Where to go dipole?

[Jonasz]

Hi!
I've been reading this eminent forum for a while now and I'm finally gonna ask a question I've been thinking about.

Looking at successful dipole designs like Phoenix, Orion and the Arvos (when the are finished :W ) they seem to go from dipole to monopole in the 1200-1500 hz region. I wonder if this is the ideal frequency if you are to avoid the room interactions in the best possible way. Would it be sufficient to use dipole to 500-600 hz or do I need to go all the way to 1500 hz?

Jonas

[RonS]

I think that as far as room interaction goes, dipole is usefull below the Schroeder frequency, approximately 200Hz, depening on the room. As far as dipole above that point, it's more about eliminating the box sound, ie. box vibrations, reflections of the rear wave off the box and back through the cone, etc. So you'll have to make a choice, do you only want to minimize room interaction, or do you also want to eliminate the box sound? Perhaps something like the B&W Nautilus above 250Hz to absorb the rear wave would be good, if you didn't want to do dipole all the way up.

Just my 2 cents, from having read a bunch of stuff.

[ThomasW]

For the designs you see here, there's no consideration being given as to dipole vs monopole operation

Our choice of XO frequencies is a function of XOing the woofer below it's first cone breakup mode.

[Jonasz]

Thanks for the answers. Box sound is almost as irritating as room interactions so I guess I will have to go dipole in the midrange too then. Well I live happy with my Phoenix's but I do want to build something of my own too (especially when reading how bad those SS 8554's are... :wink: ). I'm kind of working with an design using SS 8565, W18EX and possibly a Fountek JP3. Any advice on crossover points and slopes? The crossover will be passive between mid and tweeter and the rest active. These will be used from 100 hz and up.

Jonas