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Truss rod adjustments | Bridge adjustments | Intonation adjustments | Pickup height | General maintenance

    There are a total of five different adjustments that can be easily done at home or on the road if you take a little time to understand what you are doing. These adjustments are; the truss rod tension, the bridge height, the string spacing at the bridge, the intonation, and the pick-up height. Tools you should have on hand are the following: a l/8th inch Allen key, a .050 (fifty thousandths) inch Allen key, a 5/16ths or 8mm socket wrench, a pair of diagonal or "linesman's" wire cutters and an electronic tuner.

    The first job you will probably need to undertake will be changing your strings. With the bass placed on a flat surface loosen the string tension completely by unscrewing the tuning knobs until the strings are slack. Then, using the 1/8th" Allen key, remove the large setscrews that hold down the ends of the strings at the nut. Put these setscrews in a safe place. Pull on each string while continuing to loosen the tuner knobs until you can lift the ball-end out of its holder in the tuner block. When the strings are off the instrument it is possible for the bridge and nut to fall out of the bass, If the bridges hits the floor the saddles will fall out. Insert the ball-ends of the new strings in the appropriate holders. tighten the "G" tuner knob so that 1/2 the ball-end is hidden in the tuner block. Put the string through first slot in the nut block, replace and tighten down the set screw with the l/8th" Allen key. I suggest using the short end of the Allen wrench as the lever so as not to over tighten the setscrew and cut through the windings. Repeat the above procedure for the "D", "A", "E" (& "B") strings, however with each successive string, leave a little less of the ball-end exposed before locking down the free end of the string. I do this because the "G" string needs to be pulled 1/8th" further than the "E" to come into tune. Before putting any tension on the strings, cut the B, E and A strings 1" (2.5cm) past the end of the nut block and then bend all the strings up at a 90 degree angle behind the locking set screw (this helps lock the windings to the core). Finally, cut the strings again flush with the top of the nut block. A layer of thick tape (electrician's tape) over the cut ends will help avoid scratches and puncture wounds. Another option is to not cut the strings off at all but simply wrap then in a tight loop above the nut block. This is the best approach if you change strings frequently. If you choose to cut string ends off, you must re-tighten the setscrews to lock the string core in place. You can now bring the strings up to pitch. Once in tune it is necessary to push each string down as it passes over the nut and the bridge, do this by pressing down on the string with your thumbs on either side of the bridge and also immediately in front of the nut. This will establish the ends of the nodes at the bridge and nut and make the bass intonate correctly. If you are changing the gauge or brand of string you should check the instrument's intonation with a tuner .Be sure to check the tightness of the "hold down" set screws before going on stage.


    The truss rod nut is located in the center of the string block at the end of the neck. Tightening the nut clockwise with an 8mm or 5/16" socket will bend the neck back. Loosening the nut will allow the string tension to pull the neck forward. Ideally, the neck should have a slight amount of relief or forwards curvature. This is easily checked by pressing a string down at the first and 24th. fret simultaneously. There should be a space of approximately l/20"(the thickness of a cardboard match) between the string and the frets at the middle of the fingerboard. Too little neck relief (neck too straight or bent back because the truss rod is too tight) will cause the strings to buzz at the nut end of the fingerboard. Too much relief (truss rod too loose) will raise the strings too high off the fingerboard and may result in the strings buzzing at the top of the fret board. A heavy plucking style will require more neck relief than a light playing touch. To make the adjustment, turn the nut in the desired direction (Clockwise to tighten, counterclockwise to loosen, 1/8th of a turn at a time and re-tuning the strings to pitch before checking the results. If the brass nut doesn't turn readily, don't force it to the point of stripping the threads off the nut. It may help to remove(unscrew) the nut and grease the threads with a heavy bearing grease(bicycle lube). Loosening the strings and pulling the neck in the desired direction while turning the nut may also help.


   Adjustment of the string height at the bridge is accomplished by turning the two setscrews on the top of each bridge piece with a .050" Allen key. First loosen the locking set screw on "G" string side of the bridge back plate. (This screw locks the bridge pieces in place once the string height and intonation adjustments have been made.) In general I turn each screw one full turn in the desired direction and then check the results. It is important that each pair of height adjustment screw be turned an equal distance so that the bridge pieces remain level and both screws touch the base plate. String height is a matter of personal preference but there is a limit to how low the strings can be set without buzzing. A low action demands careful fingering and soft plucking. Be sure to lock the bridge pieces in place again by tightening the locking setscrew on the end of the bridge plate or you may loose one the next time you change your strings. The string spacing adjustment is accomplished by one of two means, depending on whether you have roller bridges (Serial #s 001-006) or the graphite saddle-in-a-slot bridge. For the roller type, loosen the string part way until you can lift it out of the roller. Spin the roller on it's threaded shaft to move it from side to side. For the slotted type, loosen the locking set screw (.050 Allen key) at the back of each bridge piece(facing the tuner block) and push the string and it's saddle to the desired position then retighten the locking screw.


   No setup would be complete without checking the instrument's intonation, it's ability to play in tune over the entire fingerboard. An electronic tuner is necessary to do this accurately. The locking set screw on the G" string end of the bridge must be loosened with the .050 Allen key before you can slide the bridge pieces. Start by tuning the open strings to pitch and then checking the 2nd octave harmonic (over 24th fret) then try fretting at the 24th fret. The idea is to compare this fretted E, A, D or G with it's Harmonic equivalent, if the fretted version is sharp then the string must be lengthened by sliding the bridge piece back towards the tuning block. If the fretted note is flat, the string must be shortened by moving the bridge piece forwards, towards the pickups. Generally the thinner strings (G and D) have their saddles set near the middle of the bridge plate while the fatter string's saddles are set progressively further back. Exposed or "taper" core strings are usually set in a straight line across the middle of the bridge. After sliding a bridge piece the string should be re-tuned and checked again before re-tightening the locking set screw on the treble end of the bridge. Setting the intonation on a fretless is the same but a temporary "fret" such as the 050" Allen wrench can be placed under the strings at the 24th position to aid in getting an accurate pitch.


   The height of the pickups has some effect over the tone of the instrument. In general pickups can be raised to increase their output. Some players like to be able to feel the top of the pickup underneath the strings when plucking. The pickups can also be tipped to favor the low strings or high strings. This is useful to balance the sound of the different strings when using heavy equalization. On instruments with two pickups, it may be necessary balance the volumes of the two pickups by raising the bridge pickup slightly. A good starting point is 1/8th" below the "E" or "B" string for the bridge pickup and 3/16 ths" below for the neck pickup. Be sure to push the strings down at the 24th fret to make sure the pickup won't hit the strings.


   If your instrument came with an oiled finish it will be necessary to clean and re-oil it from time to time. Oiling not only makes the bass look it's best, it also stabilizes the wood by sealing out changes in moisture. If you live in a humid climate or tend to sweat a lot, you should consider re-oiling yearly or even monthly as sweat dissolves the oil, leaving the wood unprotected. The best way I have found to clean and oil is by impregnating a small pad of 0000 (extra fine) steel wool with a high quality, marine grade refinishing oil (such as Birch wood Casey "Tru oil", available at your local gun emporium) and rubbing lightly with the grain. If the instrument is dirty, the new oil will dissolve the grime. Using steel wool helps clean the wood and prevent excess layers of finish from building up. Start by doing a small portion of the body at a time and then use a clean cloth or paper towel to rub off all the excess oil. It is easier to oil the instrument with the strings off, it is also best to cover the pickups with masking tape to keep bits of steel wool from getting stuck to the magnets. Be sure to remove the battery and control panel covers before the oil dries or they will get stuck. If this should happen or if the covers swell up due to the weather, use a hair dryer to gently shrink them back to size and loosen up the dried oil in the joint. Then moisten your thumb tips and push the covers off slowly, one thumb on each corner. Try to avoid prying at the covers with sharp objects, the blow dryer trick always works. If the covers get too loose then resort to a layer of scotch tape on the beveled edges of the cover. //___________\\

THE FINGERBOARD is best cleaned and protected with lemon oil or linseed oil. Stay away from products which contain silicone or tung oil. Use a small piece of cloth or paper towel to apply the lemon oil. Allow it to soak into the wood for a few minutes before wiping off the excess.

THE BRASS HARDWARE will oxidize if not cleaned regularly. It can be polished and protected for a short while with any automotive sealant, paste wax or just a metal polishing paste (Flitz, Simichrome.) Be sure to cover adjacent wood with masking tape before polishing so that the black oxide won't get into the wood grain. If left alone the brass will eventually gain a patina of age and funk.

THE PARTS LIST, If you happen to loose parts or screws from your bass you may get more from me at any time. It may be quicker and easier to ask for the screws and wrenches at your local hardware store. They are as follows: String lock down screws: 1/4"-20 x 1/4" (stainless steel).(These should be filed down on the bottoms so they won't cut through the strings).Bridge height adjustment screws: 4-40 x 3/8" (stainless steel).Bridge saddle locking screws: 4-40 x 1/8" (stainless steel).Truss rod adjusting nut: "Gibson" style, 10-32 threaded brass. (Available at most guitar stores and repair shops). Screws holding the nut block: 3/4" x 6 stainless oval Phillips head. Screws holding the tuning block assembly to the body: 1 1/2" x 8 stainless oval Phillips head. Screws holding the strap buttons on: 1 1/4" x 6 stainless oval Phillips head. Screws for the output jack and some early cover plates: 3/8" x 4 stainless oval Phillips head. (Same as Fender pickguard screws.)

TOOLS: Truss rod wrench: "Gibson" style or 8mm or 5/16" socket. (I use a 1/4" Allen Wrench with two corners filed flat as a handle). String changing wrench: 1/8" Allen. Bridge adjustment wrench: 050" Allen. Small screwdriver: #1 PT Phillips. Large screwdriver: #2 PT Phillips. All other parts are proprietary and only available directly through me unless you know a willing machinist. Prices for all replacement parts are very modest.

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© 2004 David King Bass Guitar Systems | 503-282-0327 |
Updated Feb 3 2006