The other thing to remember is that the high frequency noise is HIGHLY location specific - if it's quiet at home it might not be quiet somewhere else. Even if it's been quiet in one place, that place may get more high frequency noise sources, so if you're gigging with a non-upgraded Series I/II, best to bring a backup just in case the HF noise is bad.

1 have  a 1995 series I Europa which is doesn't appear to need the upgrade. I don't recall any issues with hum or interference with it and it's been my most gigged series bass.

Quote from: adriaan on July 21, 2022, 09:17:33 AM

Quote from: gearhed289 on July 21, 2022, 07:02:11 AM
My now former '86 Distillate didn't seem to need it. Always quiet on gigs, at rehearsal, and in the studio.

Older non-Series instruments may require an RF upgrade, but nothing quite as involved as with a Series instrument.

Oops, I somehow missed "Series" in the thread title. 

No hum from my end of things.