Courtesy of Marchand - an interesting little Sine wave generating program

[Cleve]

In another thread, Al Klappenberger posted a link to Marchand Electronics, a manufacturer of active crossovers and filters.

http://www.marchandelec.com

I have been considering adding a subsonic filter on the preamp signal that drives my CF-4s because I didn't want to waste amplifier power on low frequency signals that the these mains won't reproduce when watching movies. Since the CF-4's are rated to at the Klipsch site 34 -20000 hz, +/- 3db, I originally figured I'd want a filter that cut in around 30 hz.

Well, I found the FG Lite utility on their website. It's a sine wave tone generator that any Win 95 or newer computer can use. Unlike some other tone generators I've installed, frequency can be increased or reduced in very small increments - at lower frequencies less than 1/3 cycle! The other nice thing - it's small (50 kb uncompressed) and doesn't need to be installed - just drag n drop the EXE anywhere

The bottom line - I started at 50 cycles, cranked the amp up to an indicated 10-20 watts per channel, and began dropping towards the basement. I don't have a sound meter, but perceived output does seem to drop a bit once the cycles fall below 33 hz (dunno if that's the non-linearity of my ears, though!) However, the 'shake factor' continues down below 28 hz - I could still plainly hear windows rattling in their frames, pipes rattling in the wall, etc. The rattling level doesn't start to fall until 20 hz, is broken, and the last environmental rattling doesn't cease until 15-16 hz!!!!

I don't know if this is a function of harmonics, or what. At 16 hz, 20 watts continuous, there seems to be some port noise, and a little driver chuffing, but the only think I could hear (and see!) were the picture windows rattling and trembling.

So maybe I'll skip the plan to add a low frequency filter - my speakers may be providing more impact in the 20 - 30 hz range than I thought. Maybe I should filter only below 20 hz?

FG Lite.zip