請教器材歐美聯姻的平衡線連接問題

fyl0206

226分

21樓

fyl0206

個人積分：226分

文章編號：63501314

justthinking wrote:
http://www...(恕刪)

拜託一下，一開始樓主 1 F 並沒有特別修正擴大機的極性顛倒的問題點。喇叭線對調對喇叭端的極性改變，對擴大機的極性根本沒變..囧...

且三階分音的分音器設計如果單純地想用喇叭極性對調簡單解決相位問題恐怕也是做不到(如果..），也不說音圈上的繞線抗電導/抗電感勢聲音多半不佳不如前端直接做好轉接頭/線...

還有一點喇叭極性對調會有燒機之虞一說原因是喇叭線正負有些人習慣負線粗、正線細；喇叭正負線對調的話如果剛剛好又是大電流的功率級播放吵一點的搖滾還是電音，如果當初計畫喇叭線的耐壓剛剛好夠用的話那不查的情況之下可能就慘案發生了。

建議閣下有興趣的話可以把功率級擴大機電源的公頭或母頭其中一顆的水火線對調（擴大機極性最簡單對調的做法..），期待您的後續分享！

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寧與同好爭高下，勿與傻瓜論長短...

justthinking

58分

22樓

justthinking

個人積分：58分

文章編號：63501403

fyl0206 wrote:
拜託一下，一開始樓...(恕刪)

話不要說得太滿是您搞混了

樓主一開始問的是XLR pin 2以及pin 3 hot/cold的問題

前面也有人提到 1992年後業界大致是統一了pin 2 hot 但是還是有些公司用的是pin 3 hot (像marantz)

單純就接線的角度來講一台pin 2 hot的前級如果配了一台 pin 3 hot的後級那把喇叭線正負反過來插本來就可以解決問題

後來講到器材的輸出是否preserve absolute polarity或是inverted polarity 這是很實在的東西

您不信可以隨便去看看任何一篇stereophile的review 最後的measurement部分都會測量output polarity

如果您不懂什麼是absolute polarity 還麻煩您這幾個連結自己看一下要是英文能力不夠我可以幫你翻譯

http://forums.stevehoffman.tv/threads/how-can-one-test-for-absolute-polarity.446475/

http://www.6moons.com/industryfeatures/polarity/polarity.html

fyl0206

226分

23樓

fyl0206

個人積分：226分

文章編號：63501434

justthinking wrote:
話不要說得太滿是...(恕刪)

呵，已經補充。恕我直言，閣下恐知能未足。

建議可以補充三階分音的分音器設計理論。

寧與同好爭高下，勿與傻瓜論長短...

justthinking

58分

24樓

justthinking

個人積分：58分

文章編號：63501452

fyl0206 wrote:
呵，已經補充。恕我...(恕刪)

absoulte polarity跟喇叭沒有關係以下文章出自於galen carol audio

The phrase absolute phase, seems to be one that is widely misunderstood. The term phase is most often used to describe the orientation of the + and - terminals of the speaker and amplifier. This relationship is more accurately defined by the term polarity. In other words, a system whose + and - amplifier terminals are connected to the speakers' + and - input terminals, is properly connected from the standpoint of polarity, but not necessarily phase. It is true that reversing the polarity of one speaker will put that channel out of phase with the other, but the polarity is reversed. The following text will help to explain the concept more completely.

To better understand how phase and polarity are related, let us examine the very beginning of the process that brings music into our homes - the recording session. Musical instruments create sound by modulating the air, producing sound "waves." These sound waves are actually compressions and rarefactions of the air molecules. The pressure changes impinge upon our eardrums and are interpreted by our brain into the sounds we hear. A microphone, like our eardrums, senses these same pressure changes, converting them into electrical impulses which are fed to the recording equipment.

When the leading edge of a musical waveform (compression) strikes the microphone diaphragm, a positive voltage is created at the microphone output. Similarly, as the waveform passes, its trailing edge (rarefaction) produces a negative voltage output from the microphone. Simple, right? No, unfortunately. For in between the microphone and your ears lie a vast array of electrical "obstacles," each capable of skewing phase to some degree.

Ideally, after all the mixing, signal processing, mastering and cutting have been completed, that same positive output voltage from the microphone will produce a positive (forward) motion of the loudspeaker diaphragm. Often it does not, and therein lies the rub.

The making of records is a very complex process involving a bewildering quantity of electronic equipment, each possessing the potential to manipulate phase. The microphone, cables, mixing console, tape machines and the myriad of signal processors (delay, echo, reverb, equalizers, limiters etc., etc.) could each be wired out of polarity with respect to one another. In addition, smaller phase errors (several degrees here and there) may occur within the electronics of any of these components. Finally, your stereo system may perform tricks of its own to further complicate the issue. Many tube preamps for instance, invert polarity. Often this occurs only in the phono section, which puts the turntable out of polarity with the line sources. So, to correct this, we must reverse the + and - leads at either amplifier or speaker. This would be done for both channels. But how do we know which orientation is correct? A trial and error approach is really the only way that we can determine proper orientation.

Ofcourse, inverting polarity at the amplifier terminals will change the polarity for all sources. But this may not be desired if, as described earlier, your preamp inverts phase of the phono section only, then inverting the polarity at the speaker terminals corrects the problem for the turntable, but inverts polarity for all other sources. In a system where only the turntable had its polarity inverted (because of a phono preamp), you might choose to reverse the leads at the rear of the phono cartridge.

What happens, sonically speaking, when our system is out of absolute polarity? Most listeners experience a constricted soundstage with a pinched center-image and reduced lateral spread. In phase, the soundstage will open-up, giving a more rounded feel to the center image, and offer a more correct presentation of depth.

To test for proper polarity, choose a recording with which you are quite familiar. I prefer those with simple instrumentation rather than more complex instrumentation, thus allowing the listener to concentrate on just a few instruments or voices. Listen for the characteristics outlined above as you make the switch between connections. Choose the one that sounds more correct, to your ear.

Unfortunately, every recording is different. It is possible that the first selection you play will sound best one way, while the next piece sounds better reversed. All I can say here is that you should set the phase for a few of your favorite recordings and hope that setting will be right for most your recordings.

A "trick" devised by David Fletcher of Sumiko may help you in determining whether a particular recording is out of polarity. Sit a few feet in front of one of your speakers. Listen to see if you can readily hear the other speaker. If you can, the system is in-polarity with the recording. If you cannot, then the polarity is inverted. This test relies upon a phenomenon known as the Haas Effect, and seems to be somewhat dependent on the room and type of loudspeakers employed.

I have had varying results with the "Fletcher Test." Apparently, it depends rather heavily upon the recording used. The recording must be phase coherent to begin with (which usually suggests a minimalist recording technique using only a pair of microphones). Complex multi-miked affairs are likely to give ambiguous results.

Returning a system to correct polarity can result in significant improvements. Experiment with the process a bit to familiarize yourself with the effects, and you will readily be able to recognize and correct an inverted polarity condition.

justthinking

58分

25樓

justthinking

個人積分：58分

文章編號：63501479

fyl0206 wrote:
呵，已經補充。恕我...(恕刪)

What you have is a ground on pin one and a positive and negative signal also exist. In some cases the positive signal is on pin 2 and some it is on pin 3.

Once again, this is a balanced configuration. There is either a transforemer or an equivalent electronic circuit on each end of a balanced connection.

If one of these pieces uses pin 2 on hot and the other is pin 3 on hot, then there will be a phase reversal. As long as both channels are handled the same way both channels will have the same polarity.

Absolute polarity is the situation when a microphone puts a positive signal on it's hot pin with positive pressure on the diaphram. If you maintain absolute polarity throughout the complete recording and playback chain, than the original positive impulse will make the speaker move towards you on initial transient. If the absolute phase was reversed the speaker would pull in instead of pushing out.

The issue is that absolute polarity is rarely adhered to in record production. The truth is that usually some instruments maintain absolute phase while others do not. So you can see how futile this all can be.

Now if you have a simple recording with one or two microphones, and they and all parts of their signal paths maintain that absolute phase, you will be able to find a 'correct' absolute phase.

You can change the phase many places. We used to always carry phase shifting adapters when doing live sound. All it was was an xlr adapter which swapped the pins 2 and 3 connections at one end.

The easiest way to swap the absolute phase may be at the speaker connections. In fact with unbalanced gear that is really the only practical way to do it. It doesn't really matter much where you do it.

fyl0206

226分

26樓

fyl0206

個人積分：226分

文章編號：63501547

justthinking wrote:
absoulte polarity...(恕刪)

justthinking wrote:
What you have...(恕刪)

你解釋那麼多沒有自行理解電路原理還是以盲導盲，建議您回頭看看敝人 21F 第三段的文章（喇叭線的線徑過小耐壓能力未足..），以及三階分音的喇叭如果只有喇叭正負對調要解決相位問題也是行不通的。不再贅述..

PS.：敝人高中在加拿大完成學業，英文能力無需閣下擔心。

寧與同好爭高下，勿與傻瓜論長短...

justthinking

58分

27樓

justthinking

個人積分：58分

文章編號：63501589

fyl0206 wrote:
你解釋那麼多沒有自...(恕刪)

這邊講的是wave reproduction..無關電路...看圖最單純

只需要看wave的peak/null 就知道什麼是inverted polarity

如果系統的輸出是inverted polarity 那解決方法有三種

1. 兩隻喇叭的接線單端對調

2. 如果是平衡線那可以在線材的單端把pin 2/pin 3對調或是單端用XLR polarity switch adapter

http://www.parts-express.com/in-line-xlr-polarity-reverser--240-410?utm_source=google&utm_medium=cpc&utm_campaign=pla

3. 如果訊源或是擴大機有phase switch/polarity switch 那也可以從這著手

以上三種方案只需要選一種即可

另外還請您解是一下為什麼喇叭線的端子對調會燒機???

fyl0206

226分

28樓

fyl0206

個人積分：226分

文章編號：63501808

justthinking wrote:
這邊講的是wave...(恕刪)

我從來沒有提及前端的電位訊號相位問題，提出的一切劇理力證：

相位差一但超過 90 度無法抵銷，不僅三階分音器如此，一階分音器的原理也無法利用土法煉鋼、江湖郎中開藥式的單體極性反接解決問題（二階、四階分音設計可以利用單體極性反接..）。尤其針對閣下的方法 1，現實理論跟自我解答通常是結果兩極...

...

寧與同好爭高下，勿與傻瓜論長短...

justthinking

58分

29樓

justthinking

個人積分：58分

文章編號：63501993

fyl0206 wrote:
我從來沒有提及前端...(恕刪)

是的追求系統是否output absolute polarity其實意義不大

因為可能這片CD正確下一片就顛倒

再加上多音路喇叭大多時後drivers之間也不是完全的in phase

我自己的經驗是低頻像是鼓聲因為比較容易有明確的push/pull action

只有這樣才比較明顯聽的出inverted polarity以及absolute polarity的不同

Antus

6019分

30樓

Antus

個人積分：6019分

文章編號：63502248

買到這個等級的，我不會用負負得正的接法。
有的機器可以選pin2 hot或pin3hot, 不能選，又不想用crossover 線，那就買一套西裝或換別家，沒必要為了這個在糾結，廠牌那麼多。

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