Mbiker: I had a very well known "professional speaker repair facility" refoam a set of my F's years ago and they did the same thing. It caused the driver to bind up, resulting in much lower spl capability and limited low frequency output. I had to pay another "professional speaker repair facility" to disassemble the freshly glued ( non-brittle ) surrounds, which did result in damage, and re-install the proper surrounds in the proper fashion. After all of that, this set ran fine after all of the repairs, but not quite as good as my first set that i also still have.
With all of that in mind, refoaming an F is a tough job. MUCH tougher than a standard woofer. For one thing, you can't get around shimming the voice coil with these. Due to the length and mass of the cone, the driver tends to "wobble" in the gap. ANY type of binding due to a lack of centering of the voice coil WILL result in quick driver failure. This in itself isn't a big deal, but looking at the F will tell you how "not easy" it may be to get a shim into the necessary area.
As part of installing the shims, you're likely to encounter the foam damping material that is installed on the INSIDE of the Walsh cone. This foam is probably relatively brittle and may crumble when physically "brushed" as you try to install the shims. The loss of foam will change the resonant, transient and damping characteristics of the driver. Obviously, extreme caution needs to be taken here.
Besides that, you really need use the proper density foam surround for this driver. Due to the aforementioned length and mass of the driver itself, and the way that the driver is mounted on the baffle, the surround acts as a major portion of the suspension of the speaker. Compared to a standard driver that fires horizontally, the surrounds on the F's are working WAY more than "double duty". Use the wrong surrounds and the suspension will either be too stiff ( causing driver binding and a lack of output ) or too soft, with a lack of damping and excessive ringing.
From what i've been told and probably due to some of the reasons listed above, most "professional speaker repair facilities" consider the Ohm F to be the toughest dynamic driver to properly refoam.
With the above info, you may be able to make a more informed opinion of whether or not you are up to to tackling this type of a task.
Other than that, the amount of TRULY "deep" bass that these speakers are capable of is pretty astounding, isn't it? When you say "5 Hz", most people will think that you're joking or exagerating. Those of us with F's that are really working well know exactly what you mean though. I know this because the Ayre Acoustics disc starts off at 5 Hz and my F's are "pumping away" at great amplitude. Enough to shake the house like you wouldn't believe. Sean
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PS... If you want to drop me an email, i can share with you a few competent speaker repair facilities and one to avoid like the plague.
