Evertune Tension Calculator
Precisely calculate and understand string tension for your Evertune guitar system.
The diameter of the string in inches.
The vibrating length of the string in inches.
The desired musical note for the string.
Influences density and thus tension.
The tuning standard in Hz (Hertz).
Target tension in pounds (lbs) to guide string selection. Leave blank to calculate based on tuning.
Calculation Results
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— lbs
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T = (4 * L * μ * f^2)
Where:
T = Tension (Newtons)
L = Vibrating String Length (meters)
μ = Linear Density (mass per unit length, kg/m)
f = Fundamental Frequency (Hz)
Tension is then converted to pounds (lbs).
What is Evertune String Tension?
The Evertune system is a revolutionary guitar bridge that keeps your instrument perfectly in tune, no matter how hard you bend, strum, or pick. It achieves this by using a spring-loaded mechanism that controls string tension. Understanding Evertune string tension is crucial for setting up your guitar correctly with this system, ensuring optimal performance, playability, and intonation. When you adjust your guitar’s tuning or string gauge, the Evertune system compensates to maintain a consistent, set tension. This calculator helps you determine the required string tension for your specific tuning and string setup, or conversely, what gauge string you might need to achieve a desired tension.
Anyone using an Evertune bridge on their electric or acoustic guitar can benefit from this calculator. This includes guitarists of all levels, from beginners learning about their instrument to professionals seeking the most precise setup. Guitar technicians and luthiers will also find it invaluable for ensuring accurate Evertune system calibration.
A common misconception is that the Evertune system *adds* tension. In reality, it *maintains* a set tension. The system works by counteracting the pulling force of the string with a spring. When you tune the guitar, you are essentially setting the point at which the spring’s force balances the string’s tension. Another misunderstanding is that any string will work; however, different string materials and gauges have different densities, directly impacting the tension required to achieve a specific pitch. This Evertune tension calculator accounts for these variables.
Evertune String Tension Formula and Mathematical Explanation
The fundamental physics behind string vibration and tension is described by the wave equation. For a vibrating string fixed at both ends, the fundamental frequency (f) is related to its length (L), linear density (μ), and the tension (T) applied to it. The formula derived from this is:
f = (1 / 2L) * sqrt(T / μ)
To use this for our Evertune tension calculator, we need to rearrange this formula to solve for Tension (T):
1. Square both sides: f² = (1 / 4L²) * (T / μ)
2. Multiply by 4L²: 4L²f² = T / μ
3. Multiply by μ: T = 4L²f²μ
This formula gives tension in standard SI units (Newtons). For practical guitar applications, we often work with pounds (lbs), so a conversion factor is applied.
Variable Explanations
Let’s break down the variables used in the calculation:
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| String Gauge (d) | Diameter of the string. Affects linear density. | inches | 0.008 – 0.070 |
| Scale Length (Linput) | Vibrating length of the string from nut to bridge. | inches | 24.75 – 28.0 |
| Target Tuning Note | The musical note (e.g., E4, A4, C5) the string should be tuned to. | Musical Notation | N/A |
| Reference Pitch (A4) | Standard tuning frequency for A above middle C. | Hz | 430 – 450 |
| String Material (μfactor) | The material and construction of the string, influencing its density. | Material Type | Steel, Nickel, Bronze, etc. |
| Frequency (f) | The calculated fundamental frequency of the string in Hz based on tuning. | Hz | 80 – 1500+ |
| Linear Density (μ) | Mass per unit length of the string. Calculated based on gauge and material. | kg/m | 0.0001 – 0.005 |
| Tension (T) | The force exerted by the string. | lbs (pounds) | 10 – 30 (typical for guitar strings) |
| Desired Tension (Tdesired) | An optional input to target a specific string tension. | lbs | 10 – 30 |
The calculator first determines the target frequency (f) based on the selected tuning note and reference pitch. Then, it estimates the string’s linear density (μ) based on the input gauge and material. Finally, it applies the formula T = 4L²f²μ (after converting units appropriately) to find the tension. If a desired tension is provided, the calculator can also suggest a suitable string gauge.
Practical Examples (Real-World Use Cases)
Example 1: Standard Tuning Setup
A guitarist is setting up their Evertune-equipped guitar for standard EADGBe tuning. They are using a 25.5 inch scale length guitar and decide to use 0.010 inch gauge strings for the high E string. They want to tune the high E string to its standard pitch (E5) with a reference pitch of 440 Hz.
Inputs:
- String Gauge: 0.010 inches
- Scale Length: 25.5 inches
- Target Tuning Note: E5
- Reference Pitch (A4): 440 Hz
- String Material: Steel (Plain)
- Desired Tension: (Left blank)
Calculation:
- The calculator determines the frequency for E5 at 440 Hz A4 is approximately 659.25 Hz.
- It estimates the linear density for a 0.010 inch plain steel string.
- Using the formula T = 4L²f²μ, it calculates the tension.
Expected Outputs:
- Frequency: ~659.25 Hz
- String Density: ~0.0077 kg/m (example value)
- Tension Needed: ~16.2 lbs
- String Gauge Match: Suitable for E5 Tuning
Interpretation: The high E string needs approximately 16.2 lbs of tension to achieve the standard E5 tuning on a 25.5 inch scale. The Evertune system will be set to hold this tension. This is a typical tension for a 10 gauge string.
Example 2: Dropped Tuning with Specific Tension Goal
A metal guitarist wants to tune their 26.5 inch scale length guitar to Drop C (CGCFAD). For the low C string, they are considering using a 0.056 inch gauge string. They prefer a slightly slinkier feel and aim for a specific tension of 22 lbs on this string.
Inputs:
- String Gauge: 0.056 inches
- Scale Length: 26.5 inches
- Target Tuning Note: C3
- Reference Pitch (A4): 440 Hz
- String Material: Nickel Roundwound
- Desired Tension: 22 lbs
Calculation:
- The calculator finds the frequency for C3 at 440 Hz A4 is approximately 130.81 Hz.
- It estimates the linear density for a 0.056 inch nickel roundwound string.
- It calculates the tension required for this string at this tuning.
- Crucially, it compares the calculated tension (~25.1 lbs) with the desired tension (22 lbs).
Expected Outputs:
- Frequency: ~130.81 Hz
- String Density: ~0.045 kg/m (example value)
- Tension Needed (Calculated): ~25.1 lbs
- String Gauge Match: Heavier gauge recommended for desired tension
Interpretation: To achieve the tuning of C3 on a 26.5 inch scale, the 0.056 inch string would naturally result in about 25.1 lbs of tension. Since the guitarist desires only 22 lbs, they would need to select a *heavier* gauge string (e.g., 0.060 or 0.062 inches) to achieve that lower tension at the target pitch. The calculator helps identify this mismatch, guiding the user towards the correct string choice for their Evertune setup.
How to Use This Evertune Tension Calculator
Using the Evertune Tension Calculator is straightforward and designed to provide quick, accurate results. Follow these steps:
- Enter String Gauge: Input the diameter of the guitar string you are using or considering, measured in inches (e.g., 0.010 for a standard light gauge high E string, 0.056 for a heavier low string).
- Input Scale Length: Provide the vibrating length of your guitar’s string, measured from the nut to the bridge saddles, in inches (e.g., 25.5 inches for a Fender Stratocaster, 24.75 inches for a Gibson Les Paul).
- Select Target Tuning Note: Choose the specific musical note the string should be tuned to from the dropdown menu (e.g., A4, D5, C3). This is critical for determining the target frequency.
- Choose String Material: Select the material of your guitar string from the dropdown. Different materials have different densities, which affects the tension required to achieve a specific pitch. Common options include Steel, Nickel, Bronze, etc.
- Set Reference Pitch (A4): Input the standard tuning frequency you are using, typically 440 Hz. Adjust if you use an alternative standard (e.g., 432 Hz).
- Enter Desired Tension (Optional): If you have a specific tension target in mind (in pounds), enter it here. This is useful if you have a preferred string feel or are trying to match the tension across different strings. Leave this blank if you simply want to know the tension produced by the selected gauge and tuning.
- Calculate: Click the “Calculate Tension” button.
Reading the Results
- Main Result (Tension): This is the primary output, showing the calculated tension of the string in pounds (lbs) required to achieve the target tuning on your specified scale length. If you entered a “Desired Tension”, this will indicate if the current setup matches it, or if adjustments are needed.
- Intermediate Values: These provide important details:
- Frequency (Hz): The exact frequency the string is vibrating at for your selected tuning note.
- String Density: An estimated value representing the mass per unit length of the string, calculated from gauge and material.
- Tension Needed: This reiterates the primary result – the calculated tension in lbs.
- String Gauge Match: This offers guidance. If you entered a desired tension, it will suggest if the current gauge is appropriate, or if you might need a heavier/lighter gauge to meet your goal.
- Formula Explanation: A brief overview of the physics and mathematics used in the calculation.
Decision-Making Guidance
Use the results to make informed decisions about your Evertune setup:
- Tuning Stability: Ensure your Evertune system is set to maintain the calculated tension for reliable tuning.
- String Choice: If you entered a desired tension, the “String Gauge Match” feedback will help you choose the correct gauge. For example, if the calculated tension is higher than your desired tension, you need a heavier gauge string. If it’s lower, you need a lighter gauge.
- Playability and Tone: Different string tensions affect feel and tone. Use this calculator to experiment with different scenarios and find what works best for you. A lower tension might feel easier to play but can sometimes sound thinner, while higher tension can feel stiffer but might offer more perceived fullness.
Remember to click the “Reset” button to clear all fields and start fresh, or “Copy Results” to save your findings.
Key Factors That Affect Evertune Results
Several factors influence the calculated string tension and the overall performance of your Evertune system. Understanding these is key to achieving the perfect setup:
- String Gauge: This is one of the most direct factors. A thicker gauge string has more mass per unit length (higher linear density), meaning it requires more tension to vibrate at a specific pitch compared to a thinner string. This calculator directly uses your input gauge to estimate density.
- Scale Length: A longer scale length (distance from nut to bridge) means the string has further to travel. For the same pitch and string density, a longer string requires significantly more tension to vibrate correctly. This is a fundamental aspect of the T = 4L²f²μ formula.
- Target Tuning Pitch: Higher pitches require higher frequencies. According to the formula, tension is proportional to the square of the frequency (f²), so even a small increase in pitch requires a noticeable increase in tension. This is why tuning down requires less tension.
- String Material and Construction: Different materials (steel, nickel, bronze) and construction types (roundwound, flatwound, coated) have different densities and stiffness. Our calculator uses simplified density factors based on common materials. For instance, a brass string would have a different density than a steel string of the same gauge.
- Reference Pitch (A4): While not directly affecting the tension formula itself, the reference pitch determines the absolute frequency of each note. If you tune to A4=432 Hz instead of 440 Hz, all your target frequencies shift slightly, which in turn slightly alters the required tension.
- Evertune Mechanism Settings: Although not directly part of the string tension *calculation*, the physical settings of the Evertune mechanism (spring tension, octave adjustment) are what *hold* the calculated tension. Incorrect Evertune settings can lead to tuning instability even if the string tension itself is calculated correctly. The goal is to set the Evertune mechanism’s spring force to match the calculated string tension.
- String Break-in Period: New strings stretch significantly after installation. The initial tension calculated might be higher than the tension after the strings have settled. It’s often recommended to stretch your new strings gently after installing them and retuning before finalizing Evertune settings.
- Temperature and Humidity: While the Evertune system is designed to combat these issues, extreme environmental changes can subtly affect string tension and the mechanism’s springs. However, for most practical purposes, the Evertune system’s robust design minimizes these effects.
Frequently Asked Questions (FAQ)
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