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PAF or Patent Number?

The evolution of the Gibson humbucker, 1956–1965

PAF and Patent Number are often treated as two completely different generations of Gibson humbuckers.

In reality, the change was much more gradual.

The decal changed, but the construction evolved over several years: magnets, bobbins, wire, lead wires and winding methods all changed progressively. That's why two pickups with different decals can be surprisingly similar — and two PAFs can be quite different from each other.

1956–1957 — The beginning

Developed by Seth Lover, Gibson's humbucker first appeared in production in 1956, before becoming widely used on Gibson guitars in 1957.

The basic design was already very close to the classic PAF:

  • Two coils

  • Alnico bar magnet

  • Steel baseplate

  • Adjustable pole screws and fixed slugs

  • Plastic bobbins

  • Metal cover

  • 42 AWG magnet wire

Early examples generally used 42 AWG plain enamel wire, often dark purple or maroon.

Several Alnico grades have been found in early pickups — II, III, IV and V. There was never one single Gibson "PAF magnet recipe."

1957–1960 — The classic PAF

In 1957, Gibson began using the humbucker extensively on models such as the ES-175, Les Paul Goldtop and Les Paul Custom.

The famous:

PATENT APPLIED FOR decal gave these pickups the name PAF.

The classic late-50s construction generally featured:

  • Long Alnico magnet, around 2.5"

  • 42 AWG plain enamel wire

  • Early thermoplastic, commonly identified as butyrate

  • Black, cream or zebra bobbins

  • Nickel-plated covers

The bobbin color was mainly a material/manufacturing variation, not a deliberate tonal choice.

The winding — where the variation comes from

One of the most interesting things about vintage PAFs is that they were not wound to today's level of precision.

The operator had an important role in deciding when the coil was sufficiently full.

So turn count varied.

And that affects more than just resistance:

  • DC resistance

  • Inductance

  • Output

  • Resonant frequency

  • Harmonic response

  • Coil balance

That's why two genuine PAFs can measure differently and still both be completely authentic.

There was no official "8.0 kΩ PAF recipe." Resistance was largely the result of the winding process.

1960–1962 — The transition

Around 1961, Gibson progressively moved from the long magnet to a shorter magnet.

The transition is generally associated with magnets around 2.37", although measurements vary between references and production periods.

This created what collectors often call the Short-Magnet PAF.

Importantly, the decal did not change at the same time.

A short-magnet pickup could still carry a PAF decal.

Late PAFs can therefore show a mix of characteristics:

  • PAF decal

  • Shorter magnet

  • Increasing use of Alnico V

  • 42 AWG plain enamel wire

  • PAF-style bobbins

  • Nickel covers

  • Black internal leads

  • Variable resistance

  • Hand-controlled winding

This is why "late PAF" is a useful term: it describes a transitional construction, not simply a sticker.

1962 — Patent Number

Around 1961–62, Gibson began replacing the PAF decal with:

PATENT NO. 2,737,842

These became known as Patent Number or PAT No. pickups.

There's an interesting detail here: 2,737,842 was not the humbucker patent number. It referred to a Gibson bridge/tailpiece patent. The actual humbucker patent was 2,896,491.

The change was gradual. Old decals were used alongside the new ones, so transitional guitars can even be found with:

  • PAF / PAF

  • PAF / Patent Number

  • Patent Number / Patent Number

The decal is therefore a dating clue, not an exact production date.

Early Patent Number pickups

The first Patent Number pickups can be extremely close to late PAFs internally.

They can still have:

  • Short Alnico magnets

  • PAF-style bobbins

  • 42 AWG plain enamel wire

  • Nickel covers

  • Similar winding methods

  • Similar resistance

In other words, the first Patent Number pickups were not a completely new design. They were essentially a continuation of the PAF, with a different decal.

1963–1965 — A more standardized Gibson

By the early-to-mid 1960s, the construction gradually moved further away from the original PAF.

One major change was the move from plain enamel to polyurethane-coated magnet wire, beginning around late 1963.

Early PAF

42 AWG Plain Enamel
Dark purple / maroon

Later Patent Number

42 AWG Polyurethane
Red / orange / reddish tones

The bobbins, lead wires and winding process also evolved, while production became increasingly standardized.

By 1964–65, typical characteristics included:

  • Short Alnico V magnets

  • Polyurethane wire

  • More consistent winding

  • Black and white coil leads

  • Nickel covers

  • Increasingly consistent resistance

Chrome covers also began replacing nickel around the mid-1960s.

So, what's the real difference?

The easiest way to look at it is:

PAF = a decal.
Patent Number = another decal.

The construction changed progressively underneath them.

The earliest Patent Number pickups can be very close to late PAFs. Later Patent Number pickups gradually developed different magnets, wire, bobbins, lead wires and winding characteristics.

And by the late 1960s, Gibson had moved on to the substantially revised T-Top design.

The important part

Don't judge a vintage Gibson humbucker from the decal alone.

A PAF does not automatically mean:

Long magnet + Alnico II + 8.0 kΩ + a specific number of turns.

And a Patent Number pickup does not automatically mean:

Alnico V + polyurethane wire + completely different construction.

The reality is more interesting.

For dating or reproducing a vintage pickup, look at the whole picture:

Decal + magnet + bobbins + wire + leads + winding + resistance + inductance + baseplate + manufacturing details.