DIYSG Oval Ports- Equivalent surface area

Discussion in 'DIY Speakers and Subwoofers' started by Burnsze15, Jan 4, 2021.

  1. #1 Burnsze15, Jan 4, 2021
    Last edited: Jan 4, 2021
    Can any of the designers or folks in the know confirm for me that each oval port has the equivalent area of 2 sq in?

    I ask because I am trying to replicate a chamber and port of the 1099 (single woofer) to an equivalent slot port for a scratch design using the driver.

    I can’t seem to obtain the T/S from the driver (I dont have DATS) from anyone so I’m reverse engineering it.

    My calculations are then 6 sq in of port area, however the amount of surface area will decrease also altering the calculation.

    Optimally I want to maintain a net 1cu ft chamber ans in lieu of 50-60 tune, raise it up to 80Hz.

    My other option is to try and model a Beta 10 and see how close I get, however I know there are differences.

    Any help would be most appreciated.

    Worst case scenario, I’m going tk use WinISD to come up with three 2” ports for some theoretical driver and ask me to give me the square version of it given my 11” width.
  2. You can use the port length calculator on the Precision Port page to come up with port lengths of different port sizes and different internal cabinet volumes:
  3. That tool only calculates for round flared ports like what they sell, and nothing else. OP is asking about the rounded slot shapes like what the 1099 uses. WinISD for example only has settings for round ports or rectangular ports. When it comes to shapes other then that like the aforementioned rounded slots or the triangular corner ports.

    As lay hobbysts the tools don't seem to exist for shapes other then circles and squares. Yes if you're making a thousand speakers there's going to be prototype iterations and verification of what the actual performance of the speaker is. For the rest of us making one-offs it's a matter of using some tool and praying.

    At least the plastic ports can be popped out and fiddled with. Glued together slot or triangle corner ports are a bit more impractical to adjust after the fact.
  4. Shape of the port shouldn't matter too much in this situation because he's using something different than the original plastic slot port and wants a different tuning. So basically just figure on using something like a single 3" diameter port or two 2" diameter ports for a 10" pro woofer in a 1cuft cabinet. That site says port length comes out to around 4" to get to the tuning around 55-60hz and 2" for 80hz. 80hz seems a bit too high for tuning, but I'm not sure of the project.
  5. Thanks for the responses.

    I calculated the face area of the oval port to be just about 2”. Area of 1 one inch circle (half circle ends each side) and a 2” x1” rectangle center (if I remember right)

    I am indeed trying to determine the surface area of the port so as the previous member noted, I need to plug it into WinISD without the T/S specs on the driver. This driver has increased Xmax than a base model Delta 10, so where the Delta hits a wall for excursion this driver will give a little more as I understand it. Its all a guessing game for me at this point. The Delta 10 at a 1cu ft box and 60hz tune only takes 100w before it hits the excusrion limit so the custom variant must have more xmax to suppprt the power handling capability spec’d for the 1099 and Cinema 10.

    But yes I will be using a 90-100hz crossover on this build so a 80hz tune is my intention. I didnt see those port lengths on the site so thanks. Knowing the equivalent round or square port area will enable me to do a slot port or round stock ports from PE equivalent to the ovals used by DIYSG. Can’t buy the ovals seperately thus my perdicament.

    I would only assume the T/S specs are propietary to DIYSG and/or the cab designer. Maybe I will invest in a DATS box from PE, they’re on sale.

    Thanks, the more info I can be provided the better so thanks!

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