The ZPS-FX is a tremolo stabilizer integrated into the SynchroniZR tremolo. It was introduced by Ibanez in 2008.
The ZPS-FX (Zero Point System - Fixed) consists of a metal barrel which can be extended or retracted using a thumbwheel. By extending the barrel, the user can eliminate the floating functionality of the tremolo, thus making the tremolo push only (lowering pitch) rather than push and pull (lowering or raising pitch). The barrel is also spring loaded so that it presses against the block forcing it to return to the neutral or zero point.
The Back Stop is a system that is somewhat similar in design but with a pair of spring-loaded barrels which has been used in conjunction with the Edge double locking tremolo. The ZPS designs which are paired with the ZR and Edge Zero double locking tremolos serve a similar function, albeit with a drastically different design.
The SynchroniZR tremolo along with the ZPS-FX have been discontinued as of 2018.
- SV5470F product page, Ibanez Japan (website), archived June 2013
- SV5470A product description, Guitar World (Australian retailer website), archived from the original January 2019