Fender Stratocaster HSS volume and tone

The knobs

Volume

Turning it down puts the top part of the track in series with the pickups. That damps their resonant peak before the level drops much.

Tone 1

Works on the neck and middle pickups.

Tone 2

Works on the bridge humbucker.

Switch positions

Neck

The neck pickup alone, with Tone 1.

Neck + middle

Neck and middle in parallel, with Tone 1 on both.

Middle

The middle pickup alone, with Tone 1.

Middle + bridge coil

The middle pickup in parallel with the humbucker’s coil nearer the bridge, so two single coils. The other coil is shorted. Both tone pots are connected.

Bridge humbucker

The humbucker alone, both coils in series, with Tone 2. Its peak sits lower than a single coil’s, near 2 kHz with the 250 k pots.

Coil modes

Series

Both coils in series, the way the pickup is normally wired.

Parallel

Both coils in parallel, in phase. The pickup’s inductance and resistance drop to about a quarter, so its resonant peak moves up and its output drops.

Screw coil

The screw coil alone, with the slug coil shorted, as a coil-split switch does it. The shorted coil still sits next to the live one and pulls a little current through their coupling.

Slug coil

The slug coil alone, with the screw coil shorted. Which coil stays live in a split depends on how the pickup and the switch are wired.

Parts

Neck

The neck pickup’s own voltage, from the string moving in the magnet’s field near the neck. Each pickup’s response is measured against this voltage.

Coil R

5.94 kΩ, The neck pickup coil’s resistance, measured on a vintage-style Strat single coil (5.94 kΩ DC, 2.96 H at 1 kHz).

Coil L

2.96 H, The neck pickup coil’s inductance, measured on a vintage-style Strat single coil (5.94 kΩ DC, 2.96 H at 1 kHz).

Winding C

120 pF, The capacitance between the neck coil’s turns, across its output. A typical figure, not a measurement.

Middle

The middle pickup’s own voltage, from the string moving in the magnet’s field between the other two. Each pickup’s response is measured against this voltage.

Coil R

5.94 kΩ, The middle pickup coil’s resistance, measured on a vintage-style Strat single coil (5.94 kΩ DC, 2.96 H at 1 kHz).

Coil L

2.96 H, The middle pickup coil’s inductance, measured on a vintage-style Strat single coil (5.94 kΩ DC, 2.96 H at 1 kHz).

Winding C

120 pF, The capacitance between the middle coil’s turns, across its output. A typical figure, not a measurement.

Bridge screw

The bridge pickup’s screw coil voltage, from the string moving in the magnet’s field near the bridge. It’s half the pickup’s voltage, since the two coils are assumed to have equal turns.

Screw R

4.5 kΩ, The screw coil’s resistance, measured alone on a PAF-style humbucker (screw coil 4.5 kΩ, slug coil 4.2 kΩ).

Screw L

2.67 H, The screw coil’s inductance, measured alone at 1 kHz (screw coil 2.675 H, slug coil 2.56 H).

Bridge slug

The bridge pickup’s slug coil voltage, from the string moving in the magnet’s field near the bridge. It’s half the pickup’s voltage, since the two coils are assumed to have equal turns.

Slug R

4.2 kΩ, The slug coil’s resistance, measured alone on a PAF-style humbucker (screw coil 4.5 kΩ, slug coil 4.2 kΩ).

Slug L

2.56 H, The slug coil’s inductance, measured alone at 1 kHz (screw coil 2.675 H, slug coil 2.56 H).

Coupling

k 0.127, How strongly the two coils share their magnetic field, entered as k (0 is none, 1 is complete). Measured alone, the two coils add up to 5.235 H, and the pickup in series reads 5.9 H. So each coil adds M = 0.33 H to the other, and k = M / √(L1 L2) = 0.127.

Winding C

140 pF, The capacitance between the bridge pickup’s turns, across its output. A typical figure, not a measurement. It stays the same whichever coils are on.

Volume

250 kΩ, Volume, 250 kΩ audio taper, fed from the switch. Some HSS Strats use 500 kΩ here, which keeps more of the humbucker’s treble.

Tone 1

250 kΩ, Tone 1, 250 kΩ audio taper, in series with the tone cap. It works on the neck and middle pickups.

Tone 2

250 kΩ, Tone 2, 250 kΩ audio taper. It works on the bridge humbucker.

Tone cap

47 nF, One tone cap shared by both tone pots.

Bleed cap

1 nF, Treble bleed cap across the volume pot’s top half. It keeps the treble as the volume comes down.

Bleed R

150 kΩ, Sits in parallel with the bleed cap so the treble lift doesn’t get too big at low volume settings.

Pickups and load

The neck and middle are the measured single coil. The humbucker is two coupled coils with their own measured resistance and inductance, the Les Paul’s. The coil buttons change it in any position. Picking a position sets it back. Pot values and which coil position 2 keeps vary between makers and years. With two pickups on, each one loads the other through its coil. Without the string model, the graph adds them as if their voltages were equal and in phase. On a real string each harmonic reaches the two pickups at a different strength and sign, and that’s what makes the in-between positions sound the way they do. The string model uses a 25.5 in scale, with the pole rows measured from the bridge saddle at about neck 6.3 in, middle 4 in, bridge 1.4 and 2.09 in (the Strat’s neck and middle as measured by Swell Amplification, the bridge humbucker typical, approximate). The neck pickup sits under where a 24th fret would be. The bridge humbucker sits straight across, its two pole rows 17.5 mm apart. Harmonic n reaches a pickup x from the saddle scaled by sin(nπx/L), with L the string length, so a pickup near a node barely picks that harmonic up, and two pickups can cancel it. Each humbucker counts as its two pole rows, half its voltage each, which cancels the harmonics whose wavelength on the string is twice the row spacing. The string is ideal and each pole row is a point under it (a real pickup’s wider window softens the top harmonics). Saddle intonation is left out. The treble bleed option puts 1 nF in parallel with 150 kΩ across the top half of each volume pot. Other values are common too, and you can change both. The cable is about 15 feet (450 pF) into a 1 MΩ amp input.