Tremolo Spring Noise

Introduction

Before we dig into spring noise, let’s remind ourselves of some basic principles of operation of an electric guitar. When we pluck a string it oscillates at the frequency of the note fretted on the neck. The coils inside the pickups register those vibrations and induce a small AC voltage that oscillates with the same frequency. That AC voltages represents our analog guitar signal. We pass that signal through effects and an amplifier and finally to a speaker which converts AC signal into sound waves through the air that we can register using our ears. So speaking broadly, the pickups’ job is to register any oscillation of magnetic materials in their vicinity and to convert those oscillations into AC signal. Keep that in mind as we proceed.

The next concept we need to be aware of is parasitic oscillations. Electric guitar consists of many parts that are glued or screwed tightly together and across the length of the guitar we have six (or seven or more) tightly strung strings that oscillate as we play. Those string vibrations are going to run across the whole length of the guitar. Each part of the guitar has its own resonant frequency – a specific frequency that will get amplified when applied to that particular object. Each note we play has a different frequency that it resonates to, so as we are playing we are producing a wide range of frequencies that will travel across the length of the guitar. Some of those frequencies may match with resonant frequencies of some of the parts of the guitar and those parts may start resonating on their own and amplifying those oscillations. This phenomenon can cause a wide array of issues on the guitar – dead notes, rattle or buzz on certain notes, squealing noise, spring noise…

Now let’s focus on tremolo springs for a moment. The springs are connected to the tremolo block which is integral part of the bridge. The strings are connected to the saddles which are also part of the bridge. Both the strings and the springs are under tension, so string oscillations can easily transfer to the springs through the bridge. That means that the springs will be highly susceptible to parasitic oscillations. But why should we care? The springs are all the way to the back, far from the pickups. Wrong. The springs are actually pretty close to the pickups, just from the other side. The pickups can register oscillations of metal object on either side of the pole pieces, as they are not directed towards the strings.

Let’s see how we can investigate tremolo spring noise and what we can do to remedy it. I will follow the same steps with detecting and fixing the noise and will record audio samples that could be helpful to you. My Bancika JPM guitar uses Ibanez Edge Zero II tremolo that has five springs in total, coming in three different sizes and they all resonate at different frequencies causing a total mess in the sound.

Unplugged Test

The first experiment we can do with an unplugged guitar. Lean your good ear against the body of the guitar and try strumming few chords hard with a pick and abruptly stopping the ringing of the strings each time. Now try playing a couple of single notes and stopping them abruptly. Do you hear any sound decay as though there was reverb effect added or the sound stops immediately as you mute the strings? If it’s the former, then you definitely have an issue with the spring noise.

I tried to capture this sound by placing my phone against the body of the guitar and recording while playing few chords and open strings. It’s not as obvious as the ear-against-the-body test, but you can still hear clearly how some chords and some notes leave much more “reverby” decay reverb than others. Those chords and notes must be hitting resonant frequencies of the springs.

Pickup Test – Clean

This experiment focuses on pickups’ ability to register spring vibrations. Take the tremolo cavity cover off if your guitar has one. Mute all the strings using either your hand or a hair band, or anything really. Plug the guitar into a clean amp without any effects added. We don’t want any reverb, delay or other time-based effects polluting our test. Take a guitar pick and scrape across the springs. Do you hear anything through the speaker?

I have recorded both the clean and distorted tests with few chords strummed at the beginning just so you can have a reference for how loud the spring noise is compared to the actual sound of the strings.

Let’s analyze the clean sound first. The scraping noise is definitely audible in the middle part of the clip. Then stopping the chords abruptly the reverb is very faint, much less compared to the acoustic test we did first.

Pickup Test – Distorted

Now try adding some distortion, the more, the better. One of the side-effects of the distortion is compression. Specifically, we are interested in compression applied to quiet sounds that are now amplified many, many times. Does the scraping noise get worse? In my test it does. Under high gain distortion, the scraping is almost as loud as the sound coming from the strings. Take a closer listen to the last part of the sample where I played the chords. The decay is there on pretty much anything I play but is the loudest on those chords and notes that we identified in the unplugged test, as those are hitting the resonant frequencies of the springs.

Taming The Springs

Now that we establish there is an issue, we need to fix it somehow. I tried few different approaches that I read about over the years but the one that is the simplest proved to be the most effective. The goal is to prevent the springs from resonating, but do not affect their ability to expand and contract freely. The remedy comes in the shape of packing foam that I cut in small sizes and insert it in between the wood of the body and the springs. Not too tight, but tight enough to maintain constant contact with the springs and not to fall out. I did that to all five springs and voila, the noise is gone.

After applying the fix, repeat both the tests and observe the difference. If done properly, hopefully the noise should be gone.

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    The idea behind this site is to share my experience with Do It Yourself approach to guitars, amplifiers and pedals. Whether you want to save a couple of bucks by performing a mod or upgrade yourself instead of paying a tech, or want to build your own piece of gear from scratch, I'm sure you will find something interesting here. Also, this is the home of DIY Layout Creator, a free piece of software for drawing circuit layouts and schematics, written with DIY enthusiasts in mind.