I think it’s important to point out 50:50 power matching for max efficiency. In nowadays amplifier, use of active devices make it possible to match low and high impedance device tremendously, it makes it hassle free for matching. After all, the spec just mentioned impedance at a certain frequency makes it impossible to match input and output devices unless you are the manufacturer. The truth is that it’s behaviour is guaranteed if both devices are made from a good reputation manufacturer. Expensive equipment does not really have mismatch loading , but gain on different frequencies. With regard to audio freq, it pretty much falls in the low spectrum as major difficulties normally comes at high frequency or uhf. Thanks for bringing up the topic👍🙏
Maximum power transfer occurs when load impedance equals to complex conjugate of source impedance. This condition can only be done on a single frequency. Audio band spans 3 decades (20Hz to 20kHz) that achieving maximum power transfer across whole audio band is impossible unless both source and load impedances are purely resistive. At maximum power transfer, both source and load dissipates same amount of power which results a 50% efficiency. Efficiency can be increased by reducing source resistance or by increasing load resistance. For audio signal transfer, fidelity is much more important than efficiency. In order to achieve highest fidelity the transfer function Zl / (Zs+Zl) needs to be as close as possible to a constant. If source impedance Zs is much much smaller than load impedance Zl, the transfer function reduces to Zl / Zl = 1 which implies perfect fidelity. So, the way of low source impedance driving high input impedance suggested by Kwok-yan in the video is actually the best way of transfering audio signals in terms of both efficiency and fidelity.
@@philiptong4978 External links always use 'self clocking prototol' which integrates clocks and multi-channel data into one signal in order to eliminate synchronization problem during transmission. I²S is not a 'self clocking' protocol and was designed for internal links only. It is expected to have huge synchronization problem when I²S is used as external links with multiple cables. I don't understand why some people using I²S for external links.
![[國仁齋Talk] 大細喇叭 5 大選購準則知多少？](http://i.ytimg.com/vi/6yIrs5j5UII/mqdefault.jpg)
![[國仁齋Talk] 大細喇叭 5 大選購準則知多少？](/img/tr.png)
![[影音TechTalk] Apple Music 無損 Hi-Res 最強攻略｜唔係俾咗錢就好聲｜自選字幕](http://i.ytimg.com/vi/KScXEosg-0U/mqdefault.jpg)
![[影音TechTalk] 盡我能力 淺談阻抗 (番外篇)｜擴音機與喇叭阻抗不配怎樣接駁？](http://i.ytimg.com/vi/93RTbqu7Pr0/mqdefault.jpg)
![ROSÉ (로제) - number one girl [더 시즌즈-이영지의 레인보우] | KBS 241129 방송](http://i.ytimg.com/vi/A9oByH9Ci24/mqdefault.jpg)
![[影音TechTalk] 盡我能力 淺談阻抗 (上集)｜CC字幕](/img/1.gif)
有關字幕的事宜，因為字幕組優先處理主頻道的影片，這裡的中文字幕有機會未能兼顧，不如這樣吧，如果這個留言有超過 20 個 like，那就找字幕組加班做字幕吧
夠數，字幕會在緊接處理，需時兩天～
@@feverSoundHK2 沒事.你們是最棒的頻道.謝謝
繁簡中文字幕已經上載～
@@feverSoundHK2 萬分謝謝
最棒音響的頻道.謝謝
實用清楚明白超正
超正. 實用. thanks國仁
非常用心的講解，繼續努力，支持國仁、艾域及 Feversound 各人。
擴音一定要選8 ohm高瓦輸出，要沉實聲厚嘅高能量，而4 ohm瓦數經換算以為高，你要聲大冇力、低頻擴散細小嘅聲音嗎，或者4 ohm易推，覺得聲音細緻速度快唯一可取之處，但8 ohm 亦輕易做到。
多謝分享!我的理解能力有限,多看幾次就會明白.😀
非常清楚明白，穫益良多。
感謝講解 睇書/上網真係有排搵
非常喜欢和感谢 这类有技术分享
正呀 國仁兄
一日兩片💪💪
Good talk
Can you explain more about roll off?
尼集超正
正！講多啲呢類技術，支持～～～
國仁請教一下， 我而家用緊linn selekt dsm， balance output 係 600 ohms 4V， 我想直接駁後級， 有沒好的配搭可以推薦？ 唔該曬！
講得好好呀！至少我聽得明👍
國仁 加油🤓🤓
產品測試盡在主channel，影音技術同有趣嘅分享心得可在此頻道收看，得咗！thanks國仁～👍😊
正, 教學片好睇.
國仁你好,我是玩左幾年古董前後級和喇叭,阻抗的定律都一樣?謝謝!
I think it’s important to point out 50:50 power matching for max efficiency. In nowadays amplifier, use of active devices make it possible to match low and high impedance device tremendously, it makes it hassle free for matching. After all, the spec just mentioned impedance at a certain frequency makes it impossible to match input and output devices unless you are the manufacturer. The truth is that it’s behaviour is guaranteed if both devices are made from a good reputation manufacturer. Expensive equipment does not really have mismatch loading , but gain on different frequencies. With regard to audio freq, it pretty much falls in the low spectrum as major difficulties normally comes at high frequency or uhf. Thanks for bringing up the topic👍🙏
Maximum power transfer occurs when load impedance equals to complex conjugate of source impedance. This condition can only be done on a single frequency. Audio band spans 3 decades (20Hz to 20kHz) that achieving maximum power transfer across whole audio band is impossible unless both source and load impedances are purely resistive. At maximum power transfer, both source and load dissipates same amount of power which results a 50% efficiency. Efficiency can be increased by reducing source resistance or by increasing load resistance. For audio signal transfer, fidelity is much more important than efficiency. In order to achieve highest fidelity the transfer function Zl / (Zs+Zl) needs to be as close as possible to a constant. If source impedance Zs is much much smaller than load impedance Zl, the transfer function reduces to Zl / Zl = 1 which implies perfect fidelity. So, the way of low source impedance driving high input impedance suggested by Kwok-yan in the video is actually the best way of transfering audio signals in terms of both efficiency and fidelity.
Good
睇嚟字幕組要OT了 辛苦哂字幕組!!
哈哈, 謝謝, 字幕組正努力中, 快完成了~
技术喜欢看
前級比DAC PRE好的主要原因不是輸入阻抗高，而是輸入阻抗更恆定，高只是附帶的。
輸入阻抗講的是前級比DAC PRE直入後級
阻抗也可調配
不同的線材，對音色/質的影響，難及配抗牛(Line Matching Transformer)那立竿見影之效，以致早有不少CD名机也要暗渡陳倉(+牛)。
可惜的是市塲極少獨立成品供應，要擁有，也得先從火牛代理商(Tango,Tamura,Lundahl...)落手，購後托人或親自裝箱接座...繼而攜器招搖過市，驚嘆總不絕...
配抗牛雖然有阻抗轉換功能，但訊號源用配抗牛主要有兩個目的：第一是升壓，例如MC唱頭，動圈式微音器等等；第二是平衡/不平衡轉換。因為世間上冇理想牛，所以訊號過咗牛一定有改變，聲音一定晤同，至於好咗定差咗，冇定論。
@@wingsangcheung38 若玩牛只限MC放大及平衡分相，那就太單調了，坊間還有不少非晶及鎳合金配抗牛，知者寡，樂者渺！
@@lawjog6246 其實加牛重有一個作用係會將訊號地隔開，消除地噪音，雖然消除地噪音有好多其他方法。
@@wingsangcheung38 嗜牛者，日本玩家多的是！堅料有90年代中限量發行的Marantz Project T-1 功放，是單邊採用4只300B作前兩級電壓放大，後段電流放大(PP)用上2只845，其整流供電又用上另2只845，除正規牛外，還多三只專訂牛(UTC)是特別作平衡式耦合而設，其訉源輸入端的牛抗為1KΩ，互耦成50KΩ(計約7倍升壓)後入接給低增益的300B作電壓放大...
行家大多會驚歎但不會仿俲，但老馬卻樂此一嚐，全賴牛的調音魔力?
@@lawjog6246 我都喜歡玩牛，玩最特別嘅牛：電流牛(電流變電壓)，霍爾效應牛(變直流電)，共模牛(不允許共模電流通過的牛)，回描牛(先儲能量到場，回描時才把能量轉到次級的牛)，方向耦合牛(只耦合前向功率或反向功率的牛)，傳輸線牛(只用傳輸線製作的牛)，超小形牛(網絡LAN RJ45 插座裏面的4隻超小形牛，LAN用牛所以冇地線)，双平衡混合牛(將兩個訊號相乘的牛)。用特別牛設計嚣材千變萬化，非常好玩。
一邊講機一邊講技術咁先全面， 如果唔睇你呢個channel 淨係睇你主channel 買咗幾返嚟畀啲機玩到氹氹轉就大件事。 加油國仁💪💪👍👍
Halo ! kwok yan , what about to match simple CD PLAYER and INTERGRATED TO SPEAKER S , how to match it ? tq tq
Just follow the informations from the User Manuals would be OK.
講可以講多啲技術👍
長知識了，希望未來更多教學，音響學問很多...新手真係要學好多野先可以減少撞板!
❤❤
國仁兄可唔可以出一條片關於電平的匹配，調校，以及調校的方法？唔同器材有唔同輸入輸出電平，新舊電平標準又唔統一，校得唔好，大高會失真，太低會減低訊噪比，所以這個題目都幾重要。
我不太懂科學的方法去量度計算，只是靠直覺聽而已
@@feverSoundHK2 國仁兄真謙虛，拍片又認真，口材又好，表達技巧又高，講嘢人人鍾意聽，講真心話又唔會令供應商唔高興，其實好難得。玩音響最重要係個「玩」字，玩得過隱，聽得舒服，其他野冇乜所謂。但我發覺玩音響超貴，原因係產品供應商推銷術太利害，發燒友唔夠技術知識做判斷，就要用多好多錢去玩。我希望比多啲知識出去，令大家玩得更超值。我明白技術知識有時同有些朋友嘅經驗有衝突，有時更會令供應商唔高興，但我比出去嘅全部係真材實料，喜歡嘅就睇吓，唔喜歡就唔洗理。想知多啲有關電子學知識歡迎聯絡，唔收錢，因為我已經退休。
👍💪💪
那裏有壓迫， 那裏有⋯
👏👏💪💪
字幕5緊要... 最緊要講多D 呢D... 新手好想知多D 謝謝
這些知識 很多老手都唔識
@@andychan4554 老手識， 我新手唔識，老實講技術野唔怕聽， 有時自己都會記錯， 好似我整車咁， 都可好多方法整…
國仁講嘅風格岩我聽， 所以要支持
高輸入阻抗優點六十年前無线電世界有刊登。
六十年前喎，你仲 keep 住啲雜誌？
如果前級得輸出電平冇ohm數點算
咁就只能段估無辛苦⋯有時你要響說明書最後一頁，先會見到呢個規格數據的，試下丫
@@feverSoundHK2 真係冇寫ohm得輸出電平2v(max 4v)咁樣係膽前加膽耳擴
@@feverSoundHK2 多謝國仁講解非常好睇
一個 48kHz/16-bit S/PDIF 數碼訊號嘅bit rate達到3.072 Mbit/s，這個訊號不能用低輸出阻抗配高輸入阻抗的方式去連接，輸出及輸入阻抗都必須係75 Ohm，連接線的特性阻抗也要用75 Ohm的，否則就會有訊號從輸入到輸出端不停返射，造成高錯誤率(error rate)及高抖擺率(jitter)。
and it is a real problem with external I²S links
en.m.wikipedia.org/wiki/I%C2%B2S
@@philiptong4978 External links always use 'self clocking prototol' which integrates clocks and multi-channel data into one signal in order to eliminate synchronization problem during transmission. I²S is not a 'self clocking' protocol and was designed for internal links only. It is expected to have huge synchronization problem when I²S is used as external links with multiple cables. I don't understand why some people using I²S for external links.
出到但好唔好聲先🙂
Dac: 3pins XLR, 4.0V RMS, Zout 100 ohm ,active speaker Input Impedance: 48 kΩ
咁樣夾唔夾呢，thx
輸出 100 Ohms 4V RMS
輸入 48k Ohms
睇 sepc 完全無問題啦
@@feverSoundHK2 thx
👍,first
你先攪清楚： 電流放大與電壓放大的分别。
阻抗是交流阻抗與直流阻抗的分別。
請將正確的資訊告訴我們🙏🏻這樣我們才可以搞清楚
輸入阻抗達到1 MOhm的儀器，必定會標明輸入電容，例如20 pF，因為 1 MOhm + 20 pf 的阻抗去到 8 kHz 已經跌咗 3 dB，隨後每個八度(octave)，跌 6 dB。要測量到幾百MHz的高頻，就要用由上世紀美國Tektronix公司發明的方法：用高電阻物料造線芯的同軸線，接上有可調補償電容的10倍衰減無源探頭，然後才接到高頻訊號。所以影音器材造 1 MOhm 的高輸入阻抗，又唔用正確方法去連接訊源，雖然接到低輸出阻抗的訊源唔會影響音質，但這超高的輸入阻抗冇實際意義。
@siu-hung Hung VTVM 係古老儀器，已經淘汰。現代要測量DC的話，輸入阻抗高至GOhm級嘅儀器都有好多，但測量較高頻率的AC，輸入主要唔係電阻抗，而係電容抗，1pF 在20kHz的電容抗已經低過8MOhm，所以測量音頻AC時要留意輸入電容幾多pF而唔係輸入電阻幾多MOhm。例如10X示波器探頭標明輸入阻抗 10 MOhm / 12 pF，表示低頻(1.3kHz以下)輸入電阻 10 MOhm，高頻(1.3kHz以上)輸入電容 12 pF。
虽然听到我一头雾水，但仍然感兴趣，哈哈哈哈哈
有中文就按讚, 假若聽不懂就按那就太假了.
對於音頻訊號，低輸出阻抗配高輸入阻抗一定冇問題。但高頻訊號例如視頻及數碼訊號完全不同，高頻訊號有兩種阻抗，75 Ohm 及 50 Ohm，影音設備通常用75 Ohm，輸出阻抗75 Ohm，配75 Ohm特性阻抗的連接線，再配75 Ohm的輸入阻抗，不匹配的話會有反射，會有駐波。
原子粒擴音機的輸出阻抗等於8 Ohm 除以阻尼因數(damping factor)，通常低過喇叭阻抗好多，所以冇阻抗匹配問題。但膽機的輸出阻抗通常都幾高，而且不同端子有不同的輸出阻抗，輸出阻抗舆端子標示的阻抗成正比例。因為喇叭的阻抗變化好大，所以接不同的端子會有不同的聲音。
多隻香爌多隻鬼。
玩音響係咁架喎，否則不如玩 all in one？
國仁！不是角仁，注意懶音，自已的名都講唔掂，怎辦
毋須矯枉過正
設計1 MOhm輸入阻抗嘅工程師有啲問題，因為1 MOhm好難去到20kHz，頂多去到幾kHz就開始跌，跌到20kHz時得番一半都冇。
HDMI線的特性阻抗是100 Ohm。USB線的特性阻抗是90 Ohm。LAN線的特性阻是100 Ohm。數碼輸出接數碼輸入線的特性阻抗是75 Ohm。
輸出電壓高並不是一定有好處，我反而喜歡輸出電壓低，如果唔經前級直接落後級產瞬態互調失真都會好大顯得背景聲好嘈，動態好似好高但係唔好聽聽落去唔舒服，聽兩下就想飛咗首歌，我自己覺得正負2V, 前級夠好多層放大，比起訊號電壓大，聽出你感覺舒服😌
都要睇後級夾唔夾到，輸出大可以調細，輸出不夠無法調大（當然應該加前級吧），所以音響都是貴乎匹配
@@feverSoundHK2 當然輸入高輸出阻抗低是好的，只不過我覺得訊號太高未必一定聽得舒服，現在的流行錄音音都好大訊號，開頭個動態幾好，去到中間就飛咗首歌聽下一首🤣，以前80年代90年代嘅錄音可能係而家嘅流行個三份一輸出音量電壓
前端輸出電歷高會降低噪音，是噪音定律，因為後面衰減時會將前端的噪音一並衰減，相反前端電壓太低要後面放大就會將前端的噪音一起放大。至於邊個好聽啲人人不同，科學也解釋唔到。至於瞬態互調失真好少會發生，設計良好嘅擴音機永遠都唔會有，只有設計不良的擴音機在輸出高頻率大訊號而輸出級的電壓上升速度(slew rate)不夠時才會發生。
@@wingsangcheung38 Slew rate 和TIM 失真係兩樣野來的，TIM 瞬態互調失真，最容易產生就係直接落後級放大最容易產生，因為放大係數太大，通常一部前級已經有一到兩級放大器，靚嘅前級可能有三四級目的係令到聲音度快速嘅時候唔會混亂，當然需要音源配合，慢歌好多人都會播得好好，帶節奏一快好容易亂，（嘈），至於你訊號細一齊產生雜音你係講模擬錄音就會，現在嘅數碼錄音係唔會，但係現在嘅錄音錄到好大聲，動態好多但係一到副歌位置就亂和散開，音樂和人聲互搶
@@lalamo690 上世紀七十年代美國研究員Eero Leinonen及John Curl發現失真低至0.01%的擴音機在冇爆機的情況下竟然可以在瞬間發出很難聽的聲音，深入研究發現不單訊號太大會令電路飽和產生大量失真，即使訊號=0，而訊號的微分 dV/dt (又叫slew rate)太大也會令電路飽和，使負回輸無法運作而產生瞬間的大量失真，命名為瞬態互調失真TIM (所以冇負回輸嘅擴音機唔會有TIM)。TIM的發現不但大大影響擴音機的設計，也大大影響運算放大器芯片的設計，影響直到今天。
太技術性，唔明
很難明😅