一、請教各位先進，一般電吉他line out輸出的訊號都是非平衡訊號， 而麥克風也是嗎?非平衡訊號和平衡訊號有什麼不同呢?各有什麼優 缺點嗎? 二、輸出是平衡號或是非平衡訊號是不是和輸出用什麼接頭 (ex:XLR,phone,mono,stereo)是沒有關係的? 三、一般line in錄音時是不是都要是平衡式的訊號比較好?那像sansamp 的gt-2、tri-od那類標榜可以line in錄音的pedal它輸出的訊號是 balanced還是unbalanced的訊號呢? 感謝各位先進的指教，謝謝。
基本上一般吉他導線(jack頭)都算unbalance的 [1/4 TS connector, tip=signal sleeve=ground] balance基本上需要三條線: hot, cold, ground 麥克風(佳能頭)就算是XLR connector [XLR connector, 1=gorund, 2=hot, 3=cold] 但balance也可以由TRS connector(stereo jack)來做 [TRS connector, tip=hot, ring=cold, sleeve=ground] 簡單的說balance的方式傳遞訊號,訊號不易損失,所以可以做比較長 == 我有另一個問題: 兩台機器間balance連接, ground是否只能接其中一頭, 另一頭不接? 請知道的幫我解答一下..謝謝
It is tough for me to explain this in Mandarin... A "balanced" line is one where two conductors,...neither of which are grounded,..just carry the signal... In some references you'll see these referred to as the "signal" and "return" wires, ...but those names are a bit deceptive...Electrically, the two wires do exactly the same job.,, A balanced line may or may not be shielded.. but if it is shielded, the shield is not joined to either of the two signal conductors..... When one of these two conductors is carrying electrons to the source,... the other is taking them away.. and as the current in the circuit alternates,. the conductors, in unison,.. alternate from positive to negative. The polarity of the two conductors, at any moment, is always opposite; they never both flow to the source, or to the load, at the same time.... "unbalanced" circuits....an unbalanced circuit are still two conductors required to convey the signal... however, one of these conductors is attached to an external reference point....."ground.".. Although in practice electrons may flow along the ground conductor,....it's helpful, for present purposes, to think of "ground" as a vast reservoir of electrical charge which dwarfs, absorbs and dissipates any charge which hits it... In an unbalanced circuit, we don't rely on the ground as a signal conductor in quite the same way...We rely on it only to ensure that the circuit is "complete"....the balanced circuit involves two conductors in a mutual push-pull arrangement, in an unbalanced circuit we can think of all the pushing and pulling of electrons as occurring along the signal wire. "balanced" or "unbalanced" depends entirely on the devices, and not on the cable. If one side is grounded, the connection is unbalanced. However, we also speak of types of cable construction as "balanced" or "unbalanced" because there are two very different ways of making cable for these two types of connection. Unbalanced circuits rely upon a simple and straightforward approach to noise.... "keep it out." .. The signal conductor is protected by the shield from interaction with outside noise and as the grounded shield plays no direct role in conveying the signal,.. it doesn't matter how much noise hits it...the noise is safely shunted away to ground... In an ideal world, the shield works perfectly, and the noise never makes it to the center conductor. The world being a tad less than ideal, some of the noise may make it through, and once it meets the signal conductor, there's no way to separate it from the original, intended signal... Balanced circuits behave in a different,..... First,..., a balanced line may have a shield to carry noise away to ground...But when noise does reach the inside, it strikes two conductors instead of one... Because the conductors are closely physically associated with one another,.. the noise reaches them more or less simultaneously, and affects them in the same direction.. Where the polarity of the intended signal on these two conductors is opposite--one conductor being negative, and the other positive, at any moment--the polarity of the noise is the same. Electricity flows from negative to positive...and flows so as to resolve the difference in voltage between two points... it is important when noise gets into a balanced audio cable... The audio signal in the balanced line shows opposite polarity on the two sides of the line, and so the current must flow through the load to try to resolve the difference. But the noise presents a voltage......whether positive or negative is unimportant....which is equal on both sides of the line. While the signal is pushing and pulling on alternate sides of the line, the noise is pushing or pulling on both sides at once, and that doesn't cause any current to flow through the load. It's as though the noise met itself at the load, and cancelled itself out, without ever managing to pollute the signal. This phenomenon is called "common mode noise rejection," and it's a advantage in balanced circuits....... "兩台機器間balance連接, ground是否只能接其中一頭, 另一頭不接?".. In a balanced audio circuit,...there is a common mode signal between two conductors that are inversely phased to ground. In both cases the ground is part of an signal reference that is commonly connected the equipment chassis, which itself is normally referenced to earth ground.... A balanced line without ground,,simply should not be so called" Balanced" at all.. However,If you are doing "Lifting Ground" in purpose for skiping noise,, that is pretty useful for isolate a dirty front end gear in a balanced connection..
Welcome... there were some old threads in MM forum about "Balanced VS Unbalanced"as well.,you might be helped via them perhaps..., If any one really also interested about "Grounding Noise".. Here is a article I recommend .... http://www.equitech.com/articles/enigma.html