shunting of field through ferrous metal around magnet - problem?

I've built a prototype of an open baffle speaker. I'm supporting the midrange and tweeter drivers by clamping on to the magnet of the woofer with two straps made of (I think) galvanized steel, which is strongly attracted to the magnet. Here's a 1000-word picture:

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Someone in another forum mentioned that this might be shunting some of the magnetic field lines in between the top and bottom plate. The strap is not touching either plate, and doesn't extent over them. I don't see why this would cause field shunting, so I'd like to get some more opinions on this.

Can this arrangement cause some of the field to be diverted away from it's intended purpose in the speaker motor? Any other problems?

Thanks,

-Charlie