Im not sure about bass, but i remember reading somewhere that they did the same thing on early strats because the strings built and used in the 50s where of lesser quality than now and produced less vibration at certain frequencies! Because of that certain poles had to be raised to give a more even volume and response...
Dont quote me on that, im really not 100% sure but im think it has something to do with string quality, thats why later basses and guitars dropped the high poles when string technology caught up.
My guess is that they were designed to follow the fretboard radius to give a more even response. In fact it can be harder to get an even string to string response with them, probably why they were refined to their present state a year or so after the split-coil P PUP was introduced with the raised A's.
They are a very punchy sounding PUP, judging from the '57 RIs I've played.
Thanks all for the responses. Carlos - interesting note about the string quality-makes sense. I'm no expert but if it had to do with fretboard radius it seems they would have raised the "D" poles also(?)
The reason I ask is that I just picked up a '57 reissue ('88-'89) with a Mary Kay finish/gold hardware. Beautiful bass. I put a set of D'Addario Half-Rounds on her and she sings. Very even string response across the board, even with the raised "A" poles.
