Table 8 Maximum Cable Length (m) for Gauge of Wire and Speaker Impedance
Gauge | Area mm2 | 2 Ohm | 4 Ohm | 8 ohm | 16 ohm |
10 | 5.26 | 18 | 36 | 72 | 144 |
12 | 3.31 | 11 | 23 | 45 | 90 |
14 | 2.08 | 8 | 15 | 30 | 60 |
16 | 1.31 | 5 | 9 | 18 | 36 |
18 | .82 | 3 | 6 | 12 | 24 |
20 | .52 | 2 | 4 | 8 | 16 |
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在以太网和xDSL接入网设计中，经常会碰到诸如24AWG、26AWG等等表示电缆直径的方法。其实AWG(American Wire Gauge)是美制电线标准的简称，AWG值是导线厚度（以英寸计）的函数。下表是AWG与公制、英制单位的对照表。其中，4/0表示0000，3/0表示000，2/0表示00，1/0表示0。例如，常用的电话线直径为26AWG，约为0.4mm。
AWG | 外径 | 截面积 (mm2) | 电阻值 (Ω/km) | AWG | 外径 | 截面积 (mm2) | 电阻值 (Ω/km) |
公制mm | 英制inch | 公制mm | 英制inch |
4/0 | 11.68 | 0.46 | 107.22 | 0.17 | 22 | 0.643 | 0.0253 | 0.3247 | 54.3 |
3/0 | 10.40 | 0.4096 | 85.01 | 0.21 | 23 | 0.574 | 0.0226 | 0.2588 | 48.5 |
2/0 | 9.27 | 通宵是什么意思0.3648 | 67.43 | 0.26 | 24 | 0.511 | 0.0201 | 0.2047 | 89.4 |
1/0 | 8.25 | 0.3249 | 53.49 | 0.33 | 25 | 0.44 | 0.0179 | 0.1624 | 79.6 |
1 | 7.35 | 0.2893 | 42.41 | 0.42 | 26 | 0.404 | 0.0159 | 0.1281 | 143 |
2 | 6.54 | 0.2576 | 33.62 | 0.53 | 27 | 0.361 | 0.0142 | 0.1021 | 128 |
3 | 5.83 | 0.2294 | 26.67 | 0.66 | 28 | 0.32 国内外大事 | 0.0126 | 0.0804 | 227 |
4 | 5.19 | 0.2043 | 21.15 | 0.84 | 29 | 0.287 | 0.0113 | 0.0647 | 289 |
5 | 4.62 | 0.1819 | 16.77 | 1.06 | 30 | 0.254 | 0.0100 | 0.0507 | 361 |
6 | 4.11 | 0.1620 | 13.30 | 1.33 | 31 | 0.226 | 0.0089 | 0.0401 | 321 |
7 | 3.67 | 0.1443 | 10.55 | 1.68 | 32 | 0.203 | 0.0080 | 0.0316 | 583 |
8 | 3.26 | 0.1285 | 8.37 | 2.11 | 33 | 0.18 | 0.0071 | 0.0255 | 944 |
9 | 2.91 | 0.1144 | 6.63 | 2.67 | 34 | 0.16 | 0.0063 | 0.0201 | 956 |
10 | 2.59 | 0.1019 | 5.26 | 3.36 | 35 | 0.142 | 0.0056 | 0.0169 | 1,200 |
11 | 2.30 | 0.0907 | 4.17 | 4.24 | 36 | 0.127 | 0.0050 | 0.0127 | 1,530 |
12 | 2.05 | 0.0808 | 3.332 | 5.31 | 37 | 0.114 | 0.0045 | 0.0098 | 1,377中秋节团圆 |
13 | 1.82 | 0.0720 | 2.627 | 6.69 | 38 | 0.102 | 0.0040 | 0.0081 | 2,400 |
14 | 1.63 | 0.0641 | 2.075 | 8.45 | 39 | 0.089 | 0.0035 | 0.0062 | 2,100 |
15 | 1.45 | 0.0571 | 1.646 | 10.6紫根兰 | 40 | 0.079 | 0.0031 | 0.0049 | 4,080 |
16 | 1.29 | 0.0508 | 1.318 | 13.5 | 41 | 0.071 | 0.0028 | 0.0040 | 3,685 |
17 | 绿豆南瓜汤1.15 | 0.0453 | 1.026 | 16.3 | 42 | 0.064 | 0.0025 | 0.0032 | 6,300 |
18 | 1.02 | 0.0403 | 0.8107 | ps印章21.4 | 43 | 0.056 | 0.0022 | 0.0025 | 5,544 |
19 | 0.912 | 0.0359 | 0.5667 | 26.9 | 44 | 0.051 | 0.0020 | 文人墨士 0.0020 | 10,200 |
20 | 0.813 | 0.0320 | 0.5189 | 33.9 | 45 | 0.046 | 0.0018 | 0.0016 | 9,180 |
21 | 0.724 | 0.0285 | 0.4116 | 42.7 | 46 | 0.041 | 0.0016 | 0.0013 | 16,300 |
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由表中归纳出的AWG与英寸的关系如下：
AWG = A lg inch - B
其中，A＝-19.93156857，B＝9.73724。
以下摘自<BASSBOX XOVER>的ONLINE HELP.
The purpo of the crossover network is to divide the sound between the drivers in a multi-driver speaker. How well this is accomplished is not just a matter of good design. It also requires good execution. This topic contains advice to help with execution.
General
Let抯 begin with some general suggestions:
Measure all components
It is best to measure the value of all components before using them in a crossover network. This is best accomplished with an impedance bridge and tone generator. Ideally, the components should be measured at the crossover frequency.
Lower-order networks like 1st and 2nd-order networks can usually tolerate greater component variations than higher-order networks like 3rd and 4th-order networks. If you
are unsure whether a component value is clo enough to work, try substituting the measured value in your X昽ver Pro design and plot the results. U the graphs to evaluate the changes.
Series components are the most critical
The ries components are the most important elements in a crossover network becau the audio signal must pass through them before arriving at the driver. The parallel components rve as shunts to drain a portion of the audio signal away from the driver. There are ten ries components in the three-way crossover network below (they are highlighted in pink).
If you need to economize, it is best to do so with the parallel components and rerve the highest quality parts for the ries components.
Connections
To make a good electrical connection between two or more components, begin by creatin
g a strong mechanical connection. This can be as simple as carefully twisting their wire leads together. Take care not to put too much tension on each lead where it enters the component. A component with a broken lead is uless. Finally, solder the connections to create a long lasting, airtight connection. The wires should be heated enough to allow the solder to flow onto them but not so hot that a component is damaged.
Mounting幼儿心理健康教育
Unless you have the resources to design and manufacture a printed circuit board (PCB) for the crossover network you will need to obtain some sort of flat and thin nonconductive material to rve as a circuit board for component mounting. Commonly ud materials include hardboard and pegboard.
Create a cut pattern for the circuit board by laying all the components on a piece of paper in their mounting position and drawing a rectangle around them. U the pattern to cut the correct size piece from the circuit board material.
When mounting the parts, it is important to not allow them to touch each other (except at the connections). This is especially true of inductors and resistors.
The parts should be curely mounted to the circuit board so that they cannot vibrate. This can be accomplished by gluing them to the circuit board with a nonconductive adhesive. Commonly ud adhesives include silicone rubber and epoxy glue.
Most crossover networks are installed inside the speaker box. If this is done, it is important to keep the crossover network as far as possible away from the drivers. This is becau the magnetic field of the drivers can interact with the crossover network and cau distortion. This problem is minimized when shielded drivers are ud.
Some designers recommend using brass screws to mount the circuit board. Unlike steel screws, brass screws will not interact with the magnetic fields of the crossover network components.
Capacitors
Generally speaking there are two kinds of capacitors ud in crossover network construction: electrolytic and solid dielectric. Electrolytic capacitors must be the nonpolarized variety becau audio signals have alternating current. Electrolytics are the most common and the cheapest capacitors. Unfortunately they are considered the least favorable becau they tend to have more resistance (ESR) and inductance (both undesirable qualities in capacitors) and becau they do not age well. Electrolytic capacitors usually have greater manufacturing variations, resulting in higher tolerance values. And their resistive and inductive attributes are usually wor at higher frequencies.
