MUSIC SOURCES AND NVE
In line with the philosophy of NVE, based on "linking quality", we were faced with the question of what analog, respectively digital signal source, we can recommend to our customers to match the uncompromising quality and reproductive capabilities of the entire audio chain.
As regards the sources of analog signal, the situation is specific in that it may be a signal from a tape recorder or a gramophon, therefore two fundamentally different ways of writing and reading signal (magnetic recording on tape or mechanical recording on board) and their subsequent processing.
In the category of sound quality in a class of high-end, it makes no sense to speak today about cassette recorders, but we do not rule out their use in our audio chain considering that there may be extensive collection of audio cassettes at some customers. Then we recommend the use of tape recorders at the highest hi-fi class from the then renowned manufacturers. Even so, it is necessary to reckon with the fact that even the best tape recorder, it will be the limiting and the weakest link in the whole audio chain. Conversely, large and technically high-quality renowned manufacturer’s tape recorders of Hi-Fi and Profi techniques, on which are played the original tapes of adequate quality, still today amaze with its stunning audio capabilities, and dynamic range. Not for nothing are the digital remastering of old recordings on the original master tapes much better music sources than originally purchased 16-bit digital recordings, remastered by up-sampling. To connect these old cassette sources to our audio chains, it is usually enough when we individually prepare connecting signal cables in the required quality.
The most widespread analog signal source for our customers is a classic gramophone. Leaving aside the cheap plastic turntables in the old "mini audio systems", so virtually every renowned manufacturer’s stereo turntable, made as a separate component, is a Hi-Fi class by its very nature. Design and manufacture of high-quality turntable is part of the top precision mechanics, to which an equally supreme craftsmanship precision engineering must be. Not for nothing were often the production of phonograph chassis components part of manufacturing program of leading manufacturers of weapons, or mechanical typewriters and calculating machines. The perfection of the original structures outlasted the ages, and many of these gems are used to perfectly reproduce the analog sound also today. Just adequate maintenance and replacement of worn parts is sufficient. Given that Czechoslovakia was, and the Czech Republic still is a great power in the production of classic turntables and vinyl carriers and one of the largest exporters, take NVE this source of music signal as equivalent and still current.
For this reason, in our "quality chain" is offered (of course, how else than tube) phono preamp GPLQ 202 with XLR balanced outputs. In conjunction with the classical and high-quality gramophone chassis and with carefully selected pick-up, gain Lovers of "analog sound" a musical source of the highest quality.
Digital signal source
Digitization of the world, processes and communications meant one of the decisive moments of technical development. It brought along with the invention of the semiconductor silicon chips and subsequently a huge information-storage capacity incredible miniaturization and unparalleled user comfort. Of course, the digitalization could not avoid the world of entertainment, as one of the biggest industries. However, to convert the subtle world of color, shape and sound systems into ones and zeros turned out to be a much more difficult task than the digital engineers from the beginning expected. While shades of colors, shapes, sounds and combinations are endless, digital transcription was, is and will be limited by mathematically possible volume of information, processing, retrieval accuracy, placement in time and loss of information on the signal path. While the analog signal was, apart from the fact, limited mainly by the limited dynamics of the noise floor and the analog medium, the digital signal is limited by information capacity. Therefore, there still will be passionate advocates of analog for its nature, as passionate advocates of digital formats for their dynamics and user comfort.
One may wonder why the company NVE has actually engaged in the development of a new CD player with separate converter, while CD format now seems to be obsolete and goes commercially down.
But the answer is clear. These following reasons led us there:
- Thanks to the commercial success of CD, the biggest archive of music recordings in history originated in the world among ordinary people.
- Quite hard to imagine that the owners of such archives and collections of CDs would throw them out and from day to day switch to another music sources.
- Digital formats with higher resolution (SACD, DVD-Audio) have not made commercial success and practically disappeared (remember the disappearance of technically more advanced but commercially unsuccessful Video 2000 formats and Video Beta and victory of imperfect, but inexpensive VHS).
- The CD format in terms of capacity of musical information is limited, but due to the predominance of cheap commercial players, more information degradation apears during home playing because of errors during data capture, their timing, recalculation of correction circuits and the final conversion to analog signal. For this reason, we dare say that at least 90% of home users have never heard what the on the CD recording actually is.
This means that with the CD recordings will music-loving humanity live on for many years. And we are pleased to join the manufacturers of high quality players thanks them there will be such coexistence more pleasant.
The main future source of high-quality music recordings - legal (and paid) music downloads in high resolution is gaining ground more and more. Fast internet connection allows downloading increasing amounts of data. It is possible to switch to a better quality recordings in 24-bit resolution. Also, this area NVE intends to pursue vigorously. We prepare 24-bit D / A converter which with its sound quality will not disappoint even the most demanding music fans.
WHY OWN NVE SPEAKERS?
Concerning private acoustic transducers, which means loudspeakers, we spent probably most of the time. Theoretical information were sourced mainly from Dr. Sykora, which he published in a magazine „Amateur radio“. On the Internet in America we've also discovered a publication about construction of the loudspeaker Poly Natalia from Dick Olsher. Dick dealt not only with distribution of acoustic bands for individual speakers, but also with phase shift that occurs when the speakers are placed on a flat plate. It is due to the fact that every speaker has mostly different acoustic center. Acoustic center of the speaker is an imaginary point of origin of sound in the speaker. If all the speakers in a loudspeaker had flat membranes, so the sound coming out from the speakers would be based on the same place. However, the flat membrane has very great problems with the strength, therefore, the membranes began to be manufactured in an embodiment which is now virtually seen everywhere and it is specifically defined by a conical taper. It is because in order to achieve the highest possible strength. But different speakers have different depths and the greater the diameter of the speaker the greater depth it has.
And it also creates the time shift.
The standard design of electro-acoustic transducer - electrodynamic loudspeaker
1 - Pole piece
2 - Pole piece
3 - The central column of the magnetic circuit
4 - Magnet
5 - Speaker voice coil wound on a former
6 - Suspension
7 - Dust Cap
8 - Diaphragm
9 - Basket
10 - Surround
What are the reasons for speakers of our own design? When designing your own speakers, we first stumbled upon it, that there are not virtually any midrange driver on the market that would meet our requirements. We know from experience that the vast majority of musical instruments play in the midrange. In this area, the human ear is most sensitive. The midrange speaker is therefore in our opinion an absolute basis of loudspeaker system. It is then possible to add a tweeter and woofer that cover the edge regions of audible frequency range. We want midrange driver to play virtually the entire central zone. So we want it to play from 200 Hz to 10 kHz and also to manage the transition zones with only a slight decrease and with a reasonable phase. Theoretical assignment is then such that we need a speaker with an infinite light, infinite solid membrane with an infinitely strong magnetic circuit (motor) and with infinitely pliable membrane surround. This of course is not physically possible. But it is essential most to try such objectives. Therefore NVE speakers have a very strong and light Kevlar or carbon membrane.
Magnetic circuits are also very important. Their quality influences how will the speaker has dynamic properties, distortion and frequency characteristics. High quality magnetic materials are used to allow large saturation B. Symmetrical pole pieces are accurately grinded on a given diameter. The height of the pole pieces is chosen so that the entire coil is always in the magnetic field. The size of the magnet is limited by the diameter of the trash. Because such a large magnetic circuit is very difficult, it is not possible to use thin sheet metal for the basket of the speaker. Therefore NVE produces baskets of loudspeakers, which consists of the individual arms fired from thick steel plate. The entire basket is then welded into one piece. On the figures below (3 and 4) you can see the trash center and subwoofer:
Midrange speaker ST6
When a quality midrange-tone speaker was developed, it was also important to have adequate woofer. On this one are also placed considerable demands. The human ear is with decreasing frequency less sensitive! If you look at the curves of equal loudness depending on the frequency (picture below), you easily find that the human ear is at midrange frequencies (up to about 4 kHz) more sensitive than at the edges of the audible frequency range. When listening volume is at about 80 dB, are the high frequency (18 to 20 kHz) by about 15 dB, and bass frequency (around 60 Hz) almost 20 dB less hear!
The curves of equal loudness
The basis of the woofer is again hard basket and a powerful magnetic circuit. Because the displacement of the membrane at the subwoofer is big, it is important to avoid creating any point with compressed air. Beam construction of the trash is adapted this. There is the whole bored in the center of the magnet. Membrane surface of the woofer is larger and thus the demands on the strength of the membrane are much larger. To limit generation of vibration to the minimum size also during the maximum deflections of the membrane, is she combined from different materials in several layers. And also perimeter of the membrane has shaped reinforcement.
Woofer B12 semi-finished product
A few more words to the construction of tweeter systems. Since the air density is quite low and also small area of the membrane vibrates only a small amount of air, we say that its effectiveness is low. Known way how to increase efficiency of tweeter is using a horn. This one is in our case just short in order to avoid major delays. A plurality of drivers into a common horn reduce distortion at ½ if you have two drivers, 1/3 or ¼ if you have three or four drivers, which you at extreme volumes of Symphony Orchestra will definitely appreciate.
Recitation of these speakers is amazing. It cannot be expressed by text. It is necessary to hear. Just get in touch and arrange an appointment in the listening room NVE.
26. 1. 2015
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 0,3 s.
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.
NEW CD PLAYER
23. 11. 2014
Regarding a source of audio signal we spent a lot of time by practicing and testing of all possible CD, DVD audio and SACD players and we compared them mainly with gramophone, because it was clear for very long time that it would not be easy to substitute it by a digital signal. But development went fast on and it is clear today, that digital formats with higher bit resolution will for sure substitute the analog audio.
For testing of our products we were using long time a classic gramophone or also CD players of reputable marks. When we changed a CD player by a better one it was was always positively manifested by the final sound. So we asked a question if it is possible to build a better quality device?
We built up a prototype of CD player to be able to test possibilities of CD format. You would be surprised what CD format can achieve. To eliminate problems with reading of a CD disk in a CD drive we decided to use a professional CD drive from Philips Cdpro2M.
Prototype of CD player:
The CD drive has I2S output, which we connected to DA converter, which does not use a digital filter. According to information from Mr. Konusoki, we have chosen this variant and many of our audio friends confirmed, that it was a right decision. On the picture below you see a difference of full bit pulse on the output of DAC without the digital filter „Non-oversampling DAC” and the signal, which comes out from the standard DAC, which makes multiple oversampling (“Conventional DAC”).
The device has one common time base with very low jitter, which is absolutely necessary for the highest DAC quality.
We tested the prototype and compared it with many very expensive CD players. The listening tests were done on NVE components in well acoustically absorbed listening room of one of our friends. Most of listeners agreed, that the main difference is in purity, space presentation and in speed of fine details up to the highest frequency.
The DAC in our CD player includes famous 20-bit converters PCM1704 BB. The output filter includes high quality operator amplifiers OPA627.
But there are still possibilities for quality increase. So we finally decided for construction of split CD player, so it means separate CD drive and separate DAC.
But about that again next time.
Your NVE team.