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  • Slot Port Question

    I'm working on a Titanic 10" Mk3 in a Vented box, total available volume after bracing is = ~35 liters. My sim is below, I subtracted the volume of the port from the total volume and recalculated until I got it to the balance listed. The slot is 6.5" wide, and 1.5" tall, and the required length is 36.25", which ends up being ~5.5 liters in volume.

    I've included my drawing of the slot port, and how I calculated my length. I don't know for sure if I did it right or not. I've got the centerline measurement of the length equal to 36.25", but I don't know if it should measure that on the centerline or shortest distance.

    Let me know if I'm on the right track!

    Sim:
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    2D View: Dotted line = air path measurement
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    3S View 1:
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    3d View 2:
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  • #2
    Re: Slot Port Question

    Measurement right down the centerline.
    https://www.facebook.com/Mosaic-Audi...7373763888294/

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    • #3
      Re: Slot Port Question

      Alright, sweet! That's what I had done. Thank you!

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      • #4
        Re: Slot Port Question

        I remember somewhere that slot ports tend to act slightly longer than they measure, maybe due to all the friction of the twisting back and forth. Not sure if its true.
        Check out my website: www.uberstealthaudio.com.
        Now offering cnc cut baffles and other speaker cabinet parts

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        • #5
          Re: Slot Port Question

          I think your port might be on the small side and you might end up with some port noise.

          Here is an online calculator for determining optimal port size: http://www.carstereo.com/help/Articles.cfm?id=31

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          • #6
            Re: Slot Port Question

            The slot port here is 9.75 sq in or about a 3.5" round port. The calc suggested 12.5 in or a 4" port. That would have called for a port length of about 48in. Unless the goal is to play this at high volumes, port noise will be at a minimum in reality.
            https://www.facebook.com/Mosaic-Audi...7373763888294/

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            • #7
              Re: Slot Port Question

              Originally posted by nikbrewer View Post
              I remember somewhere that slot ports tend to act slightly longer than they measure, maybe due to all the friction of the twisting back and forth. Not sure if its true.
              You might be thinking of end correction nik.
              https://www.facebook.com/Mosaic-Audi...7373763888294/

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              • #8
                Re: Slot Port Question

                Originally posted by isaeagle4031 View Post
                The slot port here is 9.75 sq in or about a 3.5" round port. The calc suggested 12.5 in or a 4" port. That would have called for a port length of about 48in. Unless the goal is to play this at high volumes, port noise will be at a minimum in reality.
                I had to play with it for a long time in the sim to get it do a reasonable length yet not be chuffing constantly at a reasonable output. It'll be rear firing so hopefully it won't be too excessive. There's going to be two of these in the room identical, so I doubt either one will get turned up loud enough to start chuffing very often, and if it is, I'm probably not going to hear it over the sound of the system! At least that's my hope. I heard somewhere that slot ports don't often chuff as bad as round ports, but that may be false, not sure where I read that.

                Would putting a little bit of stuffing along the last section of the port slow the airspeed? Would that also lower tuning though? I'm alright with dropping the tuning up to 5hz realistically, I just didn't want the extra port length.

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                • #9
                  Re: Slot Port Question

                  I think you will be find Adam. I don't think lining the port is needed but I do like to line the walls of the enclosure with something ie mattress topper, etc.
                  https://www.facebook.com/Mosaic-Audi...7373763888294/

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                  • #10
                    Re: Slot Port Question

                    Originally posted by isaeagle4031 View Post
                    I think you will be find Adam. I don't think lining the port is needed but I do like to line the walls of the enclosure with something ie mattress topper, etc.
                    Yeah, I plan on lining it with mattress topper, stapled to the inside of the cab where I can. Thanks for the input!

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                    • #11
                      Re: Slot Port Question

                      90% of the time, I semi-build a box and clamp it together **dry** to double check tuning.

                      Fool Proof!!!

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                      • #12
                        Re: Slot Port Question

                        If you "roundover" the exit, you'll have no trouble (this is 3/8", I think). This is my "Slot Ported 10" sub. Under 1 cf net. 1" x 10.5" slot. Looks to be 51" long (OK, MAYBE 50-1/2"). You'd have to be off by at least 5% in length to appreciably alter the tuning. That COULD be a big deal on a vent that's under 10" long, but even if you're off by a couple inches (in measurement/calculation) on a vent that's 30", 40", or 50" long, it becomes a non-issue.

                        This has NO stuffing/lining whatsoever. SA250 amp, no boost. Plays from 20-40Hz. Nice. Really rumbles.
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