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  1. #21
    Senior Member JoeMuc2009's Avatar
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    Actually it's pure physics. If you push one speaker in carefully in a unit that has no power connected, the other will pop out nearly the same amount. It's an air-tight enclosure where the bass woofers are the only moving parts connecting the inside of the case to the surrounding air.
    This also means, if one bass moves, e.g. from my sample that plays a frequency just on one side, the other base is passively moving along with that. And thereby causing sound, even though it is not driven by anything but the vacuum and pressure generated by the bass on the other side. That makes it impossible to check both speakers separately unless the case with its air-tight seal is opened.
    A "mono" bass where both channels are exactly in phase might cancel itself out because both speakers try to push simultaneously out which creates a stronger internal vacuum, and pull in simultaneously creates the respective amount of pressure. This makes bass movement considerably hard. That's where they do some DSP trickery, I think. Putting the bass just a little out of phase on one side might resolve this for good, without a noticeable effect on what your ears perceive.
    All this might be completely wrong but if it isn't, it makes the Boom a true engineering marvel.
    Last edited by JoeMuc2009; 2017-11-11 at 05:00.


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  2. #22
    Senior Member kidstypike's Avatar
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    Quote Originally Posted by JoeMuc2009 View Post
    Actually it's pure physics. If you push one speaker in carefully in a unit that has no power connected, the other will pop out nearly the same amount. It's an air-tight enclosure where the bass woofers are the only moving parts connecting the inside of the case to the surrounding air.
    This also means, if one bass moves, e.g. from my sample that plays a frequency just on one side, the other base is passively moving along with that. And thereby causing sound, even though it is not driven by anything but the vacuum and pressure generated by the bass on the other side. That makes it impossible to check both speakers separately as long as the case with its air-tight seal is opened.
    A "mono" bass where both channels are exactly in phase might cancel itself out because both speakers try to push simultaneously out which creates a stronger internal vacuum, and pull in simultaneously creates the respective amount of pressure. This makes bass movement considerably hard. That's where they do some DSP trickery, I think. Putting the bass just a little out of phase on one side might resolve this for good, without a noticeable effect on what your ears perceive.
    All this might be completely wrong but if it isn't, it makes the Boom a true engineering marvel.
    Have you seen this?

    http://wiki.slimdevices.com/uploads/...dio_Design.pdf

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  3. #23
    Senior Member JoeMuc2009's Avatar
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    wow, no, never got this as a complete document. Great, thank you!


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  4. #24
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    I've seen this before, which is why I wouldn't be surprised if they push the low frequencies into mono and drive both speakers with it. The point of the DSP design is to maximise low frequency output and in a box this small no-one is ever going to get a sense of stereo separation below about 100hz.



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  5. #25
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    OK now I understand why the sound is so bad on my Boom !
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  6. #26
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    Distorted bass on the left but no visual damage

    Hi,

    I just suffered from the distorted bass on the left woofer, I've opened up the boom as I've seen the comments on the deteriorating glue on the speaker rings.
    However there is nothing noticeable on the speakers, they look like mint condition, i cannot spot any tear after thorough inspection.

    Could it be an electronic component or is there anything else I could try?
    Mid and high tones are perfect.

    Thanks

  7. #27

    Is Boom speaker deterioration inevitable ?

    I don't think it's deteriorating glue that attaches the speakers but
    rather deterioration of the speaker surrounds themselves - the material
    that supports the cones themselves.

    http://joes-tech-blog.blogspot.com/2...adio-bass.html

    Joe does this work and he has low frequency files to test your speakers on
    that page.

    Best wishes,
    David


    On Fri, Mar 23, 2018 at 4:53 AM, Neusdoorn <
    Neusdoorn.8ekv40 (AT) no-mx (DOT) fo...limdevices.com> wrote:

    >
    > Hi,
    >
    > I just suffered from the distorted bass on the left woofer, I've opened
    > up the boom as I've seen the comments on the deteriorating glue on the
    > speaker rings.
    > However there is nothing noticeable on the speakers, they look like mint
    > condition, i cannot spot any tear after thorough inspection.
    >
    > Could it be an electronic component or is there anything else I could
    > try?
    > Mid and high tones are perfect.
    >
    > Thanks
    >
    >
    > ------------------------------------------------------------------------
    > Neusdoorn's Profile: http://forums.slimdevices.com/member.php?userid=62718
    > View this thread: http://forums.slimdevices.com/showthread.php?t=107832
    >
    >

  8. #28
    Senior Member JoeMuc2009's Avatar
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    Quote Originally Posted by Neusdoorn View Post
    Hi,

    I just suffered from the distorted bass on the left woofer, I've opened up the boom as I've seen the comments on the deteriorating glue on the speaker rings.
    However there is nothing noticeable on the speakers, they look like mint condition, i cannot spot any tear after thorough inspection.

    Could it be an electronic component or is there anything else I could try?
    Mid and high tones are perfect.

    Thanks
    The tearing of the bass surround is not always visible unless you disassemble the Boom to free the woofer chassis (which you will have to do anyway to repair it).
    See here for advice: http://joes-tech-blog.blogspot.com/2...adio-bass.html


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  9. #29

    Replacement bass drivers

    Hi all,
    bumping this thread to hopefully get some detailed info.

    Got the dreaded bass fart last week and today found some time to investigate.

    Looks like the drivers are near impossible to get here in Oz.

    so.... I was hoping that some of you legends would have an old ORIGINAL driver that has already been removed from the boom case, that you could run the ruler over and get some accurate detailed dimensions.
    Then it should not be too hard to find a replacement that actually fits.

    ( I would like to order replacement drivers before pulling mine apart otherwise I would do the measurements my self.)

    Anyone up for the challenge ??

    Distance between opposite mounting hole centres
    Depth of the driver from the mounting flange to the back of the magnet
    Diameter of the opening in the front case baffle
    Distance between the edge of the "front baffle hole" and the centre of one of the mounting screw holes

    Any other measurements that you can make.

    My gratitude would be immense for this vital info that everyone can use.

  10. #30
    Senior Member JoeMuc2009's Avatar
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    Quote Originally Posted by leinster-lad View Post
    Hi all,
    bumping this thread to hopefully get some detailed info.

    Got the dreaded bass fart last week and today found some time to investigate.

    Looks like the drivers are near impossible to get here in Oz.

    so.... I was hoping that some of you legends would have an old ORIGINAL driver that has already been removed from the boom case, that you could run the ruler over and get some accurate detailed dimensions.
    Then it should not be too hard to find a replacement that actually fits.

    ( I would like to order replacement drivers before pulling mine apart otherwise I would do the measurements my self.)

    Anyone up for the challenge ??

    Distance between opposite mounting hole centres
    Depth of the driver from the mounting flange to the back of the magnet
    Diameter of the opening in the front case baffle
    Distance between the edge of the "front baffle hole" and the centre of one of the mounting screw holes

    Any other measurements that you can make.

    My gratitude would be immense for this vital info that everyone can use.
    Hi there, please see here: https://joes-tech-blog.blogspot.com/...adio-bass.html
    I have described the matter and how to repair it in detail, and there is also a draft with measurements plus a new image with all measurements you need:


    • negative terminal size: 2.8mm
    • positive terminal size: 5.2mm
    • mounting hole diameter: 4mm
    • Distance between opposite mounting hole centres: 90mm
    • Depth of the driver from the mounting flange to the back of the magnet: 59mm
    • Diameter of the opening in the front case baffle: 82mm
    • Distance between the edge of the "front baffle hole" and the centre of one of the mounting screw holes: 9.5mm


    I can send you repaired speakers from Germany for 20 EUR a piece, and shipping cost will also be around that. If you can find a source for different speakers that fit, please let us all know.

    Cheers, and in advance a Happy New Year to everyone!
    Joe


    PN me if your Boom / Classic / Transporter display has issues!

    Blog: https://www.blogger.com/blogger.g?ri...50753#allposts

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