How does this make sense?

[TLEJ]

If I have a box, designed at 33hz, then how do I set my amp?

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• Q Series Monoblock Class A/B Car Amplifier
  
• RMS Power Rating (14.4V):
  
  • 4 ohms: 250 watts x 1 chan.
    
  • 2 ohms: 400 watts x 1 chan.
    
  • 1 ohm: 600 watts x 1 chan.
    

  [*]Optically isolated MOSFET power supply

  [*]LED power indicator

  [*]Variable bass boost (0 to +12 dB bass boost at 45 Hz)

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  [*]Nickel-plated RCA level inputs

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  [*]Input sensitivity:

  • Low level: 200mV-6V
    

  [*]Variable low-pass filter (50-250 Hz, 12 dB/octave)

  [*]Variable subsonic filter (15-45 Hz, 12 dB/octave)

  [*]Frequency response: 10-20,000 Hz

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Low-pass? Subsonic? What's the difference?

[Trey_Dog650]

subsonic rolls off the lower frequencies. so if you set it at 25 then it rolls off at 25 or lowers.

Low pass rolls off the higher frequencies, so if you set it at 80 it will begin to roll off at 80 or higher

I could be wrong tho...

[TLEJ]

I under stand a high/low pass together, but maybe it's the same with sub-sonic and low?..

[Sonic]

subsonic generally set a few Hz below the tuning freq of your box to prevent lower frequency to going to the sub which can present damage. It's like a high pass filter for your sub.

Low pass generally set between 50 to 80 Hz, frequencies from that point down goes to the sub.

hence, the sub can be said to be in band pass playing the frequencies between the two filters.