<觀念討論>低阻抗耳機,才是真正難搞的耳機!

[takasehuang]

不必懷疑了！.....

我用一隻又舊又破的 SONY Z600，又試過 SONY MDR-7506，耳擴是之前專文談過的中國製 G&W；如果不使用耳擴，基本上這耳機『完全通不過』殺音響測試，暫態反應嚴重不足，連帶造成嚴重的相位失真污染了音場與定位。當然這是我目前的體驗而己....

不好意思離題了

不過所謂"暫態反應-相位失真"的解釋是有點流於玄學或前科學了
我想這應該不是標榜"音響科學"的人會說出的句子

[Leo Yeh]

Phase distortion

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In signal processing, phase distortion or phase-frequency distortion is distortion that occurs when (a) a filter's phase response is not linear over the frequency range of interest, that is, the phase shift introduced by a circuit or device is not directly proportional to frequency, or (b) the zero-frequency intercept of the phase-frequency characteristic is not 0 or an integral multiple of 2π radians.


Measurable performance


Phase distortion, Group delay, and Phase delay A perfect audio component will maintain the phase coherency of a signal over the full range of frequencies. Phase distortion can be extremely difficult to reduce or eliminate. The human ear is largely insensitive to phase distortion, though it is exquisitely sensitive to relative phase relationships within heard sounds. The complex nature of our sensitivity to phase errors, coupled with the lack of a convenient test that delivers an easily understood quality rating, is the reason that it is not a part of conventional audio specifications.[citation needed] Multi-driver loudspeaker systems may have complex phase distortions, caused or corrected by crossovers, driver placement, and the phase behaviour of the specific driver.

[remo]

不好意思離題了

不過所謂"暫態反應-相位失真"的解釋是有點流於玄學或前科學了
我想這應該不是標榜"音響科學"的人會說出的句子

“暫態反應-相位失真"的解釋是有點流於玄學或前科學了”...？？
您可以解釋一下您所說的嗎？

[Leo Yeh]

Measurable performance



Transient response A system may have low distortion for a steady-state signal, but not on sudden transients. In amplifiers, this problem can be traced to power supplies in some instances, to insufficient high frequency performance or to excessive negative feedback. Related measurements are slew rate and rise time. Distortion in transient response can be hard to measure. Many otherwise good power amplifier designs have been found to have inadequate slew rates, by modern standards. In loudspeakers, transient response performance is affected by the mass and resonances of drivers and enclosures and by group delay and phase delay introduced by poorly-designed crossover filtering or inadequate time alignment of all the loudspeaker's drivers. Most loudspeakers generate significant amounts of transient distortion, though some designs are less prone to this (e.g. electrostatic loudspeakers, plasma arc tweeters, ribbon tweeters and horn enclosures with multiple entry points).

http://en.wikipedia.org/wiki/Audio_system_measurements


Transient Response Top of Page
This is a measurement on how fast a speaker or microphone can respond to sharp attacks. The faster the transient response is better. For microphones: A lighter weight diaphragm will usually have a faster transient response that a larger heavier diaphragm capsule. Small Condenser mics have faster transient response times that a dynamic mic. They are better for recording percussive sounds. A voice mic however doesn't really need that fast of a transient response. A lesser value produces a "warmer" sound.

http://www.kellyindustries.com/articles/glossary.html

[takasehuang]

相對喇叭而言，耳機這種單純到一個極點的全音域單體是
比較沒有群延遲和相位飄移問題的

很多東西我想是不應該只求望文生義，一知半解

[remo]

相對喇叭而言，耳機這種單純到一個極點的全音域單體是
比較沒有群延遲和相位飄移問題的

很多東西我想是不應該只求望文生義，一知半解

那有沒有可能是來自訊號電流的問題？

[Leo Yeh]

若是單一單體是相位問題較少
現在有許多耳機是多單體

Transient Response還是有意義的

[takasehuang]

“暫態反應-相位失真"的解釋是有點流於玄學或前科學了”...？？
您可以解釋一下您所說的嗎？

> 暫態反應嚴重不足，連帶造成嚴重的相位失真污染了音場與定位

看到這句陳述的當下我覺得有點頭痛，混淆了很多一時難以說得清的東西
或許各家音響廠商有意無意的誇大宣傳也要負上很大責任

先講相位失真好了
大多數動圈耳罩耳機沒有分音器，自然電相位層面也幾乎沒有問題
這個"電相位" 就是那些標榜一階分音相位失真比較小的"相位"

再來是聲相位，放到喇叭的層面來談，這牽涉到各單體的擴散/指向特性統合
可是放在耳機來看,或多或少有點不是那麼重要吧？畢竟就只是個緊壓耳朵的全音域單體

嚴重的相位失真汙染了音場與定位.......這個陳述雖然很不完備，但是放在以喇叭為主的
空間聲學來講，還算是可以說得通

但是放在耳機的層面,耳機所營造出來的音場和定位,
保守一點說，立體感，跟相位失真什麼的並無直接關係

[kevintran]

我是有使用不同款式的耳機，耳道式的多用在隨身聽，另外一支MDR-CD900ST是插MD座機的耳機輸出上！

不過我發現一件事就是MDR-CD900ST在MD座機轉大聲時的音量是我受不了的，而換上耳道式的MDR-EX90，卻好像就變小聲了？:^)

除了阻抗可能不同之外，每個耳機的效侓也不會一樣。在同一個“檔位”，不同的耳機可能音量不同。

另外，有可能CD900ST的效侓較低，MD機的耳機放大為了製造夠高的音壓而產生失真？

也有可能CD900ST的頻響不算平坦，在大聲聽的時候某些頻侓被突顯出來？

[takasehuang]

那有沒有可能是來自訊號電流的問題？

我想原因大概很單純

就是他推的那台G&W 耳擴本身就是針對低阻耳機去調校的耳擴
所以在過阻尼與失阻尼之間的狀態取得了比較好的平衡

中低頻不糊不散，聽得出明確的形體和定位