World renowned for its full, balanced expression, warm bass and excellent projection, the J-45 has been refined to carry this legacy to new heights. The trick is knowing when you’ve got the neck the way you want it. Playability of the Gibson J-45 is excellent too. If you don’t, the nut can be damaged when you try to turn the wrench. This makes the Gibson J-45 one of the best and most popular flattop Gibsons to ever be produced. Also, since the Gibson J-45 guitar was in production for so long, J-45s are easier to find than most any other Gibson flattop model (lucky for us!) An old-school truss rod bolt at the bottom of the neck (Image credit: Future) When you’re adjusting the truss rod, make sure the Allen key is seated properly in the truss rod nut; push it all the way in. Your guitar must be tuned to pitch using your preferred gauge of strings when you do this and under tension, or it simply won’t be correct. Gibson J-45 Truss Rod Weirdness. Nicknamed "The Workhorse" and first introduced in 1942, this iconic acoustic has become the cornerstone of its round-shoulder, dreadnought line. Here’s how to evaluate and adjust your electric or acoustic neck with a minimum of tools. The J-45 is Gibson's best-selling acoustic of all time. Loosen the nut if the neck is back-bowed. The sound of a J-45 is very warm and fat. The same is true of Fender- and Gibson-style truss rod bolts. The truss rod adjustment on a Gibson Les Paul is done using its brass nut at the headstock end of the neck, located under the truss rod cover (funnily enough). Sight the neck to … Thread starter natebernstein; ... Over the past several months I've started doing basic setup on my various guitars so I tried to adjust the neck relief on the J-45 after hearing the fret buzz (first I took off strings, oiled fretboard and put on new strings - same 12s as before). Tighten the truss rod adjusting nut to straighten a neck that has an up-bow.