1991 Europa Electronic noise

[kreinert]

My 1991 5 string Europa has randomly started making intermittent noise, almost digital like a cell phone being too close.  It's not every gig, maybe just a few times in the last 10 shows, and the last time was in a brand-new venue with plenty of good power.  It happens for about 10 to 15 seconds, then goes away for a few minutes.  It gets worse when I face the amp.  I've tried two different amp heads, different cables, and bypassed all effects and pedals to go direct with one cable.  Battery seems to have plenty of juice.  It's loud enough for Front of House and all in-ear-monitors to take notice. 

If it's not something that anyone has experienced, I'm hoping to find someone in Colorado to take a look.  I know Alembic is very backed up on stuff like this, and I'd rather keep it closer to home if possible. 

Thanks for any help!

[David Houck]

Does your bass have a ferrite bead in the control cavity?

[xlrogue6]

There's also an RF mod for the preamp of older non-series instruments like yours. Mica can fill you in on the details of making it happen.

[kreinert]

Photo attached...

[StephenR]

I had the RF upgrade done to the activator system in my Modulus back in 2018. Lots more RF sources around in 2025 than when the I got the electronics package back in 1988.

RF upgrade would be the place to start if you are having noise issues. Mica would be able to tell you if this is something you can have your tech take care of or if the electronics have to go back to Alembic.

[rv_bass]

Sounds like a RF issue, and you do have a ferrite bead, but the molex connector on the center left of your photo looks like it is not connected all the way,  push it in tight and see if that does anything. 

[StephenR]

Good eye Rob!

[mica]

Yeah, like Kent suggests, there is an RF upgrade available that you can do yourself! I underestimated the demand so I'm getting another run of boards made. Will probably be about a month or so until they are ready and I will put them in the online store as "14-pin RF upgrade"
You basically remove the IC you have and replace with a tiny circuit card with the components needed to filter away the high frequency RF and not change the tone of the instrument.

[kreinert]

Thanks Mica!  I'll keep an eye out for the 14-pin RF upgrade.  I tightened the molex connector that Rob pointed out, but at our gig last night I had constant high-pitch noise, which is different than the other intermittent "digital" noise I first mentioned.