Phase (相位)

[Leo Yeh]

或者應該說那不是反相，而是極性相反............

這其實是兩件事..........

[小佐]

一首音樂為complex wave，經過分音器後，例如二路分音，一個高音，一個中低音，理論上這兩個聲波的相位依然要一致(in phase)，最後從喇叭出來結合，若其中有一個相位改變了(out of phase)，就會讓聲音產生變化了，跟原來的聲波不一樣

以上是同一隻喇叭不同單體

============================

若是一對喇叭立體聲又變得更複雜了

很多喇叭的中音與高音有一顆會設計反向？(左右的那顆單體同時反相)

很多喇叭的中音與高音輸出聲音經過分音器後相位有一顆會設計反向??????我的高音就是!!!!!!:O

[Leo Yeh]

其實那不叫反相，叫極性相反

[chsiang]

其實那不叫反相，叫極性相反

目前還看不出來這樣設計跟相位或是極性有什麼關聯

[Leo Yeh]

極性相反是指我們將聲波的振幅反過來
例如將平衡線的+與-反過來接

Polarity reversal is no phase shift.
Polarity reversal (or Pol-Rev) is a term that is often confused with phase Ø (phi)
but involves no phase shift or time delay. Polarity reversal occurs whenever we
"change the sign" of the amplitude values of a signal. In the analog realm this
can be done with an inverting amplifier, a transformer, or in a balanced line by
simply switching connections between pins 2 and 3 on one end of the cable. In
the digital realm, it is done by simply changing all pluses to minuses and vice
versa in the audio-signal data stream.


Reverse polarity is the opposite of normal polarity. Normal polarity in electronics is when you have the positive hooked up to the positive terminal and the negative to the negative terminal. Reverse polarity would be having the positive hooked up to the negative terminal and the negative to the positive terminal. The same concept can be used with magnets.



top: the original signal a/b (saw tooth)

middle: the 180° phase shifted signal
as T/2 time shifted sawtooth

bottom: the b/a-polarity reversed (inverted) signal,
mirrored on the time axis

[AndyChu]

果然是師大高材生.....

[Leo Yeh]

Polarity(極性)與Phase(相位)是不同的
極性簡單來說就是把正、負對調，只要一個訊號就可完成
但相位的關係是要兩個訊號才能得出他們相位的差異

圖1：兩個相同相位與極性的sine wave

圖2：為圖1結合後，就是振幅變成兩倍，但相位不變 (聲音變大6dB)

圖3：一個訊號變成極性相反

圖4：圖3兩個結合後 (無聲)

圖5：一個相位差90度

圖6：圖5的結合，一開始藍色只有一個聲波的聲音，後面的聲音就會變大(3 dB)

圖7：將一個聲波極性相反，並相位差90度

圖8：圖7的結合，與圖6很像，但其實不同


http://www.prosoundweb.com/article/p...ase_explained/

[Leo Yeh]

所以說很多人都.是玩假的屁一堆

[chsiang]

果然是師大高材生.....

不是政大的嗎

[Leo Yeh]

濕大的.......