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Parametric EQ?

Discussion in 'Amps and Cabs [BG]' started by air_leech, May 9, 2001.


  1. air_leech

    air_leech

    Sep 1, 2000
    Israel
    can anyone please explain how these exactley work?
    I espiceally want to know what effect the mid level has on the desired mid frequency band that you have premptively selected.
     
  2. Uh, it boosts or cuts it.

    The parametric and semi-parametric EQs let you select a specific frequency, and boost or cut frequencies in teh area of that center frequency. A fully parameteric EQ will let you control how wide the range around that center frequency is, while a semi-parametric EQ has a fixed bandwidth around the center that's boosted or cut.

    No bass amps that I can think of have a fully parametric EQ--they just have one or more semi-parametric midrange controls.

    Mike
     
  3. Ziggy

    Ziggy

    May 9, 2001
    Orange County, CA
    The Parametric EQ is typically divided into at least half a dozen frequencies. The mids - around 180hz to 400hz - is best left at a neutral or slightly attenuated level.

    The vocals, lower-end of guitar chords, and much of the piano sits in that range. Enhancing those frequncies on your bass will tend to mush it up and put into a 'muddle', almost undectable range with the aforementioned instruments and voices.

    The frequencies you might consider raising - depending on your bass' "natural" sound, your playing style, and the type of music you're performing - are in the 40hz to 160hz. Additionally, to add a little 'bite', try the 600hz to about 2khz range. Anything above that will most likely do nothing more than add additional hiss to your signal... hope this helps.

    ziggy
     
  4. Brad Johnson

    Brad Johnson Commercial User

    Mar 8, 2000
    Gaithersburg, Md
    Boom Bass Cabinets, DR strings
    The old Yamaha PB-1 bass preamps had parametric mids: frequency, Q (or width) and cut or boost.

    Instead of being locked into a frequency, like on graphic EQs, you have the ability to sweep a range of frequencies and zero in on a particular frequency to cut or boost. On a graphic EQ, with sliders for 100hz and 180 hz, you can't adjust 145hz specifically. With parametric you can go to that frequency and completely screw things up;)

    Here's my old amp with 4 band semi-parametric (no "Q" filter):

    [​IMG]

    While Ziggy's recommendations can work in general it's probably best to get an idea of what sound "you" want and then get an understanding of how the controls affect "you" and "your" bass.
     
  5. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    I don't know if they still do, but Peavey used to make several heads and combos with a fully parametric mid control.

    I have a retired TNT 130 that has the whole bit. Center frequency, bandwidth(Q) knob and 15db boost/cut.

    I have never seen an amp with multi band fully parametric EQ, but it seems that Bass Player reviewed an exotic(can't remember the brand) preamp that had 4 fully parametric bands of EQ.

    With four fully parametric bands, imagine how badly a hard core knob twiddler could screw things up.:p

    I used to know a guy with an old Peavey head with the aforementioned parametric mid and a 7 band graphic EQ.

    He loved lows.

    He would set the low shelving control(50 hz) at +15 DB, set the graphic eq 50 hz slider at +15 and set the parametric at ~75hz and boost it +15, on maximum Q.

    He never could understand why his sound sucked so bad, and why he blew up the ampo a few months after getting it when running it at 4 ohms and 80% volume. :rolleyes:It's amazing he never blew the 18" sub he ran it through.
     
  6. RAM

    RAM

    May 10, 2000
    Chicago, IL
    That would be the TC Electronics 1140. It's been around for quite a while. To really mess things up even more, the 2240 is a 2 rack space version of that!:eek:
     
  7. bigguy

    bigguy

    May 2, 2001
    The aguilar Db 680 (preamp) has 2 fully parametric eq bands, in addition to bass and treble shelving type eq. The parametric eq's are voiced differently from each other so that they won't be interactive.One sweeps low mids to high mids and the other sweeps high mids to 7.5.K. This arrangement means that you can make a broad band boost or cut, and not come up with a badly bent tone.

    bigguy