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鬼佬發燒天書 Stereophile 的主筆 J Gordon Holt
早在七十年代
對 octave 作出的定義 : |
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IT ALL STARTED AT WOODBRIDGE
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tks, Tequila.
mom already gets used to such 'no sound' super tweeter...... 
muRata inventor says no need to do any adjustment, just connect super tweeter from main sp. that's why it has no any knob to adjust. |
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SVS PB2-ISD [upgraded to NSD2, TW only user], Toshiba
62HM84, Onkyo NA905 [TW first user], Westlake
BBSM8, Tannoy
Stirling, Mirage OmniSat, JVC DHX1/2, Sharp
HRD2 [TW first user], IO 500R [TW first user], ep
P100, Pioneer 745 [TW first user], PURE 702 [TW
only user], Sony PS3, Sony BX500, Panny
300/500 BS, LimHD200 [TW only user], iamm36HD [TW
only user], MB200 [TW only user], zinTV...
www.hztv.org
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should be HiFi....but LoFi, hmm, funny nick. 
most super tweeter users I have asked say it improves sound quality. 
but those none users say no need to waste $ for nothing.
I connect muRata 105 to Westlake 8. sometimes can hear really quiet zzzzzzzz, sometimes no any sound. its spec is 15k~100kHz.
mom says I waste $ for such useless no sound toy...
http://photo.pchome.com.tw/lienly/022/ |
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SVS PB2-ISD [upgraded to NSD2, TW only user], Toshiba
62HM84, Onkyo NA905 [TW first user], Westlake
BBSM8, Tannoy
Stirling, Mirage OmniSat, JVC DHX1/2, Sharp
HRD2 [TW first user], IO 500R [TW first user], ep
P100, Pioneer 745 [TW first user], PURE 702 [TW
only user], Sony PS3, Sony BX500, Panny
300/500 BS, LimHD200 [TW only user], iamm36HD [TW
only user], MB200 [TW only user], zinTV...
www.hztv.org
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So many articles, need to spare sometime at night to go through them.  |
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你！ 唔好呃我呢個飲醉酒既！
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... 但 REG 亦指出，
transient sound 瞬變音效的情況，卻完全不同 :
Quote :
"Transient sounds are much different.
The steeply rising transient wavefront is received directly first, with the high frequency content unattenuated by reflection.
A sharp transient always contains extensive high frequency content ... "。
詳情已在該文章詳述，
恕不在此重覆。 |
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IT ALL STARTED AT WOODBRIDGE
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Tequila 兄 :
Quote :
>> haven't read the forum yet,
>> but I guess they are saying that
>> most sound energy in real music is below 400Hz, right?
早晨。
對。在該網頁附設的討論區，
其中一位朋友，看來是說，
這是他的親身經驗，
至今好像未見有其他回應。
至於綢主 REG ，
是 The Aboslute Sound 其中一位寫手。
他在 TAS 曾發表過一篇文章 (亦轉載在 http://www.regonaudio.com )，
題為 "Records and Reality: How Music Sounds in Concert Halls"
( http://www.regonaudio.com/Records%20and%20Reality.html )
在文章內，他引述了在美國曾經做過的一個，
歷時二十年，對音樂廳音效的的測量報告。
與我們剛談及的話題相關的部份如下。
首先，他提出音源遠近，是否會影響 tonal balance
（亦即 sound energy distribution)。
Quote :
"... Close-up and distant sounds differ in the relative amounts of direct and reflected sound.
There 'is also an important difference in the spectral balance ...
... The basic question is:
What would be the intensity at various frequencies at audience locations in the hall?
This amounts to asking how the sound heard by the audience differs from flat frequency response relative to sources on stage."
文章接著提及上述的測量報告 :
Quote :
"The most natural and convincing approach to the basic question (other than just listening)
is the empirical method of putting a known sound source on stage
and applying a spectrum analyzer to the sound at various locations around the hall.
The results of such measurements are given for a number of halls in
'Halls for Music Performance, Two Decades of Experience: 1962-1982' (R. Talaske, ef al. editors, published by American Institute of Physics for the Acoustical Society of America, 1982). "
根據 REG 所說，該報告的內容是 :
Quote :
"The data given there consist of graphs of spectrum analyses from 125 Hz (or, on occasion, 8000 Hz) of the response to a sound source with a steady state, uniform dispersion standardized essentially flat frequency response.
(The minor deviations from flat power response of the source will not be important to us, since we are only going to be considering the general picture.)
The graphs show considerable variety from hall to hall in bass and mid-bass response,
with the halls that are regarded as desirable for orchestral performances having considerable bass to mid-bass warmth.
A less desirable feature of many halls is a slight 250 Hz depression, apparently caused by absorption arising from the seating pattern.
In the midrange above 250 Hz up to the 2-4 kHz region, most of the halls are essentially flat. ... "
他那一篇文章並說:
Quote :
"... But around 4000 Hz, and sometimes as low as 2000 Hz,
virtually every hall begins a rapid roll-off
at even quite close-up audience locations."
與及
Quote :
"By 8000 Hz, there is typically a 7 to 10 dB dropoff from midrange level.
The graphs are not given beyond 8 kHz; but from theoretical considerations, the roll-off at higher frequencies would be expected to be even greater."
假如他所說的屬實，
而音樂是在 concert hall 錄製，
亦並非是以 close mic 進行錄音，
那麼，可以推論，
錄下的音樂（除涉及瞬變 transients 外)，
亦同樣地應該沒有太多
8k Hz 以上的 sound energy 。
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IT ALL STARTED AT WOODBRIDGE
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Lofi hing,
I haven't read the forum yet, but I guess they are saying that most sound energy in real music is below 400Hz, right? |
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你！ 唔好呃我呢個飲醉酒既！
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Tequila 兄 :
Quote:
>>I am not really sure what the forum trying to say.
http://www.regonaudio.com 的討論區 (見下圖)
(果度重有好多技術性的 article , review ... )
Quote :
>>Does he means switching off the sub
>>which is crossed over at 400Hz?
對。
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IT ALL STARTED AT WOODBRIDGE
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Lofi hing 
I am not really sure what the forum trying to say. Does he means switching off the sub which is crossed over at 400Hz? |
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你！ 唔好呃我呢個飲醉酒既！
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Tequila 兄 :
多謝你提供的連結。又學倒野。
好快睇左幾句，吾係句句都明白。 
不過其中一段錦講 :
Quote :
"In these particular examples,
the proportion of energy above 20 kHz is,
for the muted trumpet, 2 percent;
violin, 0.04 percent;
oboe, 0.01 percent;
and cymbals, 40 percent."
可能，討論區個鬼佬講 D 野，
都有些少真確性。
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IT ALL STARTED AT WOODBRIDGE
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louis 兄 :
小弟在外國音響討論區閱讀過的 post ，
假如是真確的話，
更令人驚訝 :
Quote :
"I'd like to just chime in with a small observance regarding power distribution.
One of the most striking demonstration I have withnessed is
when Peter Lyngdorf cuts out the corner woofers when doing a demonstration.
He usually x-overs these at 400hz.
It is really funny how little energy is being handled by the front speakers at this x-over frequency.
If you have never heard it is really quite mindblowing.
Obviously everything sound wrong if you don't have 400hz and up
but it is mostly the tingeling."
上文所指的 Peter Lyngdorf ，應該是指 Lyngdorf Audio
( http://www.lyngdorf.com/ContentId/334/Default.aspx )
的老細 (即前 TacT Audio 的老細之一)。
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IT ALL STARTED AT WOODBRIDGE
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Harmonics can go beyond 20kHz, but whether a human can hear or feel it, its another story.
Most super tweeter has the cut off frequency setup way too low, or the cut off slope too mild. Its very common to see people just connect one capacitor to the super tweeter, which is a first order (6db/oct) filter.
In this case, if the cut off frequency is set to 20KHz, the sound magnitude of the super tweeter is only -6dB @10kHz and -12db @ 5kHz, which is still a lot. Plus its super hard to get the phase in coherence with the main speakers.....
So what most commonly happening is the addition of super tweeters, creates an illusion that the sound is brighter (because it still produce moderate amount of sound energy down to 5 to 10kHz area). But the reality is the tonal balance is easily destroyed and the sound stage is blurred, and image not as pinpoint.
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你！ 唔好呃我呢個飲醉酒既！
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good info.
most instruments can't even make >17KHz tone, so what's the usage of super tweeter (usually >25KHz)?  |
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SVS PB2-ISD [upgraded to NSD2, TW only user], Toshiba
62HM84, Onkyo NA905 [TW first user], Westlake
BBSM8, Tannoy
Stirling, Mirage OmniSat, JVC DHX1/2, Sharp
HRD2 [TW first user], IO 500R [TW first user], ep
P100, Pioneer 745 [TW first user], PURE 702 [TW
only user], Sony PS3, Sony BX500, Panny
300/500 BS, LimHD200 [TW only user], iamm36HD [TW
only user], MB200 [TW only user], zinTV...
www.hztv.org
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Agreed with last one, we have tested 16kHz, 18kHz. Most "Old men" cannot hear 18Khz at all. I can still listen very little 18kHz  |
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你！ 唔好呃我呢個飲醉酒既！
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最後，是 高頻和極高頻 :  |
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IT ALL STARTED AT WOODBRIDGE
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跟住，是 中頻和中高頻 : |
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IT ALL STARTED AT WOODBRIDGE
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再補充一些也是從網頁得來的資料，
解釋不同頻段，究竟對聽感有冇，或者是有甚麼，影響。
首先，是 低頻和中低頻 : |
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IT ALL STARTED AT WOODBRIDGE
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嘩，乜管風琴o既音調到到差唔多 16 KHz 咁高o架！
我諗用一般只得 type 1 卡帶機都好難錄到咁高音，(好失雍呀!嗚嗚 )
平時一般 2.0 電腦喇叭 聽到 10 KHz 都難，
主流大電器店 D 標榜低音勁高音亮O既石機 去到 5KHz 都喇耳啦...
咁即係要聽好管風琴音真係好難........唉!!!!!!!!!  |
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唔嘥錢買貴碟！唔去機舖打機！唔嘥錢玩膽機玩貴配
件！...
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THANK YOU LoFi hing~!!  |
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富 貴 不 能 淫 ， 貧 賤 不 能 移 ， 威 武 不 能
屈 ， 此 之 為 大 丈 夫
http://www.fotop.net/silverhand
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一幅有關基音和泛音的圖表 : |
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IT ALL STARTED AT WOODBRIDGE
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第二幅圖，整幅大 D size ，易睇 D 。 |
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IT ALL STARTED AT WOODBRIDGE
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另一幅相類似的圖表 : |
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IT ALL STARTED AT WOODBRIDGE
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知少少，扮代表。
響網上抄番泥的資料。
第一幅圖，係有關
(上面個表) 十二種 樂器 的頻應範圍
(下面個表) 唱古典 人聲 的頻應範圍
【 由上至下 : 男低音、男中音、男高音、女低音及女高音 】
注意 : 以上頻應，只顯示基音的頻應範圍，
不包括任何泛音（可以比基音更高或更低）。
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IT ALL STARTED AT WOODBRIDGE
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