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。
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.
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。
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。
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。
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.
DAC-CI versus OP-AMP
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.
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.
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。
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.
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.
Please keep in mind: Our shown circuits are kept simple for explanation.
Reality is more complex.