From time to time, I see some audiophiles spend a lot of time or time to DIY speakers, but the result is not what they want. Below I will re-list some of the small experiences I have summarized based on the work situation, hoping to help those who are interested.
Some common sense about speakers
1 The speaker is basically equivalent to a high-pass filter in principle. Generally speaking, the speaker design is mainly for the bass part, and the mid-to-treble part basically only depends on the speaker unit, crossover and cabinet shape.
2 For each specific bass or mid-bass speaker unit, there is at least one suitable cabinet form. Under normal circumstances, the specific box form is selected according to the ratio of the resonant frequency of the horn unit to the total quality factor of the horn unit. It is generally believed that speaker units with a ratio of Fs/Qts less than 40Hz are suitable for labyrinth speakers. The speaker unit with the ratio of Fs/Qts between 40Hz and 80Hz is suitable for closed speakers. The speaker unit with the ratio of Fs/Qts between 80Hz and 120Hz is suitable for inverted speakers. The speaker unit with Fs/Qts ratio greater than 120Hz is suitable for exponential horn speakers. But this is not absolute. Generally speaking, everything is conditional. Avoiding conditions to talk about conclusions is of little practical significance. Modern speaker unit design, due to the guidance of T/S parameters, under normal circumstances, only some parameters need to be optimized to obtain the desired effect.
3 As far as inverted speakers are concerned, each low-frequency or mid-low-frequency speaker unit has a suitable upper limit and lower limit for the net volume of the cabinet. Generally speaking, if the net volume of the cabinet is small, the resonance frequency will increase, and the low end of the frequency response tends to bulge. The net volume of the cabinet is large, the resonance frequency will be reduced, and the low end of the frequency response has a downward trend. The best net volume of the speaker usually mentioned is only for the design of the flattest frequency response. It is common to see some improperly-tuned inverted speakers. After the net volume of the cabinet is large, the Q value is often lowered, which causes the low frequency to be soft and weak. On the contrary, when the net volume of the cabinet is set to a small value, the Q value is often adjusted higher, which causes the low end of the frequency response to bulge, the speaker is prone to rumbling and whining resonance, and the low-frequency transient response becomes very poor. .
4 The area of ​​the inverter hole increases, the resonance frequency of the inverter hole increases, and the output sound pressure level increases; the area of ​​the inverter hole decreases, the resonance frequency of the inverter hole decreases, and the output sound pressure level decreases. When the length of the inverter hole increases, the resonance frequency of the inverter hole decreases, and the output sound pressure level decreases; when the length of the inverter hole decreases, the resonance frequency of the inverter hole increases, and the output sound pressure level increases. The shape of the inverter port has a great influence on the low-frequency radiation. The smooth shape can have a good coupling effect with the air outside the inverter hole. The air friction distortion caused by the inverter hole will be reduced a lot, and the low frequency The output sound pressure level will be increased. Specific examples can refer to related patents of BOSE and B&W.
5 The damping of the speakers and speakers should be appropriate, or that there is an optimal compliance ratio and tuning ratio between them. The compliance ratio and tuning ratio of the speaker unit and the speaker cabinet with different Qts values ​​are different. For details, please refer to the Nomo diagram in ANThiele and RHSmall design method. This can also be regarded as a theoretical basis for the inverted box double-peak debugging method.
6 Generally speaking, the speaker Q value refers to the Q value of the entire speaker system, which includes the Q value of speakers, cabinets, crossovers, wires, and power amplifiers. Among them, the Q value of the speaker, cabinet and crossover is the main part, and the influence of other parts is usually small.
7 Generally speaking, the Q value is high and the damping is large, and the Q value is low and the damping is small.
Loudspeakers are classified according to their most basic uses, and there are two basic models: appreciation type and monitor type. In daily life, we are most exposed to appreciation speakers. Since it is positioned as a speaker for music appreciation, there are some targets and trade-offs when designing and debugging. For the speakers that mainly serve families and individuals and are used to enjoy music, different designers have different cultural backgrounds and cultural environments. The speakers they design and debug are also great in temperament, personality, and sound. It is different and exciting. This is also the main reason and source of different styles of sounds such as British, American, and Nordic sounds that people often say. Due to work relations, the author has had the opportunity to come across all kinds of speakers with different sound bottoms, many brands, well-known or unknown speakers. There are not only popular brands, HiFi and HiEnd brands in Europe and the United States, but also some uninfluenced miscellaneous goods in South America, Africa and other countries. Since the factories I serve are mainly for EMS, ODM and OEM services, I have also come into contact with a variety of different acoustic requirements from customers. Moreover, since it is doing EMS, ODM and OEM services, it is of course necessary to do everything possible to meet the requirements of customers. When designing, debugging, and tuning, it is necessary to do something and not to do something, and more often it is to make compromises. , Compromise treatment.
The author is not talented, and boldly put forward a "good voice" suggestion here, hoping to save latecomers from detours and pay less tuition. When designing and debugging appreciation speakers, the author prefers to tune the sound into a lively, relaxed, natural and cheerful type in terms of hearing. I don't like dull, procrastinated, and lifeless sounds. On this basis, the sound is adjusted to be sweeter and moisturized, and the frequency response of the high and low ends is further expanded, the density and layering of the sound are adjusted as much as possible, and the service angle of the speaker is adjusted to be wider. The sound sounds more open and lively. Finally, the phase response and group delay of the speakers are adjusted to a linear relationship, so that the positioning and sound field of the speakers are better. At this time, special attention should be paid not to adjust to nonlinearity. In relation to the relationship, when there are difficulties, I would rather compromise on the flatness of the frequency response than on the non-linear relationship.
Many enthusiasts tend to think that the more expensive materials and components are better. The author’s factory experience tells myself that under the pressure of cost, we can only choose suitable and suitable ones instead of expensive ones. Not only audiophiles have this idea, but many engineers also have a similar misunderstanding: they think that only expensive components can be used to design and manufacture "good sound" audio equipment. In fact, in a company with a well-designed, sophisticated manufacturing process, and a complete company, a radio with a value of tens of dollars can still make a beautiful sound to move the listener when it is well debugged. For general user products (audiovisual home appliances), first balance the sense of hearing, and then make the sound softer and more graceful. In terms of sense of hearing, the listener feels comfortable and stretched. Broaden the frequency response. After such treatment, it can basically meet the requirements of most ordinary consumers.
The basic requirement for debugging and adjustment is to try not to increase the cost. The specific method is: use the electronic part to compensate the acoustic part, or conversely use the acoustic part to deal with the difficulties of the electronic part, and use the design and structure to balance and compensate the horn or sound box. Insufficient part.
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