Questions About High Pass Filter for limiting the Bass

[2manyhobyz]

Hi, I've got a question about limiting the bass frequencies to a pair of Magnepan MMG's I recently purchased. These are only good down to about 50 hz. So I was thinking about something simple like a 6 db crossover. These measure about 5.4 ohms. A 470 uf capacitor would start rolling off about 62 hz.
So, I have a few questions, like if the speaker didn't have to interpret a low signal it couldn't reproduce anyway, wouldn't it be better not to let it get there?
Is this a good idea?
Anybody tried this?
Recommended brands of capacitors to try this?
Also, the sub I'm using (Cadence CSX-12) I can adjust the crossover and output for the sub only.
Thanks in advance for the help,
-Jeff

[whgeiger]

Recommend you introduce a active HP filter before the power amplifier driving the Magnepans . Slope should be > 12dB/Oct to reduce diaphragm displacement with decline in signal frequency below the f3 (60 Hz.) you choose. Note that driver displacement increases with frequency decline at the rate 1/(F^2). If the loudspeaker receives these signals, but does not respond to them proportionately, then the energy difference will go to heat instead. Of course the frequency and slope of the LP filter to the subwoofer amplifier needs to be coordinated with the HP filter as well.
Regards,
WHG

[Boscoe]

Yes this is possible and makes it a lot easier to design speakers that don't need the low end response like floorstanders the only thing is that the part required to make these filters are often big and expensive to get half decent ones. Also for a massive reduction in excursion to don't get that much attenuation I have found.