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Wal preamp schematics (pic)

Discussion in 'Pickups & Electronics [BG]' started by Oreomeister365, Feb 18, 2013.

  1. So I came across this

    which appears to be the schematics for a wal pro bass preamp, quite similar to a normal wal preamp if I remember correctly, well, outside of the whole filter thing. Pulling out the pickup knobs functions differently too.

    What I am curious about is the circled part, which appears to be the switchable pick attack function.

    Having no clue how to interpret a schematic as it relates to tone, is there a way to determine the approx frequency the pick attack is spiking from that schem? 330k resistor into a 2.2n capacitor....if I'm reading that right.

  2. bassplace

    bassplace Supporting Member

    Mar 1, 2009
    Annapolis, MD
    I think the pick attack frequency is 2k. I consider the Pro pre to be different from the filter pre. But I've only played my Pro. Do have an ACG though
  3. 2k seems impossibly low. That's not even treble. Unless you forgot a zero or something.

    But on the flip side, I have an acg as well, I'm pretty much trying to guesstimate where on the treble filter a wals pick attack sits.
  4. ctmullins

    ctmullins fueled by beer and coconut Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
    No it's not.

    Yes it is.

    Preposterous. Adding a zero puts you right at the border of ultrasonic. Past it if you're older than 18, or have been to lots of concerts in your life.
  5. A "normal" wals preamp filters go up to 3k. Putting the "sizzly top end pick attack" at 2k is completely silly. I absolutely do not believe that is the frequency, pro or not. It doesn't make a lick of sense.
  6. T_Bone_TL


    Jan 10, 2013
    NW Mass/SW VT
    It's definitely worth playing with a function generator (can probably find an online/java or downloadable one for free without too much searching - I have hardware versions on the bench) if you suffer from the delusion that 2000 Hz is not treble. Blah, bah, midrange blah if all you've ever done is read stereo magazines. Actually listening will tell a different tale. And it's very worthwhile to track where your hearing cuts off, as it will drop with time and exposure - I'm down around 12Khz now...

    Find a standard piano keyboard. The B&C (B6/C7) that are not hard up on the right edge are either side of 2000 Hz if the thing is in tune. The plinky C (C8) right at the high end is 4186 hz....

    Or - The highest note on a 24-fret 4 string bass is 391 Hz....

    24 fret 6 string bass - 523 Hz

    24 fret 6-string guitar - 1318 Hz.

    (yes there are overtones, and indeed, the tone control is mostly about changing how much of those you hear, but you won't notice much, if any effect from slapping a 10KHz lowpass on a bass guitar, IMHO.)

    Edit - look, I was right. Easy to find one (the first one I found, there might be "better" ones out there...)http://onlinetonegenerator.com

    Ohms * Farads = Seconds
    1/Seconds = Hz

    330KOhm*2.2nF = 726 microseconds = 1377Hz

    or depending what you are looking for/at, 219 Hz for 1/(2*pi*RC) (cutoff frequency)

    Or possibly 2190 if you read something wrong by a factor of 10 - the picture is missing, so I can't try to read it myself.