Bowtie, I am trying to getaway from adding a sub or subs.....
Then you would be well served to get away from mid-bass horn loading your woofer. I don't mean that to sound snarky or wise, just practical.

Most of us here have spent plenty of time pursuing the dream of the widest possible range in a 2-way system, and the majority end up supplementing with a woofer/subwoofer system of some variety.

That said, if i were still hellbent on that mission myself an option i'd like to explore would be a reflex horn that Altec designed for IPC and sold under the Simplex name. It's larger than an 825/828, but smaller than the 210/211, and i wonder how the 9846 engine might morph into that horn/box.

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