The bridge is a critical part of the tone chain: it couples the strings to the electric guitar.
The contact of the bridge with the top of the guitar determines the amount of string vibration transferred to the body.
Fixed (non-tremolo) bridges, which provide a larger contact surface than tremolo units, allow more of the string vibrations to pass directly into the body.
Therefore, guitars with a fixed bridge tend to sound deeper and more direct than similar instruments equipped with a vibrato bridge.
Tremolo bridges usually attach through posts or threaded screws in the body; this means that the vibrations of the strings are transmitted to the body through a very narrow contact area.
String tension pulls a double-locking tremolo bridge against its pitch-setting posts. Two small, sharp pivots on the bridge provide the sole transfer points for string vibrations.
“Replacing a standard tremolo with a double-locking system will change the sound of a guitar,” Fender legend Dan Smith once told us. “Locking the strings changes the tension. The guitar breathes differently, and that changes the timbre.”
When double-locking tremolo systems were introduced, repairmen adapted them to standard production guitars (see the scars on David Gilmour’s “Black Strat” above.)
Unfortunately, many instruments sounded thin after being fitted with locking trems; the wood and pickups of older guitars did not complement the tonal characteristics of the hardware.
“The Rose tailpiece gets a fine sound,” Eddie Van Halen remarked in a Guitarist interview.
Today, luthiers like EVH (opens in a new tab) carefully consider combinations of woods and pickups to produce instruments equipped with a locking tremolo with better tonal balance.
The metals used in the bridge components contribute to the guitar’s tonal personality.
For example, a die-cast zinc bridge, made by pouring molten metal into a mold, sounds markedly different than a solid steel unit milled from a single piece of metal.
“It definitely makes an audible difference”, renowned luthier Roger Sadowsky (opens in a new tab) tell us. “Generally, solid bridges sound better.”
Brass, often seen as a “tone sink” that robs the string of energy, was once a material of choice – particularly in the 70s and 80s – although 50s Blackguard Tele-style brass saddles have make their return.
Tremolo bridges typically incorporate a block of metal under their base plate; this is called an inertia block or a hold block. It filters the raw vibration of the strings before transmitting it to the body.
“Whether it’s steel or aluminum, it affects the sound of the guitar,” noted electric guitar designer Trev Wilkinson.
“Conventional wisdom says that steel transmits string vibrations with the least amount of added coloration. I think a block of aluminum generally allows more frequencies to pass through unaltered.”
The downward pressure applied by the electric guitar strings bridge saddle influences tone and sustain.
As a general rule, the higher the down pressure, the greater the hold.
“Different methods of attaching strings produce varying degrees of downward pressure,” Wilkinson continues. “Locking bridges provide relatively little downward pressure. String-through-the-body or through-the-block designs exert greater force at the point of intonation.”