Originally Posted by Archaea
So there is an old myth about subwoofers -- that they get "slower" and less accurate the bigger they get? IE - That a 10" sub is more accurate than a 18" sub etc.
I've not found that to be true. In all your experience testing different subwoofers - is there any truth to size vs. accuracy? They don't get much bigger than 21" inch in non custom equipment. To your ears do the 21" subs seem just as musical and "speedy" as a smaller sub?
If you can find the Dan Wiggins white paper on the topic, it's good stuff.
Woofer "speed", is a function of what you're tasking it to do.
Consider the simple physics; making bass is all about air displacement,.ie small fan spinning fast=big fan spinning slow.Theoretically;
A 15" driver being fed a 20hz tone, to hit 100db@1m
A 21" driver being fed a 20hz tone, to hit 100db@1m
The 21" driver, pumps easily back and forth, twenty times a second.
The 15" driver, pumps hurriedly back and forth, twenty times a second, because it has only half the cone size, and must stroke twice as far to displace the same amount of air. Since the smaller 15" driver has twice the excursion, yet it must maintain it's frequency of twenty outward peaks per second, it must travel at a much faster rate. Thus starting and stopping all that mass at high speed, there is opportunities for overshoot distortions, as the center of the magnetic gap is oftentimes the most linear part. Encountering the farthest most reaches of the magnetic gap is where a variety of non-linearities occur.
Similarly, if you double your system displacement capability
, you're halving each element of the system's work load. Upgrading from one sub, to two like subs, you're halving each components workload.....and slowing down each driver's "speed",.. at any given SPL.
I hope I didn't muddy things up further