Bridge and X

[CAI Kabrell]

Have done some research in that topic.

for a steel sting guitar top with no sound hole. how close can the X be placed and were under bridge is the ideal placement

In a guitar design without a soundhole, the X-brace placement is primarily dictated by its structural relationship to the 

bridge rather than its proximity to a soundhole.

Ideal X-Brace Placement relative to the Bridge

• Straddling the Bridge: The lower "arms" of the X-brace should ideally straddle and support the ends (wings) of the bridge.
• The Crossing Point (Apex): The center of the X (where the braces intersect) should be positioned slightly higher (closer to the neck) than the bridge location.
• Structural Support: This placement ensures that the ends of the bridge are directly supported by the braces, preventing string tension from pulling the bridge off or collapsing the top.
• Bridge Plate Intersection: The X-brace arms typically act as a "fence" to help align and contain the hardwood bridge plate (bridge patch) located directly under the bridge. 

Minimum Distance and Forward Shifting

Even without a soundhole to avoid, shifting the X-brace too far forward or rearward changes the tonal response:

• Forward-Shifted: Moving the X closer to the neck (forward) increases the vibrational area of the lower bout, typically resulting in a bassier, warmer, and louder tone, though it may make the top more prone to "bellying up" over time.
• Rear-Shifted: Moving the X further toward the bridge (rearward) provides greater longitudinal stiffness, resulting in a more focused, brighter sound with tighter bass.
• Proximity Limit: In standard designs with soundholes, the top edge of the X is usually located about 1-1/8" to 1-1/4" below the soundhole edge. Without a soundhole, you have more freedom, but builders generally keep the crossing point at least 1" to 2"north of the bridge to maintain a stable "vibrational triangle" between the bridge and the X-intersection. 

X-Brace Angle Considerations

• The 90-105° Range: A wider angle (closer to 100°) increases the lower bout's vibrational area but offers less longitudinal support.
• Narrower Angles: Narrower angles provide more support against the pull of strings but can "choke" some of the lower-frequency vibrations.

Hope this helps.  

Regard CAI 

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