high efficency 5" midrange

[vacuphile]

Andrew,

Take for example a 5 inch midrange, circumference is about .4 meter, corresponding to a wavelength of 875 Hz. Above this frequency, the driver will move from 4pi to 2pi radiation. This is a gradual shift, so at let's say 1600 Hz, the driver will radiate in the shape of a forward lobe. Outside that lobe, the driver will radiate less energy than inside, but it is a continuum of course. Hence the custom to demarcate the boundary of the lobe where SPL has fallen by a set number of dB.

Now, cross it over to a tweeter, which typically is much smaller. It will radiate in 4pi at crossover, so at different listening agles, the SPL will be constant.

So, now you have two drivers @ crossover, the middriver that has a gradual shift in SPL in function of listening angle, and the tweeter that has a constant SPL at different listening angles. Result: you can only get a flat FR at one specific listening angle.

[Charles Darwin]

I find the easiest way to deal with that is to remember that once the diameter = 1 wavelength the drivers dispersion will have narrowed to 90deg (this quite independent of the cone shape) and use a tweeter with a 90deg waveguide.

[murphythecat8]

Originally Posted by wintermute

I'd be pretty pleased about being able to go to 126L with WAF being taken into consideration

Tony.

Thanks moondog, will read the thread for sure. This audio hobby keeps on getting more and more interesting.
Yeah, 126L is quite big and my WAF situation was risky I can say. In fact, its more like she do not agree but now the wood is cut so there'S no turning back, shell get use to it!