Missing "A" note….

[James Durr]

I have an instrument that sounds "dead" on "A" notes. No matter where on the fretboard you play an "A" note it's dead sounding compared to every other note. The other notes ring and sustain while the "A" just plunks. If you tune up or down the problem just moves up or down accordingly. I have changed strings, adjusted the saddle and nut. Checked the break angles etc and it still plunks. All A's are dead regardless of which string is played. All other notes are clear and the sustain is good. Interestingly enough, if I tune it to an open A chord, the "A" notes ring out loud and clear which indicates to me that the strings, and other factors are operating properly. Any suggestions?

[Jeff Highland]

Acoustic guitar?

There is a good chance that the main air and main top resonances are sitting exactly on A.

The result is that the A's overcouple with the soundboard, discharge their energy quickly and do not sustain.

One way to check this is using a spectrum analyser. Then you can make decisions about remedies

I use this method

http://www.goreguitars.com.au/attachments/Technical_note_on_collect...

[Mark McLean]

Yep - if it is an acoustic, I think Jeff has the right diagnosis.  Try adding some extra weight to the top, which should change the top resonance a bit, and see if you can move it off the A note.  Play around with a temporary weight such as a coin and a lump of Blu-tack. If that fixes the problem you can then consider various permanent solutions - which other people like Jeff would know better than me, and Trevor Gore is the expert.  Could include shaving brace material, or adding permanent weight to the inside of the soundboard. 

[Jeff Highland]

Tell us some more about the instrument.

Size, bracing. soundhole size etc

[James Durr]

Hi guys thanks for your insights. It is an old beater acoustic and your diagnosis was spot on. SInce it is a "project" instrument and I like to tinker, I went ahead and removed some material from the bracing to the extent I could reach and also removed the finish and sanded the top with 320 grit emory paper. I had already cut and installed a bone nut and saddle but the guitar still felt dead and I had the missing "A"note problem. After the sanding and the thinning of the bracing it was like a night and day difference. Holy Cow… The guitar now feels alive and you can feel the vibration throughout the entire instrument. The tone and volume are remarkably improved and the missing "A" note has been found. I think the bone is transmitting vibration much more efficiently to the top and now that the top is a bit thinner and the bracing a bit less, the thing is a cannon. I am an amateur at all of this but really happy with the result. I still need to get some finish on the top but in terms of playability, intonation, action, sustain, volume and tone, it is like a totally different guitar. Since I don't care how it looks particularly I may just use a thin satin finish (the rest is gloss) and hope it doesn't kill the sound. This has been a project  / learning thing and I have learned a ton. I suspect I've had a bit of beginners luck here and hope it doesn't fall apart. Thanks again!

[Mark McLean]

Well that is a happy ending - if it sounds better and you are learning stuff, win-win.  A thin satin finish certainly won't kill any of the performance.  If you have a completely clean, stripped top the refinish could be as easy as some hand applied Danish Oil or Tru-Oil.  It won't look the same as your nitro or poly finish on the back and sides, but it sounds like you are not after a perfect cosmetic result.  It sounds like the thinning of braces and soundboard was the main factor in improving the sound.  I am sure it moved the main top resonance off the perfect A note so that it didn't kill that frequency any more.  And most factory made guitars are well and truly over-braced so you have improved the performance of the whole thing. 

[James Durr]

Again I want to thank you all. Your diagnosis and recommendations were spot on and once I knew what to do. it didn't take too long to produce the result. I'm sure a "pro" would have done a more precise job, but then I wouldn't have had so much fun. Thanks!!

[Kerry Krishna]

I knew these folks would help.