Martin Guitar Internal Sound Beam Structure Reveals

Let’s take a look at the names of the various parts.

1.Top panel 

2.BRIDGE PLATE

This is generally made of maple wood, because maple is hard enough to carry the strength of the bolt for strings, its shape and size are very sensitive to sound and size.

3,4. X-BRACING

The X-brace keel support can be said to be the mainstream. Martin’s FORWARD SHIFTED Brace means that the center point of the X-shape moves forward to a distance of about 1 inch 

from the sound hole.

5.TONE BARS

To support the X-bracing, its shape, size and position are very elegant, and it has a great influence on the panel vibration, so it also determines the tone.

6.SIDE TONE BARS

To support the X-bracing, its shape, size and position are very elegant, and it has a great influence on the panel vibration, so it also determines the tone.

Look at Martin’s several mainstream sound beam structures:

1.STANDARD X-BRACING Non-Scalloped, like Martin D-28 guitar.

2. STANDARD X-BRACING Scalloped, such as Martin HD28 guitar. Its X-shaped bracing TONE BARS AND SIDE TONE BARS have been cut, 

this part is done by hand.

3. A-FRAME like Martin D16 guitar

This is Martin’s relatively new sound beam structure, which is different from the above two. The treatment of X-BRACING and TONEBARS is carefully compared with the above two, and it is found that this is uncut, but from a certain part, it is gradually cut toward the end. The shape of BRIDGEPLATE is also different from STANDARD. The X-shaped keel, BRIDGTONE BARS forms a relatively closed ‘BOX’, which reduces the use of TONEBARS and will have different performances for the sound. Its part above the sound hole is not the same as the traditional structure, and the structure is A-shaped, which is also the origin of the name of the sound beam structure. In addition, this structure is somewhat different from the traditional STANDARDX-BRACING neck connection.

2.Hybrid Scalloped A-frame bracing, such as Martin HD16RA guitar, Martin D1GT guitar. The sound beam design of the hybrid structure uses a standard X-BRACING Scalloped structure  below the sound hole, and the sound hole is designed with A-FRAME. The tone should be similar to the second tone beam structure.

5. TOP PLATE

This is the first and second X-BRACING part of the sound hole. TOP PLATE should be used to strengthen the front end of the panel, and the neck is connected to the front end of the TOP PLATE. The difference between the design of the A-FRAME and this is obvious. It is now uncertain whether the different neck joints are designed for different sound beam structures or because of the different neck connections. This is a question of whether there is a chicken or an egg first, although the neck is plugged-in. 

6. The picture below is what the Martin HD28 guitar looks like inside. You can see the X-shaped bracing. TONE BARS is cut, BRIDGE PLATE is marked with MARTIN LOGO.