一般而言，从低音炮的构成来讲，低音也分有源与无源二大类，所谓有源低音炮指包含功率放大器的低音炮，其中电路部分除功率放大外．通常还具有音频频率滤波(滤去低音以上的音频频率成分)，相位调整。音量调整等单元；而无源低音炮即与一般音箱无二，由单元与无源功率分频器组成，其中分频器是一低通滤波器而已。使其重放频率范围仅为超重低音音频。下面就低音炮的-大单元音箱，功率放大分别做以介绍。
Generally speaking, from the composition of subwoofer, bass is divided into active and passive two categories, the so-called active subwoofer that contain power amplifier subwoofer, wherein the circuit parts except the power amplification. Usually with audio frequency filter (filter to audio frequency bass more components), phase adjustment. Volume adjustment unit; while passive subwoofer that with the general sound box no two, composed of unit and passive power divider, the divider is a low pass filter. The playback frequency range is only subwoofer audio. Below the big unit speaker subwoofer -, power amplifier respectively introduced on.
一、低音炮济南音响箱体设计原理和分类
A subwoofer sound box, design principle and classification of Ji'nan
就低音炮设计原理，可大致分三大类，即密闭式音箱、倒相式音箱以及带通滤波式音箱
On the subwoofer design principle, can be roughly divided into three categories, namely, a closed box, inverted sound box and bandpass filtering type sound box
1、 密闭式音箱
1, a closed box
顾名思义，这种音箱箱体是完全封闭的，与一般的所谓闭箱结构上一样，见图1
As the name suggests, the sound box body is completely closed, like the so-called closed box structure, see Figure 1
密闭式音箱的特点是结构简单，瞬态响应比较好．即听感深沉、清晰。不足是，在相同的体积下，与其它类型的音箱相比，其低频下潜截止频率要高于其他音箱，因此，如果要获得更低的低频下潜频率，通常需要较大的箱体容积并选用口径较大的喇叭单元，而且音箱的效率即灵敏度要低于其他类型音箱。
Characteristics of closed box is simple in structure, the transient response is better. That is, the sense of hearing is deep, clear. The question is, under the condition of same volume, compared with other types of speakers, the deep bass cutoff frequency than other speakers, therefore, if the frequency to obtain lower submergence frequency, usually need to box volume larger and select the speaker unit is larger, and the efficiency of the sensitivity to sound box is lower than other types of speaker.
在箱体容积设计方面，有一个工程设计数据供参考．当喇叭单元的谐振频率Fs低于50Hz时，箱体容积最好能够大于1.4立升。Fs大于50Hz时，箱体容积最好能够大于2立升。
In terms of the volume of the box body design, a engineering design data for reference. The resonant frequency of Fs when the speaker unit is lower than 50Hz, the volume of the box body can best be greater than 1.4 liters. Fs is greater than 50Hz, the volume of the box body can best be greater than 2 liters.
闭箱在制作、调校时通常还需要在箱体内填充大量吸音棉，材料以玻璃纤维，长纤维羊毛为主，能够改善音箱的柔顺性，也可达到等效增加箱体容积的效果，理论上达40%，实用上可以按等效增加容积15%-24%进行计算，相当于减少箱体的容积。另外，填充吸音棉，也可提高音箱的效率，正确的填充量，最大可提高音箱效率达15%，吸音棉的多少通常需要通过反复试听来决定填充量的多少，以声音不浑浊(量偏少)，沉闷(量过多)为原则，其它类型音箱也是如此。
Closed box in the production, the adjustment usually need to fill a lot of sound-absorbing cotton in the box body, the material with glass fiber, mainly long wool, flexibility can improve the sound box, also can achieve the equivalent effect theory to increase the volume of the box body, up to 40%, the utility can be increased by the equivalent volume of 15%-24% were calculated, equivalent to reducing the volume of the box body. In addition, filling the sound-absorbing cotton, but also can improve the efficiency of the filling amount of speaker, right, the maximum can improve the efficiency of up to 15% the number of speakers, sound-absorbing cotton usually required by repeated listening to decide how much of the filling amount, with sound not cloudy (less), dull (too much) for the original, too other types of speaker.
对于闭箱型低音炮，对单元的要求相对其它类型音箱要严格一些，其中希望Fs以低于40Hz为好，Qts应该在0.3-0.6，Fs/Qts≤50。除此之外单元口径最好大于20cm ,而且属于长冲程设讨。
For the closed box subwoofer, the requirement of unit relative to other types of speakers to more stringent, which wants the Fs to less than 40Hz as well, the Qts should be in 0.3-0.6, Fs/Qts is less than or equal to 50. In addition to this unit diameter should be greater than 20cm, and belongs to the long stroke design discussion.
2、倒相式音箱
2, the phase inverted type loudspeaker box
是市场上最多的一类济南音响 http://www.jnzqyx.com/ ，音箱上设计有倒相管，即所谓的低音反射式设计，见图2。
The market is the most kind of Ji'nan sound, the sound box is designed on inverted tube, namely the bass reflex design called, see figure 2.
倒相式音箱，在单元工作于谐振频率Fs以上锥盆位移相对较小，因而功率承受能力较高，谐振失真较小，但在谐振频率以下，锥盆位移量大幅度增加，谐振失真增加，在相同容积与单元条件下，倒相式音箱可以获得较闭箱更低的低频下潜截止频率。另外，理论上倒相式音箱的效率可以做到大于闭箱约3dB。
Inverted sound box, in the unit of work in the resonant frequency above Fs cone displacement is relatively small, so the bearing ability of the power of high harmonic distortion, small, but in the resonant frequency of the following, cone displacement increased greatly, harmonic distortion increases, in the same volume and unit condition, inverted sound box can obtain lower closed box goes lower cut-off frequency. In addition, the theoretical phase inverted type loudspeaker enclosure efficiency can do more than closed box about 3dB.
当然，倒相式音箱包括倒相管的设计、制作、调校难度要大于闭箱。倒相式音箱内部也需要填充适量的吸音棉，通常比闭箱少一些。
Of course, the phase inverted type loudspeaker box comprises inverted tube design, manufacture, adjustment is more difficult than the closed box. Inverted sound box also needs to fill the right amount of absorbent cotton, usually less than the closed box.
在单元选取上，Fs以低干45Hz为好，Qts应该小于0.5，而Fs/Qts取值应该在100左右为好，单元口径应该大于17cm，为获得较大的声压功率，与闭箱一样，宜选用长冲程设计的单元。
In the unit selection, Fs with low dry 45Hz as well, the Qts should be less than 0.5, while the Fs/Qts value should be in 100 or so, unit diameter should be greater than 17cm, to obtain the pressure power larger, as with the closed box, should choose long stroke design unit.
3、带通滤波式音箱
3, the band-pass filter type sound box
这种音箱比较少见，参见图3、图4，由图可以看出，它是在闭箱与倒相式音箱的基础上发展而来的.既有闭箱的设计痕迹，也有倒相式音箱的特征，其中图3所示音箱也有称四阶带通式音箱，图4所示音箱可以称之为六阶带通式音箱。
The speaker is relatively rare, see Figure 3, figure 4, can be seen from the chart, it is evolved based on closed box and inverted sound box. Both the design on the traces of closed box, there are also inverted sound box feature, which is shown in Figure 3 speakers also known with four orders the general formula of sound box, shown in Figure 4 speakers can be called six order band-pass loudspeaker.
A、四阶带通式音箱
A, a four order band-pass loudspeaker
在闭箱腔内增加了一个开口腔，其中一部分工作于闭箱模式，另一部分工作于倒相式模式，因此，这种音箱既具有闭箱的优势，也具备倒相式音箱的特点，它的效率高于纯粹的闭箱，低频下潜截止频率与倒相式音箱相近，可以用较小口径的单元获得较低下潜截止频率。另外，它的带通频率可以调整，因而分频器可以简单化，因为音箱本身就相当于自然分频器。
In the closed box cavity adds an open cavity, one part of work in the closed box model, another part of the work in the inverted mode, therefore, the sound box has the advantages of closed box, also have inverted sound box features, its efficiency is higher than the closed box pure, deep bass cut-off frequency similar to inverted sound box, can use small caliber unit to obtain lower submergence cut-off frequency. In addition, its bandpass frequency can be adjusted, so the divider can be simple, because the speaker is itself equivalent to natural frequency divider.
在单元选取上，原则上与闭箱相似，但由于效率略高于闭箱，而且锥盆位移量比较小，可以使用较小口径、短冲程的单元。
In the unit selection, principle and closed box similar, but the efficiency is slightly higher than the closed box, and cone displacement is relatively small, can use a smaller aperture, short stroke unit.
B、六阶带通式音箱
B, a six order band-pass loudspeaker
在四阶带通式音箱的闭箱部分腔内又增加了一个开口腔，即有二个开口腔，其中一个开口腔工作于较低的频率，另一个工作于较高的频率，二者合成具有一定带宽的频率响应，与上述四阶带通式音箱相比，效率与带宽的可调性更加灵活，而且可以利用更小口径的单元获得更低、更深沉的低音效果，同时、锥盆位移量更小、谐振失真更低。
Closed box section cavity band-pass speaker in the four order and add an open mouth, which has two open cavity, wherein an open cavity work at lower frequencies, another work at higher frequency, the two synthetic with certain bandwidth frequency response, compared with the four order band pass the speaker, efficiency and bandwidth can be regulated flexibly, and can use a smaller caliber unit get lower, more deep bass effect, at the same time, cone displacement of smaller, lower harmonic distortion.
在单元选取上，基本上与倒相式音箱相近，但Qts该掌握在0.4左右比较好，单元口径基本上没有严格的要求，如果要获得高声压功率、低失真输出，单元口径当然还是尽量大一些比较好。
In the unit selection, basically and inverted sound box similar to Qts, but the master of around 0.4 more good, unit diameter is not a strict requirement basically, if you want to obtain the high pressure power, low distortion output, unit diameter of course or as large as possible some of the better.
由于带通式音箱的倒相孔在工作时的气流、声压通常比较大，尤其是在大动态、超低频信号时，因此，不论是四阶带通式音箱，还是六阶带通式音箱，倒相管在可能的情况下，应该尽量大一些，以避免在工作时出现气流声。
The band-pass speaker of the phase inverting hole in the work of the airflow, pressure is usually large, especially in the dynamic, ultra low frequency signal, therefore, whether it is a four order band-pass speaker, or six order band-pass loudspeaker, inverted tube where possible, should be as large as possible, in order to avoid airflow noise at work.
在箱体设计上，其容积的取值在实际应用中并不是依据理论计算而来的，尤其是商品箱，主要是以美观、尺寸的协调方面为准，电声指标靠倒相管、吸音棉的调整来达到最佳水准即可，当然，其容积越接近工程计算值，性能越能达到最好的水准。另外，在箱体制作上，内部加强筋的作用不容忽视，在箱体接缝处以及大板中间加一些加强筋利于降低音箱的谐振，所以箱体重一些总是有好处的。
In the box body design, the values of its volume in practical application and not on the basis of the theory of computation and come, especially the goods box, mainly is to coordinate the beauty, size is accurate, electroacoustic index by inverted tube, sound-absorbing cotton adjustments to achieve the best level can, of course, its volume is more close to the engineering calculation value, performance is to achieve the best level. In addition, in the box body design, internal stiffener effects can not be ignored, in the middle of the box body joints and plate plus some stiffeners to reduce the resonant sound box, so the box weight is always good.