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Thread: Concrete speaker enclosure

  1. #1
    Join Date: Jul 2017

    Location: Doncaster

    Posts: 16
    I'm Michael.

    Default Concrete speaker enclosure

    Hello. I am planning to make some speakers out of 50 mm thick concrete paving slabs. Cutting the slabs to size is not a problem with a circular saw, diamond blade and guide. The bit that troubles me is doing the driver cut outs . Any ideas of the best way to get nice clean circles cut out ?

    Thanks.

  2. #2
    Join Date: Sep 2012

    Location: Derbyshire

    Posts: 475
    I'm mark.

    Default

    I made a slate plinth, used 2 tools. Drilled holes through, then joined the dots up with jig saw. Finished off with angle grinder.

    Not pretty and I'd recommend an air fed mask.
    Think I'd be getting water jet quotes, and/or looking at casting with the holes already formed.

    Good luck.

  3. #3
    Join Date: Dec 2018

    Location: Maidstone

    Posts: 68
    I'm julian.

    Default

    ..what Mark said - use some small re-bar to reinforce and make moulds the correct size for the drivers you intend to use.
    Maybe stainless steel re-bar ? or something non magnetic..
    PS Audio Directstream DAC, modified Dennon DVD player.
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  4. #4
    Join Date: Jul 2017

    Location: Doncaster

    Posts: 16
    I'm Michael.

    Default

    Thanks for the replies. I did not want to really go to the hassle of casting my own baffle but maybe i will give it a go It gets tricky with driver rebates as well. It's just that i have a number of slabs available for free and would have preferred to use them if possible.

    As the baffle is subject to the most vibration it seems a daft idea to make the baffle out of wood and the rest out of concrete. The other option is to cut out the hole with drill etc and then stick on a thin layer of wood on the outside so no rebates required Cabinet dimensions are getting even bigger then.

  5. #5
    Join Date: Oct 2016

    Location: Hampshire

    Posts: 306
    I'm Mel.

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    A water jet cnc will do the job and many small engineering firms have them. It would probably entail a 2 hour charge which in the south would be 50 an hour but much less up north.

    Mel

  6. #6
    Join Date: Mar 2017

    Location: Seaford UK

    Posts: 1,180
    I'm Dennis.

    Default

    I agree with Mark, and also your point about an extra layer of wood to prevent rebating needs.

    If you cast I recommend that you include a large amount of PVA in the cement, not only does it increase strength which will be good around the holes,, but it will lower the Q.

  7. #7
    Join Date: Jan 2014

    Location: london se6

    Posts: 844
    I'm AndyElectroNumpty.

    Default

    Wow , this sounds pretty hardcore

    /coat
    At the cutting edge of Numptyness!

  8. #8
    Join Date: May 2010

    Location: Worcestershire, UK

    Posts: 883
    I'm Rob.

    Default

    Find a local company that makes stone kitchen tops. They'll often cut stone to order - and if they can cut a hole for a sink - they should be able to cut the sort of hole you're after.

    Not Hi-Fi, but a local company sold me a bit of marble offcut - and cut it to a template I gave them. It now nicely fills the gap between the end of my bath and the wall.
    Rob.
    Powered by crossed fingers and clenched buttocks

  9. #9
    Join Date: Jan 2013

    Location: Durham - UK

    Posts: 1,643
    I'm Ken.

    Default

    I cast some concrete speakers about 30 years ago with 2 1/2" walls.
    They were very very heavy.
    They have been stolen 3 times over the years, twice from myself and once from a friend I gave them to. They were recovered a few yards from the property each time, the thieves gave up, yes they were THAT heavy.

    I didn't pick up on the size of your cabinets, but weight will be a problem if they are even large stand mount size.
    I saw an interesting video on casting some small bookshelf speakers in concrete, the guy used a polystyrene inner core for the volume of the cabinet and after they were cast he melted the Polystyrene out with cellulose thinners, worked well.
    Casting might be easier than cutting concrete.

    There is always light weight concrete made with Pumice stone as the aggregate, bags of Pumice are available on the internet in various pebble size, I've considered this myself, but it's a major undertaking tackling a project like that.
    Ken

    http://www.jkwynn.co.uk/
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  10. #10
    Join Date: Jul 2017

    Location: Doncaster

    Posts: 16
    I'm Michael.

    Default

    Thanks for the reply Ken.

    Very useful information. Yes the one good thing about having heavy speakers is that thieves will think twice about taking them or give up like they did with yours. 2 1/2 inch thickness - i am not surprised they weighed a ton. Was that the optimum for your size of speaker ? Mine is going to be a 3 way floor stander with big woofers so quite substantial. Thickest i thought they would need to be was 2 inches.

    I haven't got any further with it due to procrastination

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