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Is a phase switch really needed on a preamp?

Discussion in 'Amps, Mics & Pickups [DB]' started by Flat Bass, Sep 28, 2003.

  1. Flat Bass

    Flat Bass

    Dec 8, 2002
    I think I have decided to go with the K&K bass max and one of the K&K small preamps. My whole problem with the fishman bp-100 was feedback. So I want to make sure that this does not happen again. Is this a good setup that is feedback resistant?

  2. While feedback most often cannot be totally eliminated, it can be alleviated simply by changing the position of the bass with respect to the amp (or the PA speakers) - sometimes a foot or less is all that is necessary. With the K&K Bass Max, you might also try flipping the pickup through 180° (I used to do this before I started using the RavenLabs PMB-1, which has a phase-switch built-in).

    Hope this helps -
    - Wil
  3. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    I have the previous model of the Fishman Pro EQ. The phase switch is an easy way of stopping feedback or ringing. A necessity? Most players don't have a phase reverse that I've seen. Handy? Yes!
  4. atunbridge


    Apr 23, 2002
    Devon UK
    I have a phase reverse switch on my Platinum Pro EQ. It is really useful in two types of situations:

    1) Loud gigs, where you can set it to out-of-phase to reduce feedback

    2) Quiet gigs where I like to switch it to in-phase, giving a richer warmer sound.

    Essential? No.
    Useful? For sure.
  5. Touch


    Aug 7, 2002
    Boulder, CO
    I use a two-channel preamp with a Crown mic and a K&K BassMax.

    I find the phase switch EXTREMELY useful since I blend the mic and the pickup signals.

    Depending on exactly how the microphone is positioned, reversing the phase can dramatically alter the tone of the two combined signals, in most cases adding midrange that was phase-cancelled.
  6. If you use two different pickups or a combination of a pickup with a mic, you may get problems with phase.

    Try the switch

    You will notice a problem when one sound combination sounds thinner compared to another.

    It's a time thing.

    Go with the fatter sound! :bassist:
  7. Flat Bass

    Flat Bass

    Dec 8, 2002
    Will Davis,

    What did you mean by flipping the pickup 180&deg?

  8. If you have a pickup that fits in the gap you can refit the elements "upside down" That will invert the phase of the pickup. You will hear no difference by itself but in combination with another pickup or mic you should hear a change in the sound quality.

    180 degrees out of phase means a complete opposite signal. In theory the same signal from two sources will add but if you flip one out of phase they will cancel each other out.

    In practice what actually happens is you get a weaker signal that often lacks bass/depth and may sound harsher
  9. Removing the K&K pickup (it is inserted into one of the wings of the bridge); turning it upside down (180ยบ); reinserting it into the wing of the bridge.

    - Wil

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