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In the Forum: Audio Discussions
In the Thread: Exceptional loudspeakers drivers
Post Subject: A little excursion...Posted by jessie.dazzle on: 4/7/2007
I completely agree that in a home setting, even if you love "Drum & Bass" and Hip-Hop, you will never ever use anywhere near 2" of cone excursion.
Romy wrote :
"...what the companies always “forget” to mention is what percentage of their excursion is in the “underhanged” mode..."
According to McCauley, the 6174 has a maximum total excursion figure of 50mm, but in their specs they give a "Max BL Excursion" figure (the linier part of the excursion) of 15.24mm, so this is one case where the manufacturer is quite honest.
According to Aurasound, the NRT 18-8 (what the 1808 has become!) has a similar max excursion, and remains liniar through 18mm of that distance, so it is theoretically a little (2.76mm) better. They both have similarly large and shallow voice coils (each having their own in-house terms to describe the winding). A more substantial difference is a result of the magnet materials ; Aura opting for neodymium, which results in a BL factor of 24.5 T/m, where the McCauley driver is at 15.3 T/m, and gets there using a pair of really big soft iron magnets. The weight of the magnets alone (26 lbs) is nearly as much as the weight of the completely assembled Aura driver.
The other notable difference I see is cone material. McCauley sticks with a natural fiber cone, while Aura uses composites.
Aurasound's spec sheet gives an Fs figure of 25Hz, so 20% higher than the McCauley driver.
To summarize : In the case of the Aura driver, you get the high-Tesla neodymium magnet, but with it you have to take higher Fs, and a cone that has been "reinforced with fiberglass and epoxy". This may appeal to some, but if you think of the cone in terms of resonance, instead of pumping air, you will start to see it differently.
If it matters, the cost of the drivers in the US is close enough in either case for it not to be a determining factor.
In my case, the final decision was tipped by availability, and by McCauleys French distributor, who is really very good (but does not sell directly to the public). The people associated with distribution of Aurasound products on the other hand were in general more difficult, and in all cases added a fat markup.
With regard to baffle size :
In my case (front-firing) : 2ft x 6ft
Driver sits one third of the way up from the floor.
The box is deeper than it is wide... I purposely stayed "small", reasoning that it would be a simple matter to extend the baffle surface (widening it with additional panels), and that it would not be so simple to make it narrower.
I do not detect the need to alter the baffle, so have not yet tried.
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