Ok another question.
I have heard that ribbon tweeters are pretty directional another wors if you are not in the sweet spot they don't sound to good, but you use ribbon tweeters on lots of your designs. I have read a review on one or two of your designs that describe your tweeters as open. It must depend on the ribbon tweeter used? I don't think I have ever heard anything with a ribbon tweeter in it, so I guess I am curious. Most speakers in the stores use the round tweeters.
The dispersion issue come up quite often but most people don't seem to understand it very well. The horizontal dispersion of a tweeter is mainly a function of the radiating width. In this case most ribbons reign supreme with typical widths of 1/2" or less. The faceplate can also affect horizontal dispersion on ribbons or domes. If you look at the waveguides / horns used for various drivers you'll see the difference in the top octave response and in some cases also the 5-10K area.
For a dome the vertical dispersion will be the same unless the faceplate is shaped in a way to control the vertical directivity. The shorter / smaller ribbons (Fountek CD3.0, Aurum G2,etc) are longer than a 1" dome so the element has less vertical coverage; however, the faceplate's horn loading and push-pull magnet structures also affect the vertical dispersion. I've found that as long as the crossover is properly executed the ribbons sound fine; in fact, I don't remember ever hearing a complaint from a customer about that.
I've used a variety of ribbons and planar tweeters. The Founteks I like because they perform very well, are durable, and offer a great cost-to-performance ration. The ribbons for the Aurum Cantus and LCY are more fragile but if you are careful in handling / operating them they should work fine. Fountek used to use the same ribbon material but switched to a element and termination that is better mechanically and thermally. The mass is a little higher but unless you're a dog I don't think it really matters
The added internal damping of the ribbon element actually made the Fountek sound better to me when I compared it against the Aurum Cantus. A recent test of the two ribbons in Europe also seems to confirm what I noticed.
Most commercial speakers use domes because they cost less, usually require less components in the crossover, and are more tolerant of abuse. Hope this helps.
