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[#114] Speaker 有氣孔反射VS密封式? George, yes yes... =) 支持基本自由人, I have not had time to look through the web link you provided, but whatever it is, this looks like a theoretical graph/computer model based on specs. is that correct? What this graphs depicts could be correct, but it is also interesting how they all 'cross' at 30Hz regardless of the minor differences in the roll off slopes. I have also seen graphs (theoretical) showing the inferior impuse/step responses of sealed vs bass reflex... but as George said, I have a plane to catch. I will try to look for it when I return. |
wslam 正式會員 219.xxx.xxx.161 |
2009-09-19 10:42 | |
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[#115] Speaker 有氣孔反射VS密封式? I think wslam is right to point out that sealed designs rolloff earlier but more gently, while ported design rolloff later but more aggressively. But I don’t quite understand how gently rolloff can be benefited by room gain more so than ported design, I thought they both suffer in the same way. Say for a ported design targeted for home use. If the room gain at 35hz (like my room case), then a sensitive ported design should reduce the port loudness slightly to compensate the general room gain at that low frequency. The same trick can be applied no matter for ported or sealed box, am I right? I think the most importance difference between ported and sealed is their phase/group delay difference, rather than rolloff speed. ...to be continued. |
m40 正式會員 121.xxx.xxx.122 |
2009-09-19 10:49 |
[#116] Speaker 有氣孔反射VS密封式? AFAIK, the biggest advantage of sealed box is less phase shift at low frequency comparing to similar ported design. Due to crossover and box, low frequency can unavoidably shifts frequency somewhat. Sealed box has advantage of minimal phase shift and less group delay at low frequency while ported has relative higher group delay. Group delay means low frequency is several frequency cycles lag behind mid high frequency. Group delay plot of sealed box: |
m40 正式會員 121.xxx.xxx.122 |
2009-09-19 11:04 |
[#117] Speaker 有氣孔反射VS密封式? Group delay port of similar ported design. You can see the group delay is longer at low freq |
m40 正式會員 121.xxx.xxx.122 |
2009-09-19 11:06 |
[#118] Speaker 有氣孔反射VS密封式? 縮頭烏cpu8088 又扮冬眠哪?無言以對扮睇唔到呀?又多幾個人睇穿你既醜行啦,唔衰黎衰! |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 12:41 |
[#120] Speaker 有氣孔反射VS密封式? 偽鬼佬cpu8088 你自命英文程度高,但點解你每段post如果唔係copy & paste的話,每段都得個兩三行字?仲混雜埋d網上符號u呀lol等,完全睇唔到你英文文采有幾高喎。 寫唔得之餘,連睇都好有問題,人地插你既statement你又更更加過x2上去。 難道你除了心理不平衡外,還有讀寫障礙? |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 13:32 |
[#121] Speaker 有氣孔反射VS密封式? wslam your wikipedia link showing viscoelasticity as "the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain instantaneously when stretched and just as quickly return to their original state once the stress is removed. Viscoelastic materials have elements of both of these properties and, as such, exhibit time dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscoelasticity is the result of the diffusion of atoms or molecules inside of an amorphous material [1]." study of viscous materials like honey can be related to speaker cabinets? speaker drivers? cone materials? internal wires or crossover networks? also your link showing how temperature may affect the elastic coefficients or measurements. it does not explain how to convert vibration into heat. |
cpu8088 正式會員 115.xxx.xxx.214 |
2009-09-19 13:48 |
[#122] Speaker 有氣孔反射VS密封式? 我都認為寫中文大家可以學下野,英文文中太多參考標記唔知邊道是Checking point...... :> 交功課會被Profressor彈咖... |
chris66 正式會員 116.xxx.xxx.240 |
2009-09-19 15:02 |
[#123] Speaker 有氣孔反射VS密封式? 孟波 i take offence that you mentioned my dad instead of involving technical discussions. i believe 你老豆教你 use foul language in open forum and copy paste graphs without quoting sources pretending it is your own measurements done. |
cpu8088 正式會員 115.xxx.xxx.214 |
2009-09-19 16:11 |
[#124] Speaker 有氣孔反射VS密封式? 小丑cpu8088, 我老豆的確有叫我對住d偽君子,出言不遜,先撩者賤既廢物唔好客氣,一於插到佢盡,無須扮斯人。 |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 16:18 |
[#125] Speaker 有氣孔反射VS密封式? foul language??? 邊個網友俾你挑釁後會同你講斯文?上次有位紳士都鬧你係"狗"啦。 |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 16:27 |
[#126] Speaker 有氣孔反射VS密封式? >>>copy paste graphs without quoting sources pretending it is your own measurements done.>> 小丑cpu8088 笑死人,係人都會用URL,要知sources一right click再睇內容就知出處,你想用呢樣野來轉移視線又失敗啦。 你唔知醜地C&P別人的statement,當係自己既論點,但被人搵到原作者一年前post條link後,又轉口話段statement係你在其他forum作既,原作者抄你都講得出。 可是叫你post條original link上黎又交唔出,你知個醜字點寫嗎? |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 17:08 |
[#127] Speaker 有氣孔反射VS密封式? 小丑cpu8088 呢幅相都唔係我影既,知點搵出處嗎? |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 17:38 |
[#128] Speaker 有氣孔反射VS密封式? and this... |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 18:00 |
[#129] Speaker 有氣孔反射VS密封式? http://big51.chinataiwan.org/xwzx/qwqs/200803/t20080311_603480.htm |
cornercube 正式會員 58.xxx.xxx.174 |
2009-09-19 18:25 |
[#130] Speaker 有氣孔反射VS密封式? cornercube 兄: 全中! |
孟波 正式會員 218.xxx.xxx.240 |
2009-09-19 18:26 |
[#131] Speaker 有氣孔反射VS密封式? 唔好意思!你地繼續!! Sorry. |
cornercube 正式會員 58.xxx.xxx.174 |
2009-09-19 18:28 |
[#132] Speaker 有氣孔反射VS密封式? 英國老婦用冰箱幫75隻烏龜冬眠......仲以為賣龜靈膏潻.. |
chris66 正式會員 219.xxx.xxx.146 |
2009-09-19 19:07 |
[#133] Speaker 有氣孔反射VS密封式? D鬼佬唔識寶 ^^ |
catwong 正式會員 218.xxx.xxx.160 |
2009-09-19 19:29 |
[#134] Speaker 有氣孔反射VS密封式? """上次有位紳士都鬧你係"狗"啦""" who? your daddy? only a fool would be described someone as 紳士 who speaks rubbish? |
cpu8088 正式會員 115.xxx.xxx.214 |
2009-09-20 04:53 |