What factors determine tuning point

Discussion in 'Home Theater Projects' started by Russell R, Nov 15, 2003.

  1. Russell R

    Russell R Stunt Coordinator

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    Hello,
    I am thinking about building another sub. Currently have a shiva in a 142.5 tuned to 21.5hz. What determines the tuning point? Considering an Fs of 21hz for the shiva, what are the pros and cons of higher and lower than Fs?

    The above sub is awesome, especially since I only have $325 invested into it. There are times when port noise is heard from the 4" flare. I am bouncing around the idea of changing my port to ports, or larger port.

    Thanks,
    Russell
     
  2. GrahamT

    GrahamT Supporting Actor

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  3. Russell R

    Russell R Stunt Coordinator

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    What does loading and unloading of the driver mean? When does this happen?

    Thanks,
    Russell
     
  4. GrahamT

    GrahamT Supporting Actor

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    Above the tuning frequecy of the system, the port air and the driver are moving in phase, although the driver is hardly moving near the tuning freq. Below the tuning freq the port air and driver are out of phase. THis is when the driver is unloaded and excursion increases. With enough power the driver will exceed xmax and bottom out.
     
  5. Frank Carter

    Frank Carter Screenwriter

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  6. Jack Gilvey

    Jack Gilvey Producer

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  7. Russell R

    Russell R Stunt Coordinator

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    Thanks for all the replies. I want to read what Jack had sent.

    I have a question on the above:
    "Above the tuning frequecy of the system, the port air and the driver are moving in phase, although the driver is hardly moving near the tuning freq. Below the tuning freq the port air and driver are out of phase. THis is when the driver is unloaded and excursion increases. With enough power the driver will exceed xmax and bottom out."

    So, below the tuning frequency of the system means the port/enclosure tune and not the Fs of the driver, correct?

    What does this mean with the Shiva EBS alignment? The drivers Fs is 21hz and the enclosure tune (Adire) is 18.1hz. What happens with this combo versus the 142.5L tuned to 21.5hz?

    I want to understand this better for future projects. Has anyone built their port/flare that stuck out of the enclosure? Something that looks like a TL sub. I am pondering the idea for quick tuning/retuning possibilites.

    Thanks again,

    Still learning,

    Russell
     
  8. Todd Shore

    Todd Shore Stunt Coordinator

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    Sure, the port can be outside the sub. I do it all the time on test boxes.

    Remember that port volume must be deducted from the enclosure if mounted internally, but not if mounted externally.
     
  9. GrahamT

    GrahamT Supporting Actor

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    There is much to know about designing ported subs. Get a copy of the Loudspeaker Design Cookbook by Vance Dickason. This will give you the info you need to properly deign a vented sub. You can find it at a local library.
     
  10. michael-e

    michael-e Agent

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  11. Russell R

    Russell R Stunt Coordinator

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    What type/size/tune sub did you build?
     

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