String testing - Corum D string results

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kiwigeo
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String testing - Corum D string results

Post by kiwigeo » Wed Jul 20, 2016 2:16 pm

I've run two Corum D4th strings on my stiffness jig and for some reason Strobosoft and G-tune are both picking up the 2nd partial rather than the fundamental string frequency......the fundamental is markedly suppressed in amplitude compared to the partials. This is only happening when the string is plucked open. When fretted at halfway point the fundamental is being picked up no problems. This is only happening on the D string.....two strings from different sets.

Any ideas/comments?
Martin

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Trevor Gore
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Re: String testing - Corum D string results

Post by Trevor Gore » Wed Jul 20, 2016 7:17 pm

The tuners will always pick up on the strongest partial. This is usually the first, but not always. If you pluck at 50% of the open string, you should always get the first partial showing on the tuner. If you pluck at 25% of the open string (normal plucking point on a guitar) you strongly excite the second partial, which may well show up stronger than the first.

Often, with an electronic tuner, you don't know which partial is doing the triggering when tuning a guitar. Mostly, this doesn't matter, as it is triggering on the strongest one, which is the one you're hearing, anyway and so is the one you want to tune. Sometimes the strongest partial also decays the fastest, which then leads the tuner to trigger on the next strongest partial, giving a "jump" in the tuning if there is any inharmonicity (often the case). Plucking at 50% string length eliminates this most of the time.

With G-Tune, if you want to trigger on a particular partial, you can grab either end of the spectrum window and drag them towards the partial of interest. Triggering will then happen on the largest peak between the two cursors. A red "X" marks the top of the peak doing the triggering.

Why is this happening particularly on the Corum D? The Corum strings have a very fine floss core which makes them very flexible in bending, probably the most flexible I've come across. Consequently, they support the higher partials very well, which may be contributing to the higher 2nd partial. I find that I can't use Corum strings on my guitars because the D always has too much fret rattle when set to normal action. This is because of the high partial content which makes the oscillation envelope more elliptical than parabolic, hence the rattling on the frets. The standard Savarez wound strings are stiffer in bending so don't have this problem. The Hannabach 815s are stiffer still and still have plenty of audible higher harmonics (gives clarity) so I often use them.

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Re: String testing - Corum D string results

Post by kiwigeo » Wed Jul 20, 2016 7:36 pm

Thanks alot Trevor.....a truck load of really useful information there.
Martin

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