Pulsing high end 'tone' from active bass - help

I have a bass that when all EQ are flat on the active preamp, I get a fairly fast pulsing high pitch sound (not 60 cycles fast). Turn up treble, gets louder/worse. Turn down treble a bit, can’t really hear it.
Everything is grounded to the hilt and then some but don’t think that is what it is. I think it is in the electronics (SIMs pickups & Glockencklang 3-band preamp) themselves but wondering if anyone else has every heard this and what they did to fix it. It seems worse when using the humbucker mode vs. J or P modes.


What else do you have plugging into your mixer? Similar things happen to me with my setup I’m using Filo M11 Pro hi-res player, it was ok at first, then I like to keep the battery top up so I plug in the usb-c, (not that I noticed when it first happened) there’s hissing/interference. I didn’t make the connection, I kept checking swapping the cables. Not til I unplugged the usb the noise went away, lol.

If you have any electronics connected to your system it maybe from that and not the bass, unless you plug directly to the amp, then back to square one, lol.


Does the noise change if you face different directions?

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For some reason that put Stand (REM) into my head


Also check your connectors or different cables.


Not that it helps much, but none of my active preamp basses have this issue.

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  • all my active basses do this except the EB MM HH

  • plugged directly to amp

  • in Boss WAZA

  • goes away if bass is EXACTLY

  • perpendicular to the floor. Any tilt up of the front it starts.

  • turned off pc, lights (LEDs), pedalboard, no change

  • moved to next room over, no change.

I think it’s environmental but have to try out of house, upstairs etc.


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Two things in the room/area I have not unplugged:

  • Ring alarm system (base in room, extender in next room)
  • wifi extender/router (wired into cable variety, not plug into socket repeater).
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I know that cellular pulses can sometimes be picked up by speaker and pickups especially when it is communicating with a tower. Any chance one is near by.

Wifi does work on 2.4 and 5Ghz so maybe the com to and from the router when the high frequencies are jacked.

Last guess is how old are the batteries in the bass? Maybe try a fresh one?

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Also check for dimmer switches or touch activated lights on the same electrical circuits.

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It’s definitely environmental. You’re picking up interference. Got a wifi router hidden somewhere?

Ahh, yep. This is probably it.

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