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Thread: My next project

  1. #1
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    My next project

    Name:  2012-08-09 12.22.47.jpg
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    Ive got the appropriate home for my GPA 416-8b woofers thanks too Esoteric Junkie.

    Now comes the refurb. Does anyone have any advice on refurbing a pair of altec 828's?

    I was planning on changing how the back panel attaches. Glued around the parameter with a opening a little bigger then the 416 in the back. And add more bracing on the back and side panels too. Im thinking I might add an extra layer of plywood on the outside to increase the rigidity too.

    Nick

  2. #2
    Senior Member sbjacob's Avatar
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    Quote Originally Posted by NickH View Post
    Name:  2012-08-09 12.22.47.jpg
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    Ive got the appropriate home for my GPA 416-8b woofers thanks too Esoteric Junkie.

    Now comes the refurb. Does anyone have any advice on refurbing a pair of altec 828's?

    I was planning on changing how the back panel attaches. Glued around the parameter with a opening a little bigger then the 416 in the back. And add more bracing on the back and side panels too. Im thinking I might add an extra layer of plywood on the outside to increase the rigidity too.

    Nick
    Very nice look forward to more photo's on the restore .

  3. #3
    Senior Member Lee in Montreal's Avatar
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    I would be curious to see how an A7 can be tuned thru proper Bass reflex. I wonder what would happen with a 2234 in there.

  4. #4
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    I saw that thread with the diy a7's with the reflex ports.

    I though about trying something like that, and I still may. But the way I'm looking at it for the moment is altec knew what they were doing. I'll keep them stock, for now. I was already planning on running a subwoofer anyways.

    I was going to start stripper the cabinets today, but my wife had other plans for me.

    what's a guy going to do.

    There at the shop I work at. So looks like I'll be working late this week.

    I will post pictures of my progress as I go.

  5. #5
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    Good old Altecs

    Hello NickH

    Exiting project!
    I love the 828! It for sure does good thing for the low mid and lows.
    When it comes to the the bass port question, the standard opening in the front was only to get so much sensitivity out of the box as possible. They are from a time where extended lows wasn´t invented yet. The opening in the front lets a lot of midrange escape out there. I will not say it was a bassreflex hole, because it has "no tuning". I have "replaced" that open front on my 828 with three bassports. So I have lows now . Have you thought about adding some wings on the sides of the cab?
    Looking forward to read about your project, and subwoofer and stuff!

    Best
    Martin

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    Quote Originally Posted by Ear4life View Post
    Hello NickH

    Exiting project!
    I love the 828! It for sure does good thing for the low mid and lows.
    When it comes to the the bass port question, the standard opening in the front was only to get so much sensitivity out of the box as possible. They are from a time where extended lows wasn´t invented yet. The opening in the front lets a lot of midrange escape out there. I will not say it was a bassreflex hole, because it has "no tuning". I have "replaced" that open front on my 828 with three bassports. So I have lows now . Have you thought about adding some wings on the sides of the cab?
    Looking forward to read about your project, and subwoofer and stuff!

    Best
    Martin
    Hi Martin,

    I have thought about the wing, just dont know how well they would fly with the wife. Did you get that, wings, fly, LOL. Corny. I am goping to try the though, one day. I figured that If I restricted the reflex port it would probably lower the sensativity.

    But Im a long way away from this step. Ill try out a few things when I get there.

    Nick

  7. #7
    Senior Member sbjacob's Avatar
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    Quote Originally Posted by Ear4life View Post
    Hello NickH

    Exiting project!
    I love the 828! It for sure does good thing for the low mid and lows.
    When it comes to the the bass port question, the standard opening in the front was only to get so much sensitivity out of the box as possible. They are from a time where extended lows wasn´t invented yet. The opening in the front lets a lot of midrange escape out there. I will not say it was a bassreflex hole, because it has "no tuning". I have "replaced" that open front on my 828 with three bassports. So I have lows now . Have you thought about adding some wings on the sides of the cab?
    Looking forward to read about your project, and subwoofer and stuff!

    Best
    Martin
    Martin what size ports did you use and can you post some photo's also did you run any tests and if so would you mind posting the results? Thanks

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    Nick:
    Just tell your wife that she is an angle, and the idea of the wings came from looking at her . In my head, she will buy it... I haven´t installed any wings. I do not have the space my living room so it has to wait...
    I don´t know if you can say you lower the sensitivity by adding ports instead. Well yes below 100 you will flatten it more out but you might have a peak somewhere according to that big opening (also depending on the driver)... By the way, what subwoofer(s) are you going to add?

    sbjacob:
    I will post some
    pics in my thread later on today ( if I can find some on the laptop, I´m on vacation)

    Best
    Martin

  9. #9
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    Looking forward to seeing this project progression, Nick.
    Martin's DIY 828 is a cool project - you should have a look at that; essentially blocking up that giant port and put some ducts in there. What is the Fs of the GPA 416-8B? Is it around 23 Hz? Perhaps you can design a removable port board?

  10. #10
    Senior Member Lee in Montreal's Avatar
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    I always thought that the A7 design paired to a woofer with a low Fs and proper BR ducting can sound pretty sweet. That design can also be modified by enlarging/reducing the lower volume to accomodate any woofer's TS.

  11. #11
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    Agh, will the sanding ever end. That Altec gray is some tough paint. The paint stripper I got wont even touch the stuff.


    On a odd side note, the paint stripper I got looks exactly like the slime from the second ghost busters movie. Pinkish with chunks in it. Ill take a picture of the stuff.

    Ive always been a ghost busters junky. Some of the funniest movies ever made. Well Not including any Mel brooks flicks, .


    But progress is happening but slow. When I get a little farther along Ill post. I will get more done this weekend.

    Nick

  12. #12
    J.A.F.S.
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    Thumbs up Soda Blasting

    Quote Originally Posted by NickH View Post
    Agh, will the sanding ever end. That Altec gray is some tough paint. The paint stripper I got wont even touch the stuff.


    On a odd side note, the paint stripper I got looks exactly like the slime from the second ghost busters movie. Pinkish with chunks in it. Ill take a picture of the stuff.

    Ive always been a ghost busters junky. Some of the funniest movies ever made. Well Not including any Mel brooks flicks, .


    But progress is happening but slow. When I get a little farther along Ill post. I will get more done this weekend.

    Nick
    This may sound like heresy, but my proven method for the removal of recalcitrant finishes is soda blasting. It is like sand blasting, but uses Sodium Bicarbonate (baking soda) as the blasting medium. An experienced operator can remove the surface finish with no damage to the underlying substrate. I used this technique on my old Corvettes, and it didn't even harm the gel coat underneath the paint. I then went on to use it on some weirldy painted JBL 2360A fiberglass horns and some EV SM120 horns all with great success.
    Amazed I'm still alive!
    Tim

  13. #13
    Senior Member Lee in Montreal's Avatar
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    Gel coat is pretty hard compared to wood. I think that using chemical stripper remains the best way. It sure takes a long time but it works without destroying the base surface. I have myself stripped several cars before restoration. I prefer using chemical stripping to remove most of the paint and undercoats. It sure is time consuming but it will not damage the sheetmetal. I would then sand all the flat or curvy surfaces, and use beadblasting only on areas that are not easily accessible.

  14. #14
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    Well I ditched the idea of paint stripper. Too many loose strips of wood that get caught on the putty knife. Im now using a belt sander to clean up the surfaces. Helps smooth it out too. Ill do finish sanding before I go in with the filler and straighten everything out and get it square, I found the the joints do need to be reinforced. So Ill use 2x4 and plane the to size to go over the original glue blocks altec put in. Basically Ill surround the altec block.

    This is probably over kill since Im going to glue 1/2" plywood to the outside panels. But, it couldnt hurt.

    Ear4life, sorry I missed the part where you asked me about a subwoofer. Im toying with quite a few ideas. From a selaed cabinet with 2 15" woofers. Or building a jbl 4688 with 2 2240's in it. I like the 4688 because of the higher sensitivity. But I have made up my mind yet. Got to concentrate on one thing at a time or I wont finish it, LOL.

  15. #15
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    Today was the first real day I've had to work on the cabinets. One is completely stripped sanded and reactive filler. The second is stripped except for the horn. I had to replace some of the bottom glue block with 2x 2's. I have to do the same with the other cabinet tomorrow.

    I was going to take picture but my cell died. I'll take some first thing tomorrow and post them. But progress is happening.

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