NVE

LISTENING ROOM

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Lot of listening rooms and also lot of gained information proves, that the whole system is practically created by series of particular components used in the audio chain. If we skip the whole recording phase, which is usually made on professional level, we proceed to a source of audio recording, which we have at disposal and we would like to listen in the best possible quality.   
As it was already said, it is a series of individual audio components and from that follows that the final quality depends on the weakest segment of your audio chain. Every segment of the audio chain has a specific influence and according to many listeners and also according to your experience you will find out early that the closer to the end of the audio chain you are, the higher influence the audio components have! Today, when we ignore compressed formats (like MP3 and so on) current audio recordings have very high quality and mentioned parameters like distortion and signal / noise ratio only confirms it.  
If I choose CD player, then also it's cheaper variant will have better stated standard technical parameters then even much more expensive power amplifier. But also the power amplifier is mostly cheaper then particular loudspeakers and finally the distortion of the amplifier is several orders lower then distortion of actual acoustic drivers.   
We did many of measurements on different acoustic drivers and we can responsibly say that also Hi - Fi bass drivers which cost several thousand CZK have during bigger movement of the membrane (within 1 mm and more) distortion several tenths of per cent!! Listening room has by far the largest influence on final audio quality. Because dimensions of domestic listening rooms are small from the acoustic waves length point of view, conditions for it's treatment are different then for large listening rooms, like concert halls or even outdoor space. In a small listening room, there are a lot of reflections and a lot of standing waves. Direct reflections from the closest walls usually cause distortion on the middle and high frequencies. The distorion is caused by the fact that not only direct acoustic signal of the speaker comes into your ear, but there come also a direct reflection of the signal from the walls, floor, or ceiling, which is only several meters longer then the direct acoustic signal. 

Even if the acoustic signal level decreases with the square of the distance from the source, the reflected signal is only slightly lower sound level and only a few milliseconds delayed than the direct signal because his way is slightly longer than the way of the direct signal.

These two acoustic signals are summed and compared to the information from the acoustic driver a distortion is created. (To illustrate what is 1 ms delay, suppose that 1 kHz has a period of 1 ms, it means that if you have signal delayed by half ms then the resulting amplitude is then sum of direct and reflected amplitudes of the signals).         
But because there are more reflective surfaces in small listening rom, the resulting acoustic signal received by the human ear is much more distorted here. 
Another important factor is the basic dimensions of the room. They have an impact on the formation of standing waves.    Poorly chosen room dimensions can magnify the negative impact. Conversely appropriately chosen room dimensions restrict this phenomenon.      

If you can choose your listening room or rebuild it, select ratios of the room dimensions according to the following options:   
1 : 1,14 : 1,39
1 : 1,28 : 1,54
1 : 1,6 : 2,33.

Example unsuitable room dimensions:
The living room, which is connected to the kitchen so that the total space has then height of 2,8 meters, width of 5,6 m and length of 11 m, is a warning case!! It is absolutely the worst possible option in terms of internal acoustic comfort, because "height x 2" is width and "width x 2" is length!!!

Measured standing waves were so strong that in some places the signal was completely eliminated and vice versa there were places where the signal was greatly amplified.

Moreover the length of the room is so large that they cause echo. In such designed living space you can not agree even let somebody to listen to. From my own experience I can say that the acoustic treatments such spaces are not easy nor cheap.

Much worse is the situation in our stairwell, where RT601) is more than 4,7 s !!! Echoes are so strong that a normal conversation you can not understand! Acoustical treatment will be easier and the results will amaze you. The correct RT60 value in acoustically damped room is arround 0,3s. 

To be healthy, be aware that the acoustic comfort is not only important for audio listeners, but it is important for all people staying for longer periods in a given area because poor acoustics has a very negative effect on the psyche and of course human health.

Because we had in NVE long term problems with where and what to show customers, we decided to build a listening room. At present is our listening room in Břeclav finalized in terms of interior acoustics. The system is already installed and you can already hear it. 

The figure below shows that you can now hear our CD player prototype, preamp PLQ 708 (gold version), power amplifier ELQ - 140 (gold version) and loudspeaker Grandioso HE 384 system prototype.

Come listen. Just call to NVE and make an appointment.

NVE your team.

 

1) RT60 – is the time required for reflections of a direct sound to decay 60 dB. As a primarysource of sound is usually used starting gun.

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