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Semi-parametric eq?

Discussion in 'Amps and Cabs [BG]' started by Davis Goertzen, Oct 13, 2004.

  1. Hello, everyone, I see that the Fender 400Pro and 800Pro heads, as well as the Bassman 100 and 60, have this feature, and I'm wondering if someone can explain how it works and everything. I'm just curious, is all. Thanks.

    Davis Goertzen
  2. a semi-parametric EQ allows you to adjust not only the level of a specific band, but also its center frequency. it is most often used on mids, with common range being from about 250Hz to about 2kHz.

    a standard EQ only allows you to adjsut the level of a specific band. the center frequency is fixed (not adjustable).

  3. You have two pots. One to choose the frequency and one to cut/boost this frequency.
  4. Lyle Caldwell

    Lyle Caldwell

    Sep 7, 2004
    A fully parametric EQ allows you to adjust the "Q" (area affected) as well. A narrow Q will affect those frequencies near the center point but barely affect surrounding frequencies. A wide Q will affect a lot of frequencies on both sides of the center frequency.

    In the real world, here's where this would be useful to a bassist:

    Say the low mids are too congested and you want to reduce them without losing the lows. You can set a fairly narrow Q and reduce 200Hz by a few dB without affecting frequencies 100Hz and lower. Or if the overall sound is too boxy, you can set a fairly wide Q with a center point of 800Hz, and pull everything from 400Hz to 1200Hz down a bit.
  5. This jpeg is from the SWR SM 900. The BASS and TREBEL controls have fixed frequency centers. The three semi-parametric mid controls have changable frequency centers.
  6. Finger Blister

    Finger Blister

    Jul 8, 2003