Mamboni treatment

[plovati]

Da
http://www.diyaudio.com/forums/multi-wa ... esses.html

un interessante tweak parente del EnAbL, ma a differenza di quest'ultimo, realizzato con dei triangolini di feltro sul bordo esterno del cono.

Forgive my simplistic analysis, but your pattern of squares is behaving like a virtual diffraction grid, cause optimal phase cancellation in as much as the speed (and phase) of the wave are shifted as it traverses the stiffer lower impedance square-treated cone surface. Now, this in effect blurs the virtually cone-surround boundary, making the cone appear as an infinitely long transmission line.
(..)
When I conceived the felt approach, the idea of adding progressive mass to the cone to achieve wave termination and simulate an infinite transmission line was the intuition. However, I discovered something unexpected - the felt fabric is incredibly light. In fact, after the felt treatment the Fs of the woofer is lowered no more than 1-2 hz. Yet the wave terminating ability of the felt is extraordinary. I believe there is something else at work here, far more important than mass: the felt consists of thousands of fibers. I believe the fibers are acting as a huge surface and providing for a much more efficient coupling of vibrating cone surface with air. Normally, the cone-air interface is a very inefficient due to the very different acoustic impedances of solid paper and air. The felt dramatically increases the effective surface area of the cone - many tines over.
(..)
One might ask: if the felt is increasing the efficiency of acoustic radiation from the cone surface, why does the woofer not become louder per input watt? The answer is that all these thousands of fibers each cause random sound cancelling phase shifts and are behaving more as a low Q reactive impedance. In a way, the felt fibers are acting as thousands of tiny versions of your EnABL squares. Of course, the low Q results from the fibers coupling well with air and efficiently wicking acoustic energy away from the cone into the air.

Based on listening, the felt surface treatment seems exceptionally selective in damping out the resonant stored energy and perceived white noise that normally plagues the paper cone in its upper pass band. The felt has little effect on the woofer when operating in it's lower pistonic band. The result is an incredibly quiet soundstage and exceptional clarity of midrange separation. Of course, this must be heard first hand to be judged for oneself. Do you per chance live near Pennsylvania?

Un paio di immagini del trattamento sperimentato e proposto dal dr. mamboni:

mamboni.jpg

mamboni2.jpg

[UnixMan]

Interessante! è adatto solo x woofer o anche x LB/FR ?