I have one modified for BEAD; this '06 Carvin LB-20. I'm also a member of "The Modified BEAD 4 String Bass Club" (yeah, it's a mouthful) that's over on the Strings forum. So..
- Yes, depending on how heavy the strings you want to use are, you will have to widen at least the E string slot to accommodate a B. I initially strung the Carvin with the heavy strings from a 5-string set of La Bella Black Tapes, and all the slots needed widening. But, depending on your string choice, you can count on widening at least one.
- Yes, you will need a full set up done. This is a
major change to your bass. Some things might not need to change
much, but they
will change.
- A lot of people who do this, seem to have a real problem with a floppy B string. Which is odd, because most people with 34" scale 5-stringers don't seem to. But, there you are... A number of people in the Club use a lighter B string than the usual 130-135 that comes with most 5 string sets; they seem very happy with the results. I found the B in the Tapes I was using to be... marginal. It has 65-135 Roto 77 Flats on it now; the B string, IMO, would be kinda floppy, too; but heavy Roto Flats are very, very stiff anyway, so it works out OK. But, you might want to consider a B string in the 125 range, if possible...
- A lot of Club members have had trouble with intonation. 4 string bridges weren't intended for this kind of thing, and some of them just won't work, due to lack of adjustment range. The Hipshot A bridge on my Carvin will intonate with the Rotos OK; it barely would with the tapes. Curiously, nobody with a Fender-style bridge has had a problem at all...
So, yeah; if you want to do this; go for it. Just be aware that, with some strings and some basses, it won't exactly be easy-peasy. But, most of us manage to get it right in the end...
