The Last Word In Tremolo Stabilization
(Note: You can now buy the Göldo BackBoxes here in the U.S.)
Back in the 80's, when Floyd Rose and Kahler both came out with their tremolos, it was the dawn of a new era for guitarists. Up until then, people made do with the Fender-style bridges which had many problems. Most importantly, the Fender bridges would cause your strings to go awfully out of tune any time you used it, due to the strings slipping over the nut and the bridge saddles when you dove with the tremolo, and then not slipping back to their exact place when you returned the bridge to its normal playing position. I call this the "inconsistent slippage" problem. I once read an interview with Eddie Van Halen where he described life before Floyd Rose. Eddie had figured out that he could return the tuning of the guitar to something usable if, after each tremolo dive, he did a ghost bend of certain strings to "yank" them back over the nut and bridge saddles.
Floyd Rose and Kahler ended all of that when they came out with their bridges. Both solved the "inconsistent slippage" problem in different ways. Kahler used rollers at the bridge to make slippage really easy, so it became more consistent. Floyd Rose took the opposite tack, by clamping the strings right at the saddles, thus eliminating any slippage whatsoever. Problem solved.
But they introduced a new problem. Both the Kahler and the Floyd Rose were "floating" tremolos, which meant that you could pull up on the bar just as easily as you could push down on it, and the bridge was normally held in a sort of "equilibrium" position somewhere between full forward and full back. At this spot, the tension in the strings exactly matched the tension in the tremolo springs, and everything was fine...
... until you did anything that upset this balance of tensions. Certainly, breaking a string would disrupt this balance and cause the tremolo to tilt backward and pull the other strings up and out of tune. It turns out that other, more-subtle things would cause the tremolo to shift, as well. Bending a string would rock the tremolo forward and pull the other strings down (a problem when doing unison-bends). Resting your hand against the body of the bridge could tip it back and raise the pitch of the strings. (In fact, in my earlier days, I developed a technique where I'd purposely rock my hand back against the trem during string bends to help keep the trem from pulling forward). And a careful ear (or a tuner) could even hear pitch changes when the guitar was oriented from vertical (as in , when playing while standing up) to horizontal (ie, the guitar lying in your lap) as the weight of the tremolo body itself pulled it back just slightly. Lastly, merely tuning your strings with a floating tremolo became an arduous task as the adjustment of any one string affected the others.
Due to its simplicity (and probably to better marketing, too), the Floyd Rose became the tremolo to have. There are loads more Floyd Rose tremolos out there than Kahlers these days. That, combined with the fact that the Floyds have a design similar to the Fender-style bridges, results in the case that almost all of the various solutions for stabilizing tremolos have been aimed at the Floyd Rose/Fender market.
So, how do they work?
It turns out that, when you look at the physics of them, all tremolo stabilizers work the same way, by creating a discontinuous force curve exerted by the spring system.
Okay... so what does that mean?
See, a normal spring has what we call a force curve that we'd call "continuous". That means that, if you pull a little bit on the spring, it stretches a little bit. If you pull a little more, it stretches a little more, etc. etc. In other words, no matter what length you've stretched it to, it will always stretch a little bit more if you pull a little bit more, and it will shrink just a little bit if you pull just a little bit less. To put it one last way, any change in the stretching force on the springs will cause a change in their stretched length.
In a tremolo, your guitar strings are what are creating the stretching force on the springs. If you bend the strings a little bit, that increases the total stretching force on the springs, so they stretch just a little bit, and the tremolo rocks forward and the other strings go flat. Or, if you're tuning your guitar and you tune one of the strings down, this decreases the stretching force on the springs, the springs shorten a little, the tremolo rocks back, and your other strings go sharp.
The solution to this problem is to somehow devise a system where a change in the stretching force on the springs (ie, bending or breaking a string) does not result in the bridge moving. Well, we could just cement the bridge in place... cover the springs with glue... that would do it, right? Changes in the forces exerted by the strings would no longer cause any stretching or shrinking of the springs, right? Well, yeah... but then we'd have an entirely fixed bridge. If we wanted one of those, we'd have bought one.
No, what we want is a spring system that acts like a fixed bridge for small force changes (like bending a string) yet "gives" and acts like a floating bridge for larger forces (like the player grabbing the whammy bar). This is what I call a "discontinuous force curve".
The way that all of the tremolo stabilizers do it is by pre-stressing a spring. Like I mentioned earlier, typical springs have a "relaxed" position when they have no outside forces on them, and then they gradually lengthen or shorten as you gradually apply more force. Pre-stressing the spring is a technique where you push or pull the spring out of its relaxed position and hold it there with some aparatus which I'll call "the stop". The stop is bearing all of the restoring force of the spring... keeping it from going back to its relaxed position. So, if you are going to move the spring any further, you must first overcome all of the restoring force that was being borne by the stop. The spring won't budge until you overcome all of that pre-stressed force, and then it will behave like a normal spring... stretching gradually further as you apply gradually more force. If you apply gradually less force, the spring will stretch less and less until it returns to the stop and the stop will bear the restoring force of the spring, keeping it from returning back to its relaxed position.
A way to see this happen is to stretch a rubber-band between two nails. Now, grab the rubber-band at one of the nails and pull gently on it. It doesn't move, right. Pull a little harder... it still doesn't move. Not until you pull with a certain force do you finally start stretching the rubber-band further than the nail. Contrast this to a loose rubber-band where, as soon as you start pulling it with even the lightest force, it starts stretching.
Now, springs come in two types. There are tension strings which pull when you stretch them to a longer length, and there are compression springs which push outward when you try to compress them to a shorter length. The kind you have on the back of your Fender or Floyd Rose tremolo are tension springs. The kind you have holding your pickups in place are compression springs. You can pre-stress either kind of spring. You can stretch a tension spring to a longer length than it typically has, or you can compress a compression spring to a shorter length than it normally has.
Since you can pre-stress either kind, you can, conceivably, make a tremolo stabilizer out of either kind. And it turns out that they do. The WD tremolo stabilizer works by pre-stressing a normal tremolo spring and, therefore, uses a tension spring. The other designs all use compression springs, however.
I should also note that the amount that you pre-stress or pre-load the spring determines how much variation in string tension you can have before the tremolo starts to move. In other words, the amount that you pre-stress the spring determines the size of the "sweet spot", the spot at which the tremolo can accomodate variations in tension. With a smaller sweet-spot, you could use a lighter touch on your tremolo bar, but your tremolo would be more likely to go out-of-tune during multi-string bends or deep bends on lower strings. On the other hand, pre-stressing the spring more would give you a larger sweet-spot, where you could probably break a string and still keep the guitar in tune, but you'll have to use a little more force on the tremolo bar to dive and raise when you wanted to. All of the stabilizers reviewed here have a way to adjust the size of the sweet-spot.
So, over the years, I've had the opportunity to sample various methods of tremolo stabilization, and I've wrote a synopsis of each one I've tried (as well as the Tremol-no, which I have not tried... and won't).
|Hipshot Tremsetter||ESP Arming Adjuster|
|Ibanez BackStop||Goeldo BackBox|
|WD Tremolo Stabilizer||Tremol-no|
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Goeldo BackBox now for sale in the U.S.
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