
avaserfi
Audioholic Ninja
Firstly, I should point out I don't own an Ultra or F113 and am in no way interested in picking sides on which brand is better. I am only interested in quality of individual subwoofers. If a specific brand puts out an array of quality products so be it, but I am not one to say this sub from brand X performs well so there other subs must as well.If you have not spent any REAL amount of time with the JLAudio Fathom or Gotham products nor the SVS gear or whatever else people want to throw out there that's comparable, I question how you can really have a dog in this fight. I find it absurd that people, who are supposed to be into finding the best sounding gear, are trying to defend their personal purchases or, worse yet, trying to decide what SOUNDS best by looking at graphs or quoting reviewers. Is that what a hobbyist who's interested in great SOUNDING gear does? Now whether or not it's best sounding for the $ or best sounding regardless of the $ or the best sounding/looking gear is up to the individual. That's what these threads are for. All the time I see & hear gear that looks great on paper and think "Yuk!" or "That's OK" and the opposite happens as well where I'm blown away by a product that seems to exceed "specs".
As far as looking at credible 3rd party measurements to determine sound quality of a speaker, subwoofer or other piece of gear I have found this ability extremely useful. While I do realize this sounds like voodoo to most this technique is supported by years of research conducted by various members of the AES. With full understanding of the research offered one will be able to analyze specific types of graphs and correlate them with individual preference. Simply looking at specifications and/or a SPL vs frequency graph is completely insufficient for this end. Depending on the product a slew of information must be gone over. I was able to do this using the tests offered by the Hometheater Shack which are conducted by user name Ilkka.
Despite the rhetoric within the hobby saying that "everyones ears are different" the actual research on the subject has concluded the opposite in nearly all cases. There are a large variety of factors within speaker design that have been near definitively shown to be preferred over others. Examples of this can be seen in obvious things such as a smooth frequency response or less obvious such as low resonance cabinets and smooth off axis frequency response that matches the magnitude of the axial response.
The topic of sealed versus ported is just plain silly. Any well designed sub can be equalized to perform as if it were sealed, ported, open baffle, etc... in a properly treated environment. Again the proper knowledge must be had coupled with a quality equalizer. If one has a dislike for equalization well thats their own mislead prerogative as with proper use of a tool there will be no issues that arise.
As you alluded to a properly applied sealed design is far more expensive to implement compared to a ported subwoofer if high output and low frequencies are desired. The best way to achieve this in a sealed design is use of a extremely linear driver with large excursion, a parametric equalizer and an extremely high powered amp. While an extremely expensive alternative this allows for a small, high output, subwoofer that can reach low.
At the same time there is a large issue with the majority of ported subwoofers on the market as well if speaking in ideals: poor port implementation. Most commercial ported subwoofers use typical round ports which isn't inherently a bad thing, but it can lead to problems in certain circumstances. When playing at high SPL near or around tuning frequency such ports cause large amounts of port compression. There are a couple methods to combat this with the easiest being a simple trick: tune the subwoofer lower. For example, if one is designing a ported subwoofer for music and wants an F3 of 25Hz tuning the subwoofer to 20Hz and applying a crossover at 25Hz will help with the issue of port compression in the intended frequencies. The alternative, but more costly from a production standpoint, is a properly design slot port which is the method I chose in my build. With proper use of rounding and port surface area compression at tuning frequency can be reduced greatly. The issue with this is a properly implemented slot port is far harder to build than a simple rounded port.
As far as my subwoofer build it seems Mike has provided you a link with my build. If you have any other questions feel free to contact me via PM.