We talk about tone woods a lot, but Guitarsmith Richard Stanley contends the most important tonal contributor to a guitar's sound is in the bridge and saddles.
Stanley: Well, not to dismiss the input from neck and body wood, but on guitars like solidbody electrics — guitars with relatively massive bridges, the bridge is unquestionably the dominant element contributing to the instrument's basic string tone or voice. More exactly, this voice is defined by the balance among the various overtones in the string's vibration pattern. This is particularly true in the presence of very massive bridges like the Floyd Rose, Steinberger Trans Trem, and even the Strat's whammy bridge, which weighs almost a pound. When you're dealing with a bridge that massive, the body wood really fades into the background. I wouldn't say that it doesn't matter at all, but it's not the dominant influence. It's a different story with lighter bridges such as a Tune-O-Matic (TOM) bridge on typical Gibson guitars — they only weigh a few ounces, or a lightweight hard-tail Fender bridge with strings through the body. So weight, and density of the wood factor in rather more. In the presence of lighter bridges we start to hear the body (wood, synthetic material, metal, etc.) more. So if you take a typical Strat of either Alder or Ash — all other things being equal, higher mass is always going to equal more sustain — whether the mass is in the bridge or in the body. At the same time, no low mass bridge — no matter what kind of body you put it on, is going to sustain like a high mass bridge does.
Not only is the overall bridge design critical to sustain and voice, but the bridge saddle, at the very end of the string’s vibrating length, is even more so. What you're talking about at that level is called string tone. Or the balance of overtone structure within the strings. To be more technical about it, that's just an expression of the vibrational pattern in the string, and this applies to all guitars, acoustic and electric. This is where to start analyzing the voicing in an instrument. There's the vibrating string, and at its ends, the focus of the energy, it transmits to the instrument. What you first look to in basic design are the ends of the strings, particularly at the bridge. While there are many variables at the other end of the string, the conditions at the bridge are a constant. What you do right there — where the string ends, is more significant that anything else!
So when voicing an electric guitar, rather than looking to the body woods, look at what's right at the end of the string. Is it metal bridge saddles? If so which metal? There's a whole variety, for example, for TOM bridges, construction of titanium, stainless steel, brass, and aluminum are available. Of course the originals were zinc, or so-called pot metal — which I am not crazy about as a bridge material. That said, there's been a lot of bridges (and other guitar parts, for that matter), made using zinc. Different materials contribute to variations in tonal quality. Steel accentuates upper partials yeilding a brighter string tone. That is, if you were to analyze the overtone structure in the string, you'd find that there are more high partials compared to the fundamental, and the lower order partials.
I have had clients who tried and discarded bridges like the Floyd because, while it sustained a lot, they didn’t like what it did to the string tone. A heavy bridge won’t necessarily give you a brighter tone along with sustain. But you can revoice bridges by tweaking the design where the string rests, for example, you could take a bridge that's massive with a lot of metal, and totally roll off the top end of the string tone by sticking in little ivory inserts. I've done a lot of that with jazz player's guitars where the guitar was too bright — that's often a perfect fix for them. Because if you put a softer material in there, it alters the string tone dramatically. Same body — same everything else, so rather than looking at body woods, the bigger determinant is right there at the end of the string.
DRG: So let's try and make this tangible for the player. I come to you with a Les Paul. I want you to help me re-voice this guitar. Which saddle materials are going to take it which ways?
Stanley: Well the zinc bridges are kind of dead. It's not only on the low mass end of the metals that might be used there, but it's also kind of non-resonant as a metal. If you had a bar of zinc, you couldn't really tap it and get a good ringing sound from it. But with brass or steel you could. Brass saddles for a TOM brighten things up a bit, and steel really pushes more in that direction. This company called Pigtail makes really high quality TOM bridge parts. They offer two or three different bridge and saddle materials. Including aluminum, which weighs about half what a standard TOM weighs.
DRG: So if someone comes in wanting more brightness, they could go to steel or brass bridge saddles. If they come in with a steel bridge, and they want less brightness, they might go back to zinc.
Stanley: Right. Or in the extreme in the way of things that are readily available, something like Graphtech which is a low mass graphite composite. The material is also softer and relatively non-resonant. So they'd be an option for someone who didn't want to hear from high end.
DRG: So what would you say if you were to make a guesstimate of the percentage of tonal factor that the bridge plays in the overall tone of the guitar?
Stanley: Well, it is guess, but I would say that no matter what the weight of the bridge is it's at least half of the basic string tone. And more so if it's heavy. And why I always relate it to string tone, is because it applies no matter what kind of guitar you're talking about. Whether the string tone is feeding an acoustic top, or being picked up by coil-magnet pickups, that basic overtone structure is part of identity of the instrument. It's like a person's voice — the characteristics of their vocal chords. And it's very subtle. Even for a bridge like TOM — 50% of it. In other words, you can make changes in the body, or you can make changes in the bridge. And I think you'll find that you can push the string tone around more by changing the bridge design than the body design. Then if you get into massive bridge designs like tremolo bridges, it's 85% - 90% of it.
DRG: So nothing is gonna change your guitar's basic tone more than messing with the bridge.
Stanley: Exactly. That's the bottom line. And it's true of acoustics too.