Ten Questions and Answers for Audio Enthusiasts

2. **Is Bi - wiring definitely better than conventional connection?**

The main argument for bi - wiring is that some speaker cables are suitable for transmitting low - frequency signals, while others are suitable for high - frequency signals. Separating the transmission allows for the selection of appropriate cables according to different needs, achieving the most ideal effect. However, this is just one opinion. Some people believe that the disadvantages of bi - wiring outweigh the advantages. For example, well - known speaker manufacturers like Dynaudio and Thiel insist on not using bi - wiring. They think that the inconsistent transmission characteristics of different cables can disrupt the phase consistency of high - and low - frequency signals. If the same cable is used, then why bother with bi - wiring?

3. **Why do larger speakers usually have better bass?**

The low - frequency limit of a speaker is closely related to two factors: the resonance frequency of the speaker unit and the volume of the cabinet. Without a cabinet, the low - frequency resonance frequency of the woofer unit is usually considered the effective lower limit of the unit's frequency response. Generally, the larger the diameter of the unit, the lower the resonance frequency. So, using a large - diameter speaker is beneficial for reproducing lower frequencies. In addition, a larger diaphragm area can push more air under the same amplitude, making it easier to obtain more low - frequency volume. When the speaker unit is installed in a cabinet, its resonance frequency will increase due to the stiffness of the air inside the cabinet. The larger the volume of the cabinet, the smaller the effect of the air on the unit, and the smaller the increase in the resonance frequency, which is conducive to obtaining a lower comprehensive low - frequency response. Larger speakers are convenient for using large - diameter woofer units and have a larger cabinet volume, so they usually have better bass.

There are many technical indicators to objectively measure the performance of speakers. Commonly seen in product catalogs or speaker manuals are: frequency response, impedance, sensitivity, maximum power handling, and maximum sound pressure level.

- **Frequency Response**: It represents the relationship between the sound pressure level output by the speaker and the frequency. When drawn as a graph, it is a function curve with frequency on the horizontal axis and output sound pressure (or the decibel value of sound pressure) on the vertical axis. The overall trend of this curve in the mid - frequency range is horizontal, although there may be many small fluctuations due to an imperfect system. At the low - frequency and high - frequency ends, the curve shows a downward trend, and the speaker's output decreases. Usually, the two points where the output at the low - frequency and high - frequency ends drops by 3dB relative to the middle horizontal section are called the low - frequency cut - off point and the high - frequency cut - off point, and the frequency band between these two points is the speaker's frequency response range. Obviously, the wider the frequency response range, the better, as it can reproduce a broader range of musical signals. For current speakers, the high - frequency end is not a problem, as it has long reached the upper limit of audio frequency, 20kHz, and some products even far exceed it. The difficulty lies in the low - frequency end. Generally, it is quite good if a bookshelf speaker can reach around 50 - 60Hz and a floor - standing speaker can reach around 30 - 40Hz. In addition, the flatter the curve within the frequency response range and the smaller the fluctuations, the better. This indicates that the speaker can reproduce all frequency signals within the frequency band equally well without distorting the balance.

- **Impedance**: Simply put, it is the resistance to the input current signal, with the unit of ohm (Ω). The most common impedance values of speakers are 8Ω, 4Ω, and 6Ω. There are also other values such as 3Ω, 5Ω, and 10Ω, but they are less common. It should be noted that the impedance of a speaker is only a nominal value. The actual impedance of a speaker varies with frequency. For example, for a speaker with a nominal impedance of 8Ω, the impedance is only 8Ω at certain frequency points, and it may be 10Ω or 20Ω at other frequencies, and may drop to 6Ω or 4Ω at some other frequencies. The characteristic of impedance changing with frequency can be clearly seen in the speaker's impedance curve, and this change increases the difficulty of driving the amplifier.

- **Sensitivity**: It is an indicator to measure the electro - acoustic conversion efficiency of a speaker, with the unit of dB/W/m. It means the sound pressure level obtained at a distance of 1m from the speaker's axis when 1W of power is input. For example, for a speaker with a sensitivity of 90dB/W/m, when 1W of power is input, a sound pressure level of 90dB can be obtained 1m in front of the speaker. Speakers with high sensitivity are more power - saving for the amplifier, which is considered an advantage. However, sometimes it is difficult to balance sensitivity with other performance indicators. Under trade - offs, it is often better to sacrifice a little sensitivity to obtain better performance in other aspects. This is because high - power amplifiers are now common and not too expensive, so a slightly lower sensitivity is not a major problem.

- **Maximum Power Handling**: It is a safety indicator of the speaker, representing the amount of input power that the speaker can withstand for a long time. Input below this value is obviously safe. If it exceeds this limit for a long time, it is easy to overheat and burn the voice coil. This indicator provides a reference for the safe use of the speaker, but we should also note the premise of "long - time". It is allowed to exceed for a short time. the maximum power handling For example, there are many short - term peaks in music signals, and their power intensity is several times or even dozens of times higher than the average power, but the duration is very short. As long as the average power does not exceed the speaker's maximum power handling value when playing such signals, there is no problem at all.

- **Maximum Sound Pressure Level**: It represents the maximum output capacity of the speaker when the distortion does not exceed a certain standard. In simple terms, it is how loud the speaker can play at most. Usually, the maximum sound pressure level of home - use speakers is around 100dB - 110dB, and a few high - output speakers can reach around 120dB. Obviously, the higher the maximum sound pressure level, the better. If this indicator is too low, dynamic compression is likely to occur.

5. **What is the standard for evaluating the quality of speakers?**

A truly excellent speaker should have both excellent objective performance indicators and good subjective listening evaluation. Excellent performance indicators include a wide and flat frequency response, low distortion, fast transient response, high sound pressure output capacity, high power handling capacity, appropriate impedance characteristics, and reasonable sensitivity. As for what constitutes a good subjective listening evaluation, it is more of an "art", and everyone's standards may vary. Theoretically, since the speaker is a part of the sound - reproduction system (and the final part that has the most obvious impact on the sound - reproduction quality), it should reproduce sound absolutely faithfully without any personality, and not distort, modify, or beautify the original music signal. If a speaker meets or approaches this standard, it is a good speaker. This is the so - called "truth - seeking" view. However, some people believe that since the speaker is used to reproduce music, then whether the sound is pleasant to listen to is the criterion for evaluating the quality of the speaker. This is the so - called "aesthetic - seeking" view. The "aesthetic - seeking" view allows the speaker to reasonably modify and polish the music signal, and does not care too much about whether the technical indicators are perfect, as long as the sound played is "pleasant to listen to". The "aesthetic - seeking" view is more suitable for those of us who listen to music for entertainment. However, there is no unified standard for what is "pleasant to listen to", and blindly pursuing a pleasant sound or personality regardless of performance is easy to lead to misunderstandings. Therefore, objectively speaking, even a speaker recognized as good by the "aesthetic - seeking" view should be based on ensuring basic performance indicators.

6. **Can a 4Ω speaker be connected to an 8Ω amplifier?**

This is a very common question, but also a typical one with a conceptual error. The statement "an 8 - ohm amplifier" is incorrect. The questioner may have seen something like "100W/8Ω" marked on some amplifiers and thought that the output impedance of this amplifier is 8Ω. In fact, this is a misunderstanding. The correct interpretation is that with an 8Ω load as the test condition, the output power of this amplifier is 100W. Whether it is a transistor amplifier or a tube amplifier, they both belong to constant - voltage output amplifiers, and their output impedance is very small. The output impedance of a transistor amplifier is generally below 0.1Ω, and that of a tube amplifier is a bit higher, but generally also below 1Ω, not 8Ω. Transistor amplifiers have a strong load - driving capacity and can be connected to speakers of any impedance in principle. However, it should also be noted that the impedance should not be too low to the extent that the amplifier cannot handle it or even overloads. For example, connecting a pair of 2Ω speakers (if available) will be too much for most medium - and small - power amplifiers. For tube amplifiers, there is a problem of "optimal load", that is, when the load impedance is a certain value, the performance of the circuit is the best. This optimal load impedance is usually several thousand ohms to tens of thousands of ohms, while the impedance of a speaker is only a few ohms, which is a big difference. Therefore, an output transformer is needed for impedance conversion. The output transformer of a tube amplifier usually has different taps. No matter what the impedance of the speaker is, as long as the tap on the output transformer with the same (or close) value is selected, it can be "mapped" to the optimal load required by the amplifier. In summary, when matching an amplifier with a speaker, there is no need to worry about the speaker's impedance. Transistor amplifiers can be connected to speakers of any impedance, and tube amplifiers can adapt to speakers of various impedances by selecting the taps of the output transformer.

7. **Why do some speakers consume a lot of power? What causes this?**

There are two reasons: First, the speaker may have a relatively low sensitivity. For speakers with a sensitivity difference of only 3dB, to obtain the same volume (or sound pressure level), the input power difference is doubled. For example, for a 90dB/W/m speaker, to obtain a sound pressure level of 100dB at a distance of 1m, only 10W of power is needed, while for an 87dB/W/m speaker, 20W of power is required. If the sensitivity difference of the speakers is 10dB, then the input power difference under the same output sound pressure condition reaches 10 times. For example, if the 87dB/W/m speaker mentioned above is replaced with an 80dB/W/m speaker, and still want to obtain a sound pressure of 100dB at a distance of 1m, the required input power is as high as 100W, which is 10 times higher than that of the 90dB/W/m speaker. Second, the sensitivity may not be low, but the impedance characteristic is abnormal. For example, for some speakers with a sensitivity of 87 - 90dB/W/m or above, which is not low, but looking at their impedance curves, the impedance at some frequency points may be as low as 2Ω or even 1Ω. Such a low impedance is almost a short - circuit for an ordinary amplifier, so how can it be driven? There will definitely be serious overload distortion at these frequencies. To drive such speakers, only super - powerful amplifiers like Krell and Mark Levinson, whose power can still increase linearly when the load impedance drops to 1Ω, can do the job. If you encounter a speaker with both low sensitivity and strange impedance characteristics, the requirements for the amplifier will be even more stringent.

8. **Some people use a tube amplifier with only a few watts of power to drive a pair of large speakers. Is this reasonable?**

Some people think that large - diameter speakers used in large speakers are heavy and cannot be driven by a low - power amplifier, but this is just an assumption. The power requirement of a speaker for an amplifier is mainly related to the speaker's sensitivity, not the size of the unit. Many large speakers, especially those using large - diameter paper - cone woofer units, such as the products of American companies like JBL and Klipsch, have a relatively high sensitivity, usually above 90dB, and some even reach above 95dB. For such speakers, a single - ended tube amplifier with an output power of a few watts can drive them to a full - blast level. Some audio enthusiasts may know that in Japan, using an 8W single - ended 300B tube amplifier to drive high - sensitivity JBL speakers is a very popular way of playing.

9. **If a speaker is rated at 100W, can it be driven by a 50W amplifier? If driven by a 200W amplifier, will the speaker be burned?**

First of all, it should be clear that the 100W power marked on the speaker's manual or nameplate refers to the speaker's power handling capacity, which means that as long as the input power does not exceed 100W for a long time, the speaker will not be damaged, not that a 100W amplifier is needed. As for how many watts of amplifier are required to drive the speaker, it mainly depends on the speaker's sensitivity and the required output sound pressure level, and has nothing to do with the speaker's power handling capacity. Generally speaking, speakers with extremely low sensitivity are in the minority, and the sound pressure level required in an ordinary home environment is not very high. A 50W amplifier can already meet the needs of many speakers. Of course, some speakers have special impedance characteristics, which pose a severe test to the amplifier. In this case, a high - power, high - current - output powerful amplifier is needed to drive them. Now look at the second question: Will a 200W amplifier burn the speaker? It depends on how you use this amplifier. Indeed, 200W is twice the maximum power handling capacity of the speaker. If the volume is turned to the maximum and the amplifier is always at full - power output, then this pair of speakers will surely be burned. But this situation hardly occurs. No one will suddenly turn the volume of the amplifier to the maximum. In fact, when the volume is increased to a level close to overload distortion (distorted sound), no one will continue to increase the volume (equivalent to increasing the power input to the speaker) to make the speaker produce a completely distorted sound. Instead, the volume will be reduced to make the speaker produce a normal sound. In this way, the average power input to the speaker is always controlled within the safe range it can bear. Even if the power of the amplifier is larger, only the part that the speaker can bear is output. So how can the speaker be burned? On the contrary, using a high - power amplifier increases the power reserve, which can avoid overload distortion of instant large - dynamic peak music signals and is beneficial to ensuring the sound - reproduction quality.

A home theater system generally uses a surround - sound playback system, so there are many channels. Currently, popular Dolby Digital and DTS systems use five wide - frequency speakers to form the front and rear channels, and there is also a sub - woofer. The requirements for these speakers are similar to those for a high - fidelity two - channel system, still including common requirements such as wide frequency response, low distortion, little coloration, and good transient response. In principle, as long as a speaker performs well in music playback, it can also be used in a home theater. However, speakers with weak dynamic output capabilities (such as LS3/5A) are not very suitable, otherwise, they are likely to experience overload distortion when encountering large - dynamic and exciting scenes. Since the center speaker is usually placed on the TV, it should have anti - magnetic properties. In addition, the timbres of the speakers in each channel should be coordinated, and it is best to use products from the same manufacturer and the same series.