phase switch on fishman

[MIKE 450]

I was wondering could anyone explain how the phase switch on my fishman pickup works I don't know when it's on or off I just plugg in and play I never realy worked out why it there I not complaining I love the sound I get, it one of those things that puzzle's me.

[adhamh]

i second that question. my fishman has a phase switch on it...and i dont really understand what it does. but it does sound slightly better when the switch is pushed in. does anybody actually know what the phase switch is for?

[JB]

The phase switch isn't so much an "on or off" thing, more of a position 1 and 2, it's main use is to manage feedback issues in the mid-bass range.

If you're not having any trouble with feedback you may not notice it doing anything.

[chris c]

I usually hear a slight difference between the two positions. One of the two always sounds a little fuller in the bass, which is what I select. If I'm having feedback, I switch to the other position.

[MarkN]

This is from a manual I found on the Fisman website:

NOTCH AND PHASE
These controls work hand in hand to suppress two adjacent ranges of acoustic feedback. When you set them properly, you can play your instrument as loud as you like, feedback free. We use guitar as an example, but the notch filter and phase switch are compatible with all acoustic instruments.

NOTCH
Tune the Notch filter to scoop out the lowest range of feedback when you play bass notes between the open low E string and (up to and including) the fourth fret G# on the same string. This "cavity resonance" feedback can usually be squelched by setting the Notch control between 1:00 and 2:00 on the dial.
Note that for instruments that do not suffer from low frequency feedback, the notch can be defeated by moving the dial to the 7:00 position.

PHASE SWITCH
Flip the Phase switch back and forth until you find the position that sounds best and subdues mid-bass feedback. Mid-bass feedback occurs when you play bass notes above the fourth fret (G#) on the low E string.

Hope that helps,

Mark

[MIKE 450]

Thanks Lads now I feel a lot more relaxed, I'm going to the Waterfront tonight to watch Kris Kersofferson so if Kris shouts out to me in the growd " Michael these bloody US guitar's are feeding back did you bring your Avalon AS-201CE," I'll just jump onto the stage plug in twiddle my phase switch and before singing "me and bobby Mcgee" I'll tell those cowboys you should of bought a Avalon YE HA.

[Jimbo]

By trade, I am a physicist...

The phase switch on the pre amp is probably because it's a model with a undersaddle peizo and an internal mic. There will a slight difference in the time a particular note is picked up by each of the two "pick up" systems. When you add the two signals up, depending on the phase, or time difference of the 2 signals you can get a big boomy sound or a scratchy trebbly sound, or something in the middle, which is what you want You can change the phase by physically moving the internal mic or a neat little bit of electronics can do the same thing.

Hope this helps

[JB]

That's some good info Jimbo thanks for that

Good to know we've someone here we can fire the tough questions at ...

[Jimbo]

You know you can always ask. Whether or not you'll get a coherent answer is another matter!