String buzz: What's acceptable?

[John Cohen]

I'm working on setting up a new banjo, and with action lower than 5mm at the 12th fret the strings at the first 5 frets fret out a little when played with medium to hard force from the right hand.  They don't rattle about but you can hear a snap or click immediately upon plucking the string, after which the note rings out clearly.  The sound has been bothering me a lot as I prefer my strings to sound clearly when played, but I'm having trouble getting rid of the "click" so I'm wondering if this is acceptable or not since the not rings out clearly afterwards (like on a properly set up flamenco guitar).

The neck is dead straight, the frets are dressed and level, and the nut is the correct height (no buzzing on the open strings), so I can't figure out what's causing the buzz.  Neither can the luthier who's been trying to eliminate it.  Action is 5mm @ 12th fret with a 5/8'' bridge.  I'd like to use a 1/2'' bridge as the action feels good at this height, but the clicking sound at the first 5 frets is even more audible.  The problem may be that the neck is too straight and could use some relief, but there's not truss rod to adjust. The problem is worst on the 3rd string.

[Steve Harrison]

What make is the banjo?...Steve.

[Trapdoor2]

What I would do (initially), is to raise the string height at the nut...in very small increments, one string at a time. You can do this experimentally with pieces of notebook paper of various weights (no mods, etc.).

 

I don't think it will ever be 'optimum' due to the lack of neck relief...but the whole thing is a balancing act. You'll find the 'sweet spot' but don't be surprised that it may not be where you really want it.

[John Cohen]

The banjo is a B&D Silver Bell.

[Shawn McSweeny]

Hi John

When struck hard, nylon strings oscillate dramatically and will need greater clearance than when played lightly, to avoid buzzing the frets. Action lower than 5mm is pretty unrealistc for even medium volume, buzz-free, classic playing on most vintage banjos. Power players typically have much higher action.

Having said that, it is also possible your third string has some surface coarseness, with minute fibres just long enough to reach the offending frets when the string vibrates. You could try changing the string.

If there is no improvement, try what some pros might do.  Slope the top of your bridge as necessary,  to achieve your preferred action for your 1st & 2nd strings, but greater clearance for the 3rd and 4th, as needed to eliminate the buzz.

[John Cohen]

I've tried multiple string gauges with no success.  The special bridge is a good idea- I'll give it a go.

[Steve Harrison]

Hi John, I think Shawn is pretty near the mark regarding nylon strings, I've got 8 vintage banjos and the string height on all of them is set more than 5mm from the 12th fret. I tend to dig in when I play and if the strings were any lower they'd also start buzzing. A higher action is something you'd eventually get used to....Steve.