Quote Originally Posted by mbrooke View Post
Based on an email discussion with Steven mead, the Ultra 4 and the Ultra 3 are the dame depth, the same as a Wick 3. The difference is rim diameter, 26 mm vs. 26.4 mm. The Ultra 4X is a little bit shallower than the Ultra 4. I have had both the Ultra 4 and 4X and did not find much difference between the rims, although some folks have commented that the 4X rim is sharper. Compared to my Wick 4AM, the ULTRA 4X rim is sharper, but it feels slightly larger. Sound wise, I definitely prefer the 4X on my Willson. The 4AM sounds more resonant, but lacks core and has a "tinny" quality to the sound. But, of course, this may not apply to you.

A few years ago I switched from the SM4M to the SM4XM. I tried the regular Ultra (SM4MU) at the same time. I chose the X mainly because of the smoothness in slurred passages. It's effortless. Also the high range speaks very well. The low range takes more work but I have learned to give more breath support and it helped the low range immensely. Our Brass Band recently played the wonderful Peter Graham piece The Torchbearer at NABBA. There is a fantastic solo for Euphonium in this piece that goes up to a Db concert above the staff and down to a pedal C concert. The X allowed me to cover the entire range.