Trouble Build

[kiwigeo]

This will most likely be the start of a long thread. I have a falcate braced classical that I finished a few months ago and have been playing a fair bit. The instrument has the following issues:

1. a nasty harsh loud note around B flat 4 on the top three strings. The note is accompanied by what sounds like really nasty piercing sympathetic sounds coming from somewhere....a bit like when you listen to a really loud noise and your ears start ringing. I assume I have a wolf tone issue?
2. Top E string and D string generally sound metally and harsh.

So far I've carried out the following:

1. Changed top E string from Hannabach to Savarez medium tension string. No change.
2. Did a fret dress and re-crown.
3. Fitted new bone saddle.
4. Did a quick tap test but can't see any obvious peaks corresponding to B flat 4 or partials of same.
5. Internal check reveals no loose braces or anything else that might be buzzing.

[johnparchem]

Weird, did you check for loose components on the tuning machine? I assume you checked the nut as well? I sometimes temporarily lift the strings with tape at the nut to see if the sound goes away.

[kiwigeo]

Weird, did you check for loose components on the tuning machine? I assume you checked the nut as well? I sometimes temporarily lift the strings with tape at the nut to see if the sound goes away.

Hi John,

Tuners are planetary geared peg tuners.....nothing loose there. The nut...I tried a bit of paper in the top E string slot but no change. Will probably make up a new nut next.....guitar is set up for fitting a compensated nut so making a new nut requires some work on the milling machine.

Over the next few days I intend going back and doing some more intense tap tuning and Chladni work.

[Trevor Gore]

Neck relief? Back buzz? Truss rod? Loose neck attachment hardware? Pick-up if fitted?

[johnparchem]

Just throwing mud against the wall ... I build both slot head classical guitars and guitars with peg tuners. The headstock angle on my slot heads are 9-10° but I use 15° on the guitars that I use pegs to tune as they terminate the string higher.

[kiwigeo]

Neck relief? Back buzz? Truss rod? Loose neck attachment hardware? Pick-up if fitted?

Hi Trevor,

Neck relief. I've played with truss rod....there's a modest amount of relief dialed in at present. There were a few frets that were a tad high with truss rod relaxed so I gave the whole fretboard a redress.
Saddle - 4mm thick bone saddle. 12 hole tie block so strings break at a nice sharp angle over the saddle and are all clearing the ramp backside of the saddle.
Neck attachment hardware - checked and all tight. I'm using knock down bolts and cross dowels.
Pick up - none fitted.
Side weights - T nuts fitted but no bolts fitted so nothing to rattle there.

I need to do some detailed tap and Cladni testing today or tomorrow and will report back with results. Will look at the nut...its the only thing I havent replaced so far.

[kiwigeo]

Just throwing mud against the wall ... I build both slot head classical guitars and guitars with peg tuners. The headstock angle on my slot heads are 9-10° but I use 15° on the guitars that I use pegs to tune as they terminate the string higher.

Headstock/neck angle is 15degrees. Strings leave the tuner pegs fairly close to the headstock face so break angle over the nut is a tad less than 15 degrees.

I might try putting a capo around strings at back of the nut to increase break angle and see if that changes anything.

[johnparchem]

Just throwing mud against the wall ... I build both slot head classical guitars and guitars with peg tuners. The headstock angle on my slot heads are 9-10° but I use 15° on the guitars that I use pegs to tune as they terminate the string higher.

Headstock/neck angle is 15degrees. Strings leave the tuner pegs fairly close to the headstock face so break angle over the nut is a tad less than 15 degrees.

I might try putting a capo around strings at back of the nut to increase break angle and see if that changes anything.

How about a capo on the first fret?

[kiwigeo]

How about a capo on the first fret?

Its on the check list John.

Will get the guitar on the operating table this afternoon and have a nut out session.

[kiwigeo]

Okay I got the guitar on the bench and looked at the nut and string routing between the nut and the tuner posts.

I put a capo on the first fret and all strings sound better although the wolf tone is still there as more of a deadening of the note and with capo on has moved up one fret.

Top E was coming off the tuner a bit high so adjusted same so string is coming of base of the post. This resulted an improvement in sound but the dead note is still at B flat 4 (466Hz).

The high pitched ringing has subsided a bit but seems to be related to 3rd and D string. When I dampen either of those two strings the ringing disappears.

A tap test using VA indicate following:

T(1,1)1 - 108.0Hz

T(1,1)2 - 214.5hz

T(1,1)3 - 254 Hz Live back

At around 466Hz there's a little peak

[WJ Guitars]

Martin It must be frustrating not yet being able to resolve the woof note issues. Could there be a small area where the bridge is attached to the top having a spot location with a gap between the bridge and the top causing this problem?

Wayne

[Trevor Gore]

Those are fairly nasty looking VA plots, Martin. Lots of background noise or something else going on?

[kiwigeo]

Those are fairly nasty looking VA plots, Martin. Lots of background noise or something else going on?

I'm running mic output into laptop via a preamp....might have something to do with the background noise. Ive also got smoothing turned off.

Guitar was lying on its side with neck on a neck rest so there's probably a neck resonance being picked up. It was a quick tap test..I usually hold the guitar in playing position for testing.

[johnparchem]

Those are fairly nasty looking VA plots, Martin. Lots of background noise or something else going on?

I'm running mic output into laptop via a preamp....might have something to do with the background noise. Ive also got smoothing turned off.

Guitar was lying on its side with neck on a neck rest so there's probably a neck resonance being picked up. It was a quick tap test..I usually hold the guitar in playing position for testing.

I get noise like that when I am clipping. The gain being too high.

[Trevor Gore]

...Ive also got smoothing turned off...

That shouldn't create a problem.

I get noise like that when I am clipping. The gain being too high.

Definitely worth investigating.

[kiwigeo]

As mentioned earlier I'm using a preamp and it's usually turned up fairly high. You may also see peaks at 50Hz and multiples of same which are AC hum being picked from the preamp and laptop powerpacks.

I redid the tap test with preamp turned down and the main peaks are as already reported. I can't see any peaks that correspond to the dead note at B flat 4 or multiples of same.

Not in the mood for any further mucking around with this instrument today but will revisit after a few days to think about what might going on and come up with a plan.

[kiwigeo]

An update on the trouble classical.

During the fret redress a couple of frets got more of a dress than I'm comfortable with so have ripped out all the frets so I can take care of a hump in the fretboard around the 2nd and 3rd frets and at the same time do some surgery on the wedge between the upper fretboard and upper bout. I had to do a neck rake adjustment a few months back that left a bit of a gap between fretboard and top due to having to pack up the bolt down mortise.

[kiwigeo]

I haven't had much time in the workshop of late....been busy with my other passion...restoring old steam locomotives.

Work done on the guitar so far:

1. Did a full refret.
2. Made up a new nut and rough cut slots in same. (final slot depth after relief adjustment)

Just now i strung up the instrument and it seems to be behaving. Will play it a bit today and tomorrow and have a good check for buzzes and other annoying sounds.

[kiwigeo]

Okay..I'm happy to report that the issues I've been having with my trouble classical appear to have been fixed.

I'm ashamed to say that root cause was probably a shithouse fret job. A few frets were pretty high and some were way low.....I need to work on my fret dressing skills. The refret was made a bit easier with the arrival of a nice long 20' radius beam from the US and I took a bit more care with the fret recrowning following leveling.

The wolf tone around B flat4 is still there but less pronounced......Ill live with it for now.

[56nortondomy]

Good fix Martin. I've started using a triangular file to recrown frets I find it much faster and easier than the diamond z crown file I got from stewmac. I bought it from Bunnings and ground off edges and made them smooth, much cheaper than buying one from a luthier supply. $15 was all it cost. Wayne

[Dave M]

Good stuff Martin. It's still not a task that I'm happy with, but you got there. Dave