Thumb '85 and '87; OBL pickups; sound question
I am the proud owner of two Thumbs, both from the beginning of the making. I bought my first Thumb in the 80's, it is a 4-string model from 1985 with EMG pickups. Its tone and playability is absolutely amazing.


Last year I bought a 5-string Thumb, which I brought for maintenance to Paul's Bass Matters (if you happen to be in the Netherlands pay him a visit in Nijmegen). He did a wonderful job and the bass is ace to play.





The bass is from 1987, the body is a mix of Wenge and Afzelia. It has passive OBL (Bill Lawrence) pickups and a MEC 2 band eq.
In comparison with the '85 4-string the 5-string's output volume is lower and there is less bass. I turn up the bass knob fully and push the low frequencies on my amp considerately to get some low weight. I also realize that the balance in volume output between the strings is not perfect. I have low-B tuning and the D and G strings are both lower in volume than the other strings.
Although it is my instrument of choice when performing, I feel the sound could still be improved, especially when comparing it with the 4-string, which has all the frequencies you could wish for.
I thought about replacing the pickups. Do you have any recommendations for a balanced sound? The pickups are positioned in quite a steep angle in comparison with the strings. Maybe its magnetic poles are not optimally centered below the strings.
Looking forward to some suggestions from your end.