mono Amp Setup

Earlier, on a post, I was told to set the LPF for my mono amplifier to 80hz. So, I bought a Bass Mekaniks CD and played the 81hz sine wave, hoping to fiddle with the LPF until i could tune it out...But I got nothing. I was able to significantly reduce the sub's vibration, but I couldn't get it to stop making any sound. The same was true if I turned the LPF all the way to 50hz (the lowest setting). I even set the Head Unit's LPF to 78hz, but the buzzing still played on. When the Head unit is powered on, but isn't playing, there is no sound at all, so I'm ruling out interference. Am I properly setting the LPF? Or am I going about it wrong? What will solve this problem, or am I all set?~wayland

A filter does not simply cut off the sound, it filters is at a pre-derermined rate.  12 db/octave means that at one octave above the setting the relative volume level is cut by 12db (if it's set to 80Hz that would mean at 160Hz.)  You will still be able to hear it, just not as loudly.  http://www.bcae1.com/xovrslop.htm  You should be able to tell when the volume begins to drop and that is about the correct setting.Support the12volt.com

When you set a crossover to a frequency, it just begins a drop-off.  You could have the amp set to 80 Hz and still hear freqs at 150 Hz and above...they'll just be much softer in volume.  It takes a bit of an ear, but you want to try to set the LPF so that 85 Hz is noticeably softer than 80 Hz, but 75 Hz is the same volume.  So you need test tones in frequencies all around the proposed filter freq. like 65 to 90 Hz. for experimentation to nail the proper point.

I have the test tones.... from 20-99hz on the Bass Mekaniks Reload CD. But basically, all I do is wait until the sound makes the drop off, and I'll be basically set? No external crossover necessary? Or should I consider one?~wayland