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Thread: A speaker project

  1. #11
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 21,983
    I'm Martin.

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    Quote Originally Posted by mikmas View Post
    I thought an infinite baffle was basically an open baffle in a room rather than an enclosed one - now I'm confused
    Infinite baffle - driver rear wave completely contained, sealed cab.

    Open baffle - no rear wave containment - no cab at all.
    Martin



    Current Lash Up:

    Technics SLP1200 CD Player * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


    'This is the sort of music I'd be listening to if I was going shopping for a training bra.'

  2. #12
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 36,847
    I'm Geoff.

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    Quote Originally Posted by mikmas View Post
    I thought an infinite baffle was basically an open baffle in a room rather than an enclosed one - now I'm confused
    'Infinite baffle' is a general and not necessarily accurate term for a sealed box speaker. No open baffle in a room would be infinite. The nearest you could achieve would be mounting speakers in holes in the wall that are open to the outside environment (yes, it has been done).

    Martin had a point earlier. Drive units designed for ported cabinets tend to have more powerful magnets than those for sealed boxes. Using them in a sealed box would likely produce an 'overdamped system', resulting in lost bass extension.

  3. #13
    Join Date: Dec 2014

    Location: UK, East Midlands

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    I'm Mike.

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    Quote Originally Posted by Macca View Post
    Infinite baffle - driver rear wave completely contained, sealed cab.

    Open baffle - no rear wave containment - no cab at all.
    Thanks for the explanation Martin, all the internet reading just confused me (information over load)
    - see, I'm learning already

  4. #14
    Join Date: Dec 2014

    Location: UK, East Midlands

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    I'm Mike.

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    Quote Originally Posted by walpurgis View Post
    'The nearest you could achieve would be mounting speakers in holes in the wall that are open to the outside environment (yes, it has been done).
    Crazy - what did they do when it rained?

  5. #15
    Join Date: Apr 2012

    Location: Southall, West London

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    I'm Geoff.

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    Quote Originally Posted by mikmas View Post
    Crazy - what did they do when it rained?
    Surely you've heard of 'speaker brollies'?

  6. #16
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    Paull Messenger the hi-fi bloke, he had some 15'' Tannoy DC mounted in the walls of his house, but they vented into the adjoining room instead of to outside. Still do the job, though.
    Martin



    Current Lash Up:

    Technics SLP1200 CD Player * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


    'This is the sort of music I'd be listening to if I was going shopping for a training bra.'

  7. #17
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 1,161
    I'm Mike.

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    Quote Originally Posted by walpurgis View Post
    Using them in a sealed box would likely produce an 'overdamped system', resulting in lost bass extension.
    By 'lost bass extension' I presume you mean a lack of bass?
    Curious in that when they were mounted in effectively an open baffle - bass disappeared completely
    (noting that the DM-10 never had much of a bass presence in their original form to start with)
    Last edited by mikmas; 28-06-2018 at 18:29. Reason: missing 'n'

  8. #18
    Join Date: Dec 2014

    Location: UK, East Midlands

    Posts: 1,161
    I'm Mike.

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    Back to the project for a moment.

    The first step in constructing my cubes inevitably involved a cock-up. I set too jigsawing the openings in what would become the baffles but unfortunately somehow managed to fuck up the measurements and got the radius wrong (always double check .. and then check again )
    As a consequence my stock of scrap 18mm was diminished ... so back to the graph paper to revise sizes. The cube would now have an external 27 x 27 x 27 provided I made baffles from a piece of 15mm laminated chipboard instead:


    Last edited by mikmas; 28-06-2018 at 18:27.

  9. #19
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 21,983
    I'm Martin.

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    Quote Originally Posted by mikmas View Post
    By 'lost bass extension' I presume you mean a lack of bass?
    Curious in that when they were mounted in effectively an open baffle - bass disappeared completely
    (noting that the DM-10 ever had much of a bass presence in their original form to start with)
    The reason you have a cab is to imprison the rear wave, otherwise it comes out and you get cancellation between rear wave and front wave. The lower the frequency the more cancelation you get. That is the sole drawback of the open baffle principle. But it is quite a big one. There are work-arounds though.

    If you put the B&W drivers in the centre of open baffles say 4 feet square you will get some bass out of them. The bigger you make the baffle the lower the bass will go.
    Martin



    Current Lash Up:

    Technics SLP1200 CD Player * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


    'This is the sort of music I'd be listening to if I was going shopping for a training bra.'

  10. #20
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 36,847
    I'm Geoff.

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    Quote Originally Posted by mikmas View Post
    By 'lost bass extension' I presume you mean a lack of bass?
    Curious in that when they were mounted in effectively an open baffle - bass disappeared completely
    (noting that the DM-10 ever had much of a bass presence in their original form to start with)
    Yes. Bass will be compromised and deep bass missing altogether.

    Open baffles are funny things. All suffer cancellation due to sound from the back of the cone meeting that from the front. This can be accounted for with equalisation to an extent, at the cost of sensitivity. But strangely some open baffles seem to work reasonably well without it.

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