Free Advent project.

Discussion in 'Speakers' started by teal'c, Apr 21, 2018.

  1. teal'c

    teal'c It's all moo

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    I'm still not done with my first speaker project, but that's OK.
    Screenshot from 2018-04-21 22-43-02.png Screenshot from 2018-04-21 22-43-22.png Screenshot from 2018-04-21 22-44-32.png Screenshot from 2018-04-21 22-43-58.png

    Almost didn't go since the ad was an hour old, glad I did.

    Are there supposed to be positive/negative stickers at the speaker terminals?
     

     

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  2. bobins08

    bobins08 Loving the dream Subscriber

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    The 8 ohm terminal is the positive, 0 is the negative.
     
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  3. electronjohn

    electronjohn Plug it in & see!! Subscriber

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    Free=:)
     
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  4. drumbum

    drumbum Super Member

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    Doug G. and teal'c like this.
  5. GD70

    GD70 AK Subscriber Subscriber

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    My favorite looking Advents.
    Won't take much to make them look new and sound great.
     
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  6. teal'c

    teal'c It's all moo

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    Since I'm getting ready to order foams I opened these up, and they're filled with block foam.
    Are they supposed to be?
    Sure takes up a lot of air space.
    1.png
    2.png
    These three were stacked behind the woofer, and there are two more behind the tweeter.
    3.png 6.png
    Single cap. Checked the tweeters through the back connections and both worked.
    4.png
    Weird things going on with the grills. One chewed upon by something and the other with a weird cut out.
    5.png
     

     

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  7. E-Stat

    E-Stat AK Subscriber Subscriber

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    Most certainly. Acoustic suspension speakers like these along with their forebearers from Acoustic Research, KLH, etc. all required that for the design to work properly.
     
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  8. teal'c

    teal'c It's all moo

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    Seems weird, could have much smaller cabinets instead.
     
  9. E-Stat

    E-Stat AK Subscriber Subscriber

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    There was an Advent model in a smaller cabinet. The compromise for similar response was lower sensitivity.
     
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  10. jberger

    jberger AK Subscriber Subscriber

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    The grille cutout almost looks like it was made to allow the grille to be inverted and still fit around the tweeter (stackable Advents?).
     
  11. E-Stat

    E-Stat AK Subscriber Subscriber

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    Not stock.
     

     

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  12. jberger

    jberger AK Subscriber Subscriber

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    Definitely not stock.
     
  13. wmgwizard

    wmgwizard AK Subscriber Subscriber

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    The foam inside actually slows down the back wave of the speaker tricking it into behaving as if it were in a LARGER cabinet.

    If they used a cabinet sufficiently sized for the woofer it would be too large for most potential buyers. The foam allows for a smaller, more marketable cabinet size.

    There is no Red/Black or +/- designation for the speaker terminals. IIRC the 0 is negative. Many people modify these by replacing the existing connections with color coded binding posts.
     
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  14. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

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    + and - only matters if you're a believer in 'absolute polarity'. <backs away from open can of worms>

    But I would have guessed 0 was negative anyway.
     
  15. KingBubba

    KingBubba "Too Much Stuff" Subscriber

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    As long as you are the same on both cabinet, you can wire them either way.
     
  16. E-Stat

    E-Stat AK Subscriber Subscriber

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    Correct.
     

     

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  17. quiet

    quiet AK Subscriber Subscriber

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    Foam blocks after 74. Fiberglass prior to that.
     
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  18. Doug G.

    Doug G. Addicted Member

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    The grille frame is a stock frame. It's just been modified, probably for the reason jberger stated.

    Also read up on why acoustic suspension systems are filled with fiberglass or foam. It IS to make the cabinet seem larger to the woofer, thus extending low frequency response.

    Doug
     
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  19. teal'c

    teal'c It's all moo

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    I am familiar. However, it was my understanding that you wanted to reduce air movement while keeping as much volume as possible. That was why you "fill" with poly-fil, not pack tight with poly-fil. With the solid foam it seems you're reducing a lot of the volume that you want to keep. This setup seems like trying to put in a non-designed baffle system by just tossing in wood chunks.

    Wouldn't foam pieces like this be better?
    Screenshot from 2018-08-09 13-39-24.png
    15 PPI open cell foam
    You don't loose as much air space while still drastically reducing the air movement resulting in an even "larger" volume cab.

    Looking around, it appears this type of foam wasn't invented until the 80's so they couldn't have used it.

    Any thoughts on it as an upgrade?
     
  20. SpruceMoose

    SpruceMoose Super Member

    Messages:
    1,608
    IIRC, five pieces of foam, 2” thick x 12” x 12”. Works great. Still using the foam in my home-built double advents. All drivers from 1977/78.
     

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