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| [#30] Blogs: 數碼音樂重播專欄 (1) I don't invent the term. I didn't know what it means at the first time, nor understand why someone would like to make scene of it. CAS to me has been "民安隊". I also heard Eric (Editor of AV Magazine) mentioned it. Our government has a web page: www.cas.gov.hk. People I met (consumer audio world) speaks it as "CAS System". At the first time I thought they mean "CARS System". Singapore, Malaysia audiophiles all speaks this way. They do not pronounce as independent C. A. S. system but "CAS". I agree cloud base music library will become the majority of mass culture too. Computer Audio System Computer As Source Computer Audiophile System Computer Audio Server as you like.  |
DWS 正式會員117.xxx.xxx.150 |
2011-04-30 17:53 | |
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| [#31] Blogs: 數碼音樂重播專欄 (1) " can computer audio source (cas) really win cd transport for dac?" u are asking if 16/44 cds can win over 24/88 96 176 192 and above. theoretically the higher the bit rate and length the closer towards continuous analog as there are less gaps for the algorithms to do the guess work. similarly in video u are comparing 576i dvd quality with 1080p blu ray video quality. if u consider 1080p better than the 480 or 576 output then the same principle applies to audio too. 最後修改時間: 2011-04-30 22:49:13 |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-04-30 22:47 |
| [#32] Blogs: 數碼音樂重播專欄 (1) hey, I mean cas comparing with cd transport playing 16/44.1 to dac one more thing, our human ears cannot hear more than 20khz sound , why 24.96 (around 48khz) sound better than 16/44.1? |
batmanames04 正式會員 61.xxx.xxx.217 |
2011-05-01 06:28 |
| [#33] Blogs: 數碼音樂重播專欄 (1) one more thing, our human ears cannot hear more than 20khz sound , why 24.96 (around 48khz) sound better than 16/44.1? ---------------------------------------------------- If you treat PCM is sampling (snapshot) of analog waveform, at audible frequency, let said 4Khz, 96Khz have double number of sample compared with the one at 44khz sampling rate, more true to original analog waveform. Secondly, the Low Pass Filter roll off will push beyond 22khz to 48khz @ 96 sampling frequency, the sound deterioration near the top end (16-20Khz) of the audible range, the sound quality may improve.  最後修改時間: 2011-05-01 09:13:12 |
hercules 正式會員 112.xxx.xxx.58 |
2011-05-01 09:11 |
| [#34] Blogs: 數碼音樂重播專欄 (1) there are many theories about hearing beyond 20khz here is a good read http://www.earthworksaudio.com/wp-content/uploads/th_world_beyond_20khz.pdf |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-01 09:27 |
| [#35] Blogs: 數碼音樂重播專欄 (1) Hi Kent, Could you share with us the DAC part of Devalet dpremier compare with Weiss DAC2. |
mr_chan 正式會員 218.xxx.xxx.13 |
2011-05-01 10:25 |
| [#36] Blogs: 數碼音樂重播專欄 (1) """I mean cas comparing with cd transport playing 16/44.1 to dac""" assume u have a cd with no scratch and u rip the data to a hard disk with perfect bit which should be the same as u download the same music data file from internet, this should be the same as when you play a perfect cd thru a cd transport. the difference lies with scratched or imperfectly made cds. when u rip a scratched cd to hard disk it all depends on your chosen software how to handle the errors and make corrections by guessing. this error correction can be made many times like 20 to 50, for example. with cd transport it is a different matter. cd transport has limited time frame to make error corrections in may be say 3 to 5 times read and then the inbuilt software will make rougher guess work and transmit the info through to the digital analog converter. a good cd transport may handle error corrections better than crappy ones but no match to more reliably ripped data. does this make sense? |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-01 12:44 |
| [#37] Blogs: 數碼音樂重播專欄 (1) Batmanames04 Let me say something to complement answers to your question that I understand to be “whether CAS with a higher resolution track could sound better than a CD track from the same source, both played with the same DAC and audio system”. WOULD KENT POON PLEASE CORRECT ME IF I SAY ANTHING INCORRECT RELATIVE TO YOUR PROFESSION. Nowadays first hand digital recorders come with ADCs with higher resolution than the CD format. This was what a proprietor of a relatively new record label told me in our correspondence when I asked him why his “master” and DVD-ROM is at 32/192. You are probably aware Professor Johnson of Reference Recording uses 24/176.4, Morten Lindberg of 2L uses 24/352.8 etc. Because consumers are stuck with the 16/44.1 format in the ubiquitous CD players, the music industry have to “master” down their native or original masters to suit. You may also be aware there are a series of masters coming out from the native masters and mastering, amongst other things, include, “improving” bad recordings to acceptable level; mixing down multi tracks into 2 for CD; and relevant to our topic here, down converting the higher resolution tracks to 16/44.1. Music industry personnel have us believe the higher resolution tracks contain no more musical data than in their CD offspring and recording at higher resolution merely facilitates subsequent mastering that may be easier carried out with flatter slope filters. The majority of consumers are convinced! Now let us look at what that particular mastering process is doing to the high resolution tracks. A 24/352.8 DXD master has a bit rate of 16, 934 kbps and a file size of roughly 120 MB per 1 minute of music. A CD has a bit rate of 1,411 kbps and a file size of roughly 10 MB. In other words, the CD master only contains 1/12 of the data in the native or original master, meaning 11/12 of data have been filtered out! A CD in comparison with its 24/96 master, has 5/6 of the data filtered out. Playing high resolution tracks with the computer means playing with the same bit rate and sampling rate as used in the native or original master. Now you make your own judgement as to whether the 11/12 filtered out data are absolutely useless for our appreciation of the music in the track or perhaps there are overtones, upper harmonics and reverberation that enrich the fundamentals and harmonics within that hearing limit of 20 KHz. One point to bear in mind is that when “mastered down” from higher resolution, the CD master loses the filtered out data. Therefore even when a CD track is up converted subsequently, the missing data previously filtered out are merely interpolations. The up converted track only resembles the native or original master. How close the resemblance depends on the algorithm used in the upward conversion. Factually, MP3 involves similar mastering down. You may ask a similar question: whether a CD track could sound better than a MP3 track from the same source, both played with the same DAC and audio system. Say you have a MP3 track of 320 kbps that has about ¼ of the bit rate and file size of the CD. I wish the MP3 sounds as good as the master because I would be able to buy the albums of 2L in the iTunes store at a fraction of the price. Another important issue relevant to the topic under discussion: We are often told our hearing is between 20 Hz to 20K Hz at best and based on Nyquist 20.05KHz (half of 44.1) is already beyond our hearing, thus CDs are more than good enough for practically all of us. Don’t trust people like me in forums who may merely be talking crap. Listen to what your admired engineer, the mastermind for the Invicta DAC has to say in the Owner’s Manual that you referred me to. There are too many pages there to be reproduced here and I merely paraphrase the key issue. The human brain, as supported by tests that he quoted, is able to sense and fill in sound above 20 KHz, up to 50 KHz. Listeners are able to sense fullness if sounds above 20 KHz are captured in the recording and retained in the playback. And there are listeners able to detect differences when higher resolution tracks are played in comparison with CD tracks from the same masters. Well observational listening to pick out the difference is another topic. If you want to talk about it, please tell us your previous encounters with listening to CD tracks and CAS high resolution tracks and why you have doubt about any difference between the two. We then start from there. I must make clear I do not sell anything or help anybody to sell anything, thus no ulterior motive to convince people to use the computer and buy tracks or DAC. |
momei 正式會員 203.xxx.xxx.61 |
2011-05-02 08:52 |
| [#38] Blogs: 數碼音樂重播專欄 (1) thanks momei, i need sometime to digest it |
batmanames04 正式會員 203.xxx.xxx.116 |
2011-05-02 10:31 |
| [#39] Blogs: 數碼音樂重播專欄 (1) there are master recordings made with 24/192 and convert to cd format 16/44. u will notice that half of 192 is 96 and half of that is 48. so from 48 to 44 there will be another downscale. better fit is from 176 to 88 and then to 44. also note that there are some so called hi rez downloadable files in the format of 24/88 or 24/96 actually upscaled from 16/44. they are cheats and not necessarily mixed from master recordings. from 20khz to 40khz there is only one octave. similarly to 200w to 400w is just 3db difference. not much at all. |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-02 13:04 |
| [#40] Blogs: 數碼音樂重播專欄 (1) "A CD has a bit rate of 1,411 kbps and a file size of roughly 10 MB. In other words, the CD master only contains 1/12 of the data in the native or original master, meaning 11/12 of data have been filtered out! A CD in comparison with its 24/96 master, has 5/6 of the data filtered out. " The data size doesn't directly reflect the amount of musical information, a 16/44 recording of piano have more musical information than a 24/192 recording of "silence", but the size is much smaller. The data size only reflect the space occupied for storing sample, more room for more information, a store room can store a bicycle or tyres of the MPV but not a MPV, but a big garage can store many bicycle with one or two MPV at the same time. |
hercules 正式會員 112.xxx.xxx.58 |
2011-05-02 14:05 |
| [#41] Blogs: 數碼音樂重播專欄 (1) Yes Hercules I take your point. The crux of the matter is whether the data filtered out represent utter silence that is totally useless (over 7 GB in the case of a 2L album) or therein are overtones and harmonics that enrich the fundamentals and harmonics within the 20 to 20 KHz hearing limit. Well I belong to the camp accepting the enrichment concept. New equipment, for example, both the Wadia S-7i CD player and McIntosh preamps incorporate up conversion processes on the incoming CD format of 16/44.1. Therefore audiophiles have to decide for themselves whether these are merely marketing gimmicks or they actually will bring about improvements in sound. 最後修改時間: 2011-05-02 14:46:47 |
momei 正式會員 203.xxx.xxx.61 |
2011-05-02 14:37 |
| [#42] Blogs: 數碼音樂重播專欄 (1) in video u will view all black or all white using 576i format data the same as 1080p format data, irrespective there is upconvert of 576i to 1080p. however when there are motions and multi colour images it is a different story. most people can see true 1080p better than upscaled 578i to 1080p. why is it so hard to hear similarly in audio with upsampling of 16/44 format to hi rez to approximate true hi rez? |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-02 15:02 |
| [#43] Blogs: 數碼音樂重播專欄 (1) quoted from BobKatz (great recording engineer) Mastering audio the art and the sciencethe ultimate listening test: is it the filtering or the bandwidth? in December 1996, I sought to systematically find reasons for sonic differences between sample rates, performing a listening test. with the collaboration of members of the Pro Audio maillist. The question we wanted to answer was. Does high sample rate audio sound better ( or different ) because of increased bandwidth, or because of less-instructive filtering? we developed a test that would eliminate all variables except bandwidth. Other major factors were held constant, sample rate, filter design, DAC. and Jitter. The test were devised was to take a 96khz recording, and compare the effect on it of 2 different low pass filters. The volunteer design team consisted of Ernst parth (filter code), matthew xavier moral (shell), rusty scott (filter design), and bob katz (coordinator and beta tester). We created a digital audio filtering program with two impeccably-designed filters which are mathematically identical, except that one cuts off at 20khz. the filters were designed for overkill, with exemplary characteristics : double precison diethered, FIR linear phase, 255-tap, ＞ 110dB stopband attenuation, and ＜ .01dB passband ripple. Fort the first listening test, I took a 96khz orchestral recording, filtered it and laid both versions into sonic solutions DAW for comparison. I expected to hear radical differences between the 20khz and 40khz filtered material. BUT I COULD NOT HEAR ANY DIFFERENT! Next, I compared the 20khz filtered against "no filter" (of course , the material has already pass through two 48khz filters in the converters) Again I could not hear any difference! The intention was to listen double blind ; but EVEN sighted, 10 additional listeners who took part in the tests (one at a time) heard no difference between the 20khz digital filter and no filter. And if no one can hear a difference sighted, why proceed to a blind test? I then tried different types of musical material, including a close-milked recording of castanets ( which have considerable ultrasonic information). but there was still no audible difference. I then created a test which put 20khz filtered material into one channel of my Stax electrostatic headphones and the time- aligned wide bandwidth material into the other channel. I was not able to detect any image shift-there was always a perfect mono center at all frequencies in the headphones! This must be a pretty darn good filter! As a last resort, I went back to the list and asked maillist participant robert bristow johnston to design a special Dirty filters with 0.5dB ripple in the passband. Finally, with this filter, I was able to hear a difference... it added a boxy, veiled, " gritty" quality that resembles the sound of some of the cheaper cd players we all know. After I conducted my test, several others have tried this filtering program, and most have reached the same conclusion: the filter is inaudible. one maillist participant, eelco grimm, a netherlands based writer and engineer, performed the test and reported no audible differences using a sonic solutions system, yet he and a colleague passed a blind test between filtered and non filtered using an augan workstation. He did not compare the sound of the 20khz versus 40khz filters, so we are not sure if he was hearing the filter or the bandwidth ( i suspect the filter). We are not certain, but perhaps the reason eelco uniquely reported a sonic difference is that the sonic system produced sufficient jitter to mask the other differences, which must be very subtle indeed! ! Be aware that two other 48khz filters in the chain may have obscured the audible effect of the test filter, so it is very difficult to design a perfect test. this 1996 test seems to show that a " perfect 20khz filter" can be designed. regardless of whether eelco s group did reliably hear bandwidth differences, it should be clear by now that differences people hear between sample rates more likely due to filter design than to supersonic bandwidth. Ironically, it was necessary to make a high sample rate recording in order to prove that high sample rates may not be necessary |
batmanames04 正式會員 61.xxx.xxx.217 |
2011-05-02 19:54 |
| [#44] Blogs: 數碼音樂重播專欄 (1) My DIY DAC hear almost no different between 16 44.1 and 24/96 material if they are derived from the same source |
batmanames04 正式會員 61.xxx.xxx.217 |
2011-05-02 20:02 |
| [#45] Blogs: 數碼音樂重播專欄 (1) if you believe nyquist theorm, a good dac should hear no big different bewteen 16 44.1 and 24 96 material ( provide they are from the same source)  |
batmanames04 正式會員 61.xxx.xxx.217 |
2011-05-02 20:16 |
| [#46] Blogs: 數碼音樂重播專欄 (1) 1996 thats 15 years ago. there was no diamond beryllium or other tweeters with exotic materials. could those old tweeters output properly the frequencies above 20khz? how good was the room treatments for the tests? if it was one that absorbed a lot of high frequencies of course there was less chance to hear properly. |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-02 21:10 |
| [#47] Blogs: 數碼音樂重播專欄 (1) """a good dac should hear no big different bewteen 16 44.1 and 24 96 material""" i must be wrong. how can a dac hear things? i thought human can hear but a dac? |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-02 21:11 |
| [#48] Blogs: 數碼音樂重播專欄 (1) from wiki: Theorems have two components, called the hypotheses and the conclusions. The proof of a mathematical theorem is a logical argument demonstrating that the conclusions are a necessary consequence of the hypotheses, in the sense that if the hypotheses are true then the conclusions must also be true, without any further assumptions. The concept of a theorem is therefore fundamentally deductive, in contrast to the notion of a scientific theory, which is empirical. |
cpu8088 正式會員 115.xxx.xxx.214 |
2011-05-02 21:32 |
| [#49] Blogs: 數碼音樂重播專欄 (1) Batmanames04, Merely to mention the view of Bill Schnee to balance that of Bob Katz who is associated with Daniel Weiss. Bill advocates 24/192. In my book I have heard and read about Bill Schnee more than Bob Katz though I do not know in reality who is more famous. Anyway, back to the subject matter. If you use a PC and Foobar 2000 or WASAPI, then I get stuck because I have never used them. If you use MAC and iTunes then follow test 1 below. Test 1: You need to open MIDI, play a track of 24/96 and check whether you have set your computer to recognize you DIY DAC and also whether the setting displays 24/96 and not 16/44.1 whilst you play the 24/96 track. If the recognition and setting remains at 16/44.1, then it means you have always played your 24/96 tracks at 16/44.1, thus you heard no difference. If you have already done this previously and the recognition and setting is correct, please come back for test 2. |
momei 正式會員 203.xxx.xxx.61 |
2011-05-02 22:25 |
