Up Bow Normal???

silversport · #1 02-09-2008, 07:54 AM

Alright...my Bass (Carvin LB70A) had some upbow in the neck...I have adjuted the neck using the truss rod adjustment but now the strings all buzz...should I have left it with its upbow or do I now need to raise the strings???...
To start with the neck appeared pretty straight except as it neared the headstock...it "upbowed."...so I adjusted the truss rod...about three 1/4 turns in about three weeks...now the neck looks straighter and there still is a bit of "upbow" as it nears the headstock...but now all the strings buzz up and down the neck...
I guess my question is, did I just adjust the neck too much or are the strings just set too low???
I realize this is hard to diagnose without pics or actually seeing my neck through Carvin but any help would be greatly appreciated...
I have read all the stickys here and I could find on the web but there seems to be some slightly contradictory statements made and I am thinking I adjusted the truss rod too much causing my buzz...
Thanks for any help you care to share...

Bill

silversport · #2 02-09-2008, 09:45 AM

I'm heading out to buy a feeler gauge...can't find the one I already own :roll: and I'll measure the height Carvin recommends and send their out with...at least I'll have a starting point...thanks for the input.
Bill

dbcandle · #3 02-09-2008, 10:06 AM

Each bass is a little different, but in general, when you fret the low E (or low B) string at both the 1st and last frets, there should be a gap at the 8th fret between the top of the fret and the bottom of the string of 1-2 business-cards thickness. People generally capo the 1st fret so they can measure the relief themselves.

Personally, I use a metal 24" straight-edge rather the string, and feeler gauges for more accuracy.

If there is too much relief, the strings will be too high. If there is absolutely no relief (or worse, a "hump" in the neck pushing into the strings!), the strings will buzz.

Step 1: Set relief (don't over-tighten truss rod!!!)
Step 2: Set string-height at the bridge

thumpbass1 · #4 02-09-2008, 10:22 AM

Yes you should have a tiny bit of up bow in your neck. This is called relief and it
takes into account the elliptical vibration pattern of a vibrating string.

It sounds like you may have straightened the neck out a bit too much if you have
the bridge adjusted to what you like in terms of action etc. It's a balancing act of
adjusting your bridge and the neck releif until both come into that balance that makes
your bass feel fantastic to you. It seems you are on the right path by checking out
the " How to set up your bass" threads.

You never did say if the action and feel of your bass weren't to your liking or if you
just happened to see a bit of upbow in your neck and thought it was a defect. It
could take you some time to get it set to what you like but it's worth it. Also don't
over tighten your truss rod is my first advice. Welcome aboard to the world of learning
how to adjust and set up your own basses.

silversport · #5 02-09-2008, 10:23 AM

Before heading out I checked it the neck again with a steel straight edge ruler...the neck still had some bow to it so I gave it another 1/4 to 1/2 turn (I haven't given it an adjustment for a week before this) and the straight edge is now flatt across the neck frets...
Bill

silversport · #6 02-09-2008, 10:26 AM

thanks...it started with visually seeing the upbow but using the straight edge showed me that it didn't lay flat across the neck frets...I could see light between the straight edge and the fret near the middle of the neck...shouldn't I start with a somewhat straight neck???...THEN adjust the string height???...the strings are right on the fret near the top of the neck (near the headstock) right now but I'll let the latest adjustment settle in for a bit before adjusting anything else and THANKS for the help...
Bill

ehque · #7 02-09-2008, 11:31 AM

A completely straight neck is not the recipe for lowest action, imho. A very slight relief ("upbow") can allow lower action. If all your strings buzz at all frets then you need to raise the action at the bridge. If you have to raise your action too high to remove uniform buzz a little more relief is needed imho.

This is of course if you want a low action. If you don't mind a slighly (VERY slight) higher action then a completely straight neck is doable.

KJung · #8 02-09-2008, 11:46 AM

Quote:

Originally Posted by silversport

Alright...my Bass (Carvin LB70A) had some upbow in the neck...I have adjuted the neck using the truss rod adjustment but now the strings all buzz...should I have left it with its upbow or do I now need to raise the strings???...
To start with the neck appeared pretty straight except as it neared the headstock...it "upbowed."...so I adjusted the truss rod...about three 1/4 turns in about three weeks...now the neck looks straighter and there still is a bit of "upbow" as it nears the headstock...but now all the strings buzz up and down the neck...
I guess my question is, did I just adjust the neck too much or are the strings just set too low???
I realize this is hard to diagnose without pics or actually seeing my neck through Carvin but any help would be greatly appreciated...
I have read all the stickys here and I could find on the web but there seems to be some slightly contradictory statements made and I am thinking I adjusted the truss rod too much causing my buzz...
Thanks for any help you care to share...

Bill

Three 1/4" turns is a HUGE neck adjustment. My basses typically take one 1/8" turn or less at the change of season (fall to Winter, and Spring to Summer).

An 'up bow' or hump (seems like we are using 'up bow' to represent different things.. to me an 'up bow' is a neck with the rod tightened too much) will cause everything to buzz... just loosen the truss rod a 1/4 turn or so to start, since you cranked it so much to start with.

The easiest way IME to check your neck adjustment is to angle the bass at about 45" degrees, with the body on the ground and the headstock in your hand, placed directly in front of a lamp or other light source. The lamp will cause the stings to create a shadow on the neck. Since the strings are absolutely straight, it's very easy to compare the 'curve' of the shadow to the straight strings. You should, for a well set-up bass with no fret problems, see just a slight curve of the shadow on the neck. It works better for me than exact measurement!

Most necks seem to be most sensitive to buzzes around the 5th fret on the D string also... that's the place (i.e., around the G note on the D string) I always use as the 'threshold' point when I change the tension on the neck. When that area of the neck just starts to buzz a slight amount, it usually is an indication that the neck tension is optimum across the entire neck (again, assume the instrument is set up correctly.. saddle height, frets, etc.).

Also, remember that when you tighten or loosen the rod, the neck can keep moving in the direction of the adjustment for a day or more. It's always better to underadjust a bit and then recheck the next day.

IME!

willsellout · #9 02-09-2008, 12:05 PM

I use this for checking relief in my basses

Rather than using a straightedge across frets that might not be level I cut out the middleman and get the most accurate read on it. Of course it's expensive and no practical but since I do my own fretwork it was a necessary purchase.

What I would do is get a straightedge and measure and adjust the neck so that you can see a little bit of relief in the neck. Then work the string height to get buzz free. If the strings are too high you can adjust the relief a bit more if you need to but that's more likely covering up bad fretwork which might be your culprit.
I'm not sure this has been mentioned but if you don't know what your doing...research before making any more adjustments or changes. You have made some rather large adjustments with negative results so far. slow down and do some reading.

Dan