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Digital Organ Subwoofers

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  • LOUT
    I think a pair of Ultimax18's inside a single 25ft-cu box with a pair of 3ft-long X 8inch-diameter ports will reach F3~15hz and keep pretty low port-velocity (23-29m/s) up to 120-123db.
    This should also avoid unloading unless there's content below that 15-16hz bottom.

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  • fpitas
    Be cautious about porting. If the port is tuned above 16Hz, it will unload the woofer below its tuning frequency, and you'll get a lot of cone motion. The danger is exceeding Xmax. You might try tuning the port to 16Hz and EQ the result.

    Another note, you'll need a pretty large port area to minimize chuffing at 16Hz. WinISD will help you get an idea.

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  • billfitzmaurice
    Originally posted by Keys View Post
    Probably the first question should be whether it's possible to get that pitch in that room.
    Why wouldn't it be?
    The Ultimax 18 works best in a 10 cu ft sealed box. How many you need depends on the SPL you want to realize.

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  • Keys
    started a topic Digital Organ Subwoofers

    Digital Organ Subwoofers


    I have a project going and need some advice. Tech support referred me to this forum. Their advice seems trustworthy, so here goes. I have a digital organ built from a computer and a couple of multi-channel audio interfaces equaling about 40 audio channels in all.

    The organ is in a room that is 30' X 50' with a 15' ceiling. The organ--like many--has a lowest pitch of 16 hertz which has a wave that is just over 68 feet long. There are two small transept-like extensions but they are on the 30' sides of the room.

    Probably the first question should be whether it's possible to get that pitch in that room. The organ does well down to low G, which is 24.5 hertz. That wave is just under 46 feet.

    I have four boxes available, all built by an organ company. Two are each 25 ft3 and two are 17 ft3. These are in addition to other speakers, of course.

    How many of the 18" Ultimax subwoofers do I need? These subwoofers consume a good bit of power, but an adequate amplifier won't be a problem. Do you recommend anything beside the Ultimax?

    Would one of the larger boxes be enough? Should it have two subwoofers in it? Would two of the larger boxes be better? Do I need all four boxes? IF I need the two smaller boxes too, should they each have one or two subwoofers? Does any or all of this need to be ported? Be sealed? Have passive radiators?

    The boxes will not be visible, so adding ports would not be a problem, even if the ports are outside the boxes. If they should have ports, how many, how long and what diameter? I can probably make whatever you tell me needs to be done. It won't be pretty or have much wife acceptance factor, but it won't be seen.

    I apologize for not trying to work this out myself, but I don't want errors. I can use the computer to make an organ, but for some reason the T/S parameters sort of make my eyes glaze over. Maybe I've spent too much time doing minor electrical work or on the bench practicing.

    An unusual thing about organ sound at that pitch is this: On many pipe organs, the sound can still be heard/felt even at the fullest organ sound, while still not overpowering quiet sounds. So, while I'm not looking to fill Notre Dame with sound--may she be restored soon--I still want a good rumble, if you know what I mean.

    The system for the organ is of custom design, and one can easily direct which sounds--even which notes--go to which channel(s).

    Thank you in advance for your help.