While it is the largest saxophone that it popularly used, it it not the largest saxophone. There are Contra-bass saxophones that are much deeper, and much larger.
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The 2 biggest brands in today's modern times are Selmer and Yamaha.
Keilwerth and Yanagisawa are also in there, but Selmer and Yamaha are the 2 top brands.
We can't forget the past 80 years with...