8 Inch Subwoofers Vs. 10 Inch Subwoofersby David Lipscomb
Although the difference in usable speaker diameter is only two inches between an 8- and 10-inch subwoofer, sometimes the difference in power handling and overall attributes makes a big difference. However, since two subwoofers of identical size may be built significantly different than the next, you will find that there are more important issues involved with subwoofers than mere cone size.
Voice Coil Diameter
Eight and 10-inch diameter subwoofers will often have differently-sized voice coils. The voice coil is the metal wiring that transfers amplifier power to an electromagnetic field, causing the driver to move forward and back. Voice coil size is often directly related to power handling. Remember that although this is commonly the case, you should always pay attention to power handling and low frequency performance expressed in hertz more than simply speaker size.
Low frequency extension is measured in hertz, and you are looking for the lowest possible number. For example, a subwoofer that descends to 18 hertz produces more low visceral bass than a sub going down to 22 hertz. This is true regardless of cone area. Enclosure size in this case often makes more of an impact than driver size, due to the way speakers respond in enclosures. Larger enclosures usually assist in low frequency extension, while smaller enclosure save space but sacrifice extension. Consult the sub's documentation to see the type of enclosure for which the sub is designed.
The more power the subwoofer can handle typically translates into how far the driver can move, called excursion. This in turn translates to the amount of bass energy the subwoofer can produce. Since bass is largely a function of how much air the speaker can pressurize in a given space, it follows that the farther a speaker moves, the more air it displaces. This results in lower, more powerful bass. Given two identically built 8- and 10-inch subwoofers, in theory the 10-inch model should displace more air. Lesser subwoofers generally have lower excursion, given their weaker suspensions and materials.
In car audio, a phenomenon called cabin transfer naturally reinforces bass response. This is due to the relatively small space the listener sits in. In this environment, a single 8- or 10-inch subwoofer is sometimes indistinguishable. However in a home audio or theater environment, room size is a critical consideration. Too small of a sub and you hear little bass. Too large a subwoofer and you may either be wasting money or find the sub is harder to place. Between an 8- and 10-inch subwoofer, these considerations are too small to make a significant difference. However, adding a second identical subwoofer of either size in spaces over 3,000 square feet largely mitigate the natural peaks and valleys in bass response.