Are there wolf notes on classical guitars and is it the same as unwanted resonance

[John Cadd]

When I play some simple chords on a flamenco guitar the A string starts a little howl going.If I drop the tuning down slightly on all the strings this nuisance stops .Is the cure to remove some wood from one of the bars,and which one?

[John Cadd]

Thanks Bob ,I did a little measuring to get a change in the sound.Put a card on the top with lines parrallel to the bridge so as I moved the a second card higher I could check the soundhole overlap.
The best sound came with an overlap of 25 mms.Seems a lot but that`s what my ears told me.So drawing a circle 89mms with a slice off the edge 25 mms at it`s thickest gave me a familiar sum to do.Area of circle 1 minus the curved slice gives area of circle 2.The final diameter comes to 85.4mms which is close to the Spanish measurement. I can make some circular rims out of plastic cards to fit inside the hole as a test.soft Bluetack will hold them long enough for experiments.When I fit the veneer ,would that be vertical to the plane of the top?A bit like a piston ring?I have enough surface to glue onto fortunately.
This fits in with my query about the exact tuning note for backs and tops before gluing the body together.It makes late adjustments possible.Best for new makers to know there`s a get out of jail free card. Cut circles by scraping the compass round till the plastic wears through.

[Bob Webster]

Sounds like you have it all figured now and have a good plan. An 85mm soundhole diameter is right in the middle of mainstream and that's comforting. Gotta love physics. As for the veneers to reduce the diameter, the piston ring analogy is perfect. :Have a go and let us know how it turns out. I think you'll be pleased.

Bob

[John Cadd]

Bob Lots of veneers are 0.6 mms thick.So three layers would be OK.I thought for flexibility it would be best to tilt each layer diagonally to the other.A ticklish little job.

[Bob Webster]

No need to make it any tougher than it its, John. I've found that the toughest part is just getting them cut to the right length. Also, CA does a fine job in gluing these.

Bob

[John Cadd]

Well Bob I haven`t taken the plunge with any glue just yet but I still felt the resonance was too much and have a cardboard disc doing the job nicely with about 76mms.Also the Spanish guitar got sucked into the game with a blanked off section and the low notes are no longer woolly.Overall it sounds like a different instrument with bags of personality.Something I never expected.Is there a business oportunity here for someone?

[John Cadd]

After playing around with cardboard discs I was still not satisfied with the Flamenco guitar,which is only ever used as a classical.
The "best" results were with a hole much too small.Then I wondered what effect the large plastic scratch guard was having. I warmed it up with a lamp and tinfoil covering the varnish.It came off quite easily .Now those nasty bitter sounding resonances are gone.The card disc which was fitted is no longer necessary.
The best part of all this "mucking about" is I have found an easy way to improve the sound of my other guitars.That is solid progress.

[Tim Mace]

You never mentioned the plastic pickguard(that I remember) or we could have solved this months ago!

[Bob Webster]

I'll be damned! Good sleuthing. I bet you're relieved. It sure beats where the alternative was heading.

Cheers,
Bob

[LARRY KLOSE]

I know nothing about classical or flamenco guitar construction but I had a problem with a mandolin that raises a question. could the unwanted resonance be occurring between the nut and one of the tuning pegs? On the mandolin, I was getting a wolf tone on one of the D strings, mostly occurring when I was tuning with an electronic tuner or testing intonation with the same device. It sounded like the D pair was not in phase, no matter how I tuned the two D's. I could never get that string in tune with the other. It turned out that one of the D strings was just the right length to produce an overtone about 3 cents higher than the fundamental. I put a grommet between the two D strings above the nut to damp the overtone and the problem disappeared.

Larry

[Bob Webster]

Actually, the difficulty of tuning the two Ds together could be because of manufacturing variances in the string that effect the relative amplitudes and frequencies of some of the overtones. What I've found out is that electronic tuners take many of the overtone frequencies into account when judging whether the string is tuned to the right frequency. The result is that the two strings could have exactly the same frequency for the fundamental but sound different to the tuner. Our ear works much the same way but not necessarily in accord with the tuner, but our ear is what we llive by. So, ;when all else fails, trust your ear.

Bob

[John Cadd]

To Tim Bob and Larry
It pays to be cautious sometimes.Still being relatively new to guitars I had only just got round to thinking about that one .There was an idea growing in the back of my mind and it was a combination of how much wood affected the frequency , just by it`s weight.I had started to question why the scratch guard was underneath the strings.A picture of a guitar with a very small scratch guard ,on the treble side only ,tipped the balance.
I know the weight of anything on the top is critical as French polishing is very thin as well as attractive.
It`s certainly made me conscious of soundhole sizes,and I shall be using the old scratch guard to act as a "reducer" on the Spanish guitar.This seems like a very effective fine tuning trick as all the construction processes can create an important uncertainty area.The disc idea is removable and not as awkward as a resonator.Although maybe it`s time for a fresh look at those as well.
The mandolin problem was unusual as the shorter strings are closer in length to the tuning end strings.Was the overtone not just "wrong" but bitter ,acidy sounding?Like a hint of Dandelion juice?
If you ever see Jacqueline Du Pree playing her cello,there`s a brass wolf note adjuster on her Strad just above the bridge.
With the Mandolin, I`m glad you got the resonance sorted rather than using damping as the single string sound is not nearly as nice as the natural resonances ringing.The Strad magazine a few months back told of a violin player enjoying the pleasures of a mandolin and saying the fast metalic "Italian" sound is not the only way to play the instrument.--Not a lot of people know that.

[John Cadd]

The scratch guard is no more.The thick varnish is gone.I replaced it with some Liberon Finishing oil quite thin.Then replaced the nut with a new compensated nut.I hate the idea of cutting bits off the fretboard and made a nut that just overhangs the board.After readjusting the Octave notes the result is a much nicer sound ,very clear and well in tune.With a Spanish Cedar back as a classical it gives a sweet crystaline sound that is no longer strident using Savarez strings. I still have a strip of leatherette partly across the sound hole ,however ,as this brings the air resonance down to just above the third fret tuning. That`s right ---Down to just above.The old scratch guard will form a reducer for the hole.That way it will look no worse than a guitar with glasses.I had the chance to get the strings spaced evenly too.I never mentioned that.