High action on an acoustic guitar can make playing difficult and uncomfortable. If your strings are sitting too far from the fretboard, they require excessive pressure to play, leading to hand fatigue and potential intonation issues.
Luckily, fixing high action is a straightforward process that can make your guitar more playable and enjoyable.
This guide will walk you through identifying the causes of high action, tools you’ll need, and how to adjust your guitar step by step.
What is High Action on a Guitar?
High action refers to when the strings of your guitar are too far from the fretboard, making it harder to press the strings and play clean notes. Action height is typically measured at the 12th fret:
- Low E string (6th string): 2.5mm to 3.0mm
- High E string (1st string): 1.5mm to 2.0mm
Anything above these ranges is considered high and may require adjustment.
What Causes High Action?
Several factors can contribute to high action on an acoustic guitar:
- Neck Bowing: Caused by changes in humidity or improper truss rod tension.
- Worn Saddle: Over time, the saddle can shift or wear unevenly, raising the strings.
- High Nut Slots: If the nut slots are too shallow, the action will feel higher, especially near the first few frets.
- Bridge Issues: A poorly designed or damaged bridge can increase the action.
- Humidity and Temperature Changes: Wood expands and contracts with climate changes, affecting the neck and bridge.
Signs Your Guitar Has High Action
- Strings feel stiff and hard to press.
- Difficulty playing chords near the nut.
- Intonation issues or buzzing when fretting notes.
- Uneven string height along the fretboard.
Tools You’ll Need to Fix High Action
- Capo: To measure neck relief.
- Allen Wrench/Hex Key: For truss rod adjustments.
- Feeler Gauge or Steel Ruler: For measuring string height and neck relief.
- Sandpaper: To lower the saddle height.
- Shims: To adjust the saddle or nut height.
- Soft Cloth: To protect the guitar during adjustments.
How to Fix High Action on an Acoustic Guitar
Step 1: Check Neck Relief (Truss Rod Adjustment)
The truss rod adjusts the curvature of the neck (relief), which can directly impact action height.
- Check the Neck Relief:
- Place a capo on the 1st fret.
- Press the low E string at the 14th fret.
- Measure the gap between the string and the 7th fret using a feeler gauge.
- The ideal gap is around 0.25mm to 0.5mm.
- Adjust the Truss Rod:
- Tighten (clockwise) to reduce bowing and lower the action.
- Loosen (counterclockwise) to increase relief.
- Adjust in small increments (1/4 turn) and check frequently.
Step 2: Adjust the Saddle
The saddle sits in the bridge and determines the string height. Adjusting it can significantly reduce high action.
- Remove the Saddle:
- Loosen the strings and remove the saddle from the bridge.
- Sand the Bottom of the Saddle:
- Use fine-grit sandpaper (320-400 grit).
- Sand evenly across the bottom of the saddle to lower its height.
- Remove small amounts of material and check frequently.
- Reinsert the Saddle:
- Place the saddle back in the bridge and retune the guitar.
- Measure the action height and repeat if necessary.
Step 3: Adjust or Replace the Nut
If the action is high near the first few frets, the nut may need adjustment.
- Deepen Nut Slots:
- Use nut files to carefully deepen the string slots.
- Be cautious to avoid going too low, as this can cause buzzing.
- Replace the Nut:
- If the nut is too high or damaged, consider replacing it with a properly fitted one.
Tips for Maintaining Proper Action Height
- Regular Maintenance: Keep your guitar in a stable environment with consistent humidity.
- String Gauge Matters: Heavier strings exert more tension, which can raise the action.
- Frequent Checks: Measure the action height periodically and make small adjustments as needed.
- Professional Setup: If you’re unsure, consult a professional luthier for a proper setup.
Common Mistakes to Avoid
- Over-Adjusting the Truss Rod: Turning the truss rod too much can damage the neck.
- Uneven Saddle Sanding: Always sand the saddle bottom evenly to avoid uneven string heights.
- Ignoring Intonation: After adjusting the action, check the intonation to ensure proper tuning.
- Skipping Measurements: Use tools like a ruler or feeler gauge to make precise adjustments.
FAQs About Fixing High Action
Can I fix high action myself?
Yes, with the right tools and guidance, you can adjust the action on your guitar. However, for major adjustments, consult a luthier.
How do I know if my action is too high?
Measure the string height at the 12th fret. If it’s above 3mm for the low E string or 2mm for the high E string, it’s likely too high.
Does high action affect tone?
Yes, high action can make your guitar sound louder and fuller but may also cause intonation issues if excessively high.
How often should I check my guitar’s action?
Check the action height every few months or whenever you change strings, tunings, or notice playability issues.
Can I adjust the action without a truss rod adjustment?
In some cases, lowering the saddle or nut alone can fix high action, but checking the truss rod ensures the neck is correctly adjusted.
Final Thoughts
Fixing high action on your acoustic guitar is a crucial step in improving its playability and sound. By adjusting the truss rod, saddle, and nut, you can achieve a comfortable and balanced string height tailored to your playing style.
Take your time, make small adjustments, and don’t hesitate to seek professional help if needed. With the proper action height, you’ll enjoy a smoother playing experience and better sound quality.