Sierra Tower Specifications, Measurements, Pricing

[GaryB]

Harmonic distortion for both tweeters is extremely low and so far below what is considered the audible threshold that I honestly did not see a reason to spend much time evaluating.

Fair enough... I suspected as much.

One more thing comes to mind. I'm not surprised that the RAAL demonstrates excellent horizontal off-axis response... most ribbons do, due to the typically narrow width of the reproducing element in the horizontal plane (20 mm, in this case). It's the vertical dispersion of ribbons which tends to be much more restricted, since the ribbon is typically several wavelengths long (in vertical dimension) at high frequencies. This is likely not terribly significant for the Tower, where the tweeter is at ear level for a seated lstener, but may be a factor for the Tower Center, which might be positioned somewhat lower or higher than the listener. I understand that crossover issues are also important here.

Would you consider publishing a comparison between the vertical off-axis response of the ribbon-equipped Tower Center vs. that of the dome tweeter version?