Zayit, There are many pros and cons on wax potting of pickups..There are have been several discussions here in the past..Here is my opinion.
If a coil is wound properly and the bobbin is made correctly, there is no need for potting..In situations where, usually with age, a pickup becomes microphonic and noisey , then waxing potting can sometimes correct these conditions..
However, most everyone will agree that potting does effect the sound/tone of a pickup..Usually by rolling off some of the high end frequency response..Whether or not this is good or bad is a matter of individual taste and opinion..
I prefer a properly wound coil and a tight well made bobbin rather than wax potting..
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Jerry Wallace-2001 Zum: D-10,8+6, "98 Zum: D-10,8+8,Nashville 1000,Session 500 ,Session 400 head only amp,Tubefex,ProfexII, Artesia, New Mexico
http://communities.msn.com/jerrywallacemusic http://www.jerrywallacemusic.com