Thanks James four your usual thorough and fully documented review. I hope I will have an opportunity to hear these beasts. The design decisions made raise some interesting issues. First, and most obvious, the complexity of the design, including the number of drivers and the unconventional crossover topology, would clearly have been far easier to implement with an active dsp approach, and the results might well have been even better. The explanation is equally clear--active audiophile speakers just aren't very popular, a fact that keeps me in business but is probably irrational. \n\nThe much more complicated issue is that of controlled vertical directivity. Reducing floor and ceiling reflections in a controlled manner certainly has intuitive appeal, and I participated in an experiment with a local electrical engineer to see whether such a response pattern could be implemented in a tower version of my BMR using concepts borrowed from radar radiation theory, which was my friend's specialty. The approach required 7 drivers critically spaced and integrated drivers with asymmetrical crossover slopes, and differing output levels for the two sets of BMR midrange drivers. It could be that the theoretical basis was similar to that used by Perlisten, although as the picture below shows, no wave guide was involved. In addition to the "radar" crossover slopes used to control and restrict vertical directivity, I also developed a perfectly conventional crossover using garden-variety 4th order Linkwitz-Riley slopes with no particular consideration of vertical directivity, which was quite ragged given the layout of the drivers. \n\nThe Radar version of the tower pretty much hit the target radiation pattern, and the vertical dispersion was definitely narrower and more even than for the conventional crossover slopes. I thought the Radar version sounded great--clear as a bell and very neutral. I thought the regular tower sounded great--clear as a bell and very neutral. I just listened to Erin's very interesting interview with Floyd Toole, which touched on vertical dispersion issues. In uncharacteristic fashion, Floyd punted when it came to whether or not there were audible virtues to restricting vertical dispersion. He claimed that people are so used to hearing floor reflections in real life that listeners thought one of his speakers that limited floor bounce just sounded kind of weird. His remarks on ceiling reflections were less focused, but unlike his opinions concerning just about every other aspect of sound reproduction, Floyd just shrugged his shoulders on this one.\n\nAll of this isn't to throw any doubt on the quality of the Perlisten speaker. The measurements pretty much tell the story. But I don't think we're at the point where we can say with any certainty that Perlisten's attention to vertical directivity is an important contributor to James' enjoyment of the speakers. I think we all need to keep an open mind on this issue and recognize that the returns aren't in on this one yet.\n\n\nI tend to agree with your views on this. I would say however that since Jo D'Appolito introduced his MTM configuration, I would say I have a preference for it, but not an exclusionary one. That configuration does favor horizontal dispersion over vertical. Speakers that significantly limit horizontal dispersion have never found favor with me. I tend to believe the main reason these speakers found favor with the reviewers, was because of their superb frequency response more than anything else.\nThe other big issue is getting the bass right. An uncontrolled high Q bass destroys the illusion. So a tight articulate bass, is mandatory for me. To some up, for me if a speaker has a good flat frequency response, with a good transients, wide and accurate horizontal dispersion, and a well defined articulate bass, it will be a winner.\nThe unfortunate fact is that so very few speakers have it all.