Question About ER18DXT Bracing

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I am now considering Zaph’s SR71 and Mark K’s ER18DXT for my first build. Both designs use the same Seas ER18RNX (H1456) woofer. I plan to build the cabinets and construct baffles and crossovers to the designer’s specifications for whichever design I choose.

The SR71 is based on a Madisound cabinet with the addition of two dowels side-to-side for bracing. The ER18DXT uses a Parts Express (PE) cabinet which comes with a vertical brace which I understand may make crossover installation a bit difficult.

I would like to know if the vertical brace is necessary for the ER18DXT or if I can brace the cabinet with dowels (similar to the SR71) without a reduction in sound quality?

As usual, I appreciate any comments. Thank you,


  • Madisound SR71 Cabinet.pdf
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  • Parts Express ER18RNX Cabinet.pdf
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I don't actually like the way that PE has oriented that brace in their cabinets - it provides a large surface area closer to the back of the front baffle for the sound to reflect back into the driver. Most frequently you will find shelf bracing oriented in a back to front direction whether or not they go from the top to bottom or from side to side or both. See the B&W matrices for example.

Just fyi, as long as you keep the net internal volume the same for whatever design you choose, you are free to employ your own bracing and damping strategies. So if you add something that takes up more internal volume just increase the depth of the cabinet to compensate. Since both designs need a relatively small cabinet, you don't have to go crazy with bracing. Zaph's strategy is the cheapest, simplest way to take care of it. However it's possible for the single dowels to themselves flex so if you wanted to take it just one step further, you could effectively brace the braces in the vertical and possibly in the horizontal planes as well.

Also if you are constructing your own cabinets, you are free to make the back or the front baffle removable or both, just make sure that you have airtight seals. That may help to overcome any difficulties you have getting the xo's installed.
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