wrote in message
...
That's primarily because most subwoofers aren't: they tend to have
substantial output at higher frequencies anyway. The very low
frequency material could well be in mono, but stuff an octave or
two higher could have substantial difference information, and
that can easily find its way through many subwoofers.

So true, I find it annoying that what we once called simply a woofer, is now
called a "sub woofer" by many manufacturers. Many don't go anywhere near
20Hz, and may go well over 200Hz by design. And many more go there simply
because of inadequate filtering.

MrT.