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| Why low E does not ring like the rest? http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=10395 |
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| Author: | microsmurf [ Mon Jan 15, 2007 10:57 am ] |
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I am on my second build project and I was wondering about this. How come the low E strings fundamental does not ring loud like the rest of the strings? especially the A string? I've played my share of nice guitars, but I never ran into any of them that had really nice E string sound? They all seem to have higher overtone content than the fundamental on the low E. Is the guitar physically not able to vibrate at that low frequency? What design guidelines can you share with me to make the low E string sound better? (I want it to ring like the A string) (I think the fact that most typical guitar strings have higher tension A strings than E strings also make the problem worse.) |
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| Author: | JJ Donohue [ Mon Jan 15, 2007 11:30 am ] |
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Do you hear the effect on an open E or fretted or both? |
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| Author: | microsmurf [ Mon Jan 15, 2007 6:03 pm ] |
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I don't remember on other guitars, but I tried on mine and it seem to be mostly affected on the open E. Once I fret it, it seems that the overtones die out more and more fundamental comes out. I am using bone nut and saddle. I wonder if they are causing this? |
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| Author: | gburghardt [ Mon Jan 15, 2007 6:20 pm ] |
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I'm sure there are way more informed folks than I, but how well your guit-box responds to particular notes is a function of a lot of things. It could be due to body size (bigger resonates lower), soundhole size (bigger resonates higher), bracing, nut/saddle composition, string size and many more. I know that on a mandolin, the g string rings nearly twice as loud on the first harmonic as on the fundamental. That, I thought, is due to string thickness and scale length. I could be wrong though. I think this is interesting. I'd like to see what more informed folks know. |
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| Author: | Alan Carruth [ Tue Jan 16, 2007 6:17 am ] |
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In the low range, the guitar is effectively a 'bass reflex cabinet'. The two lowest frequency box resonances, the 'Helmholtz' air mode, and the 'main top' mode, work together to form the spectrum in that region. The 'Helmholtz' mode is what you hear when you blow across the mouth of a soda bottle. The pressure changes everywhere inside the bottle, which 'breaths' through the neck. By itself, with a 'rigid' box, the 'Helmholtz' resonance would probably come in at around 125 Hz; say about B on the A string. The 'main top' resonance is where the lower bout area (mostly) is vibrating like a loudspeaker cone. On a guitar with no back this would happen at around 185 Hz; something like F or F# on the D string. However, on real guitars these things are not independant. The pressure changes of the 'Helmholtz' air mode push on the top, and the top pushes air in and out of the soundhole. The effect of this is that the two resonances shove each other aside a bit in pitch. The 'main air' mode is usually dropped to around G on the low E string, but can range anywhere from F to A#. The 'main top' mode on most guitars is bumped up to around the open G string pitch, but can vary a lot too. The 'main air' mode is the lowest resonance on the instrument that can actually produce much sound. There's nothing else on the instrument that can effectively move much air at that low a pitch. Often, for example, there is a 'neck' resonance down around 70-80 Hz, but the only thing that's moving much is the headstock, and that's just too small to radiate sound at that pitch unless you get right on top of it. If the 'main air' part of the 'bass reflex couple' is up around A, it's not really very effective at the low E note: there's not much fundamental. You start to notice it more as you get closer to the pitch of the resonance. It's fairly easy to hear the 'main air' mode: it's the pitch you tend to associate with the 'tap tone' at the bridge on an assembled box. You can alter it by changing the soundhole size, or by changing the stiffness of the top or the back. A smaller soundhole gives a lower pitch, but a weaker, 'main air' resonance. Making the top or the back more flexible, by shaving braces, increases the strength of the 'bass reflex couple', which causes the pitches of the 'air' and 'top' resonances to push each other further apart. |
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| Author: | Steve Saville [ Tue Jan 16, 2007 6:40 am ] |
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I really don't know and I have heard that problem on a number of guitars. It seems to me that the following can cause bad response particular to the low E. So in no particular order. An over braced top. Too thick top. Top too coupled to the sides Saddle that does not fit well in the bridge - too loose To heavy a bridge. To sharp or too radiused edge on saddle Nut slot too wide/too radiused Too small of a sound hole Sides not tall enough Not enough break angle Dead string Poor execution of the X-joint Overly dampening material on bridge/bridge pins/saddle/bridge plate I'm not sure of all of these, but I'd love to read others opinions on these. |
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