A few years ago I built this OM out of Black Limba and SItka Spruce. I don’t know why, I was just never really satisfied with it. It sounded good enough, but when I started out building it I’d thought that I was onto something. When I first strung it up I was stunned. It exuded everything I’d hoped for. It wasn’t until it had been able to be a guitar for somewhere around a month that I started to really dislike it. The trebles were very displeasing- somehow quiet and shrill all at once. And if you tried to drive it with any sort of heavy handed attack, thats when the wheels really fell off. I hung it on the wall and figured I’d get back to it at some point.

There’s always been something that alluded me about guitar tone- the way we hear and define bass and treble. I can hear bass and I can hear treble. But, what I mean is, I’ve had a hard time discerning or finding distinction between a guitar which is built so stiff and tight that all it can do is produce high frequency sound and a guitar which is built so loosely that it cannot effectively move as a unit to support a good low end, equating to a guitar which lacks low end but provides enough vibrating possibilities to support high frequency vibration. Both cases produce a guitar which lacks bass. And such is the case with this OM. Looking at the braces I wouldn’t say that they were too tight, however I’ve built guitar with braces that were much more stout and that didn’t produce the results I’m after, either. This contemplation went on for the better part of 2 years. Any chance I’d get I’d pick it up, play it, look inside again, sometimes take some wood off of braces, sometimes attempt to add stiffness, add mass…you name it. My latest assumption has lead me to believe that I took too much off in the lattice area and effectively uncoupled the system.

Leading up to this my tops (and backs) have gotten progressively thinner and more lightly braced. It seemed I was headed in the right direction. They were sounding more full, more balanced, better low end, and just an overall more complex and pleasing character. That is until this particular OM. So, in order to get to the bottom of this and allow a major lesson to be learned, I knew I had to be able to get to the area behind the bridge and add some stiffness back in. Getting to it from the sound hole sounded like a nightmare and also very time consuming. So, I decided to cut a big ol’ hole in the end of the guitar and give myself easy access.

Access panels are not anything new. I’d seen plenty of them before, typically on guitars which lack a traditional sound hole in case of the need for future repair. So I loaded a cutting wheel onto my Dremel and went to work opening it up. Once it was cut out I added a new block to the sides to stiffen and frame the new opening. And added some ebony trim to account for the kerf of the saw from cutting it out and the cleanup.

Once the new block was in place and the cover re-installed, I laid down a sound sample just to get an accurate baseline and try to account for any tonal changes that may have occurred just by changing the mass at the tail block. Just to be sure, I even strung the guitar back up with no tone bars or bracing behind the bridge whatsoever, just to further verify my suspicions.

As you can see here I’ve got amazing access to the tone bar area as well as the last brace on the back, not to mention the rest of the guitar in general. Ive removed the old lattice bracing, cut and fit a new one and here you can see it being glued back in.

Tomorrow I’ll be able to take the clamps off and string it back up with the new lattice at full height and get a read on the changes that are occurring tone wise. But what I’m excited about is the chance to voice a guitar with the strings on it and hear the changes not just from a tap, but from the guitar’s actual response to string energy. This is going to be a fun ride.

-Brad