|
Our reference is the realistic sound When discussing the subject of sound, you must clarify what a "good" sound is. Good sound is realistic sound.
The explanation for this statement is very simple: The only real way to measure the quality of sound is to compare it to the reality. Everything else is subjective and can not be measured or rated. In other words, the reproduced sound should equal the original sound to the greatest possible extent. Sound is a matter of taste
What the single listener experiences is subjective and highly personal. However, independent tests show that the average listener prefers loudspeakers that they have a realistic sound. The more experienced the listener becomes, the more he / she appreciates this sound.
To appreciate a clean and realistic sound may be compared to taste samples of wine. To really enjoy an old vintage wine you need experience and references to compare with (and just like better sound equipment these cost more money). Which type of sound do I prefer?
There are many variations on the types of sound different people prefer.
When it comes to mid range and treble the difference in taste is small - most people appreciate a neutral sound with a frequency curve as clean and smooth as possible.
However there are bigger variations in taste when it comes to bass reproduction:
" Different people have different taste.
" Different rooms influence the bass reproduction in different ways.
" There are also differences between music and home cinema. Bass for both music and home cinema?
A recent topic is if the subwoofer is suitable for both music and home cinema. Below XTZ gives their view on this issue A subwoofer that recreates a neutral sound is suitable for both music and home cinema.
Many people classify and separate subwoofers as "music subwoofers" or "home cinema subwoofers". However, XTZ think that this division is incorrect. As explained above, the only way to measure the quality of a sound is to compare to a real sound reference - and this holds for both home cinema and music. Some audio magazines, for instance, may report that a tested subwoofer has a "good sound for music but not for home cinema". But when you say so, you have only made a subjective judgment and this is not the correct way to test a subwoofer, XTZ think. However, it is generally true that a subwoofer with deep bass characteristics is more suited for home cinema, while a more "quick" bass is better for music. But still this is only a subjective judgment and can not be rated. XTZ think the best way of solving the problem is to construct the subwoofer so that it is possible to alter the sonic characteristics in many different ways. Many of the XTZ products have this possibility to alter the sound, utilizing what we call "Room Tuning". Examples include:
" 99 W12
" 99 W12 S
" 99 W12 DSP The art of compromising
A product is always a compromise if you take into consideration the price of the product. And in pursuit of the optimal compromise, it is easy to ignore an important parameter, for example, the cutting back in an area where you shouldn't can reap disastrous results. It is therefore important to ensure that consistency does not affect the outcome negatively, in order to reduce cost. In other words, this is a constant balancing act, where long experience makes a big difference to find the optimal compromise for price / performance. When designing and developing a new product, you are faced with a number of compromises. You have to balance different parameters. Here are some examples:
" The room - to adopt the product for different rooms.
" Between cost and the difference in quality that the cost means.
" Setting a reference room for the best reproduction of sound.
" Between different crossover filters.
" For loudspeakers, decide between dispersion and direction of sound.
" Bass reflex port or a closed construction.
The room
The fact that the listening room is of great importance for good sound quality is well known, but unfortunately many manufacturers are unclear on this issue. For example, Constructing a high-end loudspeaker without specifying how the room should be designed for optimal sound quality - we need to be more serious than this! Even if the speaker's frequency range is from the lowest bass to the highest treble within +-1dB, the normal room can vary + 15dB - and even the best loudspeaker may not sound good. Follow this link to learn the affect of room modes All the acoustic properties of the room, for instance characters of reflection, are much more important than what most people think.
A regular modern living room often has too few absorbing materials such as fabrics and other muffling areas, producing reflections and room nodes or reflection patterns in the room. The echoes and reflections in the room clutter the recorded sound and we lose information from the recording, the frequency response is uneven and we may experience fatigue when listening. The room may have many problems over the whole frequency range, but normally the largest problems are within the bass range. Luck controls your sound reproduction
If you do not know the problems of the room or have not got any possibility to do anything about the position of the speakers, it's all about luck as to whether the location of the system is good or bad. This is why XTZ has developed the Room Analyzer, software that can help you analyze your room and find the optimal place with help of the software. Do all the room has standing waves?
Yes!
It is almost impossible to get rid of all the resonances considered in a room. (Even if you spent a lot of money) Example: XTZ have done several measurements at Chalmers University of Technology in Gothenburg, in their anechoic chamber. Even in this room where every frequency is absorbed, we found a resonance at 50Hz. The size of the room DETERMINES the frequency of the resonances considered. The above example proves that even if we optimize our listening room, which is a great advantage and a sure investment for better sound, we will still have use for DSP technology. A better room has fewer resonances and in most cases lower amplitude makes it easier to compensate for the problems. But even in the worst room, the DSP technology facilitates major changes. The following link explains about the difference between rooms and the big variety it has.
Click here How big is the difference?
A well designed speaker should be within ± 3 dB in frequency response to be considered good quality. A standard room can easily vary ± 15 dB. If you do comparative measurements of amplifiers, CD players, interconnects and tweaks, you will realize how small the differences are between the equipment and accessories compared to the room, when it comes down to frequency response. Everyone knows how big difference there are between two different speakers and we would say that the rooms characteristics has the same important role as the speaker. It is a fact that even the best systems can sound mediocre in a room with bad acoustics. If the room has very bad acoustics it is a waste to buy an extremely expensive system (unless the system has room adaption functions) and then let the room destroy the sound reproduction. XTZ think the dealers are of extremely expensive hi-fi should inform the customer how the room should look like to be optimal for their products. But this is a risk they don't want to take, because if they specify how the room should be they will close the door for many potential customers (who don't have a room like that) Creating a perfect room for speakers takes huge effort and a lot of money. Everything must be optimized, size of the room, wall materials, ceiling and floor. To REALIZE the significance of the room is a huge benefit and an "investment" and we must concentrate on the right things in the correct order and priority. Buying expensive cables if there is a room problem is completely the wrong priority, it calls to mind the saying "strain a gnat and swallow the camel." There are indeed differences between cables, but they are so small compared to the influence by the room. Does the room really make a difference?
The answer is yes, without a doubt! See how much the room adds
One of the best ways to find out the significance of the room is to set up your stereo system in the garden and listen to some music there. You can easily find out how your stereo system sounds in the outside environment. Then test the system inside a room made of concrete and without any soft materials with long reverberation. Many people might have experience in talking at the same time in rooms like this and failing to hear each other properly. Size of the room
It is easy to get better sound reproduction in bigger rooms. Placement
Even in a good room, the sound reproduction can be worse if the placement of the speakers is not optimized. The sum of sound quality is always a combination of the room and the placement of speakers. For example, in a bath room, it is difficult to find a good place for speakers (sometimes impossible) but it is easy to find a good place in a good room. Some may not want to change the listening room structure, but still want a good sound. An active subwoofer with DSP technology is the best investment you can do in this case. You can place the speakers / subwoofer almost wherever you want and use the DSP technology to optimize the sound quality. With advanced DSP technology, the speakers and features can be adjusted to a nearly perfect balance. A better room creates better conditions for a perfect result in the end. Solution to the problems
Enhancing the sound properties of the room is a good investment for a better sound, but even with large investments it is hard to "remove" all the resonances considered in a room. This is why the DSP (Digital Sound Processor) technology is the optimal solution to the problem. The sound can be tuned perfectly in all rooms. Normal DSP technology often suffers from bad resolution and software, which degrade the quality. We use the absolute newest and best DSP technology, used by professional studios. This guarantees all the benefits of the DSP without reducing dynamics, increasing noise or degrading the quality. The information above shows that even if you optimize the listening room, which is always a benefit and a good investment to better sound reproduction, you have use for DSP technology. A better room has less reason to be considered and often with lower amplitude, which makes it easier to compensate for the room nodes. The owner of a room with bath resonances considered has even more to gain by using DSP technology. We call this concept - Room Tuning.
Our loudspeakers are highly flexible and allow a large amount of different settings. The speakers are also designed to adopt the sound to different rooms and preferences. Cost and quality
If you construct an extremely robust and expensive cabinet with extremely expensive drivers but not the correct crossover filters and well suited box, the end result will still be bad. In the search for the optimum compromise it is easy to disregard some important parameter and the importance of something that really should not be cut back. It is equally important to save where the consequences will not have any negative influence on the end result, to reduce the product cost. Setting up a reference room for the best reproduction
Different rooms have very different characters and quite different qualities. Therefore, we have to specify what type of room would be suitable for each product. In what type of room do you measure the frequency response? To have a uniform standard, loudspeakers are measured in sound dead rooms. However, when you construct the loudspeaker you must take into consideration that it will be used in a common room.
This means that no manufacturer can say that their loudspeaker is the "optimum" or "best", since the room has a big influence on the sound. The solution of this problem:
Making the loudspeaker flexible by implementing a range of settings possibilities for adaptation to different rooms. Crossover choice
The crossover filters are very important - no matter how the excellent drivers you choose, they will sound bad if the crossover filter does not work properly. When it comes to crossover design, it's all about the art of compromising. The problem is to arrange these parameters in a good way:
" The phase
" The transient response
" The frequency response The following two extremes explain it well:
1. Crossovers of the first order yield the best transient response and minimal phase shifting, but the frequency curve is very hard to make smooth. An advantage of this type of crossover is the very low price.
2. For a long time, the fourth order Linkwits-Reilly crossover has been regarded as the best crossover. The advantages are a very smooth frequency curve and excellent phase relations. However, the transient response is not that solid. Another disadvantage is the high price. We think that the best compromise is a hybrid of a powered crossover / amplifier for the bass and a passive crossover between the mid-range and tweeter elements. A powered amplifier provides an exact crossover function with a steep curve. In addition, it is adjustable and cheap.
Another advantage of the powered subwoofer is that the power amplifier is coupled directly on the elements, thus the filtering occurs prior to the amplification. The powered amplifier also provides several settings possibilities which are not possible to have with a passive crossover. These settings, includes phase, frequency and volume boundary. The use of a powered amplifier also means that the main amplifier is set so that it only drives the mid-range and tweeter which makes it work better and also decreases the risk of damage on it.
This hybrid crossover is what we have for instance in the XTZ 99 2.2 systems. Dispersion of Sound
Should the sound from a loudspeaker be dispersed or directed? Different opinions exist and hence there are two different ways of creating the "correct" sound.
A. You have the loudspeaker to disperse the sound so that the room can "aid" in this dispersion. The idea is you get equally good sound no matter where you are in the room.
B. You direct the sound as much as possible so that the room has as little influence on the sound as possible. The advantage of A is of course that the sound is dispersed. However, different rooms disperse the sound in very different ways. Also the size of the room is of importance. This makes the sound random. As the sound is dispersed and bounces on the walls or similar, you also get big problems with phase errors and phase disappearance This causes both uneven frequency range and a blurred sound. Therefore XTZ have chosen not to have a dispersing construction in our loudspeakers. Bass reflex cabinet or closed box?
Bass reflex cabinets have during the last years dominated the market. They provide a more powerful bass than the closed box. The disadvantage is that the bass tones may become somewhat uncontrolled at the lowest frequencies. XTZ have several products where you can alter between bass reflex and closed box. Sensitivity & Sound Quality
Sensitivity is the amount of sound pressure at A Certain inputs to the speakers. Sound greatly depends on the sensitivity of drivers. The box type also affects the sensitivity. Sensitivity should not be extremely low since it makes it necessary to use extremely powerful amplifiers. If the sensitivity is too high, we tend to experience quality related problems. In order to achieve the highest degree of sensitivity possible without losing quality, single run optimization is the key. We need to find the right balance between sensitivity, quality and price. For example, we can raise the sensitivity levels by making the membrane lighter, but in such a case the membrane will be less stable and lead to distortion. We can treat the membrane to make it more stable, but in this case it is heavier and the sensitivity drops and the cost also increases. In general, we can say: - Extremely good drivers always have limited sensitivity
- Drivers with extremely high sensitivity always have a limited quality or area of use How do you know when the sound is good?
When measuring or competing in the best sound you have to have a clear reference, without this the comparison is not relevant.
So if you disregard your own preference you need to know the following information when test-listening:
" The qualities of the recording
" The qualities of the room, and how it affects the sound
" At what level the recording characteristics are correct. Is there one single-level where the characteristics of the sound are reproduced correctly?
" How the peripheral equipment affects the quality and characteristics of the sound. To make a perfect and correct judgment of the sound reproduction you need to consider all of this.
Who are capable of this? XTZ claim: Not many people possess the knowledge you need to do this. So when you read tests, listen to advice and also listen to the equipment yourself, you should consider this. One example:
A light character of the sound that may depend on the room or a high level of the tweeter speakers may be solved using a new "better" cable that reduces the treble, making the sound better in total. Does this imply that the cable is good? No. You cure the symptoms but the basic problem is ignored. Tone matching
You do not have to buy all the speakers from the same series or brand. Unfortunately too many people claim this.
You can mix speakers, both from different series and different brands, the important thing is that you obtain the best possible sound for the money spent per unit. Example: If you have five similar speakers of lower quality, these are completely tone matched. If you switch two of these to a pair of better speakers, the resulting sound will be better; however the speakers are not tone matched since they are different.
How important is the matching, differs from person to person, however there may be a great diversity in quality and character between for instance the front-and rear-system without a person being able tell any big difference. Some people may find disturbing the difference, then you should of course tone match.
A subwoofer and satellites however can never be matched since they have completely different frequency range they operate in. Testing of equipment
If you listen to a single component compared to another component in the same system, it's easy to come to the conclusion that the one you found is the best. Is it that simple? In fact not! Normally we listen to the complete chain from microphone, recording, mixing and mastering (all of these are affected by the studio it was recorded in) to the following reproduction: Source preamp, power amp, speakers and listening room.
It's hard to identify where coloration of the sound appears and where sound disappears.
The precision is to detect the quality of one component compared to another. For example, a cable with dark character can be compensated by an amplifier with bright character. But this assumes that we have a reference. Personal opinion about sound
Everyone has the right to have a personal opinion, but without conducting a good test procedure, it is difficult to judge. This is the reason for those never-ending discussions about good sound and what makes sound reproducing equipment in a better way. Good reference - what's that?
Good reference is an impartial reference. For example, good recordings - without a good recording a test can be misleading. If we only have one record as reference, we might have listened to the recordings in a system with no coloration and in a room with good acoustics otherwise there will be incorrect judgments. To use several records as reference is our final advice!
Full-range from a subwoofer? A problem due to Room Gain.
Subwoofers reaching down to 20 Hz are a problem in a regular room.
(Since the room affects bass reproduction that much we have a new dilemma when developing the "perfect subwoofer.)
A subwoofer covering the whole frequency range down to 20 Hz is considered ideal in theory, but in practice will only work perfectly in very large rooms or rooms where the bass range absorption is very high. All ordinary and normal sized rooms have so called room-gain which is a general amplification of the lower frequencies. General Explanation of Room Gain
Frequency response is normally measured as direct sound from the subwoofer (within a narrow time span). In a regular room sound is reflected by the walls rather than absorbed, thus creating standing waves (see explanation of room nodes) this in turn results in a louder level and higher energy compared to only the direct sound from the subwoofer at a place given. How much more energy depends on several factors such as: room dimensions, wall materials, how much absorbing materials, the walls contain, and the placement of the subwoofer, etc. All rooms show more or less Room Gain. Room Gain is the product of reflected sound bouncing back and forward between walls, fading slowly. The direct sound from the subwoofer mixes with the reflected sound, causing a "lagging" phenomenon, and a "slow" bass response. This phenomenon has fueled the everlasting discussion amongst HiFi interested people regarding the "permanent" and "slow" types of bass reproduction. When experiencing a subwoofer as "slow" in response, many people come to the conclusion that the driving element in combination with the amp doesn't "keep up" with the music. This assumption is in most cases incorrect. Rather, this is due to the room and the degree of Room Gain which introduces a lagging effect depending on the rate at which reflected sound fades. If the subwoofer reaches very low frequency and the room has a high-Room Gain the result will be a very "slow" bass reproduction, constantly lagging and not able to keep up with the music. The obvious solution would be to rebuild the room, but this usually costs a lot of money. Another solution is cutting away the lowest frequency from the subwoofer. This way the additional energy from the Room Gain equalize the subwoofer dip, nothing resulting in an even frequency response. Since all rooms have some Room Gain at different frequencies XTZ's conclusion is that it's virtually impossible to create the perfect subwoofer that sonically fits every room. Considering this, XTZ find their concept with DSP the best possible compromise, and that's why XTZ implemented it in the W12 DSP. When a customer replaces his "slow" subwoofer to a new "faster" one, it's the other words not the sub itself being technically faster, but rather playing the deepest bass tones at a lower level, minimizing the influence by Room Gain. With a regular subwoofer this becomes the "art of compromising." Research shows that a subwoofer is reaching a lower end of 30-40 Hz (-3dB) usually is a good compromise, giving the average room a frequency range down to 20-30 Hz measured in the room, including the influence of Room Gain. Conclusion:
A subwoofer with completely flat frequency response down to 20 Hz usually results in too high bass energy for an average room. The Room Gain problem is most noticeable in the lowest frequency spectrum where it tended to cause a "lagging" bass reproduction.
A subwoofer which is not reaching that far down in frequency is usually experienced as "fixed" since the Room Gain affects reproduction less, and therefore also the "lagging" phenomenon. Please feel free to read more about the room influence in this very interesting article! Explanation of Room Modes
Room modes are due to sound reflections in the room. Direct sound and reflections makes a pattern in the room and when same frequency is in phase, you get room modes. (Standing Waves) Explanation of Dips
If the frequency is in counter phase it produces dips in the frequency response. (Nodes)
If extreme dips are found with the Room Analyzer (1 position measurement) it may be impossible to correct it. Change of the sweet spot or speaker's position is recommended in this case. An extreme dip is shown as a valley in the frequency response measurement. Advice when buying equipment / speakers:
When it's time to buy new equipment, many people run in and out of stores, trying to find "their sound". Below you will find a few hints to keep in mind when listening on different speakers and amps.
Listening to speakers
? Make sure you listen to different speakers at the same sound level. If the level differs undoubtedly you will tend to prefer the ones playing louder. Research shows that even a difference of 1-2 dB matters. The classic A / B switch (mechanical switch - two sets of speaker connected to one amp) is not favorable, especially when quickly switching between speakers. How loud a speaker will play depends on both efficiency and impedance, and has nothing to do with quality. The ideal solution is having separate amps for each pair of speakers, adjusted to match with a dB meter.
? Make sure the amplifier is set to "flat" character, so you listen to the speaker character, not the amp.
? Use a neutral amp, non-neutral amps such as certain tube amps are not preferred in this case.
? Different characters of speakers make it harder to set an average sound level. If the speaker character is different try listening for a little bit longer to each speaker before switching.
? The classic "loudness" type of frequency response is easy to fall for in a store, but it's the kind of sound that quickly becomes annoying.
? Listen to your own records, that is if you have some good quality ones, preferably with different characteristics and types of music to DETERMINE the speakers characteristics.
? Select reference records with neutral characteristics. Many recordings are "coloured" and biased in some direction due to the mixing process from the recording studio. This results in misleading results when you carry out testing of speakers. Typical thin 'plinky-plonky' music with lots of "air" into it often sounds good in most speakers since it does not demand that much from the equipment. Tight music, with high density, played at a high volume (read rock etc), polish the speakers to the test much more efficiently. Rock / hard rock records does not generally provide that high quality from a sonic point of view, and this has to be taken into account while trying out speakers.
The biggest problem when testing hi-fi equipment in a store is again the room since it affects the listening experience in such an extensive way, especially in the bass region. The speakers may sound fantastic in the store, but mediocre back home in your listening room. A good solution is trying them at home before you buy, but the drawback is that you might not have anything to compare them to. Since the room affects the listening experience in such a striking way, we think testing a subwoofer in a store is almost a waste of time. At least considering the vast possibilities of settings normally found on a competent sub. It becomes very complicated and time consuming, even for an experienced listener, to come to any conclusions. When listening to subwoofers in a store, or at home, any adjustments should be made with great care and precision. For example, changing the phase should be compensated with a proper change in cross-over frequency as well since they both directly affect the total amount of sound energy. The correct settings for the front speakers and subwoofer is essential, for instance a A / B test between subwoofers where A is out of phase will be completely misleading. Even if both subwoofers have the phase set to zero degrees, one of the subs may have an internal phase shift. Changing the crossover frequency usually alters the phase shift too. Two different subwoofers do not necessarily have the same performance simply because they are both set to 100 Hz. The characteristics of the driver, type of box construction, and the filter slope greatly affects the result. The only parameter you can really test in a store is how loud a subwoofer can play before it starts sounding bad. This test should be done with the same settings for each subwoofer in order to avoid misleading results. Typically, many brands construct their speakers to sell quickly in a store rather than sounding ideal. This is done by making the sound louder with the help of low impedance, high sonic efficiency, or a "loudness" type of frequency response.
When the A / B switching quickly between a typical speaker according to the above description (A) and a more musically correct speaker sounding lower with a more linear bass / treble response (B), most people will find the "bad" speaker (A) clearer and much more brilliant with a heavy bass reproduction. As soon as you have installed this pair of speakers in your home, you soon find them increasingly annoying while the more music oriented speaker (B) is the better everytime. The best way of discovering this in a store is listening for a longer period of time before switching to another speaker. A good Parable:
A TV in the store that has elevated color saturation, definition and contrast levels tend to look much more attractive compared to a TV with neutral settings. This is "standard procedure" in order for the store to sell that TV rather than the really good one with the more natural picture.
|
