P-Bass buzzing after fret level

[eliya]

The title says it all. Frets are leveled and crowned, but I'm getting buzzing in the the middle of the neck mostly on the D and A strings. Some buzzing on the E and G, but it's not as bad.

It's not too horrible, but noticeable. Everything is alright by the nut or past the 12th fret (I leveled some fall away over at the fretboard extension), so only the middle of the neck is problematic.

I tried shimming the back and front of the neck pocket, but no dice. Saddles are fine and don't contribute to the buzzing. Nut is also good, but I can't see how it would cause the buzzing anyway since it's fretted notes that buzz. Different amounts of relief do nothing. Straight neck does nothing.

The one thing I thought could be the problem is that I leveled the frets without simulating string tension. Here's what makes me think that: without strings, and the truss rod adjusted so the neck is straight, I get my straightedge touching all the frets, except for the last few, because of the fallaway. With strings on and tuned to pitch, I can't get the neck straight in the same way, meaning that it always touches both ends of the fretboard. Please note that this doesn't mean I didn't tighten the truss rod enough. I did, and I even can bring the bass into backbow, if I want, but as long as the neck is "straight", the straightedge touches both ends of the neck. In other words, I don't see the fall away under string tension. This makes me think that the tension from the strings causes the bottom of the neck to rise, and thus the middle of the neck is essentially lower than the fretboard extension, which is why it buzzes.

So right now I'm thinking of leveling the frets again, but this time simulate string tension. However, before I do that, I'd love to hear people's opinions. Maybe I'm overlooking a simpler solution.

[Hesh Breakstone]

What's your leveling process and what do you use to do the leveling?

Thanks

[eliya]

Hi Hesh,

I use StewMac's 16" leveling beam. I started with 100 grit and then moved on to 320. I crown the frets with a 3 corner file, then "flap" along the fretboard with sandpaper starting at 400 up to 200. Then 0000 steel wool.

[Hesh Breakstone]

"Flap" is a good term that I may borrow from you in the future if you don't mind?  It describes perfectly what we want to do with the sandpaper.

Your leveling method sounds like ours as well so I don't suspect that.

When Dan E. visited us last time he spoke about "rubber necks" and as we all know basses can be good candidates for being a rubber neck.  This might be a case for a neck jig so we can see what's happening in the playing position.

[eliya]

Sorry for taking so long to respond to this thread. Other things came up.

Yes, please use "flap". I don't know if I came up with it, but maybe!

I'm definitely suspecting that this bass has a rubber neck. Everything looks good without strings, and when I put it other string tension it starts behaving very differently. It's not a very well made instrument, from the over-sized neck pocket, the ridiculous wiring (so much extra wire left inside!), and funky hardware. I wouldn't be surprised if the neck isn't made from the best maple they had.

[Hesh Breakstone]

On second thought were we see the most ski-ramping on the fret board extensions (over the body) is with Fender style, bolt on necks.

I think that you may be right that the kick-up of the body frets and no fall-away is the issue.

When we level we are creating two different fret planes.  The first one is the 1st through the 12th and we do not want the long beam to even kiss any of the frets beyond the 12th.  The second fret plane is the 12th though the last and we put a piece of tape on the short leveling beam for this and try to keep the tape riding on the crown of the 12th.  This inverts the beam slightly creating that second fret plane with fall-away.

Often it's the case that some instruments have such a profound kick up or ski ramp over the body that we resort to flat files with a shop-made handle and again the tape to ride on the 12th.

You might want to address fall-away and see what that gets you?

[David Farmer]

Wait, did I hear Hesh advocate the use of a neck jig? Just kidding. Hesh your the man.

ok. one method. I use sometimes.

1)  strung to pitch, put a straight edge between 1st and 12th  with max planned  relief ( .006"-.008"?)

 If it's touching frets past the 12th, block up the straight edge with matching feeler gauges on the 1st and 12th until it clears all the upper frets. These feeler gauges,  represent the minimum amount the upper frets fret must be lowered to have sufficient fallaway. Measure the height of the last fret above the fingerboard. Write it down.

2) Remove the strings and adjust t-rod so 1st to 12th is flat. Sand/file fallaway until last fret is has had it's height above the fingerboard reduced from the original measurement at least the amount of the feeller gauges.

For example: if  mesurment #1 required .010" feeler gauges on top of frets 1 and 12, and the last fret measured .030" high, than fallaway in #2 must lower the last fret to .020" above the board.

Make any sense?

 

[eliya]

Thank you for your response, David, and my apologies for taking so long to respond.

I like this method a lot and it seems to address the problem at hand. I'm going to try it.

Following this method (or really, any time when leveling fallaway), how do you decide where to put the tape to pitch the leveling beam. When I think about it, I believe that the tape (and how much) can be placed on any fret, as long as the distance between the bottom of the beam and the 13th fret is the same as the amount of material to be removed from the last fret (or a little less). This way, once that amount of material has been removed from the last fret, the beam would kiss the 13th fret. Does this sound right to you? It does to me! Hesh, I'd love to hear your opinion also.

Thanks again, fellas!

[Mike Kolb]

Great to hear all the leveling ideas here. Just need to remember where to find 'em later! 

One little trick to use sometimes if (a). there's a question of a leveling beam actually "kissing" a particular fret or not, and if (b). you don't want to redress that fret top at the moment... is with a VOM. 

One probe touching the fret in question, the other probe clipped to the leveling beam.  If the circuit's open with the beam in place, it's not touching... and closed if it is.  

[David Farmer]

I see, re-reading my response, that I gave relief numbers I would use for a guitar not a bass. Maximum bass relief would be significantly more.

 You seam to have the idea.

I have gone back and forth over the years between tape methods. I like taping farther towards the headstock because it allows a longer stroke when removing a lot of material and it tends to keep the  fallaway in a more predictable relationship to frets 1-12. Taping over the 12th  requires closer monitoring to make sure you create the amount of fallaway you want. The down side to the first method is it's difficult to make sure you don't graze the 12th fret. especially important if the 1-12 section has already been leveled. I some times use both methods. taping towards the headstock initially, and finishing by taping at the twelfth.

If you have a lot to remove,especially with large frets as on a bass, you may need to use something very aggressive such as a file initially. Knocking down a ,"ski jump" can take a long time.

Calculating how much needs to be removed above the 12th with the strings up to tension compensates for the imperfection of just using the t-rod to create a flat neck for leveling.

These are just my experiences and methods. There obviously are others that work well too. Good luck.