graphs&pollyfill question

Discussion in 'Home Theater Projects' started by steve_gal, Feb 9, 2004.

  1. steve_gal

    steve_gal Auditioning

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    hi,just waiting for parts to build my first sub.but could someone please explain the relationship between freq/db in the graphs of box design programmes,like what should i be looking for in the response line of the graph.whats good whats bad how do i read it?.
    next! my design was 8.1ft^3 ported but someone pointed me to the adire ported design on their website which is 7.8 net(does this mean the volume will decrease with driver,amp,bracing fitted and f3 increase) but with 64ozs of pollyfill stuffing,i thought this stuffing was put into sealed units to make the volume appear larger.any help appreciated.
     
  2. ThomasW

    ThomasW Cinematographer

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    Software models give a 'net' internal volume. So it's necessary for the designer to add in extra volume to compensate for the amount displaced by ports/drivers/bracing/etc.

    I haven't looked at the specific Adire design. Multiply the dimensions and see if they have already done the compensation.

    The relationship between frequency and dB is just that; it the amount of output the speaker will have at a given frequency
     
  3. steve_gal

    steve_gal Auditioning

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    thanks thomas.sorry my question was'nt really clear enough i am new to this,i understand it is output at given freq but i can't relate it to anything they are just numbers. how do i know lets say for an example 16hz relates to 80db on the graph how loud is it is it good or bad.what is the freq hump where is it on the graph again what is good what is bad,like i say i can read the numbers but don't understand what they really mean,grateful for any help
     
  4. ThomasW

    ThomasW Cinematographer

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    No 80dB at 16Hz isn't very loud.

    If you want to understand the relationship between the dB numbers and loudness, buy a Radio Shack SPL meter. Then take some measurements of differing sound pressure levels.

    To begin to understand what's going on the a speaker design, buy a copy of this book
    http://www.audioxpress.com/bksprods/books/bkt12.htm

    btw, compound complex run-on sentences with little or no capitalization or punctuation are just a little difficult to read and understand aren't they
     
  5. steve_gal

    steve_gal Auditioning

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    If You Would Spend a Little More Time Reading The Question And Answering In Full Rather Than Worrying About Punctuation I Would Be Really Grateful.
    If Members Of This Forum All Purchased Books To Answer Questions There Would'nt Be Much Point To This Forum. Would There?
    Thanks For Your Input Anyway (ENOUGH CAPITALS FOR YOU)
     
  6. Ken_R1

    Ken_R1 Auditioning

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    Is there a formula to take into account the net effect of a given amount of stuffing, such as, 64 oz. of stuffing = 10 liters?
     
  7. Brian Bunge

    Brian Bunge Producer

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    Steve,

    Why should we kill ourselves trying to figure out what you're trying to ask because you won't take the time to write in simple, easy to understand sentences? Everyone here is expected to behave as an adult and as such, should be capable of forming a decent, coherent sentence. If you'll do this I promise you that you will get much more help from the regulars around here.
     
  8. Rob Formica

    Rob Formica Stunt Coordinator

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    Steve: No offence … but what happened to Thomas is a very knowledgeable / helpful member here... and I don't think his punctuation comment was deserving of the backlash. Don't worry so much, it's a friendly place here... [​IMG] If you don't want to buy the book, you can also read up on the primers at http://www.diysubwoofers.org/

    Ken: there is no magic number, but Tom Nousaine did do some tests on the matter awhile back which give a general % perceived increased volume. Check out the article at http://www.integracaraudio.com/carau...ces/fiberfill/

    Later...
    Rob
     
  9. steve_gal

    steve_gal Auditioning

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    I am very sorry for any offence caused.
     

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