I recently switched from a Lifeline to Full Circle....everyone in the band and a few folks in the audience said my sound was clear and focused. Some of them weren’t even aware I was using a different pickup but mentioned I was easier to hear than usual.
This tracks. The timbres of each pickup are not the same; the Full Circle has a bit of midrange "push," which can help with clarity and breaking through a dense instrumental mix. Whereas, the midrange of the Lifeline is more "open" and subtle, and its bass response is warmer and fuller than the Full Circle.
Which is "better?"
Either may be better
for a particular player based on their band, their bass, or their musical style. A player in a duo or trio might favor the more natural sound of the Lifeline, where their own instrument's sound is not fighting for as much sonic space in the smaller ensemble. But a player in a larger band and/or louder group might do better with the Full Circle, as its more "brash" response helps their bass to not get "lost in the sauce," without having to have their volume in the mix be "too loud" and overwhelming the band/room in other parts of the sonic spectrum.
And in the mix, it still sounds great. It's a common trap to choose a pickup based on what one sounds best to you, playing by yourself in your living room at home. But what sounds best soloed doesn't always work out best in the context of the band - all the subtlety can get overwhelmed by the sheer need to "slot into" the mix of other instruments. Ask a mixing engineer! (Or, listen to one of those YouTube clips of Paul McCartney's isolated bass tracks from classic Beatles tunes - those great bass lines sound AWFUL when listened to naked and out of context!)
This is why it's a faulty premise to ask, "What is the BEST upright bass pickup?" Each one has its pros and cons, and I always find out what the player's needs are before steering him/her in one direction of many.
On a side note, remember that the Full Circle's tone is somewhat "tune-able" - the wheel with the elements inside actually has 4 transducers, arranged in a "cross" pattern. Turning the wheel within a quarter-turn's adjustment actually shifts where those transducers sit (1/8 of a turn changes the "cross" to an "X" pattern, for instance - see below).
Shifting how the pickups are aligned can actually alter the tone through phase adjustments and other changes, so it allows for a noticeable adjustment in tonal response, without making a major change in height/action. I suggest putting a "dot" on the adjuster with a Sharpie marker to allow one to monitor what placements work best (you can also use the entry point of the wire as a landmark).
