真正的冷凝器opa mics

让我们建立一些特殊的质量冷凝器麦克风。这些是真正的冷凝器，因为它们是外部偏见的。它们使用基于OPA的阻抗转换器电路和十六进制逆变器电压乘法器，用于产生偏置电压。一个是你的基本心形态，另一个是使用双光圈，让我们选择响应模式。但是我们正在这样做的不同于大多数麦克风。

这种可调整的是大量麦克风研究的高潮，建筑，不建造，几步向前，一步或两个背部前进。声音和录音一直很着迷我，作为一个孩子，我的朋友们得到了吉他，我建了一个合成器。随着他们的音乐家进展，我被绘制到科技和混合委员会。我的第一个“真实”麦克风是Radioshack PZM，然后是肯定的SM57。电子始终着迷于我，我通过1990年代建造和设计了许多模拟工作室装备。所有的符合保持简单的心态，保持安静，保持清洁。随着思想的想法：我可以改善一些东西还是做某事？

当然，数字世界接管了。我拥抱了这一点，知道这是音频的未来。我在1993年观看了一张专辑，掌握了一个带舷外A / D转换器的Apple电脑。它通过模拟搅拌板从验尸2英寸24轨道下来。我知道事情正在发生变化。我们也有一个2轨卷轴到卷轴运行，但从未需要使用它。我仍然觉得尽快让音频进入数字领域是最好的解决方案。并不是那里没有非常酷的模拟物品，而管吉他放大器将永远存在。好的，我骨折。返回给：保持简单，干净，安静，哦是的，创新。

这将我们带到了今天建立的两个麦克风。它们是“真正的冷凝器”麦克风，使用过敏胶囊，TSC-1和TSC-2。两者都是中心终止，这意味着胶囊中间有电连接和电线。另一电气连接是背板，这是麦克风胶囊中间的黄铜金属环。这些类似于Neumann K87胶囊。其他主要风格是CK12。那些是边缘终止的。看照片。TSC-1和TSC-2之间的大区别是TSC-2允许您从胶囊两侧获得信号。通常，与内部麦克风电子器件一起使用，允许您将MIC的模式从OMNI更改为CARDIOID，如图8所示。我们将这样做，但不是麦克风内部。 We are going to take both signals out of the mic body, allowing us to create whatever pattern we want in post. That lets us do some very interesting things. Both microphones use the OPA impedance converter I layed out in a previous instructable. For the TSC-2 we have a new board. This puts two of the OPA circuits on one board with a common ground. This lets us bring both signals out of the mic with a 5-Pin XLR.

麦克风胶囊的历史上有很多伟大的文件。看到这一点现场。Georg Neumann，是的Georg Neumann，用他的团队的M7胶囊发明了多点麦克风。这是1948年。所以它已经有一段时间了。中心终止和边缘终止胶囊的基本设计已经存在了大约很长时间，并且两者都很好，声音的微妙差异。看到马特的伟大描述在麦克风零件的情况下，没有进入它们是如何机械加工的内部机械细节，只知道需要大量的精确度。并反复制造它们需要固体质量体系，以及声音制造实践。我提到这就是为什么我选择这些特定的胶囊。在全球范围内，有几家公司可以直接构建或源电容胶囊。这里有一些真正的好的订单：

Beesneez，澳大利亚，Beesneez.

Peluso麦克风，美国，Peluso MIC实验室

Microphone Parts, US麦克风零件

telefunken., Germany (repair parts)telefunken.

The prices vary and all the Telefunken ones list as unavailable. There are also a lot of very inexpensive ones on ebay and aliexpress, none of which I can vouch for. I can for the ones above. They are all good and you are free to use them as they will all work with the rest of this project.

我找到了我今天使用的公司通过同一家公司使用我以前的教师，横跨我之前的耳机中使用的TSB2555B和其他驻极胶囊。他们是一家20岁的台湾公司，拥有一个非常强大的质量体系。作为一个OEM，他们每年制造很多麦克风胶囊。一年前，我发现了他们的外部偏见胶囊，并订购了几个TSC-1。经过一个伟大的建设和一些头脑风暴，几个TSC-2的。除了他们的巨大的声音品质之外，公司拥有多种ISO认证，历史意味着这些应该有一段时间。它们也用于多种商业麦克风。为了发布DIY项目，能够让零件对我来说非常重要。我仍然从我的原始电子邮件和评论中获取电子邮件和评论，因为人们仍在建立它。使用的独立通孔FET晶体管仍然可用，但速度快。 There is a term used by engineers who have been around a while called “Unobtanium”, meaning that something, usually something critical, is impossible to get. That is the nightmare of service and sourcing teams everywhere. Here is my audio story of that: In my peak of analog design years a company called SSM (Solid State Music / Solid State Micro Technology for Music) existed that made great analog synthesizer chips. They were later acquired by Precision Monolithics, which was then bought by Analog Devices. Precision Monolithics released a dual dynamic range processor, the SSM2120 in 1990. It was a dual VCA with log level detectors built in. In short, it was the building block for a fantastic compressor or downward noise expander/gate. I was connected with the product manager for it, had engineering samples up front and helped design the reference circuits for the data sheet. I built many of them and put them into every channel of an analog console in Central Florida used by, among others, Deep Purple in the early 90’s. I also licensed my compressor design to PAiA electronics as a kit and wrote several DIY articles on how to build them. Then in the mid 90’s, they went obsolete. No notice. This was right about the time you could easily do compression digitally with a DSP chip. I mention this as I am very sensitive to supply chains and parts availability. Do not take them for granted.

将胶囊变成工作麦克风的另一件事是偏置电压发生器。所有我的其他MIC建筑赋予者都使用了驻极体胶囊，这意味着材料和构造提供内部充电。在这种情况下，我们需要外部电压来供电。我们将使用十六进制逆变器电压倍增器从OPA板上取12 VDC，然后将其转换为80 VDC。另外，将胶囊握住胶囊是印刷的3D，可从轮胎上获得。STL文件也包含在此处，用于访问3D打印机的那些。

这些是冷凝器麦克风。这是一个带固定背板和薄柔性隔膜的胶囊，即“金属化”，所以它将是导电的。这些形成电容器通常在10-60 picofarad范围内。较小的胶囊，电容较少。柔性隔膜会由于空气中的声波而移动。不是很多运动，但如果存在施加到胶囊的电压以充电，我们可以通过移动隔膜移动的声波来拾取电压的变化。这就是冷凝器麦克风的工作原理。它们也有内部机械特性，但这超出了我们今天要去的范围。

OK, how much voltage is needed? That is a great question that I set out to answer. Traditionally (as in today) capsules are typically 60 VDC. Historically some older tube microphones used 100 VDC. Brüel & Kjær use 200 VDC or more on some of their small ½” capsules. Changing the voltage does a few things. It changes the sensitivity of the microphone by the ratio of the voltage difference, larger voltage, more sensitivity. It can also change the frequency response by stretching the diaphragm. Brüel & Kjær goes into detail in their handbook这里。RØDE麦克风在一些麦克风中使用80 VDC。对于这些麦克风，我们使用80 VDC，让我们更灵敏度。通过我们使用的OPA电路，我们使用的是，我们创建了一个“虚拟地”，这意味着它是用作信号返回路径的低阻抗，但它实际上并不归零。这取决于齐纳二极管实际电压约5.5-6V。即使ZENER在过滤后额定12V等，我们也在11.5米左右。我们的虚拟地是1/2。结束结果电容器上的偏置电压约为75。

传统上，这由小型晶体管振荡器提供使用几个小线圈和电容二极管电压倍增器提供的。我试图远离通孔晶体管，绝对是线圈。我在那里了解了几个麦克风，特别是CAD正在使用CMOS逆变器来驱动电压倍增器电路，所以这就是我决定做的。

我们正在使用一个六角逆变器4584或者40106, either will work. The key specs are that they are Schmitt-Trigger and that they will work with 12VDC or higher. A “Schmitt Trigger” means that as the input changes on an input, the inverter will change state as you cross a certain threshold and it won't change back until the threshold is exceeded in the opposite direction. This provides hysteresis and provides a nice clean square wave for us. Both data sheets explain how this works. We are using one of the inverters as an oscillator with a 1nF capacitor and a 10K resistor. This gives us about 100Khz -ish for a clock frequency, well above the audio range. Then the next five inverter stages are used as voltage multipliers. Doing this with a CMOS inverter was invented in the 1980's. See这个for background.

这是它的作品。我们的二极管字符串的一端连接到+ 12VDC。假设第一阶段的输出是接地。该级的电容器通过连接到所提供的电压的二极管开始。当逆变器阶段的输出从地面变为下一个时钟周期的12伏时，将电容器的“接地侧”提升到12伏。假设电容器完全充电，使电容器的正侧带到24伏，然后通过下一个二极管进行电压，以将下级电容器充电至多24伏。现在，当我们向下移动每个阶段时，在相反的时钟周期上，我们向每个阶段增加了大约12伏。所有这一切的美丽是我们需要忽略不计的电流。足以将偏置电压施加到胶囊上。在加入12伏的六个阶段之后，我们最终在原来的12个或大约84V最大的顶部有72伏。 Following the inverter stages we have an RC filter. This cleans up any ripple or noise left from the process. A 1M resistor supplies the voltage to the capsule. Taking into account voltage drops across the diodes, and other fun things, we end up with about 80 supplied to the capsule. The original 12 volts is supplied by the OPA board from the zener regulator circuit. Both the original OPA board and the new two channel one bring this out to a connection point. Interestingly, there are some mics out there that actually use the incoming phantom power to directly supply the bias voltage. In a perfect world, that would be 48 volts, which doesn't sound bad. The reality is that the voltage is always lower because the internal electronics draw power and lower the voltage supplied. Most are about 34 volts. Remember, the 48 volts is in series with two 6.81K resistors, one to pin 2, and one to pin3, of the input preamps XLR connector.

现在在阻抗转换器上。我们使用与TSC-1麦克风的这种指示器的相同，以及双隔膜胶囊的两个通道版本。我不能强调这些是多么好，他们的表现如何。有两个功能是内部电子器件需要执行。电路必须具有非常高的阻抗，使得它不会加载胶囊。这最初通过管道完成，然后用FET完成。然后它需要能够驱动长麦克风电缆，同时不会影响信号。该电路实现了这么好。有趣的是，我们正在使用的OPA可以将轨道转向轨道，因此胶囊将在内部电子设备之前长时间扭曲。电路的噪声底板比胶囊自噪声更少，而且整体电子设备的动态范围大约是130dB的动态范围（如果我穿上营销帽）。 One small change in components. On the OPA boards we are using wima polyester .1uF capacitors now. I originally spec'ed a MLCC one that can exhibit a “micr” phenomenon. This was pointed out to me and while they can, I’ve never noticed it and decided to experiment. I put one in place of the capsule in my OPA Alice build. If you tap it with a small screwdriver, you can get some sound. Real world: You would have to drop the microphone or hit it to have any effect, and that will be swamped by the dropping noise anyway. But, for the sake of argument, I replaced them in the BOM for this build. They are 61 cents each vs 41 cents for the old ones from Mouser. They are also used for filtering and not in the audio path either so I am most certainly not retrofitting anything I have already built. :-)

The final thing we will need to build the mics are donor bodies. I wanted something nicer than a BM-800 body for these and found something called a “mini U87” on Aliexpress. I bought a pair based on a recommendation of a friend and was very impressed. The first of two orders were machined very well and made out of some kind of copper/bronze alloy. So took all the paint off and hand polished them giving me a steampunk retro look. I built two of each and then realized I can do something really cool with three of the dual capsule one’s so I went to order another body and… They were discontinued. I found something that looked similar and ordered it. OMG, supply chain at its finest here: The body is great and physically identical to the original orders machining included, except it was made of a silvery metal I am assuming is a zinc based alloy. And it came with a mic mount that looks just like the original Neumann U87… Except it doesn't fit the mic body. No worries for what we are doing. You can use any donor body from the BM-800 to some of the more inexpensive MXL microphones. Enough already, let's build them!
零件清单:所有PCB的可用命令from PCBWay. They do a fantastic job and are very inexpensive. One note on color selection. In the past I ordered red, blue and green, which are all great with white silk screen. My first batch of the Dual Channel boards I picked yellow. Because I thought it might look cool. It really doesn't, it really isn’t yellow, and it is hard to read the white silkscreen with it. Stick with one of the primary colors. I do recommend a different color for each board type so they are easy to tell apart at a glance. Huge shout out to Homero Leal who laid these out and let me upload them. We are working on fully populated versions if there is interest. And my only request here. If you order the boards please consider tipping us. We make no money off of these and it helps buy the next build.

PCB的：十六进制逆变器倍增器十六进制逆变器倍增器

单通道双OPA电路（用于TSC-1）单通道

两个通道双功率电路Dual Channel

完整的BOM连接有每个PCB的单独纸张。包括Mouser部件号。

我们将需要五个引脚XLR插入物，我发现的最简单的解决方案（至于至少昂贵）是购买其中一个和拆卸：这个

对于双输出MIC，需要分配电缆：

15pin女性xlr.

23PIN男性XLR.

10英尺双麦克风电缆

白色和红色XLR靴子添加到订单时选择颜色

TheTSC-1胶囊（单输出心脏）

TheTSC-2胶囊（双输出）捐助者 - 见文字

K87鞍座, 3D printed

伺服扣眼

公制小螺钉分类

M2.5螺旋类别

一些最终建设说明：

如果您有任何嗡嗡声或处理噪音，请确保您在彼此接触的身体部位的表面上砂。通常，违规部件是主体圆筒，特别是端部。如果最后有涂料，则不会进行，因此它不会连接到地面。

OPA板真的需要清洁，特别是在1Gig电阻和OPA本身周围。当我焊接时，我使用水基通量并用洗碗肥皂和水清洁它，像牙刷一样小磨砂刷。然后用异丙醇冲洗并彻底干燥。

If you don’t get 80VDC at the 1M resistor and diode junction at the output, check the diode polarities. I had one backwards on a build and it caused some weirdness. The Hex Inverter board also needs to be really clean as well. One of the downsides to water based flux is when damp, it conducts. So it is affected by humidity.

我用耳机动力，确保从胶囊的两侧得到输出。通过两个输入的PANNED中心，将前置放大器一直处于下降，并在谈话时只能抬起前胶囊。接近和亲密，您应该听到邻近效果。现在慢慢提高后胶囊水平，随着收益变得甚至，麦克风变成了全部的全部，并且近距离效果将消失。继续提升它，你将开始制作它的心脏，但是后囊占据主导地位，因为它将基于它背离你的前方。

以下是麦克风可以具有的一般模式：

要在帖子中制作您录制两个频道，然后执行此操作：

对于Omni：正面和后部的平等混合。

对于亚阶层：混合在后部的混合。

对于心档：只是前面。事实上，您只需插入前XLR并将其独立作为心电图麦克风。

对于图8：前部和后部的相同混合，后极和后部倒置。

用于高速呢磷脂和超心动件：

用倒置极性在较低水平的较低水平中混合。（谁发明了这些条款？）

我制作了一个是矢量的pdf，所以你可以放大详细信息。
现在这是最好的部分：如果你用麦克风作为图八个而且没有完全得到你不想要的声音的零点？好吧，如果你看看图8的图表，你会看到null完全在90和270。你看一个超卡，麦克风背面的空头是大约30度。只需调整后方的级别，可以引中帖子中的空斑。多么酷啊？

谢谢Homero Leal为PCB布局，汤姆·佩德特CAD设计和Kady Speeks以及她的麦克风测试仪的声音。

我不是第一个思考同时从MIC中取出的人。以下是商业人员的链接及其故事以及一些伟大的阅读材料。对我来说，我们正在达到一个DIY家伙更难解决机械开关等，以使麦克风模式可以从麦克风中取出它。多通道界面的成本和质量随着当今计算机的存储和编辑电源而急剧下降。我的麦克风零件RK12建造有一个用于Omni和CandioID的内部开关。我必须拧下麦克风机身来达到它。然后请记住，当我无法弄清楚人声不对的时候，我把它留在了Omni中......如果我正在做我的数学，那么这些建筑有大约8个或9dB的自我噪音，真正的世界级。我正在研究测试设置以验证并更新。就像本田和丰田一样开辟了汽车制造业的变化，在大多数机械的情况下，董事会发生了相同的进展。查看TSC-1或2个胶囊。 You will be impressed.

https：//www.neumann.com/homestudio/en/what-is-a-co ...

https://en-de.neumann.com/file-finder.

https：//www.lewitt-audio.com/microphones/lct-recor ...

http：//www.sennheiser.com/studio-condenser-microph ...

https://austrian.audio/oc818/

https://microphone-parts.com/pages/introduction-to...