Originally Posted by zheka
This stands to reason. But if you were to measure spectral decay in room, you would probably find that 0.3 ms difference between the tweeter and the ribbon in Sierra Towers is insignificant compared to the influence of the room. So the explanation for the difference in sound may have to be found elsewhere.
But I maybe way wrong here. At least this is a measurable difference unlike the HOM explanation Geddes is pushing.
Correlation is not causation, but it just seems to me that time domain performance is an area where direct radiators tend to outperform CDs and may explain what some people are hearing. Just how senstive the human ear is to these differences, I don't know. It would be an interesting study, to say the least. It would be difficult to control the other variables, though. Perhaps the best you could do is conduct controlled listening tests with a horn loaded speaker with an active crossover and use different CDs with different diaphragm materials. At least in this case the on and off axis responses could be kept as close as possible.
I must confess I am not a horn guy, but I am capable of being persuaded. For example, the Danley Synergy Horns intrigue me and I would really like to hear them. They are ugly suckers, though.