B.M.C Audio 設計者 Michael Conrad

在代理商的會議室中，Michael就像教授般的跟學生(我)"重點式"解說B.M.C產品的獨特設計想法，從輸入線路、輸出線路、唱頭放大、DAC、轉盤、唱放，甚至電源供應都一一解說，一下子一小時就飛快的過去了，雖然我沒辦法完全吸收，但我會盡可能說明我所理解到的，若有錯誤之處也請大家不吝指正。在訪談最後，Michael也提到其正在進行錄音，講到這，當然跟我就很有話題了聊啦！

真材實料，具有很強know how的B.M.C
這張圖就可看出我是真的像在上課一樣喔！
B.M.C是CANDEIAS齊下的一個品牌，CANDEIAS是一家歷史悠久的音響設計公司，如CEC就是他們所設計的，創辦人為Carlos Candeias，在兩年前慕尼黑上有看到他，會說流利的中文，去年音響展也有來台，B.M.C是CANDEIAS自有品牌，想當然爾，是最能實現與應用CANDEIAS技術理念精華的產品，也難怪上市時間不長，卻已有各地許多的代理商了。

http://www.my-hiend.com/leoyeh/2011a/IMG_1547c.jpg

http://www.my-hiend.com/leoyeh/2011a/IMG_1551c.jpg

AVVA線路跟B.M.C.的不同
B.M.C.的特別技術
LEF 技術的解釋
CI = Current Injection 技術的解釋
CI技術在DAC上
DAC-CI versus OP-AMP
唱放 PHONO MC-CI
最少的訊號COPY


.

我說，站長啊...下次有這種好事能不能讓我跟一下...

原來有人認為這是好康的.......沒問題 :D

引用:

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作者: drunkenlife

我說，站長啊...下次有這種好事能不能讓我跟一下...

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http://my-hiend.com/vbb/picture.php?...ictureid=14374

這次Michael來訪，主要是說明B.M.C擴大機最重要的特色與技術核心，也是為什麼B.M.C的聲音會出色的原因，這些技術的主要重點就是CI、DIGM與LEF。

CI (Current Injection)：低阻抗的訊號輸入會使訊號以原來的電流經過放大線路，直到到達喇叭所需的輸出電壓。所有的B.M.C產品都可與CI輸入搭配，擁有最好的聲音可能。

DIGM (Discrete Intelligent Gain Management)：這個是非常特別的一項技術，只有在喇叭輸出電壓的這個地方，增益(Gain)會精準的對應到所調整的音量，也就是說是透過增益的調整來進行音量大小的控制，這樣的好處是可以避免一些不必要的放大導致訊號衰弱下來，更少的放大就會擁有更少的失真與噪訊，音樂最會有更自然的品質。(傳統擴大機的放大倍數很高，其實是不需要這麼高的倍數，變反過來將原本的輸入訊號降下來，從下面這張圖就可很清楚的看出來差異)

http://my-hiend.com/vbb/picture.php?...ictureid=14375

LEF (Load Effect Free)：LEF輸出級調整輸出電壓到喇叭所需要的值，喇叭不需要負責調整，因此信號電晶體非常的重要，必須在一開始就能避免失真，LEF即使在高功率輸出也能維持單端的運作，也因失真減少，聲音會更為自然。將電壓與電流輸出分離的設計也可避面相位轉動的問題，聲音表現甚至比A類還要更清楚。

除了以上3個特點外，B.M.C 超大的2kW環型變壓器提供了超額設計的電源供應。

另外B.M.C的CD轉盤使用皮帶驅動，Michael表示這是讓CD轉動速度最能穩定的方式，就像黑膠唱盤一樣，也是能有效降低jitter的設計，唯一會讓速度變動的時間就是在換曲目的時候，可是這時候沒有音樂，當然就沒有影響了。

引用:

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作者: 小葉

另外B.M.C的CD轉盤使用皮帶驅動，Michael表示這是讓CD轉動速度最能穩定的方式，就像黑膠唱盤一樣，也是能有效降低jitter的設計，唯一會讓速度變動的時間就是在換曲目的時候，可是這時候沒有音樂，當然就沒有影響了。

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「唯一會讓速度變動的時間就是在換曲目的時候」這句話有點怪怪的？不同於LP的恆定轉速，CD讀取的轉速本來就是持續變動的啊？不懂...:^)

不好意思，我寫的太簡短了

使用皮帶的意思就是因為皮帶趨動的方式能像黑膠的轉速具有穩定性一樣

在"切換"曲目的時候才會有劇烈的轉速變化，然而這時候是沒有音樂的播放，所以沒有關係

引用:

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作者: ericc0922

「唯一會讓速度變動的時間就是在換曲目的時候」這句話有點怪怪的？不同於LP的恆定轉速，CD讀取的轉速本來就是持續變動的啊？不懂...:^)

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引用:

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作者: 小葉

http://www.my-hiend.com/leoyeh/2011a/IMG_1547c.jpg

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這張圖真是重點中的重點啊～
DIGM這迥異於傳統擴大機的電路的祕密就在此囉～
LEF也是由此架構而來

幾年前PS audio也推出Gain Cell，目的也是排除CD player那高輸出被擴大機衰減後又放大這種脫褲子放屁的架構

yes.......我聽到時，也覺得很酷........所以他們家的音量是直接真的調Gain的

Source訊號不變,只調整Gain去做音量調整,避免訊號失真的方法~

Accuphase的AAVA也是直接改Gain，用好久了，現在連綜合擴大機都全用上了。

最後那級與Devialet的概念有些類似，都是以伺服電路參酌電壓放大級以校正電流放大級
http://www.google.com/patents?id=g6X...page&q&f=false

CI, current injection這詞有趣...
定名者，說不定是車迷...彷缸內直噴吧...
http://my-hiend.com/vbb/picture.php?...ictureid=14375
最下面這張圖的基本前提是擴大機內部總是會有某個程度的電源雜訊，
若輸入訊號一進擴大機就衰減，那麼訊號中的微弱變化量小於電源雜訊者，就會被雜訊蓋過去了...
這等效於放大雜訊的效應

因此才說，數位音量調整真的比擴大機內的VR衰減來的好嗎？難說...

這個幾個圖好像只對綜擴有意義。

如果前後級分開，除了唱頭放大之外，其他的訊號在進後級前不是都是衰減嗎？

沒有傳統前級的存在
Michael只提到input stage 與 output stage的處理方式
可看出目前B.M.C的產品沒有前級這一樣
http://www.bmc-audio.de/en/products.asp
也因為這樣的設計，他們的產品最好一套使用是最佳的

若有時間我會把錄音檔給放上來，大約40分鐘
其實我能理解的應該只有70~80%左右 (sweat)

前面的描述是我先就印象寫的

引用:

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作者: kevintran

這個幾個圖好像只對綜擴有意義。

如果前後級分開，除了唱頭放大之外，其他的訊號在進後級前不是都是衰減嗎？

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可能想法想似，作法不一樣
B.M.C在Output Stage 採用電流與電壓分離的處理方式 (可參考第一張黑板的右方圖)

Accuphase的AAVA
http://www.accuphase.com/aava.html

http://www.accuphase.com/image/technology/aava_dia.gif

YES
Michael 說一般的作法是在Input Stage會Copy訊號.......然後進行放大 (如10倍？)

引用:

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作者: 查德

Source訊號不變,只調整Gain去做音量調整,避免訊號失真的方法~

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這不是全部 (有些講完已經擦掉)

http://www.my-hiend.com/leoyeh/2011a/IMG_1557c.jpg

MY-HIEND的朋友
你們有認真在聽嗎？
(站長我是聽完霧煞煞啦...)

http://www.my-hiend.com/leoyeh/2011a/IMG_1550c.jpg

[QUOTE=小葉;132373]這不是全部 (有些講完已經擦掉)

MY-HIEND的朋友
你們有認真在聽嗎？
(站長我是聽完霧煞煞啦...)

有聽沒有懂8)8)

引用:

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作者: kevintran

這個幾個圖好像只對綜擴有意義。
如果前後級分開，除了唱頭放大之外，其他的訊號在進後級前不是都是衰減嗎？

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以DAC的高輸出而言，前後級加起來的gain實在太高了，沒啥必要吧...

引用:

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作者: 小葉

也因為這樣的設計，他們的產品最好一套使用是最佳的

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這項該是指current injection，
若是DAC的輸出電流量不夠（例如我改的DAC），那就不佳
以一般的DAC而言，都會有個buffer級，應該沒問題，BMC文件也提到這點

引用:

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作者: 小葉

Accuphase的AAVA
http://www.accuphase.com/aava.html
http://www.accuphase.com/image/technology/aava_dia.gif

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輸入級取的是電流，電壓放大級仍舊是固定gain（但有幾段可調），最後仍舊轉成電壓，以電壓驅動喇叭
這些與BMC不同

引用:

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作者: 小葉

YES
Michael 說一般的作法是在Input Stage會Copy訊號.......然後進行放大 (如10倍？)

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一般輸入級是組差動電路，取的是電壓
在這之前是音量衰減可變電阻，
之後是固定電壓放大倍率的電路

BMC的架構與此完全不同，
Accuphase的架構只改變了輸入級

引用:

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作者: 小葉

http://www.my-hiend.com/leoyeh/2011a/IMG_1557c.jpg

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輸入級以電流方式運作，一顆BJT就搞定了，
這架構若是搭上早期必須外掛I/V轉換的DAC IC，那，不就可以拿掉I/V轉換，更是簡潔...

突然看到設計者姓Conrad？與Conrad Johnson有關嗎？

Dear Leo,

Thanks a lot for your therad about BMC Audio! I can only read a little, and the google translation is not always correct... It is even harder to contribute something to your website, because my written Chinese is ZERO. But may be I can write to you by email, and step by step offer a little more information. As our technology is really new and unique, it is difficult to understand - even for people with a solid technical background. May be you can help me translating my comments to Chinese and publish them?

(以上翻譯略，就是Michael感謝MY-HIEND的報導，也希望我幫忙把他進一步解釋的部份翻成中文給大家，BMC的理論非常新與特別，就算是讀電子的可能也不太容易懂)

"Accuphase's AAVA circuit has nothing to do with our BMC design - much to complicated. AAVA has an input buffer, a V-I converter stage, a current addition and finally an I-V converter stage with a feedback loop and gain.

Accuphase AVVA的線路跟BMC不同，BMC複雜多了，AAVA有輸入緩衝，一個V-I轉換級，會增加電流，最終會有一個回授與增益的I-V轉換級。

To understand our approach it does not need to think that complicated.

瞭解BMC的方法不需要想得這麼複雜

CI input with DIGM volume control is a 1-stage amplification. The volume
control is just done with resistors (switched by transistors) at the output of this stage. After this gain adjustment there is no more voltage amplification. This means: The volume control happens at the voltage level of the speaker output.

使用DIGM音量控制的CI輸入是一級放大，音量控制是由輸出級的電阻(電晶體轉換)來處理，在這增益的調整後沒有任何電壓的放大，這意味著音量控制發生在喇叭輸出的電壓水平。

The only thing in common with the AAVA is: we have a potentiometer in the DAC1, a CPU reads out the position of the volume knob and translates it to a digital word, then this word is sent to the amplifier AMP S1 (or M1) by an optical connection. In the amplifier the digital word is used to activate some of the transistors of the DIGM to switch the required resistor (or combination of resistors).

與AAVA唯一相同的是，在B.M.C DAC1中，有個分壓計，CPU可以知道音量選鈕的位置將其變成數位語言，然後透過光纖將其發送到擴大機AMP S1 (或 M1)。在擴大機中，這些數位語言會啟動DIGM的電晶體來轉換成所需的電阻 (或將電阻組合)

It is a 1-stage design. The ouput of this stage is a current source. The gain is adjusted by the termination of this stage with a resistor, thus setting the I/V conversion."

這是一級的設計，在這級的輸出的來源是電流，增益是在這級最後由電阻來調整，就是I/V轉換

I hope this helps a little for a better understanding of DIGM.
I'll follow up with more explanations...

Best regards,

Michael

引用:

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作者: 小葉

CI input with DIGM volume control is a 1-stage amplification. The volume
control is just done with resistors (switched by transistors) at the output of this stage. After this gain adjustment there is no more voltage amplification. This means: The volume control happens at the voltage level of the speaker output.

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對照組是傳統擴大機的架構，
可變電阻衰減->差動輸入級->偏壓級->功率晶體驅動級->輸出級

引用:

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作者: 小葉

The only thing in common with the AAVA is: we have a potentiometer in the DAC1, a CPU reads out the position of the volume knob and translates it to a digital word, then this word is sent to the amplifier AMP S1 (or M1) by an optical connection. In the amplifier the digital word is used to activate some of the transistors of the DIGM to switch the required resistor (or combination of resistors).

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這段很有意思...
這點出了BMC DAC的音量控制能夠直接調整BMC二款後級的gain，而非在數位端調整，也不是在DAC的類比輸出處衰減（這等於傳統前級擴大機的手法）
因此若使用BMC DAC + S1或M1，無需前級擴大機

引用:

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作者: 小葉

It is a 1-stage design. The ouput of this stage is a current source. The gain is adjusted by the termination of this stage with a resistor, thus setting the I/V conversion."

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傳統擴大機的架構則是五級，功率晶體驅動級->輸出級這段是電流，其他都是電壓
gain固定，音量控制是以衰減輸入訊號方式處理

引用:

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作者: martin

Accuphase的AAVA也是直接改Gain，用好久了，現在連綜合擴大機都全用上了。

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什是Gain,分享些給門外漢.

gain＝增益
也就是放大倍侓。一般是以dB來計算。

Dear Leo,


Let's go on with the special BMC technology.

來說說BMC特別的技術

Please understand our basic difference to most of the circuits: We don't use operational amplifier designs for audio, and we don't use any kind of negative global feedback loop for the audio signal. Thus comparing our approach with AAVA or gain cell makes no sense.

請瞭解我們跟大部份線路根本上不同的地方：聲音方面我們不用運算放大設計，聲音訊號也不用任何種類整體負迴授迴圈。因此跟AAVA或是Gain Cell比較是沒意義的。

My last email was about the DIGM. At DIGM we are at the speaker terminal voltage (電壓 ), but there is not the power (電功率) and specifically not the current (電流) to drive a speaker. Thus we need a buffer stage to provide the current.

我上一封Email關於DIGM，在DIGM下，達到喇叭終端的電壓，不是電功率，特別是指不是電流來驅動喇叭，所以我們需要一個緩衝級來提供電流。

In all usual power output stages one pair (or more pairs) of transistors has to handle the signal precision, the voltage and the current. As this is quite demanding, it usually failes in precision - and needs a feedback loop for reducing distortions. There is even the difficulty to handle complex loads, like real world speakers, as they are partly inductive and / or capacitive. This means signal voltage and signal current are not allways in phase. Means: There are moments when the voltage is 0, but there is still a demand for current. How can this be handled by a transistor having the task of caring for the right voltage AND the right current?

在所有一般的功率輸出級，一對或多對的電晶體必須處理Signal precision，就是電壓與電流，且需要回授迴圈來減少失真。處理複雜的阻抗是困擾的，就像喇叭一樣，部份是電感或電容。這意偽著訊號的電壓與訊號的電流通常不是相位一致。也就是說，當電壓為0，但還是對電流有需求，那麼一個電晶體如何處理正確的電壓對應正確的電流？

LEF is different. It is like giving different jobs to different people.
LEF means Load Effect Free. Means: The LEF signal transistor (responsible for the signal quality - the precision) has neather to handle the voltage, nor the current. Thus it needs "assistants": A cascode transistor to handle the voltage changes, plus a pair of current sources to deliver the required current.

LEF是不同的，他將不同的工作給不同的人，LEF意思為Load Effect Free。也就是LEF訊號電晶體(負責訊號的品質- precision)不是處理電壓或電流，他需要"助理"，一個cascode電晶體處理電壓的改變，加上一對電壓來源來提供所需的電流。

This circuit design is intended to avoid distortions by a new and unique design, instead of a later correction by feedback.

這樣全新與特別設計的線路用來避免失真，而不是後來回授的修正。

Beside of avoiding distortion, the independend handling of voltage and current by different "experts" makes handling inductive or capacitive loads just a piece of cake: The LEF signal transistor together with the cascode transistor care for the correct voltage. The current servo circuit with the current sources deliver the required current, not "knowing" anything about the voltage, just keeping the current through the LEF signal transistor constant.

除了避免失真外，由不同"專家"獨立的處理電壓與電流，讓處理電感與電容阻抗變成非常容易的事。LEF訊號電晶體與cascode 電晶體共同確認正確的電流。電流伺服線路和電流來源提供了所需的電流，而不用需要知道電壓的狀態，只要保持有足夠的電流到LEF訊號電晶體。

I know, it is difficult to understand, mainly because it is so different from usual amplifier designs.


Best regards,


Michael

Dear Leo,

Here some more information about LEF. We are often asked, if out design is Class A or AB. As we don't have a traditional design, class A or AB does not really fit. The efficiency is that of Class AB. But the circuit design has nothing to do with Class AB: The LEF signal transistor, that is responsible for the sound quality, works in single-ended Class-A-Mode. But it does not have to handle the change of voltage. As this transistor is supported by a cascode transistor, the voltage over the LEF signal transistor is allways constant, it would be better to call it a "Cascoded Single-Ended Class-A Circuit" - as a first step. There is - as a second step - the current source circuit, separating the signal transistor and the cascode transistor from the current requirement of the load. Should we call it "Cascoded Single-Ended Class-A with Current Relieve Circuit"? (Or "CSECAWCRC"?) Sounds complicated...

針對LEF我再提供多一點資訊，我們通常會被問是A類還是AB類，事實上都不算是，效率可能跟AB類一樣，但線路跟AB類一點也無關。LEF訊號電晶體負責聲音的品質，以單端A類模式運作，但其不負責電壓的處理。當這個電晶體被1個Cascode電晶體所支持著，稱為Cascoded Single-Ended Class-A Circuit比較合適。再來電流來源的線路將訊號電晶體與cascode 電晶體從負載所需的電流分離出來。或是我們要稱之為Cascoded Single-Ended Class-A with Current Relieve Circuit(Or "CSECAWCRC"?)，好像很複雜

We think "LEF = Load Effect Free" hits the nail on the head: The signal transistor is free from every effect of the load, free of the voltage swing, and free of the current demand. Because of this reason the LEF signal transistor is free to care for his main task: Reproducing the music signal as best as possible.

LEF恰到好處，訊號電晶體不受到任何負載下的影響，也不受到電壓轉變的影響、也不受到電流需求的影響，也因為這些理由，LEF訊號電晶體可以專心的、達到最佳再生音樂的目的。

As LEF by design avoids distortions, there is no need for a signal feedback loop. This means as well: The LEF stage is independent from a voltage gain stage. (You even could use a tube circuit for the voltage gain and use the LEF circuit as the output buffer...) This independency allows further new circuit designs like the DIGM gain management, as it is explained on page 2.

LEF設計來避免失真，因此就不需要有訊號回授的迴圈，意味著LEF級是與電壓增益級所獨立的 (你甚至可以用真空管線路給電壓增益，然後用LEF線路為輸出緩衝...)這樣的獨立允許進一步的線路設計，如DIGM增益管理，像第2頁提到的

Next time I will explain the CI input circuit.

下一回我將解釋CI輸入線路

Best regards,
Michael

Dear Leo,

Sorry for delay due to a lot of urgent work! I like to explain more about our CI = Current Injection technology. First let's see how most of the amplfier circuits are working. Please have a look in picture T1. The way of showing this transistor looks a little unusual with a tiny line for B (Base) and much stronger line for C (Collector) and E (Emitter) - but it reflects reality: A tiny signal into B modulates a much bigger current flowing through C and E. We name it: We make a COPY of the incoming signal! And a copy is not the same as the original, always adding some own signature. Same is right for tubes or FETs and MOSFETs. This way some of the characteristic of transistors (or tubes or FETs or MOSFETs) is imprinted to the music signal.

不好意思，最近忙一些，所以有些延遲，我想要進一步解釋 CI = Current Injection 技術。首先我們先來看大部份擴大機運作的方式，請看圖片T1，這圖中電晶體的表達方式跟平常有些不同，B (Base) 的線較細、C (Collector) 與 E (Emitter) 的線較粗，不過這反應了實際的情況，較小的訊號進到C，較大的訊號進到C與E，因此這就是我所們所謂要COPY進來訊號的意思，而這樣的COPY會使得其跟原來的訊號不同，通常會加入自己的東西。這種作法在真空管或FETS與MOSFETS都一樣，而這樣會讓這些電晶體的特性跑到了音樂訊號中。

http://my-hiend.com/vbb/picture.php?...ictureid=14969

Anyway, making a copy can not be totally avoided. As long as you need more current at the output than you get from your source, there is the need for modulating a higher current by a less powerful signal. At least you need this process for driving speakers. But very often it can be avoided making a copy. How? Have a look at picture T2: The same transistor is turned, B is connected to ground, the music signal is feed into E, and this original current is flowing through the transistor to C. If you could mark the incoming electrons, you could find the same electrons at the output.

不過，COPY訊號是無法完全避免的，只要你在輸出需要比輸入更多的電流，你必須這樣的過程才能驅動喇叭，不過我們卻能避免進行這樣的COPY，要怎麼做？請看圖T2，相同的電晶體，B連接到地，音樂訊號到E，這樣原來的電流就會通過電晶體到C。因此C與E的電子會一樣。(輸入與輸出相同)。

http://my-hiend.com/vbb/picture.php?...ictureid=14970

Now let us have a look at a simplified schematic of our AMP M1 or AMP S1 input circuit (picture AMP-CI): The input signal from a source like our DAC1 is flowing through resistor R1 (in this case needed to define the current) and through E and C of the transistor, terminated by resistor R2. The current is same through R1 like through E and C of the transistor and as well through R2. But the voltage depends on the value of R1 and R2: If R1 and R2 are same, the voltage at the input of R1 and the output (C) of the transistor are same. If R2 is only 1/10th of R1, the voltage is 1/10th as well, means an attenuation of 20dB. If R2 is 10 times higher than R1, the voltage is 10 times higher as well, means a gain or amplification of 20dB.

現在我們來看我們AMP M1或AMP S1輸入線路的概要(圖：AMP-CI)，從像我們DAC1的訊號輸入通過電阻R1(在這裡要定義電流)，然後通過電晶體E與C，最後為電阻R2，這電流與通過R1、電晶體E與C一樣。不過電壓則視R1與R2的值來決定，如果R1與R2一樣，電壓在R1與C會一樣，如國R2只有R1的1/10，則會變小20dB。如果R2比R1高10倍，電壓會高10倍，就是增益或放大20dB。

http://my-hiend.com/vbb/picture.php?...ictureid=14971

This way we do the gain management (DIGM) of our amplifiers, by changing resistor R2. As this is the only stage for changing the signal voltage in our amplifiers, the output voltage of this stage is the same as the speaker voltage. This means: If you use the CI input of AMP M1 or AMP S1, there is no copy of the original input signal until the speaker voltage is chieved.

Still, at the end we need to drive the speaker. Means: We need much more current than our source can deliver. At this point we need to make a copy, and we do it with our LEF stage. But it means only one copy of the signal received at the CI input.

這就是我們B.M.C.擴大機增益管理(DIGM)的方法，從改變電阻R2來處理。這也是我們擴大機唯一會改變訊號電壓的地方，輸出電壓在這邊是與喇叭電壓一樣的，這意味著，如果你使用AMP M1與AMP S1的CI輸入，直到喇叭電壓，在原來輸入訊號是沒經過COPY的，當然在最終我們仍要驅動喇叭，因此我們需要的電流比我們訊號提供的電流來得更多，因此我們還是需要COPY，但我們在LEF級來處理這部份，這意味在CI輸入下，只有COPY訊號1次。

This is CI explained for amplifiers as used in BMC AMP M1 and AMP S1. The same technology we use for PHONO and DAC as well - explained next time.

這是使用在BMC M1與AMP S1中CI技術的解釋，相同的技術也用在我們的Phono與DAC，我在下次將解釋。

Best regards,
Michael

Hi Leo,

Thanks a lot for your translation! Today just a short one: CI for D/A-Converter:

Allmost all DACs are based on several current sources 电源 ［電源］ diànyuán , that are turned on or off. The most significant Bit (MSB) switches the highest current source, the second Bit switches a current source with half the current of the former one, the third Bit switches half the current of the second one, means one forth of the MSB, and every following bit switches a current source that has half of the current compared to the former one. And this for 16 Bit, 24 Bit or 32 Bit (the most common DACs are 16, 24 or 32 Bit). (See picture DAC-CI)

今天要介紹是CI技術在D/A轉換的應用，大部份的DAC以許多電流來源 (電源) 為基礎，電源不是開就是關。最重要的Bit (MSB，most significant Bit) 轉換最高的電流來源，其次的Bit則是只有轉換前面電流的1半、第3個Bit又是只有第2個的1半，也就是只有第1個的1/4，接下來的每個Bit都是依此原則轉換，大部份的DAC大都是16Bit、24Bit、32Bit。

http://www.my-hiend.com/vbb/picture....ictureid=14975

Now these current sources are connected to a CI-circuit, feeding the sum of the switched currents to E of the transistor. At the output the voltage is set by the resistor. At this point there is the output voltage of the DAC, without making a copy. That's it about CI for DAC.

現在這些電流連接到CI線路，提供了全部轉換的電流總合給電晶體E，因此輸出電壓是由電阻決定，在這點這是DAC的輸出電壓，而不需要經過COPY，就這就CI技術在DAC的應用。

Best regards,

Michael

http://www.bmc-audio.de/bilder/dac_front_big.jpg

http://www.bmc-audio.de/bilder/dac_rear_gross.jpg

http://www.bmc-audio.de/bilder/dac_intern_gross.jpg

http://www.bmc-audio.de/bilder/dac_power_gross.jpg

引用:

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作者: 小葉

http://www.my-hiend.com/vbb/picture....ictureid=14975

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這裡就是老的DAC IC後面必須外加的電流/電壓轉換（因為一般擴大機吃的是電壓變化，所以必須經過這個轉換
DAC IC的datasheet上通常都會建議用OP做這件事，例如這個例子
http://www.audiodesignguide.com/DAC_...mOutAD1955.GIF
http://www.audiodesignguide.com/DAC_...mOutAD1955.GIF
用OP嘛...通常就慢...

DAC-CI versus OP-AMP

Hi Leo,
Thanks for your translation again!
Drunkenlife made a nice addition, showing the usual way of I/V conversion by an OP-Amp. Yes, over 99.9% of all D/A-converters use this approach, feeding the DAC current into the negative feedback-loop of an OP-AMP. And the example shown by drunkenlife is for sure one of the better OP-AMP solutions, having only one OP-AMP in each line. Most times there are even more.

感謝你的翻譯，Drunkenlife做了很好的補充，顯示了一般使用OP-AMP進行I/V轉換。是的，有99.9%的DAC都使用這樣的方式，提供DAC店流到OP-AMP的負迴授。drunkenlife所舉例的是其中一個OP-AMP不錯的方案，每一個線路只有一個OP-AMP，一般來說會有更多。

We have a different approach, and we have it for a reason. We don't like overall feedback loops in the audio range. We don't like making COPIES. And OP-AMP-ICs have a limited bandwidth, causing distortions, especially with the unfiltered high frequency trash of the digital domain. From our point of view OP-AMPs can not handle this task without creating distortions. We are sure the frequent complaint of digital sound is the
complaint about the sound of a "tortured" OP-AMP.

B.M.C 有不同的方法，我們不喜歡在聲音的範圍有整體回授，我們不喜歡COPY，OP-AMP-ICs的頻寬有限，會造成失真，特別是數位未經濾波的高頻。我們認為OP-AMPs無法解決這問題而沒有造成失真。我們確定一般抱怨的數位聲就是這裡所產生的。

As I explained in post #25, we prefer avoiding copies by using our CI circuit. Attached is a schematic of one of the most used OP-AMP-ICs, the 5532. I have marked all the copy stages. You can see there are 5 copies done with this IC, means at the output you get a copy of a copy of a copy of a copy of a copy of the original input signal - just with one IC. Most circuits use several ICs in series.

在這篇編號#25中我有解釋，我們偏好在我們的CI線路中不要COPY(訊號)，這張圖是最常用的OP-AMP-IC之一，5532，我標記了所有的COPY級，你可以看到這個IC有5個COPY地方，意味著在輸出時，你得到的是a copy of a copy of a copy of a copy of a copy of原來的訊號，且發生在只有一顆IC上，大部份的線路又使用了許多的IC。

http://my-hiend.com/vbb/picture.php?...ictureid=15171

OP-AMP-ICs only can be used with an overall negative feedback-loop, otherwise distortions and gain are too high and frequency response is decreasing a lot in the audio range. Due to the decreasing frequency response the phase is changed as well. All OP-AMP-ICs used for audio have a phase turned by 90?over most of the audio range. That is not ideal for a feedback-loop... I could go on with OP-AMP-IC-bashing some more pages... But just take it as our reason for a different circuit design without any need for overall negative feedback.

OP-AMP-ICs使能使用在整體負迴授，不然失真與增益會過高，頻率響應會在聲音範圍減少很多。由於頻率響應的減少，相位也會改變。對迴授這不是非常理想的方式。我可以說更多有關OP-AMP-IC-bashing，不過我只想說明這是為什麼B.M.C採用不同的線路設計，且不需要整體負迴授。

Thus we use a different approach, feeding the original current of the DAC chip into E (emitter) of the transistor and using this original current, until we define the output voltage with a resistor. At the output we still need a small LEF buffer for driving cables and following loads. But this means we make just one single copy.

因此我們用不同的方法，給DAC晶片原來的電流到電晶體的E(emitter)，使用原來的電流，直到我們在電阻來確定輸出的電壓。在輸出我們依然需要LEF緩衝來驅動線材與阻抗。不過這意味我們只需一個單一的COPY。

Please keep in mind: Our shown circuits are kept simple for explanation.
Reality is more complex.

請記得這裡舉例是經過簡化的，主要為了解說方便，B.M.C的線路實際上是複雜很多的

Best Regards,
Michael

小葉，這一句“I could go on with OP-AMP-IC-bashing some more pages”是說，“如果我想要的話，我可以寫好幾頁OP-AMP－IC的壞話”。

另外，電晶體的三極：
E(Emitter): 射極
B （Base）：基極
C （Collector): 集極

Bash............

唱放 PHONO MC-CI

Hi Leo,
Now some more about CI, this time for PHONO, Moving Coil (MC) at a CI input. This explains the name of the B.M.C. Audio Phono Amplifier: PHONO MCCI

這次解釋CI在唱放PHONO MCCI上的應用。

There have been some phono amplfiers in the past with something like a CI input, most times a simple grounded-base-circuit with several transistors in a Faulkner array. In the 1980s I myself had a Threshold SL10, designed by Nelson Pass.

過去有些唱放使用了像CI的輸入，大部份使用多個以Faulkner排列的電晶體，簡單以接地為基礎的線路。在1980年代我自己有Nelson Pass設計的Threshold SL10。

There is a difficulty with this circuit. Please look again at T2 (Picture T2):
With the usual unbalanced RCA connectors the Moving Coil Pickup is connected on one side to ground, and ground is connected to B (Base) of the transistor, whereas the hot signal is connected to E (Emitter). The problem is: Due to the nature of a transistor there is a voltage of about 0.6V between E and B! 0.6V at a very tiny coil may easily burn this coil! The usual solution (as in my old SL10) is to put a capacitor between the MC pickup and E. Working? Yes. Perfect? Far from it! The signal of an MC is a very tiny signal and should be treated with great care. A capacitor not only blocks DC, but some sound quality as well.

這樣的線路是有困難的，請看T2圖：在一般非平衡RCA下，MC唱頭的一邊是接到地，地是接到電晶體的B(Base)，正級則是接到E(Emitter)。這樣的問題是，因為電晶體本身的特性，在E與B間存在0.6V的電壓，0.6會讓較小的線圈燒掉，一般解決的方法是在MC唱頭與E間放一個電容，不過這種方式雖然可解決問題，但對聲音不好，MC的訊號非常微小，應該受到很好的照顧，一個電容不僅阻擾了DC，對聲音的影響也一樣。

http://my-hiend.com/vbb/picture.php?...ictureid=15207

....I'll better make a shortcut to the BMC MC-CI solution:
As a Moving Coil Pickup itself is a perfect balanced and earthfree source, and all our designs are balanced, keeping it balanced is the perfect solution. For some it may need some new wiring or balanced connectors, but that's it.(Picture MC-CI)If the MC is connected with both ends to one and the other E of a balanced CI-input, all problems are gone. This is the perfect solution for Moving Coil Pickups!

我簡單的對BMC MC-CI解決方案說明，當MC唱頭本身是完美平衡與免於接地的來源，包括我們所有的設計是平衡的，那麼保持平衡就是最完美的解決方案。某些也許需要一些新的接線或平衡的端子，請看圖MC-CI

http://my-hiend.com/vbb/picture.php?...ictureid=15208

As the impedance (resistance) of an MC is quite low, there is a good chance to get high gain. Let us imagine the MC pickup plus cable plus input resistance of the CI input has a resistance of 5 Ohm. If we use 5 kOhm at the output of the CI stage, we get a gain of 1000. But if you have a High-Output MC pickup with 50 Ohm, gain will be just 100. This means there is some kind of an "automatic" correction of pickups with different output voltages.....Add a resistor-capacitor combination at the output of the CI stage and you can get the first half of the RIAA correction.

當MC的阻抗(電阻)非常低，有一個很好的機會可以得到高的增益。讓我們想像MC唱頭加上線、加上MC輸入的輸入電阻其總共電阻為5 Ohm。如果我們使用5 kOhm在CI輸出級，我們就有1000倍的增益。但如果您有高輸出的MC唱頭是50 Ohm，增益只有100。這意味著存在自動效正不同輸出電壓的唱頭。增加1個電組電容到CI的輸出級，您能得到第1個RIAA修正的1半。

The second gain stage needs making a copy, and the second half of the RIAA at the output ensures a complete correction. The final output stage is a small LEF buffer for driving cables and the following input. Thus there are only 2 copies made in the PHONO MCCI.

第2個增益需要1個COPY(訊號)，以及在輸出的第2個1半的RIAA確保了完整的修正。最後的輸出級是一個小的LEF緩衝來驅動線材與輸入。因此總共只有2次的COPY在PHONO MCCI中。

CI has one more advantage for PHONO MC: As the current of the MC flows into the CI input, there is a natural damping of the electro-mechanical system. If you use a usual voltage input (Picture T1) there is nearly no current flowing into B - and the moving parts keep oscillating. That's why usual phono inputs have resistors for finetuning the damping. But it is always a compromize: The lower the resistor, the better the damping - but: The energy is distroyed in the resistor - and it really sounds like lost energy. CI makes use of the energy, and thus it sounds like energy.

CI還有一個對PHONO MC的優點，當MC電流進入CI輸入級，有1個電磁系統的天然阻尼存在。如果你使用一般的電壓輸入 (如圖T1)，將近沒有任何電流會進到B，移動的部分會持續擺動。這也是為什麼一般的唱放書入有電組來調整阻尼。不過這樣總是是妥協的作法，較低的電阻，越好的阻尼，但能量會在電阻中遭到破壞，聽起來會沒能量。CI則是使用能量、聽起來有能量。

http://my-hiend.com/vbb/picture.php?...ictureid=15206

A last hint for using B.M.C Audio PHONO MCCI: This Unit is working with almost all available Moving Coil pickups, even the ones designed for stepup-transformer use. The best dynamic performance is to be expected if a strong magnetic circuit is used and the impedance is low (recommended: under 10 Ohm).

最後一個使用B.M.C Phono MCCI的重點，其可對應使用大部份的MC唱頭，甚至是需要升壓器的唱頭。如果有夠強的磁力線路與低阻抗(建議低於10 Ohm)，那麼會有最佳的動態表現

Best Regards,
Michael

http://www.bmc-audio.de/bilder/phono_front_big.jpg

http://www.bmc-audio.de/bilder/phono_mono_gross.jpg

http://www.bmc-audio.de/bilder/phono_spannung_gross.jpg

http://www.bmc-audio.de/bilder/phono_rear_gross.jpg

這兩句要重翻一下：

”Add a resistor-capacitor combination at the output of the CI stage and you can get the first half of the RIAA correction.” 在CI級的輸出加個電阻電容，你就完成了RIAA等化的前一半的工作。

“The second gain stage needs making a copy, and the second half of the RIAA at the output ensures a complete correction.” 第二個增益級需要複製訊號，在它的輸出端加上RIAA等化的另一半的線路，RIAA等化就作完了。


我個人一直認為，唱放應該要作成全平衡的放大（像BMC或是AQVOX的Phono 2 Ci），因為唱頭輸出的訊號本來就是全平衡的。看來我得存點錢來支持BMC的產品（美國有賣嗎？）

請洽aa importer

引用:

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作者: 小葉

請洽aa importer

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這樣會找不到的...

是Aaudio Imports

引用:

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作者: Musk

這樣會找不到的...

是Aaudio Imports

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謝謝Musk大！不過，第一步是先找錢:D:D:D

最少的訊號COPY

Dear Leo,
This time I like to write about reducing the process of "making copies“ to the minimum. And it is related of how to connect the B.M.C. units.

這次我要解釋B.M.C的設備是要減少COPY訊號的數量到最小，這同時也是對B.M.C.器材間如何相連的解釋。

Translation may be difficult. After reading your translations to Chinese, I can see that "copy“ is not translated. I could not find an online translation with the exact same meaning. What do you think: Is it better to use "generation“ instead of 'copy“? Means: If you make a copy of the original signal, you get the second generation of the original signal.

翻譯或許很困難，我看到你並沒有翻COPY，或者是用"generation"這個詞比較好，如果你COPY原來的訊號，那麼你就會得到原來訊號的第2代。
PS 其實我沒翻COPY主要有兩個原因，第1個是因為大概所有人都懂COPY這個英文的意思，第2是保留COPY比較不會因為翻譯造成原文許多精神遺失

As I explained before: There are copies of the input signal needed, in case you need more current at the output as you can get at the input. As a Moving-Coil pickup or a DAC-Chip does not deliver enough current for driving speakers, there is at least one copy required. Means: In the best case you listen to the second generation.

如同我解釋過的，當你輸出需要比輸入更多的電流時，就存在COPY輸入訊號的需要。當MC唱頭或DAC晶片沒提供足夠的電流驅動喇叭，那麼就只少要COPY一次，也就是說你聽到的是第2代的訊號了。

Our units are intended for using the fewest possible copy processes. But they should be compatible in a setup with other units as well. Our DAC1PRE should be working with active speakers as well as with other power amplifiers, and our power amplifiers should work with other preamps as well. In case you use DAC1PRE and AMP S1 or M1 as a set, there is a shortcut, avoiding some copy stages, or generations.

B.M.C 要使用最少的COPY過程，但是他們要能與其他器材相容，如DAC1PRE要能與主動式喇叭或是後級搭配，B.M.C的後級也要能與其他品牌的前級搭配，如果您使用AC1PRE與AMP S1或M1搭配，就不會有任何的COPY或Generations產生。

First let's have a look at a traditional setup with B.M.C. components:

先來看看B.M.C傳統的設置方法

http://my-hiend.com/vbb/picture.php?...ictureid=15404

This looks pretty "business as usual“: There is a DAC with integrated Preamp and a volume control, connected to a power amplifier. If you turn the volume knob, the signal is attenuated by a potentiometer, and the power amplifier has the usual fixed gain. In this combination you can exchange AMP S1 or M1 to a different power amplifier, or as well exchange DAC1PRE to a different DAC and a preamp – still working. This kind of setup should be familiar for every HiFi user.

這個圖與一般系統的連接情況差不多，就是有音量前級的DAC然後連接到後級，如果轉音量，那訊號就會隨電位計調整，後級的增益是固定的，在這樣的組合下，您可以將AMP S1或M1換成不一樣的後級，或是將DAC1PRE換成不同的DAC與前級。

But: Let us have a look at the copy stages: First there is the DAC section with the D/A-converter, a CI-I/V-converter (no copy) and the LEF buffer (one copy). This signal is attenuated by the potentiometer and buffered by the LEF output stage (one copy). The output signal goes to the XLR input of the AMP S1/M1, amplified (one copy) with a fixed gain to the output voltage, and finally the LEF buffer (one copy) adds the required current for driving the speakers. That's a total of four copies. Or: At the output you get the fifth generation of the input signal.

不過我們來看COPY的部份，首先DAC有D/A轉換、CI-I/V轉換(No Copy)與LEF緩衝(one copy)，訊號隨電位計調整，且由LEF輸出級(one copy)所緩衝。輸出訊號到AMP S1/M1的XLR輸入，以固定的增益放大(one copy)到輸出的電壓，也就是輸出是輸入的第5代的訊號了。

Still not bad if compared to most designs, needing five to ten copies in the DAC, another five to ten copies in the preamp and another at least four copies in the power amplifier (differential stage, voltage gain – needed for feedback loop, driver stage plus output stage), a total of fourteen to over twenty copies. Or: You listen to the fifteenth (or more) generation.

與大部份DAC的設計相比，需要5~10次COPY已經好多了，前級一般要5~10次COPY，後級要至少4次的COPY (動差級、電壓增益、迴授、驅動級與輸出級)，一共有14~20次的COPY，您聽到的是第15代或更多Gereration的訊號。

But we can do even shorter (= better). Let's have a look at the short signal path our B.M.C. chain is intended for:

但我們可以讓這個更短 (=更好)，讓我們看看B.M.C最短的路徑

http://my-hiend.com/vbb/picture.php?...ictureid=15405

In this setup the preamp section of DAC1PRE is configured by an internal jumper setting to loop-through mode, means the signal of the DAC section (as well as the analogue XLR input) is just routed to the output. (The unbalanced RCA input needs an extra stage to get a balanced signal.) For all digital inputs it means: The music signal is same as at the fixed output of the DAC section. Volume control doesn't do anything to the music signal inside of DAC1PRE. This means: The unattenuated signal is connected to the XLR-CI input of the AMP S1 or M1. The volume control of the DAC1PRE just generates a digital word, transmitted by an optical waveguide to AMP S1 or M1, where the gain is adjusted (DIGM) according to the digital word. And for the user's information we display the DIGM setting in the window.

在這樣的設置下，DAC1PRE前級部份從內部的跳線設定為loop-through模式，意味著DAC的訊號(XLR類比輸入也是)是傳到輸出。(非平衡輸入確實需要額外的輸入來得到平衡的訊號)。對所有的數位輸入意味著：音樂訊號在DAC固定輸出是一樣的，在DAC1PRE音量對音樂訊號並沒有做了什麼，這意味著，訊號連到AMP S1或M1的XLR-CI輸入時並未改變(no copy)，在DAC1PRE的音量只有產生數位語言，將光學波導傳到AMP S1或M1，在這其增益是依數位語言來調整的(DIGM)，我們在後級的表頭會顯示DIGM的設定。

Once set up this way, there is no handling difference compared to the traditional connection.Let's have a look at the copy stages again: First there is the DAC section with the D/A-converter, a CI-I/V-converter (no
copy) and the LEF buffer (one copy), available at the output of the DAC module, and this signal is routed to the preamp output as well. The output signal is connected to the XLR-CI input (no copy) of the AMP S1/M1, amplified with adjustable gain (DIGM) to the output voltage, and finally the LEF buffer (one copy) adds the required current for driving the speakers. That's a total of only two copies! Or: At the output you get the third generation of the input signal.

我們近一步看COPY的部份，首先在DAC有D/A、CI-I/V-converter (no copy)、LEF buffer (one copy)，輸出訊號連到AMP S1/M1的XLR-CI (no
copy)，使用DIGM調整增益到輸出電壓，最後LEF buffer (one copy)增加驅動喇叭所需的電流。

The above explanation is about digital sources.

以上是對數位部份的解釋。

Let's have a look at a B.M.C. chain with the PHONO MCCI involved: PHONO MCCI has a CI input (no copy), a second gain stage (one copy) and an output LEF buffer (one copy). In a traditional setup with B.M.C. components this means: PHONO MCCI: two copies, Preamp of DAC1PRE: one Copy, AMP S1 or M1: two copies. A total of five copies (means listening to the sixth generation) – still not bad for the tiny signal of a moving coil pickup amplified to drive speakers.

若是PHONO MCCI有CI輸入(no copy)、第2個增益級 (one copy)與 output LEF buffer (one copy)。在B.M.C傳統的設置下意味著，PHONO MCCI:有兩個COPY，DAC1PRE的前級 (one copy)、AMP S1或M1(two copies)，總共有5個copies (意味第6代訊號)，依然對微小訊號去擴大驅動喇叭不是太差。

The B.M.C. shortcut with DIGM means: PHONO MCCI: two copies, DAC1PRE: No copy because of Loop-Through, DAC1PRE volume control
sets the DIGM inside of the power amp, AMP S1 or M1: No copy at CI input, one copy in the final LEF stage. That's a total of just three copies (means listening to the fourth generation) from PHONO MC to the speakers!

B.M.C的DIGM則是捷徑： PHONO MCCI: two copies、DAC1PRE:無，沒有COPY是因為Loop-through、DAC1PRE音量控制設定了在擴大機裡的DIGM，AMP S1或M1：在CI 輸入這段是沒有COPY的，有一個COPY是在最後的LEF級發生，總共就只有3次COPY。 (也就是從Phono到喇叭是聽到第4代訊號)

That's the general description of how we look at the signal path, and why we like to keep it short. What counts in the end is the listening experience of the music reproduction. Sure, even one of our units in an existing HiFi setup may provide some new listening experience. But may be you got the idea: If you use one of our units, making only two copies (or two more
generations), in a chain with already ten copies (or ten generations), it may make a difference, but it is far from how we intend music to be experienced. If you like to get an idea about how we like music to be reproduced, try our "shortcut“ B.M.C. chain, using the CI input.

這是我們對訊號路徑的基本解釋，為什麼我們喜歡讓他越短越好，最後就是反應在音樂的再生。當然，任何一台B.M.C的器材都能有一些新的聆聽體驗，但當您使用一台我們的器材 (只有2個COPY) 到1個已有10個COPY的系統中，雖然會不一樣，但跟我們想要表達的音樂再生體驗有落差，如果您要體驗B.M.C的器材聲音，那就是使用CI輸入。

Best regards,

Michael

　　老字号 新品牌---B•M•C Audio　2012-06-12 11:42:46　　---采访B.M.C Audio推广经理Mr·Michael Conrad　　http://www.3dsound.cn/news/17681465.html　　老字號 新品牌---B•M•C Audio　　---採訪B.M.C Audio推廣經理Mr·Michael Conrad　　B.M.C Audio，一個來自德國的新品牌，雖品牌很新，但旗下產品從CD轉盤到大功率後級，一應俱全，外觀造型新穎別緻，個性十足。對於B.M.C Audio，我也是早有耳聞，並在多個場合充分感受過它的魅力，但一直沒有機會真正做到較為詳細的了解，直到這次來到2012年SIAV20年上海音響大展才知這個在中國還並未人所熟知的德國品牌實際已有20多年的發展歷史了，且擁有多項獨家專利。　　B.M.C Audio，對於中國的很多人來說還很陌生，20多年來它一直堅持為很多國際音響客戶做設計方案，直到2001年將公司從德國遷移至中國大陸才開始了OEM與ODM的生產，主要客戶群是日本音響品牌，而唱機中的名家CEC就是由他們代工完成的。據說B.M.C Audio的創辦人也是業內頗具影響力的人物，1975年成立的德國Restek（力無敵）既是他的傑作。 B.M.C Audio推廣經理Mr.Michael.Conrad在接受筆者採訪時這樣告訴我，B.M.C Audio當下最有名的可算是他家的唱機，而這一切皆因他們與CEC千絲萬縷的聯繫。他家的創辦人之一Carlos從學校畢業就在柏林自己開公司為很多音響公司做專案設計，主要客戶就是日本CEC，我們現下知道的許多膾炙人口的CEC頂級音響，都是出自他手，如重量級的CD轉盤TL-​​1與TL-2，及後來相當暢銷的TL-5100 CD唱盤。而這些唱盤最大的特點就在於都採用了“皮帶驅動”，有別於一般唱盤的機械驅動。其實對於“皮帶驅動”，若各位對黑膠唱盤有一定了解的話，就知道這是唱盤的設計主流，但當時間進入數字唱機時代，則全部換成了直驅馬達，原因是黑膠LP轉速恆定，利用皮帶驅動可以降低馬達震動的負面影響，但數字唱機的轉速隨時都在變化，皮帶驅動很難做，於是所有的數字唱機和轉盤全部改成了馬達直接驅動，如此才能精確控制轉速的變動，而CEC利用獨創的轉速伺服系統控制，可以精確控制變動的轉速，同時擁有皮帶驅動降低震動影響的好處，在當年的音響市場可說是風投佔盡，風靡全球市場，宣稱是最有LP味的CD轉盤。在與Mr.Michael.Conrad的交談中他告訴我目前他們在中國大陸的公司仍保持著與很多世界音響公司的合作，仍以OEM/ODM為主，但自主品牌B.M.C Audio也已開始逐漸成為公司主力。　　關於B.M.C Audio，其實很多人都不了解，雖然筆者之前也有過多次聆聽，但對其歷史卻是知之甚少，在這次與B.M.C Audio推廣經理Mr.Michael.Conrad的採訪中就特意對B.M.C Audio進行了一番了解。 B.M.C Audio推廣經理Mr.Michael.Conrad告訴我他們之所以選擇在德國設立公司，為的是技術本位，旗下產品是希望大家都願意也能夠購買的音響，且無論是性能還是操控上B.M.C Audio都絕不輸於諸多世界Hi-End音響，其價格卻是較為合理。 Mr.Michael.Conrad告訴我B.M.C Audio其實早在2009年便於德國上市，且有著較高評價，2010年正式參加德國慕尼黑音響展，進軍全國市場。很快它合理的市場價格和技術本位的內容讓B.M.C Audio在市場上得到最好的回報，讓太多的消費者燃起了換機、購機的慾望。　　那麼B.M.C Audio的聲音特色是如何呢？ Mr.Michael.Conrad告訴我，B.M.C Audio對於聲音整體設計追求的是絕對的均衡（balance），這種均衡不僅講究線路，還包括聲音的價值均衡。如他們為音響專門訂製的電容，規格上要求其充電與放電速度要一樣快。而且B.M.C Audio的產品外觀設計有著完全相同的設計元素，從唱機到功放無一改變，讓人一看就知道是來自於同家公司。他家正面特大號的表頭和居中特大號的旋轉掣，漂亮的銀/黑雙色機箱，這些都是B.M.C Audio的產品特徵。　　現場Mr.Michael.Conrad不光為筆者講述了B.M.C Audio公司，更多的還為我們講了很多技術性東西，譬如利用雙同軸電纜的Super-Link數字傳輸技術、皮帶驅動數字唱機或轉盤、增益控制、電流注入（Current Injection，簡稱CI）……等等，都是非常技術的東西。如B.​M.C Audio與眾不同的設計理論中的音量控制設計，所謂的CI技術可以免除了傳統可變電阻的訊息損耗，另外LEF技術可將電流與電壓做分開處理，完全不需要傳統的負迴路設計，如此就能讓功放擁有非常線性的工作輸出。　　今天我們看到的這個B.M.C Audio雖然是音響界新星，誕生並不久，但卻是集結了諸多音響前輩，旗下很快就面向市場推出眾多型號產品，各系列齊全，可見是有備而來，相信在不久的將來B.M.C Audio一定能以高品質的德國設計加上優質的中國製造擄獲世界各地消費者的心。　　http://pigimg.zhongso.com/space/gall...1490390397.JPG