We engineered a high efficiency type of ported box, then set about engineering a speaker to optimize the box energy. We keep the moving mass low, energy high and add a suspension with high restoring force to help control cone motion. Instructions on how to use AJ Vented Designer to design speaker enclosures or boxes. The following graph from WinISD, compares a ported sub (The Sidewinder) with a sealed box using the same driver and amp. Notice how the port augments the output as the response from the driver is rolling off.
The design approach enhances the reproduction of the lowest frequencies generated by the woofer. Ported speakers stagger two resonances, one from the driver and boxed air and another from the boxed air and port, in order to achieve their bass output, a more complex case than an equivalent sealed box. Sealed cabinets are much easier to design and build than ported enclosures and are typically smaller in size. Also, there’s less control below the box tuning, which allows the cone to move more freely. When you went to smaller boxes, you lost bass and/or efficiency. Today at Ohm, we employ both the sealed and vented designs, utilizing the strengths of each in particular applications.
This works with the woofer to generate more bass than a sealed box. The vented-box design article has three related goals. The first is to present an algorithm that provides a more flexible way to design a vented-box loudspeaker for a given driver than the techniques specified in the classic vented-box design literature. Subwoofers in sealed boxes play tight bass, while ported boxes sound boomy. Travis, a Graphic Designer at Crutchfield for over 12 years, decided to join the fun, too.
Design considerations for DIY Subwoofers. In the case of vented systems, a too-large box may introduce a response peak around the the resonance frequency of the system. 2nd order sealed enclosures are simple to design and offer outstanding performance in a wide variety of applications. Sealed boxes can be half the size of vented boxes yet can be made even smaller if a higher Q is allowed. It should give you some insight into subwoofer box design. While designing a subwoofer box, many will model a vented alignment using BassBox Pro, WinISD, or a variety of other enclosure modeling software. Sealed vs. ported subwoofers is is one of the great debates in the audio world. The simplest type of subwoofer to design and construct, sealed subwoofers consist of a driver, an enclosure, and an amplifier; the driver is responsible for 100 of the system’s output. Frequency response of driver X modeled in boxes with a Qtc (system Q) of 0.5 (critically damped), 0. Vented box loudspeakers were patented by Albert Thuras, a Bell Labs researcher, in 1932. Earlier this year, during Winter NAMM 2014, Thuras was inducted into the TECnology Hall of Fame for this invention.