Welcome to the Subwoofer Tests forum!
This is the place to get accurate and comparable info how different subwoofers measure against each other. Many magazines (both paper and online) also measure subwoofers, but their time is limited and not too many subwoofers gets measured per year. It is also much harder to get one’s favourite subs measured in a magazine, not to mention DIY subs. Also different testing methodologies used by reviewers/magazines often makes comparing results almost impossible. But people are always interested to find out how different subwoofers measure against each other, and also because most specifications released by subwoofer manufacturers themselves are somewhat “unreliable” and hard to compare, I decided to start helping people (and of course to satisfy my own enquiring mind) to find out how they compare using accurate gear and more advanced and versatile tests than many magazines take (sad but true fact).
Since I don’t have access to an anechoic chamber, I'm performing my tests outdoors on a big field with no nearby large reflective surfaces (usually ~10 m distance is considered adequate for testing frequencies down to 10 Hz). Naturally testing ourdoors has its cons like random background noise, wind, ambient temperature, air humidity and atmospheric pressure. All these are unfortunately uncontrollable variables and therefore can and will affect on measurements. The key thing is try to keep their influence as small as possible.
Another great source for accurate subwoofer measurements can be found at AV Talk forum. It should be noticed that our testing methods and rigs are not identical, meaning one shouldn’t compare our results directly.
Naturally measurements are only one part of the subwoofer evaluation. If the particular subwoofer doesn’t sound good in your own room and to your ears, it doesn’t matter how good it looks on paper or sounds to some random reviewer. Measured performance and perceived performance/sound are of course tightly connected, which means that one can have a pretty good picture how a specific subwoofer will perform/sound by just looking at the measurements. Of course the final judgement should be done in your own room with your own ears.
One should not forget the importance of the final in-room frequency response and the integration between the sub and the mains, which IMO are the most important factors (if the max output level is high enough for your needs) when pursuing good bass reproduction. Especially the importance of good/strong mid-bass output from the main speakers is often underestimated. Pair of 5.25” or 6.5” woofers won’t be able to keep up with a strong subwoofer even at 15 dB below reference or higher (in a 15-25 m^2 room), when a typical 80 Hz crossover frequency is used. 80-300 Hz range must be balanced with the range below at all levels in order to have a solid and strong sounding bass. Subwoofer should be just the dot on the i on a system, not the dominating component which around the system is built to.