Need an amp with a 'turbo' top end

a brute of an ss amp will do the trick

Yes, asuming the speaks are in good working order, you do need a decent quality "brute" of an amp due to inefficiency and difficult load, if you do not already have one.

A high power Class D digital switching amp (250 or 500 W/ch into 8 ohm doubling into 4 ohms) would be most cost effective. This is the route I pursued with the newer large Ohms.

I use a 100W/ch Musical Fidelity A3CR (not class D but doubles into 4 ohms) with good results with the newer Ohm Walsh 5 drivers, but the F is even less efficient, so that may not cut it for you if you want to go loud.

However my understanding is that Fs suck power but canalso be damaged easily if overdriven, so be careful.

The F's, are an original and classic work of engineering. There is nothing else in the world quite like them. If your Fs are in good shape, you have a very unique work in your possession. I'd keep them and get the right electronics in place to drive them properly. If not, they will be difficult but perhaps not impossible to get repaired back to original specs or better.

You might consider having Ohm upgrade them to newer series 3 drivers if you just want to go for a more modern design that is less finicky and easier to just enjoy. I believe this can be done with F's for as little as ~ $1000 or less for smaller 100 series 3 drivers or as much as a few grand for the larger 300 or 5 series 3 drivers. Which drivers exactly to get would be determine dlargely by your room size. I have had good results with both smaller 100 and larger 5 series 3 drivers in a moderately larger size room.

Realize though that the newer series 3 drivers are technically superior than the Fs in terms of specifications (including efficiency, ability to go loud, and top end extension), but are a two way design with a different omni-directional dispersion pattern, so they are not quite the same as original Fs.

I am not sure yet what I am going to do but I am taking all of your advice into consideration.

-Donn

Donnwags,

If you want to give the Fs a go and keep the investment minimal up front, you might pick up a used Musical Fidelity A3CR like I did for $600-$700 and give it a go.

From there, three things could likely happen:

1) you're satisfied with what you hear and are done

2) you get the improvement you're looking for but want to go louder. Then you could sell the A3CR and get something similar but with more power, like a more powerful MF or a more powerful class D amp, without taking much if any loss

3) you're not getting any closer to what you are looking for. In this case either sell the Fs or replace them or upgrade them via Ohm and keep the A3CR. You have a lot of fantastic options with speakers using this amp.

Donnwags,

I also just noticed the you indicated the Fs are modified in some way.

May I ask what the mods are and what they accomplish?