1. Soundpost Materials and Violin Tone:

Spruce produces a soft and rich tone, making it suitable for pianos with overly bright and hard timbres. However, due to its very soft wood, it results in a loss of volume and an unstable tone;  

2. Northeast spruce is suitable in terms of timbre, but less stable than sandalwood. After installation, it requires a period of adaptation to stabilize and is affected by climate conditions;  

3. Camphor wood has a pleasant sound quality, being relatively loud and stable, unaffected by climate conditions. It also emits a fragrant aroma, resists violin worm infestation, but possesses mild toxicity;  

4. The sound of檫木 is excellent, relatively loud, stable, unaffected by climate, and resistant to violin worm damage, though it has slight radioactivity;  

5. American red pine has a decent tone, is relatively stable, and is less affected by climate conditions, but it tends to be somewhat rigid. It is more suitable for instruments with a mellower and overly mellow tone;  

6. The timbre of iron and wood is acceptable, relatively stable, and unaffected by climate, but it tends to be rigid. It is more suitable for instruments with a softer and overly mellow tone;

7. The sound of Manchurian ash is bright and crisp, but noticeably harsh;  

8. The tone of the kettle drum is pleasant, crisp, and bright, but slightly a bit too harsh.

II. The Diameter of the Soundpost and the Tone of the Violin:

When the sound post diameter is 3 millimeters, the soundboard vibrates naturally, producing a clear and bright tone, though it slightly lacks a sense of uniformity and breadth.  

When the sound post diameter is 6 millimeters, the vibration of the soundboard is also very natural, with clear, bright, and even high tones, while the low tones are soft, broad, resonant, and full-bodied, making it the most ideal configuration.  

3. When the sound post diameter is 9 millimeters, the vibration of the soundboard begins to be damped, resulting in unnatural sound quality with noticeable heaviness, numbness, and constrictiveness. This is not desirable.

 III. The Length of the Sound Post and the Tone of the Violin:

1. The distance between the initial contact point (when the lower end of the tuning pin just touches the back plate at an angle without force) and the final contact point (when the lower end of the tuning pin is pressed vertically against the back plate) is nearly zero. This allows the soundboard to vibrate freely, producing the most natural and mellow tone, with only the second string exhibiting a slightly raspy roughness. However, when played forcefully, the tuning pin moves freely; when touching the body of the instrument, the tuning pin easily falls off. This is impractical.

2. When the distance between the initial and final contact points is 3 millimeters, the soundboard vibrates very freely, producing a natural and mellow tone. The rough, hissing sound of the second string is slightly better. However, the sound post is still prone to falling when the body is tapped by hand or the strings are loosened, which is not practical.

3. When the distance between the initial and final touchpoints is 5 millimeters, the soundboard vibrates more freely, producing a naturally soft and beautiful tone. However, when the body is tapped or the strings are relaxed, the sound post becomes less prone to falling. Only one violin experienced slight loosening and displacement of the sound post in humid weather. This is the most ideal scenario.

When the distance between the initial and final contact points is 10 millimeters, the vibration of the soundboard begins to be constrained, resulting in a brighter tone with slightly less mellowness. Even with a slight forceful push from a carving knife, the sound post remains intact, making it relatively ideal.  

When the distance between the initial and final contact points exceeds 15 millimeters, the vibration of the soundboard is severely restricted, resulting in a harsh tone, which is also impractical.