Pass - The Zen Amplifier 自己做的一些功课，欢迎各位指点

magicbox4me

（注：此图为自己所画，不在原文里）

magicbox4me

（注：此图为自己所画，不在原文里）

magicbox4me

（注：此图为自己所画，不在原文里）

magicbox4me

         Figure 2 reveals the complete circuit of the amplifier. Q1 is the gain stage, biased by the constant current source of Q2.
         图2显示了完整的放大电路。Q1是放大级，偏置由Q2的恒流源完成。

    Dealing first with the current source, we note the circuitry associated with Q2. Q3 is used to regulated the gate drive for Q2. It is fed current (biased) by R6/R7, with C5 used to filter out power supply ripple. As current passes through Q2, it develops a voltage drop across R1, and when this voltage drop reaches about .66 volts (2 amps through Q2/R1), it turns on the junction of Q3, and Q3 then limits the voltage appearing at the gate of Q2 to about 4 volts. This little loop operates to keep the current through Q2 at a constant 2 amps. R3 and R4 are there to add stability to the loop and prevent parasitic oscillation of the Mosfet Q2.
        首先来看电流源部分，就是与Q2相关的电路。Q3用于调节Q2的栅极驱动器。这是美联储当前（偏）R6 / R7，C5用于滤除电源纹波。由于电流通过Q2，它开发了R1电压下降，当这个电压降达到约0.66伏特（2安培通过Q2 / R1），它打开的交界处的第三季度，第三季度，然后限制电压出现在第二季度的大门约为4伏特。这个小循环，以保持电流通过Q2在一个恒定的2安培。R3和R4有增加稳定的循环和防止MOSFET Q2的寄生振荡。

magicbox4me

（注：此图为自己所画，不在原文里）

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         This constant 2 amp current is fed to Q1. Resistor R8 and potentiometer P1 form a DC feedback loop which operates the gate of Q1 at about 4 volts and places the Drain potential of Q2 at the midway point of the power supply, or about 17 volts. Input signal passes through C6 and R5 to the gate of Q1, and output signal passes through C3 and C4 in parallel to the loudspeaker. R9 and R2 are there to bleed off DC, but are not particularly essential. Z1 is essential to insure that an input transient cannot exceed the 20 V gate rating of the Mosfet.
         这种恒定的2安培电流被馈到Q1。电阻R8和电位器P1组成直流反馈回路由Q1的栅极在4伏的电源和地的中间点，Q2的漏极电位，或约17伏特。输入信号通过C6和R5到Q1的栅极，输出信号通过并联的C3和C4的扬声器。R9和R2有直流，但不是特别重要。Z1是确保MOSFET的栅极输入瞬态不能超过20 V ，这至关重要。
   

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         Fig 3 shows the PC artwork for two channels. The pattern is for singlesided (of course!) construction, but I had boards made with a ground plane on the top side of the board and plated through holes, since the difference in cost is very slight.
       图3显示了两个通道的PCB。模式是单边（当然！）。

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Note that the output connections appear to be reversed in polarity. Because the topology reverses polarity, the loudspeaker plus terminals should be attached to ground and the minus terminals are attached to the active output of the amplifier.
Fig 4. shows the component placement, Fig 5 is the parts list. Note that the transformer T1, the fuse F1 and the diode bridges B1 are not on the PC board. The board connections labels L POWER and R POWER attach to the diode bridge + and -. Part substitutions are certainly possible. The first requirement for the Mosfets is the ability to dissipate 30 watts continuously without failure, which means selecting devices rated at 125 watts or more. The Mosfets must be rated at 50 volts or more, and I suggest that they be rated at continuous drain currents of 10 amps or more. I have chosen International Rectifier parts in this case, and numerous substitutions will meet these requirements on the IR page of the Digikey catalog.
A very important element is the heat sink. The sink for each channel must be capable of dissipating 70 watts continuously at a temperature increase of about 25 degrees Centigrade. Less heat sink will shorten the life of the Mosfets. If you find that you can't touch the heat sink in operation, I suggest the use of a fan.
The power transformer should source about 25 volts AC at 6 amps or so for each channel. While the actual DC draw is exactly 2 amps per channel, the power factor created by charging the power supply
capacitors results in transformer dissipation greater than suggested by the 2 amps. From Fig 5 you can see that the suggested power transformer has a secondary coil for each channel, however it is acceptable to drive both channels from a single secondary and diode bridge.
请注意，输出连接注意要极性反转。由于电路图反转极性，所以我们应将扬声器正端连接到地和负端连接到放大器的有效输出。

请注意，变压器T1，保险丝F1和二极管桥B1不在PCB上。
该板连接标签L功率和R功率附加到二极管桥+和—。
要替换部分元件当然是可以的。【MOSFET】的选择第一个要求是能够连续地消耗30瓦没有失败，这意味着选择设备额定在125瓦或以上。MOSFET必须额定在50伏或以上，我建议他们具备连续漏电流为10安培或更多。我在这种情况下，整流器部分的选择，和众多的元件选择会在Digikey目录页查这些要求。
一个非常重要的因素是散热器。每个通道的散热器必须能够在大约25摄氏度的温度下连续地消散70瓦。较少的散热片将缩短MOSFET的寿命。如果你发现在操作中不能触摸散热片，我建议使用风扇。
【电源变压器】选择应为每个通道6安培左右的交流电压为25伏特。而实际直流是每个通道正好2安培，通过充电电源电容器的结果造成的功耗大于建议的2安培的功率因数。从图5中可以看出，建议的电源变压器有一个次级线圈的每个通道，但它是可以接受的驱动两个通道从一个单一的次级线圈和二极管桥。


图5. 是零件清单。

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五、 Operation
         上电操作

         When you have completed the construction, plug it in. If the power supply fuse does not blow, you will be looking for about .66 volts across R1, no DC voltage at the output, and about 17 volts at the drains (center pins) of the Mosfets. With an input signal and an 8 ohm load, adjust P1 for symmetric clipping. Readjust P1 after the amplifier has warmed up.

        完成焊接后，通电。如果电源保险丝不烧断，您将测量到约66伏在R1，输出端没有直流电压的输出，以及约17伏特的MOSFET中心引脚。随着输入信号和8欧姆负载，调整P1为对称。在放大器预热后重新调整P1。

        

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图4. 显示组件的位置

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Fig 6 shows the harmonic distortion curve from 10 milliwatts to 20 watts at 1 Khz and 8 ohms. Below 10 watts the distortion is purely second harmonic. Fig 7 shows the distortion at 2 watts across the audio band. Fig 8 shows the frequency response. The amplitude is about .25 dB down at 20 Hz and about .5 dB down at 20 Khz.

图6显示了谐波失真曲线从10毫瓦至20瓦在1 kHz和8欧姆。低于10瓦的失真是纯粹的二次谐波。
图7显示了在音频波段的2瓦的失真。
图8显示频率响应。振幅是0.25分贝衰减在20赫兹，0.5分贝衰减在20千赫。

jhAL

中文是楼主自己翻译的吗？ 赞

snlzq

向楼主致敬！辛苦了！

magicbox4me

The output impedance of the amplifier is approximately 1 ohm, with a damping factor of about 8.

There will be loudspeakers that are not suitable loads for this amplifier, either because they need high damping factor, have an impedance below 8 ohms, or require more than 10 watts.

At impedances below 8 ohms, the output of the amplifier will not increase, it will drop off. This is because the single-ended design can source only the value of the bias current, and will not operated linearly beyond the bias point.

There are quite a few loudspeakers with 8-16 ohm impedances and sensitivities in the 90-100 dB range which are quite suitable. The amplifier is also quite at home as a midrange or tweeter amp, and is particularly good with horn loaded drivers.

If you desire to drive 4 ohm loads with twice the power, l suggest simply paralleling the two channels into mono at the input and output terminals.

【放大器的输出】：输出阻抗约为1欧姆，阻尼系数约为8。

这说明有些扬声器将不适合做这个放大器的负载，或者是因为它们需要高阻尼系数，或者阻抗低于8欧姆，或者需要超过10瓦才能驱动。

如果用低于8欧姆的阻抗，放大器的输出不会增加，反而它会下降。这是因为单端设计只能提供偏置电流的值，并且在超出偏置点时不会线性地工作。

有相当多的扬声器有8-16欧姆阻抗和90-100分贝灵敏度，这些都是比较适合的喇叭；该放大器非常适合在家中听些两分频塔式或号角型音箱；

如果你想用两倍的功率来驱动4欧姆负载，我建议简单地并联两个通道的输入端子和输出端子为一个单声道的就可以了。

magicbox4me

The input impedance is 4.75 Kohms, and the gain is about 8.5 dB. This means that the amplifier must be driven by an active source capable of delivering 3.5 volts at 700 microamps. The input characteristic can be adjusted for sources with more voltage and less current by increasing R5, and can be adjusted for sources with more current and less voltage by decreasing R5 in proportion.

【放大器的输入】输入阻抗为4.75 Kohms，并有约8.5 dB的增益。这意味着放大器必须由一个能够在700微安提供3.5伏有源驱动。输入特性可以调整为更高的电压和较小的电流通过增加R5来实现，并可以调整更多的电流和更多的电压，通过成比例地减小R5即可。

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So how does it sound? With the right loudspeaker, simply wonderful.

【听感】
           那听起来怎么样呢？只要有了正确的扬声器，声音简直棒极了。

magicbox4me

Inevitably after publishing a project such as this, I receive a large number of inquiries as to how to improve the design How to make it bigger, smaller, better; Use better wire, better capacitors, better connectors. Do I offer kits, parts; Do I sell directly; Will I repair amplifiers?

A similar amplifier should be commercially available from dealers of Pass products around the time you read this. Information on products and dealers and white papers on Single-Ended Class A operation can be obtained from:
Pass Labs, PO Box 219, 24449 Foresthill Rd.Foresthill CA 95631, fax (530) 367 2193
I don't offer kits, sell directly, or repair. Free advice is sparingly dispensed.
By way of improving the amplifier, you are free to use any better part you like. It is highly unlikely that you will ask for a smaller amplifier, and if you desire a larger amplifier, l suggest that you find bigger parts and build it. All the elements here are easily scaleable, and you can either find bigger Mosfets or run the existing ones closer to their limits. I have constructed larger versions of this circuit using industrial Mosfet packages which are rated at 600 watts apiece, and they work fine.
The simplicity of the amplifier allows a great tolerance to modification. Unlike most designs, it is not parts-critical, and there is no frequency and feedback stabilizing compensation required. When evaluating parts for a scaled-up version, the dissipation and voltage ratings of the components are the elements which deserve attention.
Aside from better capacitors and such are there other ways of making the circuit better? It so happens that there are, and the best of them is the subject of a patent recently granted to Pass Labs. If there is sufficient continued interest in this approach to amplification, perhaps it will form the basis of another article.
Copyright 1994 Nelson Pass


不可避免的是，在发布这样一个项目后，我收到大量关于如何改进设计的建议，如何使它更大、更小、更好；使用更好的电线、更好的电容器、更好的连接器。
这一切都让我觉得，难道我像是一个修理功放的吗？呵呵

一个类似的放大器应该在你阅读这本书的时候从商品的经销商那里买到。关于产品和经销商的信息，以及单端A类操作的白皮书：
通过实验室，邮政信箱219, 24449福里斯特希尔路福里斯特希尔CA 95631，传真（530）367 2193
我不提供成套工具，直接出售或修理。免费忠告少之又少。

通过改进放大器，您可以自由使用您喜欢的任何更好的部件。如果你要求一个更小型的放大器，很不幸，这不太可能；如果你想要一个更大的放大器，倒是可能，我建议你找到更大功率的元件，并建立它。这里所有的元件都是容易扩展的，你可以找到更大的MOSFET或使元件运行在它的极限值附近。我用工业MOSFET封装制造了这个电路的更大版本，它们的额定功率为每声道600瓦，而且它工作的相当正常。

放大器的简单性使其具有很大的耐修改性。与大多数设计不同，它不含什么关键部件，没有负反馈来稳定电路等的稳定补偿电路。只有两点：在对放大版本进行评估时，元件的损耗和额定电压是值得注意的元素。

除了更好的电容器，还有其他方法可以使电路更好吗？碰巧的是，其中最好的是我们实验室的刚刚获得的专利。如果对这种方法有足够的持续兴趣，也许它将成为另一篇文章的基础。

版权所有 - 1994年 - 纳尔逊.帕斯

【完】

magicbox4me

以下为自己制作的图片：

流着眼泪唱情歌

老外说的东西别当真，看看就好。