Double Bass Original Fishman Pro-EQ?

[Don Hergert]

I'm guessing you're talking about the 60Hz “sub” control on the back of these units...

The user guide I have doesn't even discuss this control. I don't know what it does, but this is what DoubleMIDI said earlier in this thread...

More likely a notch filter for 60 Hz. The bandwidth is probably not too narrow, because the frequency of the AC power that could get blended out that way can vary a bit.

FWIW, there is also a "Phase" control which is supposed to "suppress acoustic feedback and can drastically affect your amplified tone"

 

[Warpeg]

Just wondering, does the sub preset on the underside act as an HPF? If it does it could be a useful backup to my FDeck which I wouldn’t without. My whole sound revolves round Francis’s little gizmo and I get nervous that one day I won’t have it with me, for one reason and another. Anyone?

I experimented with the sub control pretty extensively. While I didn't open up the box to see if it is truly a HPF, I can confirm that it does do an excellent job of controlling subsonic feedback. To test this, I faced my GK rig directly at the front of my bass at high-ish' volume. It began a subsonic feedback loop. As the feedback kept going, I used a screwdriver and slowly turned the control counter-clockwise until the feedback stopped. I began playing again (with the GK rig still right in front of the DB) and never had any more subsonic feedback. The tone was audibly unaffected.