String Spacing Explained: Humbuckers vs Trembuckers

If you’re upgrading your guitar’s pickups for the very first time, here’s a tip which will help you maximize your tone and get the most out of your investment: Seymour Duncan offers most humbucker models in two sizes: Humbucker and Trembucker. But what do these mean, and how do you know which is right for your guitar?

Humbuckers and Trembuckers are actually both versions of the same pickups, and most can be easily identified by their model numbers. For example, the Humbucker version of the Alternative 8 model is named the SH-15, while the corresponding Trembucker variant is the TB-15. But why is a Trembucker called a Trembucker, and how is it different to a Humbucker?

A standard Humbucker’s pole pieces are built according to a traditional Gibson string spacing of 1.930″ (49mm), measured from the center of the high E string to the center of the low E string at the bridge pickup location. But guitars with tremolo bridges – particuarly Floyd Rose style locking bridges, six-screw vintage types or two-point fulcrum bridges – have a wider string spacing of 2.070″ (52.6mm). This means that a pickup designed for a tremolo guitar (or one with the same string spacing) needs the pole pieces to be spaced slightly further apart in order to more accurately sense the vibrations of their respective strings. An early solution to this problem was to simple angle a regular humbucker slightly so that at least one pole piece would pick up each of the outermost strings, but this was a stopgap solution until wider spacing was developed.

This only applies to the spacing for the bridge (sometimes called treble) pickup. By the time the strings pass over the neck (or rhythm) pickup, their spacing has narrowed down, so a Humbucker will be properly spaced for your needs whether you have Gibson or Floyd Rose spacing at the bridge.

If you’re not sure which spacing your particular guitar requires, simply measure from the centre of each of the E strings. If the spacing is two inches (50mm), you require a Humbucker. If the spacing is greater than two inches, you need a Trembucker.

There are a few instances where these rules don’t quite apply: Blackouts don’t have exposed individual pole pieces, so there’s no need for separate Humbucker and Trembucker versions. Ditto for the Dimebucker, Scott Ian’s El Diablo and the Invader. And three models are only available as Trembuckers: the Parallel Axis Trembucker Blues Saraceno, the Parallel Axis Trembucker Distortion and the Parallel Axis Trembucker Original.

As for why guitarists still often use the term ‘tremolo’ (meaning rapid changes in volume) instead of the more accurate vibrato (rapid changes in pitch), that’s a mystery for the ages!