Creating the Stetsbar vibrato

"The music we were playing at the time meant I had to carry around my Les Paul, my 335 and my Stratocaster, all of which are fine instruments," says Eric, "but my passion is the Gibson guitar with the humbucker sound. I would have loved to put a vibrato system on that guitar, but there wasn't much available. The Bigsby system was developed in the early '50s and Paul Bigsby did a great job, but as guitar playing demands have changed a lot since then, I didn't think it would do what I wanted to do. Other options, such as fitting a Floyd Rose, would mean carving into the instrument, and as it is a '71 Custom, I didn't want to destroy the guitar not knowing what the result was going to be.

I've been a machinist now for over 35 years and own a small machine shop, so decided in the late '80s or early '90s to try to develop one of my own. After several prototypes hitting the trash can, and an early version that used a rack and pinion gear, I finally came up with a design that performed the way I wanted it to and that could mount using the stop-bar stud mounting points already on the guitar. The engineering is all done in the US, except the bridge unit itself, which is a Gotoh part. I also contract out processes, such as plating, and buy in bearings, but essentially we build the product ourselves.

In my design, the bridgeplate skates on the mounting plate so the bridge and string termination point move together when you operate the trem. This approach eliminates many of the moving parts that cause tuning and string-breakage issues — you're not dragging the strings over the bridge saddles or using rollers that may buzz or seize."

"The next stage was to develop the Pro II," says Eric. "The original Stetsbar Pro was a fully floating trem with a full octave drop on the low E-string and a third on the pull-up. But the disadvantage of a fully floating setup for some players, especially country players, is that when they're finger-bending strings, the other strings drop in pitch slightly. What the Pro II does is allow you to adjust the trem so it splits the action of down from up by preloading the springs and then, as a unit, moving both the springs and the rear stop back on the pull-up. Essentially, when you drop the pitch you're working against the springs, but when pulling up you're working against the string tension. If you break a string, the others stay in pitch, and you can bend strings without having to worry about the others going flat. You can still set the trem for conventional floating operation, but if your playing style demands, you can just make a simple adjustment and you're done."

Inevitably, unless set up fully floating, the feel of the trem changes slightly when you move from bending down to bending up, as it does with some other designs that address this pitch issue. Having the choice to select fully floating or Pro II-style operation is clearly important, so as to give players the option to adjust the trem to their playing style. The adjustment is done simply by tweaking a couple of screws using an Allen key, and the spring tension is also adjustable to allow for different string gauges.

The Stetsbar Pro II comes in a number of finishes and with a couple of different mounting options, but it just isn't possible to make a trem system that can retrofit to any guitar without having to modify the instrument or make new screw holes in it. Eric designed the original model to fit his Gibson Les Paul, and apparently Gibson adopt a standard spacing for their bridge and stop-bar geometry, so the Pro II will fit the vast majority of their instruments. Eric tells me he's only seen around two percent of Gibson instruments that differ from this spacing, though the Epiphone range has a slightly different stud spacing, as it is built using metric measurements, rather than the imperial used by Gibson.

"We solved that one by making the mounting holes very slightly slot-shaped so that they can accommodate both Gibson and Epiphone stud spacing," explains Eric. "We also make versions for hard-tail instruments, including one with piezo saddles that will fit the Line 6 Variax, mounting into the existing screw holes. The same hard-tail design is compatible with hard-tail Fender thinlines, Strats and some Ibanez models. We also make a version for a Telecaster where our bridgeplate replaces the original, again mounting in the existing holes. I still adhere to my original concept of offering a product that won't wreck somebody's guitar by forcing them to modify it — I'm not going to change that, though we also produce an OEM model that can be fitted to new guitars during manufacture."

As my main guitar is a Fender Strat, I'm curious to see whether Eric has considered designing a retrofit unit that would fit into the standard Strat-routed trem cavity to improve on the trem unit that is fitted as standard. "There are a number of existing aftermarket solutions — such as the Super-Vee trem — that already provide an improvement on the standard trem," he tells us. "From a mechanical point of view, we believe we could provide a good solution. Our challenge, however, with our use of what we call a Nashville bridge, would be to make something that aesthetically fits the look of the Stratocaster. We have been asked to consider this a number of times, but at the moment a Strat version doesn't figure in our current plans."

The fixed baseplate and the moving bridgeplate are separated by small, German-engineered, roller-bearing raceways that need no lubrication, which accounts for the incredibly smooth sliding action, while the pivot assembly for the arm movement is supported on two small ball-race bearings. A locator block made from reinforced MDS nylon holds the swing link — they use it for timing gears in the automotive industry, so Eric figured it would be tough enough.

The screw thread for the removable arm is a good fit, which is important to eliminate play, and a compressible O-ring provides the necessary friction to keep the arm in place during use. In all, this is exactly the approach I would expect from an engineer working in metal and is far removed from the trem units on most of my own instruments, where the fulcrum comprises a simple steel plate that rocks on half a dozen wood screws with not a bearing in sight!

"I also wanted the Pro II to look good," says Eric. "And it had to be easy to use, so the strings mount from the top through slots, rather than being threaded through a sustain block."

Having a trem system that is close to mechanically perfect may not be a complete solution to tuning problems, as the strings can still hang up at other friction points. Gibson guitars have an unfortunate design feature in this respect, as the strings break away from the nut at a significant angle to reach the tuning machines and this area of the instrument has been known to create tuning problems even on non-trem instruments. "A good guitar tech will be able to shape the nut slots to minimise friction," says Eric, "You can change to a graphite nut and you can use a good lubricant, such as Big Bends Nut Sauce, which I swear by. Gibson guitars are not designed for a trem, so I always tell my customers that they may need some nut work, but once that is done the system works very well."