Chasing a wolf tone ...

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Simon Magennis
Posts: 452
Joined: Sat Jan 07, 2012 7:51 am
Location: Menorca. Spain.

Chasing a wolf tone ...

Post by Simon Magennis »

I have done two very similar, yellow cedar with spruce classicals. One unfortunately has a nasty wolf note(s). The high A note (440) on the high e on the fifth fret and on the 10th on the b string dies very quickly as if something is sucking away the energy. There is a nasty side note some of the time.

If I play the high and low open E strings at the same time the open A resonates extremely strongly long, sounding very harmonic like, after muting the the two E strings. I tapped the top and back while muting the strings on both guitars. Does anything jump out from the Bad Guy that might suggest a course of action for evicting Mr Wolfie?

In the meantime I will have a go at attaching some weight in various locations to see what happens.

Bad first, good second.

The Bad guy,
Top tap tone.
monday G  top tap.png
The Bad guy,
Back tap tone.
monday g back tap.png
The Good Guy.
Top
YC Udo Top tap.png
The Good Guy.
Back
Udo back tap.png

Paul Kincaid
Posts: 37
Joined: Wed May 23, 2012 11:42 am

Re: Chasing a wolf tone ...

Post by Paul Kincaid »

I would start with treating it like a dead spot on a bass. Try adding weight to the headstock with a c-clamp and see if it is moved or changed. Adding small weights to the bridge area or top may give some more information.

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Barry Daniels
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Joined: Thu Jan 05, 2012 10:58 am
Location: The Woodlands, Texas

Re: Chasing a wolf tone ...

Post by Barry Daniels »

The graphs are not setup very well to pickout the peak frequencies. Can you re-do them and only graph up to a top frequency of about 800 Hz. Then someone might be able to diagnose the problem using Trevor Gore's methods.
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Simon Magennis
Posts: 452
Joined: Sat Jan 07, 2012 7:51 am
Location: Menorca. Spain.

Re: Chasing a wolf tone ...

Post by Simon Magennis »

@ Paul. The clamp was the first thing I tried. No effect I could notice. Weights are next up. I will pick up some BlueTac today for sticking weights on.

@ Barry. OK. Will do.

Alan Carruth
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Joined: Sun Jan 15, 2012 1:11 pm

Re: Chasing a wolf tone ...

Post by Alan Carruth »

This is almost certanly not a neck vibration, so a clamp on the head is unlikely to do much. I suspect the 'cross tripole' mode of the top is implicated: it can come in at about 440 Hz, is driven by the bridge, and radiates well. If that's the case, then a fairly easy fix would be to reduce the stiffness of the bridge wings. The bridge flexes a lot in this mode, and that would drop the pitch. Try putting your weights on the top just outboard of the bridge ends.

Simon Magennis
Posts: 452
Joined: Sat Jan 07, 2012 7:51 am
Location: Menorca. Spain.

Re: Chasing a wolf tone ...

Post by Simon Magennis »

The strangest thing. Wolfie has vanished today!

Or at least moved his abode and quietened down a lot. Puzzled. However, one minor change: when I noticed it, I had a little bit of card tape to the back of the bridge to protect the soundboard while I put on strings. I did note remove it till today. However, putting it back on did not bring back Wolfie though it did seem to have some effect. It was about 7g. The other possibility is that a bit of playing made it go away. I have seen my teacher do that in the past. And I believe people have mentioned it on the forum that sometimes a it goes away with a bit of playing. We will see if it stays away.

However, I finally download some PC software and set it up in addition to Audacity on my mac. So my set-up has improved. I will put it to use on a guitar I am planning to "improve" by adjust the top and back a bit.

Todd Stock
Posts: 394
Joined: Tue Feb 28, 2012 7:57 pm

Re: Chasing a wolf tone ...

Post by Todd Stock »

More proof that time heels most wolves...consider giving the guitars a chance to settle down and work out their particular kinks before making changes that may have to be undone. A few weeks to a few months is not unusual to see the transient issues resolve and persistent problems settle in for a nice, long stay.

Alan Carruth
Posts: 1012
Joined: Sun Jan 15, 2012 1:11 pm

Re: Chasing a wolf tone ...

Post by Alan Carruth »

Seven grams is plenty of mass to make changes in top modes on a Classical. Also, as Todd says, it takes guitars a while to settle in, so it never pays to be too hasty. Finally, even changes in humidity can alter the modes enough to bring on or 'cure' a wolf. I gave a talk on wolves at a GAL convention a few years ago, and brought out a 'test mule' guitar that was a shining example of the breed: the 'main top' mode exactly matched the pitch of the open G string, so the fundamental 'warbled' when you played it. The problem was that the humidity in Tacoma was enough different from what it is in New England in the summer that the wolf went away, so my nifty demo was trashed. It's back now, of course, but most people don't notice it.

Simon Magennis
Posts: 452
Joined: Sat Jan 07, 2012 7:51 am
Location: Menorca. Spain.

Re: Chasing a wolf tone ...

Post by Simon Magennis »

My first attempts with VA on a PC. No nice grids and the scale pretty horrid but the set-up is working. I don't like the fourth peak (416) being pretty much dead on G#4. I was able to move it to 421 with about 6g of putty on the top behind the treble wing of the bridge.

I will investigate further. A new hobby for 2016. :-)

top mg.jpg
back mg.jpg

Simon Magennis
Posts: 452
Joined: Sat Jan 07, 2012 7:51 am
Location: Menorca. Spain.

Re: Chasing a wolf tone ...

Post by Simon Magennis »

p.s. to the last post. I stumbled on how to get a better scale in output. Seems that you have to turn log mode on and then off again to get it to display nicely. The initial non-log view goes off the picture on the right and the interesting area is just a bit on the left. Switching to log views gives what I have above (cut a bit) but switching log back off again gave a different (and more useful) view than the original. Will play with that a bit more.

Oops, just noticed the labels got lost above. Upper shot is the top, lower is the back. Instrument is strung up, tapped by hand and strings deadened by the hand holding the neck.

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