What are the options when purchasing KTV professional audio?

There is hardly anything in the world that is more subjective than evaluating the speaker by hearing alone. The beauty of an audio fan may become the poison of another audio fan. But for experienced listeners -- those who have spent hundreds of hours comparing controlled speakers under controlled conditions and those who agree that there should be a set of guidelines -- they should be in terms of methods and conclusions. There are some common basic points.

But that doesn't mean we have to be consistent. If you think that the most beautiful sound is the strongest bass impact at the dance, then it is! The advice of “purchasing your favorite things” is straightforward and will not go wrong, but if you agree to use “accuracy” as the ideal quality for your speakers, you will find the following knowledge to help you find one. Accurate speaker. The definition of "accurate" here is to reproduce the details of the original recorded tones, dynamics and ambient atmosphere in the widest possible frequency range under the inevitable price and size constraints. The less the change, the better. Of course, this definition is also roundabout and indirect, because if you don't play it with a certain speaker, how can you know what its original sound is like? You and I don't even know that the world famous painting "Mona Lisa" is a bit like the 16th century lady, but we believe that Leonardo da Vinci is a skilled painter. I believe that his paintings are accurate, in addition to artistic. Similarly, if we choose an artistic record, we should assume that it can be replayed to be almost as real as the original. Although recording devices (such as microphones) have the same inherent sound quality as speakers, the difference in sound quality between several good recordings should be much smaller than the difference between a good and a mediocre speaker. Much more.

Auditor's duties

Nothing can replace experience, so every opportunity should be seized to listen and compare speakers. It is important to remember that the listening environment is always important, and always use good amplifiers or receivers and good sound source components to reduce the variables. But you can be sure that even a similar speaker, when you hear the sound is different, is far more different than finding an amplifier and a record player.

If you use the A/B comparison test set, it has a set of switches that are connected directly to two or two sets of speakers. Care should be taken to balance the comparison work, that is, to keep the volume of the two sets of test speakers within 0.5 decibels (this can only be measured with an accurate sound pressure gauge). This is a psychological fact: if one speaker is louder than the other, and the sound is a little louder, people will think that the speaker sound quality is "good".

Another point to be aware of is that the assembly of the speaker's position on the sound is unexpected, so you must interchange the pair or set of speakers you are listening to, even if you place them side by side. It will be able to hear the effect of the position on the sound. But don't rely solely on A/B comparison tests, but also listen to them one by one (or group by group) to understand their sound characteristics.

Obviously listening to the material is very important. To select some demos, the point of choice is not based on the beauty of the music, but on the accuracy of the recording, while showing a particular aspect of the sound quality. There are many ways to choose a record for evaluating a speaker. I often use a few familiar pieces of music so that I can test a key sound feature. (See the appendix of the sound recordings below). The advantage of this method is that you will soon be familiar with the music, that is, you have not listened to it as music, but just focus on how the music is re-transmitted accurately.

Audition list

What sound characteristics do you want to listen to? Different experts may have different answers, and I offer the following:

1. Timbal uniformity - I think this is the first thing, it means uniformity from bass to treble in a wide frequency range. In fact, it is difficult to judge the tone color as a whole, so I divided it into four small categories:

A. Vocal-range smoothness - This part is dedicated to listening to the IF part of the human voice (including singing and speaking) contaminated by the tone of the speaker - this is a disadvantage of some general speakers. The most common "error" performance is the same for different people. It behaves like a horn or nasal sound, or a sound that is made through the closed palm. I think this is the biggest shortcoming that can be heard. It distort the singing of vocalists such as Janis Joplin and Gordo Inghtfoot, whose sounds are fundamentally different.

B. Low frequency / low frequency and low frequency - this situation is easier to hear. The usual signs are squeaking or shallow (a tendency to aggravate or shorten certain sounds), or a hollow voice (lower males are overly arrogant or weak).

C. The roundness of the lower treble--I usually use collective string performance to test this. I heard the sound of the stringed instrument is not sharp or dry (no angry sound) or too sweet. This is the most demanding requirement for the listener, unless you have some experience listening to the band's string group live performance. Due to the acoustic conditions of the hall and the playing style of the band, even the best string groups sometimes have rough or hard stretches. It is necessary to concentrate on listening to whether there is often a harsh or metallic sound, and at the same time pay attention to whether the sound is too full and sounds unnatural. Try listening to a few albums to see if this bad quality is caused by the record itself.

D. Tip-top treble--In most music, there is almost no sound that exceeds 13 kHz. If we do hear the sound of this frequency, it is just a "light flash" rather than a tone. Listening to jazz or rock slaps is an easy way to master this sound. The popular high-hat rides combine jazz and rock, and recording natural recordings is an excellent test material that contains clean, repetitive momentary treble. You should concentrate on listening to each of these momentary trebles to see if it is dark (lack of the highest octave), too sharp (too much highest octave), and blurry (some unclear, seemingly unclear non-metallic Sound, the real thing will not have this kind of sound).

2. Audiovisual Positioning - Here I am referring to the sense of space, sound field, depth, and many terms used to describe how the speaker creates a realistic acoustic space atmosphere. In general, audio and video positioning is the most varied speaker quality, and certainly the most difficult to evaluate, because even the best reproduced sound is not very similar to the original sound.

I first listened to the stability of the audio and video. When the frequency of the music changes, is the position of the singer or instrument soloist erratic, moving from one side to the other, or from the front to the back, is the entire sound field spread out between the two speakers? Or tighten in the middle? Is the depth of vocals and instrumental sounds from front to back natural? Is the reverberation excessive or insufficient?

All of these questions are rough and there is no "absolute" answer. Each speaker distort the sound "reality" in some way, so the above changes are purely personal taste issues. Different types of speakers have essentially different audio and video positioning characteristics. For example, a dipole speaker, like most electrostatic or planar magnetic speakers, typically produces a greater depth and spatial feel, but with respect to the accuracy of the audiovisual positioning and the stability of the sound field position of the instrument. There are not enough. The nature of the speaker design using a horn or some sort of push unit to align such a control direction is just the opposite. The nature of most common two- or three-channel speakers is usually somewhere in between.

3. Dynamic Range - Virtually all speakers compress the dynamic range to some degree. That is, if a certain volume limit is exceeded, the speaker will no longer be able to produce an equal, clean audio output over the entire frequency range.

One of the obvious manifestations of dynamic range limitation is that the drive unit (usually an intermediate or low frequency unit) produces a click, click, or click when a strong transient sound occurs. The other form is more elaborate, it is the response of the nonlinear frequency. The speaker does not maintain a constant output over certain frequency ranges (usually deep bass), and the result is excessively bright at high volume levels (the IF/HF portion is usually more clean than the low frequency portion). In strong, wideband transients lack weight and impact.

It is obviously difficult to judge these dynamic constraints in the case of accidental listening. Can you be sure that the bass unit's "bottoming" is heard instead of the amplifier's clipping? Can you hear the distortion of the speakers instead of the vibration of furniture, floors, windows? Can you hear that the sound is too bright due to the limitations of the speaker rather than the natural "distortion" of your own ear at very high volume? Unless you listen in a very familiar environment, you won't find the problem.

4. Low-Frequency Extension - A speaker that can actually replay the entire audio band up to 20-25 Hz is extremely rare, while few speakers can't produce a more powerful output above 80 Hz. When we refer to low frequency extension, it refers to the lowest two octaves of ten octaves. This type of vibration is rare in traditional instruments (except for rumbling bass in percussion instruments, synthesizers, and recording tracks).

Recordings with about 40 Hz of audio are quite rare, and the bass drums in classical music (such as Copland's "Drums for the Ordinary") and the ultra-low synthetic sounds in pop music are the best test materials. Unfortunately, unless the speaker is moved to your home, it is extremely difficult to judge its deep low-frequency response because the speaker position and room acoustic environment have a greater impact on the bass than on any other performance of the speaker.

Based on the above points, use one or two very familiar, solid and powerful hits to evaluate the speakers, and listen to the unrestrained deep bass and realistic sound with a relaxed mood. However, I have to wait until I have the opportunity to repeat this test in my listening room before I think that my judgment is qualified. At that time, I have enough confidence to assess which speaker is “good”, “poor”, “medium” or “absolutely difficult”. Confidence."

Test record introduction

Below are some CD samples that I use to listen to speakers. You will notice that most of the albums have been released for more than five years. But if they can be used, there is no reason to change. Please use it as a starting point and gradually add your own test materials.

AMANDA MCBROOM: amanda (Sheffield Lab 10066)

I heard the roundness of the bass and mid-bass in the two songs "amanda" and "The Rose". This is a remarkable natural live recording with very neutral vocals, natural audio and video positioning and warm bass.

THE HOLMES BROTHERS: Jubilation (Realworld 92127)

I usually listen to this record in order to listen to the pronunciation of the male voice in the song "I want Jesus to walk with me", the openness of the top octave and the stability of the audiovisual positioning. The entire CD naturally and closely reproduces the outstanding human voice of Holmes Brothers - used to evaluate the quality of the mid-range vocals. Another song "I've had my chance" represents an imaged left-right Sound field, the depth is not deep but can be distinguished. It is very suitable for comparison of audio and video positioning.

JOHN EARGLE: Engineer's choice (Delos 3512)

Each track of this record is perfect for testing a project. Includes various hall acoustic conditions and sound fields. I usually use the following:

1. A fragment of Shostakovich's eighth symphony used as a string sound for testing sound image localization and sound field depth and lower treble. The music is complex and deep, but with precise and broad stereo images, as well as a wide frequency band and rapidly changing sound, it provides a rigorous test of the speaker's ability to create a recording depth and breadth.

2. Messien's Pentecost Mass for organ. If you are tired of Bach's D minor prelude and fugue, this music is the best replacement, it is a really good organ recording with low frequency extension.

THOM ROTELLA: Without Words (Dmp 476)

This is a very clean recording studio made by the Rook/Fusion small rock band. It is characterized by a wide dynamic range, a large number of powerful electronic bass, and a reasonably natural maximum octave. I often use the increasing loudness of the first track ("Since I met you") to test dynamic retention. Although for some speakers, a large amount of power is required to prevent the amplifier from producing clipping distortion when the pedal drum, bass, and string drums are sounded together. It is also used to test dynamically restricted signs, as well as obvious mechanical limitations and more.

PHIL WOODS: Here's to my lady (chesky JD3)

I used this great jazz quartet to test the stability of sound image positioning, treble space and bass smoothness. It represents a very natural small room audio and a prominent drum sound. Drummer Kenny Washington likes to use the timbre of the sound, so I mainly test the depth instead of testing the "flash" of the highest octave. The second track I used the most, "Johnny Hodges," which started with an excellent test piece.

BEETHOVEN: Early String Quartet (Alban Berg Quartet EMI 47127/8)

I used these two records to test the sleekness of the lower treble/string, the accuracy and depth of the audio. The record is very warm and full of "woody". If the sound of the string is rough or overly sharp, it must be something unusual. The cello shows the fullness of the middle bass. Each sound track can be used to test, but don't indulge in music and forget yourself for this track.

How to test five (or six) speakers

When testing surround sound system speakers, the above four listening categories - uniform tone, audio position, dynamic range and low frequency extension - remain unchanged. But for movies, the dynamic range and low frequency extensions may have to be strengthened.

The center speaker is the most important. For the movie, the middle channel delivers all the conversation, most of the music and sound effects. The biggest point in choosing a center speaker is to be as consistent as possible with the left and right main channel speaker sounds. If you want the sound field to connect seamlessly and smoothly transition, these speakers must be perfectly matched. The most straightforward solution is to buy a product that matches the same manufacturer or the same model or original design.

The following is a useful test method that requires vendor assistance. Listen to a speech-based mono program with only three speakers on the front (TV programs can cancel stereo). Use the A/V receiver or processor level matching device to balance the output of the center speaker and the Phantom center channel produced by the left and right main speakers (the selector switch is placed in the "no center speaker" position) . Then disconnect the surround speakers or select the Dolby 3 surround format (use only the front speakers) and then sit in the dead center. Use the remote control to keep pressing the "Yes" or "None" center speaker switch until you I heard that the center speaker is closest to the left and right speaker sounds.

Listening to the bass in the store environment is a waste of time. Because the acoustic conditions and placement of the room have too much impact on bass performance. I believe you will rely on the seller's recommendations, the manufacturer's instructions and magazine articles (like this one). If there is a seller who agrees to take the subwoofer home to audition and the effect is not good, you can buy it from him. This is the best advice.

There are similar situations in listening to surround speakers in the store. This incident seems interesting but not worth it. For surround sound, the "space" of the treble and the deep bass extension are usually less important. Fortunately, most experienced listeners prefer scattering-type bipolar surround speakers to movies and certain music, rather than direct-radiation speakers. Buying surround speakers and subwoofers is best available for purchases and returns.

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