Project Background

The PI, V.J. Manzo , who also served as the project sponsor, primarily plays Parker Fly model guitars and wanted a 12-string electric guitar with the unique qualities of a Parker Fly guitar: thin, lightweight instruments with incredible wrapped in a carbon fiber exoskeleten that have exceptional resonance and sustain. Parker Guitars never produced a 12-string Fly model (or any other 12-string model) and, in 2015, ceased production of Fly guitars altogether.

We needed to understand the maximum amount of string tension a Parker Fly could handle. Parker Fly guitars most commonly have a floating bridge with a unique flat spring rated for specific string tensions; Flys ship with a set of 9-gauge strings and a “9 spring” installed as well as an additional “10 spring”; additional tension springs up to a “12 spring” could be ordered from Parker Guitars.
Tension spring in Parker Fly rated for a set of 9-guage strings

The Parker Fly comes in several model that primarily differ from one another in the woods used for the body and, in some cases, the neck; we needed to select which of these Fly models would best meet the objectives of this project. The Fly Deluxe, Classic, Supreme, Artist, and Concert, for example, have necks made of basswood; the Fly Mojo has a mahogany neck. Mahogony is a stronger wood than basswood, so, in order to select the right Fly model to use for this 12-string modification, we performed stress test simulations on both basswood and mahogany in order to determine the safe zones for tension before the wood begins to compress.

Through our tests, we determined that, in principle, both basswood and mahogany Fly necks are well within the safe-zones to support the added string tension without causing wood compression.

We needed to design a new bridge to accommodate 12 string saddles. The bridge of most Parker Fly models is capable of switching between two distinct modes of operation: a floating mode in which the bridge is capable of bending forward or backward (down or up in pitch, respectively) with the use of a whammy bar, and a fixed mode in which the bridge locks in position and is only capable of bending forward. A permanently fixed bridge was available on very few early Fly models (not the Fly Mojo).
Parker Fly Floating Bridge

The saddles used on the Fly were nearly identical among Fly models. They were adjustable using a setscrew in the bridge and contained piezo sensors underneath that ran into the Fishman preamp on the inside of guitar.
New saddles in "left right" pairs

In order to improve tuning stability of the bridge, we developed a Fly “bridge block” to replace the tension spring; this effectively turned our bridge into permanently fixed bridge.
Bridge spring to be replaced by a removeable block

We needed to fit six additional tuners somewhere on the Fly headstock, which is quite thin. We chose to set the additional tuners through the top of the headstock with the posts buried into the wood. The tuner string-hole is accessible from small holes in the headstock.
Placement concept for the additional six tuners; shown here with a regular "long-post" Sperzel locking tuner

We developed piezo sensors to affix to the underside of the 12 new saddles.
Piezo sensors developed for our new saddles

We wired each sensors to one of two summing boards and piezo preamps; this gave us the ability to use a volume knob to “shut off” the six higher strings allowing the guitar to function as a six-string or a 12-string.

The guitar nut was replaced with a blank “new old stock” Parker Fly nut purchased online. Eddie Hulse, luthier at Hulse Guitars , carved new nut slots and adjusted the saddle intonation.
Nut blank cut for 12-string