet version

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    Member macsic's Avatar
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    Quote Originally Posted by RMC View Post
    Nice cab you shown on pic.
    Thank you, it's a work in progress and I'm very happy with it so far

    Quote Originally Posted by RMC View Post
    On the two versions of 817 tech sheet i have (817A and 817A/B) i don't see the 421 driver but it doesn't matter.
    The 421 refers to info on the Stanley Screamers 1120

    Quote Originally Posted by RMC View Post
    On 3/84 version of 817 sheet the 416 is there as well as the 515.
    I did not have those of 1984 only those of 1986, thank you

    Quote Originally Posted by RMC View Post
    On 11/86 version of 817 sheet the 416 is gone, only the 515 remains. The 416 disappearance is a little curious. Maybe the cab was modified making driver less suitable? or the 416 has changed? or it was discontinued? Have no clue.

    Richard

    The T&S parameters 416-A are similar to the 416-C but not to the 515 or 421 at the level of the Vas, must believe that I attach too much importance to the Vas parameter. Initially these 817a were with PHL B383, I had 416 available and I thought I would try it. The PHL are good but they have a more disco sound, the 416 are more neutral, I prefer them.
    Thank you very much for your info, it's appreciated.
    Music is emotion.

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    Senior Member RMC's Avatar
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    RE must believe that I attach too much importance to the Vas parameter.

    System performance allows some leeway in either direction (+ or - Vas) but its not unlimited or at will. Vas remains somewhat important since it is related to proper box size.

    Altec provided cab volume info for some of their enclosures and none for others unfortunately.

    I gave some more thought to your initial question about internal box volume. I came up with an idea, a simpler and faster way to estimate that volume reasonably close vs having to go through all the dimensions in the box plans. Can't say its a new method, rather doing things differently when cab Vb info is unavailable.

    If you really need an accurate volume number it might not provide this, but if you only needed a good approximation i think it should do the trick, using only a measuring tape and a pocket calculator. In the old days with much less data available, no PCs or Laptops, one had to be resourceful to find or figure out some data. Sometimes knowing one or two numbers you could calculate another one. Kept all my older box design material.

    Quickly, kind of "reverse engineering". It starts with finished box perimeter dimensions providing an enclosure's gross volume. From that you subtract various element's volume displacement in the cab in order to get to an acceptable estimated Vb. Not really complicated, and shouldn't take too long in your case.

    Haven't written the procedure's details yet, have some notes. If there's a need i'll try to find some time to write it.

    Richard

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    Member macsic's Avatar
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    Good morning Richard,

    Calculating the volume by hand was the last solution considered but I can do it, thanks for the offer but it won't be necessary.
    In fact all this stems from my test with the 416, the information I had at the start indicating drivers with Vas really different than the 416, now that I know that the 416 are also suggested in the Altec documentation I am less surprised from my experience with a driver with a Vas almost twice as high.
    Now, I know that my 817 are B's and not A's. If I take the time to calculate the interior volume I will post my results.
    Thank you for your lights

    Michel
    Music is emotion.

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