Guitar Setup

Sunday, November 25, 2012

Acoustic Guitar Bridge Saddle Slot

Breedlove J350

The Breedlove Atlas J350

      I recently purchased another guitar (used), and the deal was so sweet I really couldn't refuse. I already have a Breedlove Atlas dreadnought and a Breedlove Cascade concert with western red cedar top. I happened upon a Breedlove Atlas J350 Jumbo (which is no longer in production), on Craigslist and figured it was worth taking a look. Aside from the excessively high action, the original battery in the onboard pickup preamp and never having been setup properly, it had been played very little.

      After playing the guitar, I decided to make an offer, figuring if it didn't turn out like I wanted I could turn it over and make a couple of hundred bucks. Sure enough, the owner accepted my offer and away I headed home to the shop. As with all my acoustic guitars, the first upgrades are new bone nut and saddle. With an Engleman spruce top and curly maple laminate sides and back (my knowledge of and opinions on the new laminates for acoustic guitars is in another post), I chose unbleached bone to match the finish and fashioned the new nut and saddle.

Unbleached Bone Nut
      The new nut went well, leaving plenty of bone mass to aide in string to neck coupling. When I went to work on the saddle, I noticed the old one fit a little sloppy in the bridge saddle slot and teetered back and forth, but I didn't pay much attention to it knowing I would get the perfect fit I wanted as I shaped the new one. I selected my bone blank, cut, shaped and compensated it accordingly. I installed it in the slot and strung the guitar in great anticipation of an even better sounding J350. I took it to the studio, plugged it into my acoustic guitar amp and wouldn't you know it, uneven string response.

In The Bottom of The Slot

Bridge Saddle Slot Problem

      I loosened the strings, pulled the saddle and checked it. Please visit Accu-Tech Guitar Repair LLC for flatness with a straight edge. Everything looked good, but when I plugged it in again, uneven string response. After going through this process several times, I was beginning to get a little fuzzy. Remembering that the new saddle fit really snug, I decided to lift the UST (under saddle transducer), out and check the saddle slot bottom. Passing one of my bridge slot bottom files over it a few times, all appeared to be OK, that is, until I took a scribe and checked the length of the slot and found a ridge on either side at the bottom. Now remember, the new saddle fits really well, yet the old one was sloppy. Because of the ridges in the edges of the slot at the bottom, the new saddle could not fit down on top of the UST properly.

Unbleached Bone Saddle

Why The Slot Was Defective

      As I pondered how this could happen, it dawned on me that because most all saddles are cut out on CNC machines, the plunge router bits wear out on their bottom edges and cause the bit to leave somewhat of a 'U' shape in the bottom of the slot. I went to work with a very small chisel and my slot bottom file and cut out the edges and leveled them with the file. I installed the saddle checking the new height to make sure my action was not too low. I took it to the studio, plugged it in and got perfect string to string response.

In Conclusion

      This is one area that is not covered in most articles about UST's and why they do not give even response. After this episode, you can bet I check EVERY bridge saddle slot in the bottom edges for ridges and imperfections on all UST installations on my customers guitars, especially when I'm making a new saddle to go along with the new pickup. I also keep two router bits, a 3/32" and a 1/8" that are ONLY for slot bottom leveling and removing ridges in the slot bottom. As of this article, I have used them many times and spend a LOT less time trying to get even string to string response during final testing. I hope this article will help you in your UST installations and problem solving...

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