The guy wrote: "... when you're talking about MOVING AIR then the sensitivity is almost irrelevant.
With low frequencies the dominant limitation is the volume displacement of the woofers. You can have all the sensitivity and all the thermal power handling in the world, but if you don't have the volume displacement to make use of them then they're no good to you."
Keeping it short and sweet:
99% of the sensitivity specs you read are marketing department fabrications. There are no bass cabs currently on sale (August 2013) which have higher sensitivity than ours when comparing equal sized enclosures, fact.
I'm not sure that's true, but maybe more applicable to direct radiators than FLH's.
Here's my rational.
Sensitivity is sensitivity. Higher sensitivity means less power amp requirement to drive it to the same or higher output level as a cab with less sensitivity.
It doesn't matter if sensitivity as a cab spec is inflated by the company as such (other than trying to compare specs to another companies product).
If it does have higher sensitivity, it will need less power to drive it to the same or higher output level than any cab that has less sensitivity.
Having higher displacement is simple method of comparing 1 driver to (a number of) smaller drivers.
For example:
In the T39 plans it says something like 1 x Lab 12 will have the same output as 3 x BP102 drivers.
That makes sense within itself. The Lab12 has greater displacement and greater maximum output than BP102 loaded T39's.
However, now compare max output in a T39 (ie the same cab) loaded with either the Lab 12 or the 3012lf.
In this cab, sensitivity, regardless of driver, is the same.
Lab 12 Vd is 659cc
3012lf Vd is 496cc
So, given the higher Vd, the Lab 12 should win right?
Nope, max output is the same.
So is displacement limiting, ie the max safe voltage for each driver.
And so is the high pass point of the cab.
So, that extra Vd in the Lab 12 has given you absolutely nothing in that scenario!
Except you've added a significant amount of weight to your cab.
No lower frequency reproduction, no extra output.
Power compression can be eliminated as a variable to some extent, as every driver will experience power compression.
If old mate's musings were true, the Lab 12 would have won...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel. Bunter's Audio and Lighting "like"s would be most appreciated...
Ozmirage wrote:
The guy wrote:
when you're talking about MOVING AIR then the sensitivity is almost irrelevant.
With low frequencies the dominant limitation is the volume displacement of the woofers. You can have all the sensitivity and all the thermal power handling in the world, but if you don't have the volume displacement to make use of them then they're no good to you.
That's half true. Sensitivity is just as relevant as displacement. It's the product of the two that determines output, not one or the other alone.
There are no bass cabs currently on sale (August 2013) which have higher sensitivity than ours when comparing equal sized enclosures
That's also half true. From a given size direct radiating cab you can have higher sensitivity or you can have lower extension. You just can't have both. If sensitivity is higher then there's less low frequency extension, and vice versa.
99% of the sensitivity specs you read are marketing department fabrications.
True. If the claims made aren't accompanied by SPL charts to back them up they should be dismissed.
