sub distortion?

In a cone driver distortion increases rapidly as the excursion of the cone (travel in and out) increases. Drivers made for subwoofer use generally have a large range of excursion, but it's obvious by looking at a busy subwoofer that the full range is easily used up. The more cone area you have the less excursion is necessary, and therefore the lower the distortion. Large drivers, 12" 15" 18" (and even 30") are most suitable. Multiple drivers also help, and a pair of 10" (roughly equal to one 12") is sometimes used.

The custom design subwoofer systems of my three front channels include three 15" and three 12" cone drivers. Even so, they have less area than my Maggies.

Distortion is very important because it is often harmonic and you hearing is WAY more sensitive at 80 Hz then at 20 Hz! A mere once percent harmonic distortion at 80 Hz from a reference signal at 20 Hz is LOUDER to your ears then the primary signal!

So guess what.....unfortunately most of what you hear from impressive subs is the harmonic distortion (usually around 10% at 20 Hz on good subs and perhaps 50% or more on not such good subs). There is very little out there with less than 1 % THD. Those who shun subs altogether have a good argument for doing so...

Why I perfer bass horns limited excursions allow detail to bass that sub designs lose to excursion and distortions. Also bass horns are always at ease never pushed hard. This again allows more bass detail than subwoofers which need 100 watts or more just to move the cone with such a stiff surround. Toss in the one large null instead of the many peaks nulls that happen with subwoofer systems. This 1 null is located near bass horns so is not a issue at all volume is slightly reduced as you move close to bass horn this is slight and basicaly means bass pressures very even through out room something one subwoofer can not do. And why multiple subs are used in the best HT and music systems. Subwoofers are all about comprimised design small cab thus you need massive power and driver with much excursion that needs boundery reinforcment to generate bass. Trying to get deep bass out of such a comprimised design is mostly sub optimal:)