question sur jazz bass

non c pas normal les niveaux de sorties doivent être équivalents , la sonorité seule change

la hauteur des micros ça compte oui ! verifie qu'il ne soit pas trop bas .

distance cordes, micro, fender

PICKUPS

Setting pickups too high can cause a number of unusual occurrences. Depress strings at last fret. Using a 6" (150 mm) ruler, measure the distance from the bottom of the first and fourth strings to top of the pole piece. A good rule of thumb is that the distance should be greatest at the fourth-string neck pickup position and closest at the first-string bridge pickup position. Follow the measurement guidelines from the chart below as starting points. The distance will vary according to the amount of magnetic pull from the pickup. Note: Larger string gauges need wider vibrational allowances. If you have a five-string bass or are using heavier-gauge strings, your measurements must be increased accordingly.

                                                 Bass Side                           Treble Side
Vintage style                                8/64" (3.6 mm)                    6/64" (2.4 mm)
Noiseless™ Series                          8/64" (3.6 mm)                    6/64" (2.4 mm)
Standard "J" or "P"                         7/64" (2.8 mm)                    5/64" (2 mm)
Special Design Humbuckers              7/64" (2.8 mm)                    5/64" (2 mm)

non non il me semble que c'est ça sur la mienne , l'action est alors très basse et très confortable

exact , verifiez bien: votre manche, vos pontets et hauteur micros.
c'est la base...