我該多久換一次琴弦？【世界級吉他製作大師專訪】

【世界級吉他製作大師Abraham Wechter的訪談節目第四集，這周Wechter先生一直在忙，沒能抽出時間面談。這集的內容是以郵件的形式給我發過來的，所以沒有錄音了。這次提到了吉他琴弦的選購、保養，還有一些小趣事】

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最直接的回答就是，當琴聲聽起來沒有你預想的那麼好了的時候。

通常情況下，如果每個星期只彈幾次的話，至少一個月一換。如果每天都彈的話，每次換弦的間隔時間更短。我認識幾個職業音樂家，每完成一套組曲就換一次，一晚上會用掉好幾副琴弦。

琴弦老化有以下幾個原因：

其中一個因素叫「金屬疲勞」，因為金屬弦在彈奏的過程中不斷地經歷「彎曲」和「伸展」，而使它的彈性逐漸降低。某些合金比其他的金屬更「抗疲勞」，能夠使音質更長時間的保持「清亮」。不同於其他軟合金，磷銅就是這樣一種「抗疲勞」的合金。（琴弦的包裝上一般都有「92/8」這樣的標示，其含義是這種琴弦由92％銅/ 8％的錫組成。磷銅是在青銅基礎上做了磷化處理，工藝比較複雜）

另外一個因素是，裹在琴弦（內芯弦）外層的線圈變得越來越鬆弛。弦芯的橫截面大部分呈六邊形，而不是圓形，目的是為了讓外層的線圈更能緊緊地「咬合」住弦芯（增加了外層線圈與弦芯的摩擦力）。但無論如何，最終外層線圈還是會鬆開，這時候琴聲就開始變得渾濁無力。

手上的泥垢還有汗水，存積在外層線圈裡，也會讓琴弦變得反應遲緩，缺乏彈性。

最後一條，人體產生的酸還會和金屬產生化學反應。我們當中的有些人的身體的化學性質比普通人更具酸性。記得我當時在吉普森（Gibson）的技術研發部工作，我的一個同事彈奏短短的幾分鐘，就能讓琴弦變黑。所以大家經常邀請他來為新研發的琴弦做測試：如果琴弦在他的手中能活下來，那麼基本上全世界人用起來就沒什麼問題了。

某些琴弦會塗上專屬的高分子聚合物，用來延長琴弦的使用壽命。這些被塗過的琴弦的售價要比未塗的琴弦高得多得多，當然考慮到它的使用壽命也大幅度的延長，其實還是值得的。而這項技術自它首次引入到現在，也經歷了一段漫長的道路。在最初的時候，這種塗層會磨損的很厲害，甚至會剝離琴弦，尤其是在撥片常常光顧的地方，會起一層像汗毛一樣毛絨絨的東西。而且早期的塗料技術更傾向於「厚塗」，這讓琴弦的聲音聽起來很沉悶，雖然壽命延長了不少，但是聽起來就沒有未鍍膜的新琴弦那麼好了。不過這種鍍膜技術已經大有改善，但即使到了現在，我不得不承認，考慮到音色純正的問題，我更推薦未噴塗的80-20琴弦（青銅弦又稱黃銅弦，這種材質的琴弦是比較傳統的一種，一般琴弦的包裝上會有「80/20」的標示，其含義是這種琴弦由銅80%/20%鋅組成。這種材質的琴弦音色明亮有穿透力，喜歡清脆音色的琴友可以選擇這種材質的琴弦）。然而它的壽命也更短，你得樂意去更頻繁的去換琴弦。

不管是有塗層的，還是沒塗層的，想要延長琴弦的使用壽命你必須要保持琴弦的乾淨衛生。在你拿起吉他前，花點時間去洗個手先。彈奏結束把吉他收起來前，用擦銀布把琴弦上上下下擦拭乾凈。

不過，有時候，你需要的僅僅是一副新琴弦。

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The quick answer is when they don』t sound as good as you want anymore.

Generally I』d say at least once a month if you play a few times a week, more often if you play almost every day. I know some professional musicians who change strings a few times a night, between each 「set」.

Strings go dead for a number of reasons.

One factor is just 「metal fatigue」 or the decreasing elasticity of the metal as it is stretched and bent when you play. Some alloys are more resistant to this than others and can sound 「bright」 longer. I think phosphor bronze would probably be in this category, as opposed to softer alloys.

Another factor is the loosening of the grip of the outer windings on the inner core wire. Core wires are most often hexagonal rather than round in cross section to allow the outer windings to 「bite」 in a little better but eventually the windings lose their grip the strings start sounding dull.

Dirt or dried sweat gets built up in between the windings. This makes the strings less responsive and springy.

Finally there is the chemical reaction between your body acids and the metal. Some of us have more corrosive body chemistry than others. When I worked in Research and Development at Gibson we had one co-worker who could make strings turn black in a matter of minutes. We often asked him to test new string sets- if they survived his touch we knew they were probably going to be OK for just about everybody.

Some strings are coated with proprietary polymers to extend their effective life. These coated strings are often considerably more expensive than standard uncoated strings, but the trade off is they can last much longer. This technology has come a long way from when it was first introduced. Initially the coatings would sometimes fray and hang off the strings like strands of fine hair in the area where the pick would strike. Also the early coatings tended to be heavier and they dulled the sound of the strings, so they might last longer but never really sounded as good when new as uncoated strings. Coating technology has improved a lot but even now I must admit that for pure tone I still prefer an uncoated 80-20 bronze string. However they go dead much faster and you need to be willing to change strings much more often.

One thing you can do to extend the life of your strings, coated or uncoated, is to keep them clean. Take a moment to wash your hands before picking up your guitar, and wipe it down with a polish cloth a little before you put it away.

But sometimes you just need new strings ; - )

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