Mysteries+of+the+phase+plug 相位塞设计与制作.docx

相位塞的奥秘在这页上我将试图迷惑相插头适用于号角喇叭（不是愚蠢的抛光的子弹，有时出现在高保真扬声器，）而相位塞的设计和建设可以介入，这当然是在DIYer达到可以提供有价值的好处了中音喇叭。一些不同的设计，看这里，以及如何他们可以。图1Why are Phase Plugs needed?当为锥形扬声器喇叭设计一个号筒，这个号筒喉口区域的面积可以在高频率的效率有显著影响。一般来说，在喉口面积较小，更多效率曲线被推向更高的频率。然而，在实践中喉部面积显着较小比扬声器纸盆地区能产生的高频输出严重减少。如上图1由一个有1 / 3锥形扬声器鼓纸面积组成的圆形的号筒喉口的横截面面积。这里将会发生两个主要问题：首先，远处的声音从A点的防尘盖是大大短于从锥形边缘的距离在B。如果这些距离的差异是任何频率的12波长，那么严重的相位抵消将发生在该频率。例如，考虑一个12”喇叭，差异的不同距离，可以很容易地发生在100mm（12波长1.72khz）。其次，在扬声器鼓纸和号筒喉口部之间有相当大的空气空间（虚线）。这些空气体积作为一个低通滤波器，高频率的衰减。一个减少前腔体积的方法是把喇叭喉部靠近扬声器锥如图2所示。这使得路径长度差异更明显的缺点。我们需要的是一个小面积的均匀线配线在鼓纸锥形体的整个表面的一种方法手段，并尽可能地靠近它。虽然这是不可能的，相位塞提供了一种有效的妥协（折中解决方法），这一目标，并已应用于相当长一段时间的压缩驱动器中。有一些好的信息在这个JBL的网站和从AES网站。图2图3A simple Phase Plug一个最简单的相位塞实现包括增加挡板开孔直径和悬挂的锥形木（或其他固体材料）在中心位置。它可以由薄木腿或钢丝连接，只要这些支撑的连接件不影响声音的传输或喉部面积。喉口现在由一个挡板开孔面积不塞区中的面积和宽度为D的环。认真仔细设计锥形塞逐渐变尖和号筒反射面之间的角度比值保持适当的输出比率至E点，这将是号筒长度正常的向外扩张区区。请注意， A，B和C点的距离差异现在是更接近对方比前几幅图。这时候的前腔体积只是略有减少，这种类型的相位塞只是适合在路径长度抵消比高频效率更重要的应用。我将这一类型的相位塞曾经使用在我的双8”的设计中，它允许8“喇叭操作的上限至2.5kHZ分频点。图4A variation (type 2?)类形2如果上述相位后的轮廓根据防尘帽形状和环挡板增加在在扬声器一侧，喉口可以更有效地接近于扬声器，释放前腔体积。如上所述，代价是加大路径长度差（既前面的B-A的距离差），这种方法可以用在最高效率要求到开始抵消消的点。这种类型提供了优良的效率在我的12“中频箱体至1.5kHz分频点。图5A bit more complex - type 3 类形3，更复杂为得到更高的工作频率，路径长度的差异变得更重要。进一步分配喉部面积，该区可分为两个环插入一个泪滴状的环形中心插头和挡板开孔之间，如上图5所示。现在的总面积是环宽D的面积与环宽E的面积的总和。此方法是缩短路径长度的差异和减少前腔体积，但它是更加难以设计和制作，但也并非绝对不可能。最好的方法就是画（用手或通过CAD）实际的用户配置文件和规模所需的喉部面积，杂耍的事情直到你在试图使其满意（这适用于一些简单的类型以上为好）。这种类型的压缩驱动器是常见的，但往往多达5路环的使用。我用这种形式在一个6“的设计案例，详细见下面，使良好的响应在4kHz，以及实验12版”。Practical construction（实际应用）这些相位塞并不太难做出，只要使用正确的工具。有一件事你需要的是一个车床，它并不一定是昂贵的，你甚至可以让自己运用你的电钻，看工具部分在我的DIY页面了解详情！（所有下面的例子都将使用这些）。施工方法我使用的是中密度纤维板或环切圈，堆叠粘在一起，然后机器他们塑造。栈是安装在一个1 / 4“螺纹杆贯穿在我的DIY车床夹头夹头，或在环的情况下，暂时拧紧，垫板。下面的照片会更清楚。Simple type 1This was used in my twin 8 box, and plug size is 62mm dia x 44mm long. Using a hole saw, I cut 4 discs from 12mm MDF : 2x 62mm dia, 1x 44mm dia, and 1x 18mm dia as shown in photo below left. These were then glued together (centre photo), then machined to shape (right photo). The central hole was then plugged with 1/4 dowel. No supports were designed into this plug, as it was glued to a central flare divider. For mounting options, see others below.Simple type 2This is the plug used in my 12 mid/high box. As with the plug above, construction started with a collection of discs and, in this case, rings as well, as shown at left. These were glued together to form the plug and outer ring, front view below left, rear view below right. After machining, the profiles can be seen in the next photos. The assemled plugs are shown at the bottom. With this assembly, I used small pieces of MDF to support the centre plug.Type 3 - 12 versionThis was an experiment to get more top end from my 12 box. It did achieve an improvement, but not enough to warrant its use.Note the slots cut in some of the parts - these formed holes through the parts after assembly, and facilitated mounting by steel wires as shown below.View of the plug assembly mounted in the box - the 12 speaker mounts down over top of this. The top path is clearly visible around the centre plug, the other path is between the ring and baffle plate.Type 3 - 6 versionOops, forgot to take pics of the components before building, however construction pretty much the same as 12 version above - just smaller and more fiddly.At left is an Autocad render of section through plug and Eminence Alpha 6 speaker - the paths can be clearly seen. Centre plug is 25mm dia x 31mm long, made with 2 disks of 16mm MDF 25mm dia & 17mm dia. Outer toroid is 80mm dia outside, 36mm dia inside x 27mm deep, made with two MDF rings 80mm OD, 36mm ID x 16mm thick & 65mm OD, 36mm ID x 12mm thick. The assembled view is shown below left, while below right shows how close the plug sits to the Eminence cone.Below this is shown the treatment of the baffle - 72mm dia hole chamfered 45 degrees to a depth of 9mm. Note the support wire retention slots.View down the throat of an experimental straight exponential flare. In this configuration response extends past 4kHz, and suits situations where limited beamwidth is acceptable (eg small rooms, home hi-fi etc)For my application, I wanted wide horizontal dispersion which means transforming the flare to a narrow vertical slot. However, the steep transition from 72mm hole to 250mm high slot resulted in other cancellations below my target 3.5kHz crossover point. I am therefore working on a different throat approach, meaning this plug will not be utilised further (unless I make up some home stereo horns).Other plug types - Radial SlotAnother type of plug is the Radial Slot type, sometimes seen in piezo tweeters, but not commonly used. EAW use a variation in some of their boxes, but dont run them to a high crossover frequency - seelink.Here is shown an experimental version I tried for an 8 speaker - extremely difficult and time consuming to make (and to visualise while designing it), and it gave absolutely no benefit over the simple type ultimately chosen.