This Tremsetter installation was requested by the customer so that he could easily replace a broken string on his Charvel whilst gigging, without upsetting his tremolo setup.
There are several variations of this device on the market but I reckon this one is one of the easier ones to install and setup.
Basically, the middle spring of the tremolo is moved one place towards the 6th string end of the block. The Tremsetter is then installed in place of the middle spring. Then, with the tremolo inits neutral position, the Tremsetter is adjusted for length and locked off using the locking screw.
After the Tremsetter installation, when changing strings or replacing a broken string, the same tension is maintained on the tremolo, holding it in its “neutral” position.
