Speaker cone shape

Don't let people under complicate it either, as that is the insanity of dunning-kreueger come to life in the limit ranges of the minds of all humans, as it is wont to. 

Hence the use of the word 'reasonable'.

The hoary common sense aspect.

A human is projected in and out of and filtered by the confines of a fleshy filter box that is animal based, so problems abound in that area...especially so, when exploring limits. Which was my point. To talk and tackle tech limits - is to talk and tackle human limits. 

Eg, at the limits, a ham sandwich is built out of myriad things we definitely don't understand.  Or one can roll it all back, and just eat the damned thing.

I'm beginning to realise there is enough known and unknown to keep your brain occupied for a lifetime :^).

I have just built a set of 3 way units with new 8" Kevlar - 6.5" Kevlar - 4" Silk, and better crossover units. They are rebuilt in a pair of cabinets I already had, I just relined the cabinets with acoustic absorbing material. For some reason, as to which one of you will no doubt enlighten me, they sound even better when the 6.5" are wired out of phase with the 8" & 4".

There are far better forums to ask that question, many specifically on speaker design for DIYers, however, the most obvious answer would come down to phase angle introduced by your cross-over and the driver itself, such that the 6.5" wired in phase, is actually out of phase during the critical cross-over transition regions and is causing suck-out in the frequency response.  


What Vienna Acoustics wrote is no more than marketing. I cone moves as a complete signal unit every bit as much as a flat surface. It is meant to impress people who don't know what they are writing is just market speak.  Sort of like the Phase Technology guy claiming that his drivers are acoustically opaque to the back wave (and others are not), and yet his cone is only 3.1 grams (ignores the weight of the flat piece). If you believe that, I have some swamp land for you in Florida. Don't tell me in marketing speak, show me actual measurements that prove what you claim. If you can't show your driver has lower distortion, more even dispersion, lacks resonances, and can truly block the back wave, then it is just market speak. 


Don't get me wrong, designing a good speaker takes work, but as you will see in DIY sites, people with limited physics knowledge, by building on the work of others, can achieve very significant results.


(Side note, there is technical merit in Dunlavy's time and phase aligned design, however, that does not necessarily translate into higher levels of listener satisfaction. It has technical merit, but it is not proven out to be psychoacoustically critical. <-- Not even 1 area of physics needed.   Dunlavy didn't push the boundaries of any physics in his implementation and most of what was accomplished was "math", i.e. the mathematically modelling to achieve time alignment, but I digress). 

“they sound even better when the 6.5" are wired out of phase with the 8" & 4”... I believe some companies actually do this sometimes to help with phase response in certain designs, not sure though.

A company named Phase Tech made speakers using FLAT woofers. In fact, the owner/designer invented the first dome tweeter!