[BOBBO]

Here's a cool pic showing the interior of a PAF with magnet showing in the middle ! ...






The range of 1956-1961 is usually dubbed the era of early PAFs. These pickups were first used on lap steel guitars in 1956, on Les Paul Gold Top, and Les Paul Custom electric solid-bodied guitars in 1957.

These early PAFs tend to differ from each other significantly in terms of output level and tone - many factors are quoted as a reason for such difference:

Gibson pickup winding machines were manual-operated at that time and had no mechanisms to automatically cut the wire after a set number of turns. Thus the pickups had a different number of wirings and that lead to variation in the output and tone.
Gibson used Alnico magnets in PAFs, the same magnet as used in the P-90. Alnico has several different grades and different magnetic properties (grades 2, 3, 4 and 5 are usually used), and Gibson assigned them quite randomly until the end of the era of early PAFs. The most common of these are though Alnico IV. British pickup designer Tim Mills of Bare Knuckle pickups had spoke with Seth Lover, who revealed this. They had also been found in many order sheets that Gibson oredered many Alnico IV magnets.
Original pickups manufactured in that time are over forty years old and thus their characteristic may have changed significantly over time.
Early pickups were wound with #42 plain enameled wire, this wiring looks purple, as opposed to later varieties.

Since July 1961, Gibson standardized the PAF construction process. A new, smaller Alnico 5 magnetic plate became standard. In about 1963, Gibson switched to polyurethane-coated wire, thus changing the tone yet again, and wire color from purple to red. About 1965-1968, automatic pickup winding machines came into use, thus making pickups that had a consistent number of turns and fixed impedance.

In about 1967, the original PAF design changed, so it became known as a next Gibson humbucker, called T bucker