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Speaker simulator with high-pass filter

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  • LOUT
    replied
    The VituixCAD (free program) has cabinet simulation for infinite baffle, reflection simulation for open baffle, and XO simulation for HighPass information.
    You can drop your speaker's FRD and ZMA (it also has an easy tracer to make your own FRD and ZMA if the manufacturer doesn't provide) into the program and manipulate it to show OpenBaffle or InfiniteBaffle results...then save those and rightclick your frequency response in the XO and open that result as an "overlay" so you can play around with different high-pass circuits on your driver to see which comes the closest.
    Don't forget to add a bafflestep simulation (in the reflection simulation) to your driver's response if it isn't in-wall.

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  • hitsware2
    replied
    Originally posted by JRT View Post

    At the link is John P. Kreskovsky's ABC Dipole:
    http://musicanddesign.speakerdesign...._C_Dipole.html
    Sorta over my head

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  • hitsware2
    replied
    Originally posted by jhollander View Post
    You can also use the Edge program to see the open "baffle" response, but ABC Dipole has both pseudo driver and baffle response.
    Basta is even somewhat better for my purpose .... Thank You ..

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  • jhollander
    replied
    You can also use the Edge program to see the open "baffle" response, but ABC Dipole has both pseudo driver and baffle response.

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  • JRT
    replied
    Originally posted by hitsware2 View Post
    What I want to do is model an open baffle...
    At the link is John P. Kreskovsky's ABC Dipole:
    http://musicanddesign.speakerdesign...._C_Dipole.html

    Leave a comment:


  • Billet
    commented on 's reply
    Open baffle losses ~= 13500 in/sec (speed of sound) / 12" (baffle width) / 3 (???) = -3db at 375 Hz. Falling at 6 db per octave: -9 db at 375/2 = 188 Hz (1st octave), -15 db at 188/2 = 94 Hz (2nd octave). That is how I did it, more or less. I spent some time adjusting it to my room afterwards, but at least it gave me some kind of reference point.

  • billfitzmaurice
    commented on 's reply
    Not quite. So long as the front and rear waves don't meet it's technically an infinite baffle. As of late the term has been mainly applied to large rear chamber installs, like in walls between rooms, in closet doors or ceilings, but going back to when the term was originally used it applied to sealed boxes of any size as well. Comb filtering doesn't enter the equation at all, as that applies to what can occur with multiple drivers/speakers of any alignment.

  • hitsware2
    replied
    Originally posted by Billet View Post
    I think I see what you are trying to do, planning to use the first order filter to simulate the open baffle response?

    I have modeled open baffles in a similar way, but instead of adding a high pass filter, I just add a large amount of baffle step to my response (low pass). I use a very large closed box, like 999 liters, and about -12 to -15 db cut above 100 Hz has worked for me.
    How did You arrive at Your numbers ?

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  • hitsware2
    replied
    • An open baffle isn't the same as an infinite baffle.
    • Totally the opposite, actually.
    • An open baffle allows the front and rear waves to meet,
    • an infinite baffle doesn't.
    • The roll off frequency of an open baffle is where it is one wavelength in dimension.
    That is why it is called " infinite " ....
    It is longer than all wavelengths .....
    Like an infinitely wide baffle ...........
    With the same frequency response
    IF ( As I do ( for this exercise ) )
    One chooses to disregard the comb filtering .

    Leave a comment:


  • Billet
    replied
    I think I see what you are trying to do, planning to use the first order filter to simulate the open baffle response?

    I have modeled open baffles in a similar way, but instead of adding a high pass filter, I just add a large amount of baffle step to my response (low pass). I use a very large closed box, like 999 liters, and about -12 to -15 db cut above 100 Hz has worked for me.
    Last edited by Billet; 05-27-2022, 09:33 PM.

    Leave a comment:


  • billfitzmaurice
    commented on 's reply
    An open baffle isn't the same as an infinite baffle. Totally the opposite, actually. An open baffle allows the front and rear waves to meet, an infinite baffle doesn't. The roll off frequency of an open baffle is where it is one wavelength in dimension.

  • hitsware2
    replied
    What I want to do is model an open baffle ,
    using the old way of looking at it .
    I.E.....
    The response is equal to that of the driver
    in an infinite baffle ( big sealed box )....
    With a first order high pass determined
    by the size of the baffle .

    Leave a comment:


  • Chris Roemer
    replied
    Actually, if all you care about is a system's possible F3, just take the diff. between 0.40 and a driver's Qts (must be in a "reasonable" range, like 0.3Os through 0.6Os) and add/subtract that from its Fs ...

    Given a set of drivers w/an Fs of 50Hz, you CAN get a ported box to reach (F3):
    50Hz if its Qts = 0.40,
    only 60Hz if its Qts is 0.10 lower (= 0.30, a stronger motor),
    40Hz if its Qts = 0.50 (0.10 higher, so subtract 10Hz),
    and down to (about) 30Hz if its Qts = 0.60.

    This is VERY general, and won't give you a box size (or tuning) w/out Vas, but is still a pretty reliable rule-of-thumb.
    If you choose to go sealed, your F3 will end up (nearly) an octave higher (and the box size will roughly halve).

    Leave a comment:


  • Chris Roemer
    replied
    Click image for larger version

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  • fpitas
    commented on 's reply
    As we discussed above, actually obtaining a first order response may require a Zobel etc. Anywhere near the driver resonance there's an enormous reactive impedance peak.
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