What is the ideal string tension for a 39-inch spruce-top classical guitar? | KASPAR Guide

What is the Ideal String Tension for a 39-inch Spruce-Top Classical Guitar?

Choosing the correct string tension is crucial for ensuring a 39-inch spruce-top classical guitar performs at its best. This article reviews industry standards and expert recommendations on the ideal string tension for optimal tone, playability, and instrument longevity—addressing frequent questions from guitar professionals and technicians.

Understanding String Tension

• Definition: String tension is the force applied by a tuned string, measured in kilograms (kg) or pounds (lbs).
• Significance: Impacts playability, sound quality, neck and top durability, and intonation consistency(https://berklee.edu).*
• String Types: Classical guitars commonly use nylon strings available in low (light), normal (medium), and high (hard) tension variations.

39-Inch Spruce-Top Classical Guitars: Key Details

• Scale Length: 39-inch classical guitars typically have a 650 mm (25.6-inch) scale length, affecting tension required for standard concert pitch.
• Spruce Top Advantage: Known for responsiveness and a wide dynamic range, spruce-topped guitars pair well with carefully selected string tensions(https://stringjoy.com/guitar-string-tension-chart).*.

Recommended String Tension for Professionals

Optimal String Tension Range

• Normal (Medium) Tension: 75–80 Newtons (8–8.5 kg or 17.6–18.7 lbs) per string is widely accepted for 650 mm scale lengths(https://daddario.com).*
  • Delivers balanced tone, projection, and safe stress levels for spruce tops.
• Low or High Tension:
  • Low: Easier fingerstyle play, less projection.
  • High: More volume, brightness, and sustain, but increases risk for top/neck strain with spruce tops.

Manufacturer Recommendations

• D'Addario EJ45 (Normal Tension): Industry reference set, 75.05 Newtons total tension.
• Savarez 510 CR (Normal): Approximately 80 Newtons total, supports a wide dynamic and expressive range.

Factors Influencing String Tension Choice

• Playing Technique:
  • Aggressive strumming may benefit from higher tension.
  • Delicate classical techniques often favor normal tension for better control.
• Guitar Construction:
  • Spruce is strong yet flexible; normal tension preserves structural integrity without compromising sound.
• Climate & Humidity:
  • Varying environments can affect top sensitivity; normal tension minimizes warping risks.

Professional Tips for Maintaining String Tension

• Regularly Check Neck Relief: Adjust if you notice buzzing or high action.
• Monitor Top Deformation: Excessive tension can lead to warping in spruce.
• Replace Strings Periodically: Old strings lose elasticity, altering tension and response.
• Consult Luthiers: For custom setups or if experimenting with alternative tunings.

Authoritative Sources

• The Physics of the Guitar, Berklee College of Music
• D’Addario String Tension Guide
• Savarez Classical Strings Data Sheets
• Acoustic Guitar Magazine, Industry Comparison Reviews

Quick Reference Table: 39-Inch Spruce-Top Classical Guitar String Tension

Key Takeaways

• Normal tension (75–80 Newtons total) is ideal for a 39-inch spruce-top classical guitar—balancing tonal richness, playability, and instrument health.
• Consult string tension charts and luthier advice for specific needs.
• Avoid consistently using high-tension strings with spruce tops without professional setup.

For further consultation or custom solutions, contact the guitar specialists at KASPAR.