- #26 [hotiron], 18-09-16 12:57
- #25 [Pilotrol], 18-09-16 11:28路過...只想分享一則1940年Research Council of The Academy of Motion Picture對劇院音響的"Minimum" power requirement standard!
當年一個400人小型戲院Minimum power requirement只需10 Watts就已經足夠了,當然40年代劇院揚聲器效率普遍高過今天揚聲器,重播頻寬也只是要求PA Standard!其實我們在音響技術同思維上究竟是在進步還是退步當中呢,這點值得我們大家一同去深思!
最後修改時間: 2018-09-16 11:30:26 - #24 [RFC], 18-09-16 07:49.,ATC SCM 40 . Max SPL is 112db do require 500W by the chart , but Recommend Power Amplifier is 300w , only meet 109.8 db . TAD R1 Max SPL is 115 db , Amplifier requirement is 50w- 300w ., meet 114.8 (115db) . Both spk assume to be non linearity if driven above their max SPL but not depends on their spec expression
最後修改時間: 2018-09-16 07:54:13 -
- #23 [etsang3], 18-09-15 12:06
http://atcloudspeakers.co.uk/hi-fi/loudspeakers/entry-series/scm40/
Loudspeaker = ATC SCM40
Frequency Response (-6dB): 48Hz-22kHz
Sensitivity: 85dB @ 1W @ 1metre
Max SPL: 112dB
Recommended Power Amplifier: 75 to 300 Watts
================================
Form the max SPL 112dB check from the chart can assume, form 300W to 400W, it can still maintain Linearity
最後修改時間: 2018-09-15 12:06:21 - #22 [etsang3], 18-09-15 12:05這是我的經驗,通常到達喇叭標出的max power 但還未到達喇叭的max SPL.或甚至還有很多餘位才到max SPL。則那隻喇叭的音色線性度很高(高中低的比例)。那隻喇叭在接近或少許超過最大承受輸入是,音色能保持一樣,不致散了。
這一項低靈感度(dB @ SPL, 1m , 1W) 的喇叭多數有保證。
擴音機的輸出功率(W)每升高一倍的時候,能忠實重播的喇叭,應該按照音量提升3dB。不能按照這樣提升音量dB的,喇叭應該已經飽和了,音色再不能保證。
以下做了擴音機輸出(W)和喇叭相對音壓(dB)提升表,供大家參考。
也選來了兩隻喇叭比對能耐。(聽各類型音樂,喇叭如能做到有20-25dB的動態音壓表現,便會覺得很滿足了)
https://static1.squarespace.com/static/55f2f41ee4b0ef7e0849e07a/t/5615a58ae4b021d269b8efff/1444259210343/TAD-R1_en.pdf
Loudspeaker = TAD-R1
Frequency response : 21 Hz to 100 kHz (-10 dB)
Sensitivity: 90 dB (2.83 V/2.83 V @ 1 m free space)
Maximum sound pressure level : 115 dB
Amplifier requirements: 50 W to 300 W
================================
Form the max SPL 115dB check from the chart here, form 300W to 400W, it exceeds it's Max SPL so it starts difficult to maintain Linearity
最後修改時間: 2018-09-15 12:08:42 - #21 [aheung], 18-09-15 09:22Dynamic range can be adjusted by using different power cord?
- #20 [行內人], 01-10-21 13:13Kcm
靈敏度287dB,它的含義是向Spk輸入1W pink Noise,在離音箱正前方1M處所接受到的音壓值是87dB.這個定義測試方法是IEC的方法.需要說明靈敏度的測試方法,不同廠家,不同國家都可能不同.所以不同廠家的音箱靈敏度,他的含義不盡相同,還要看一下它的定義與測試方法.
這是大部份廠家的測試方法,有必要考慮1M或1/2,1/4米內之測試值嗎?這埵陪虓妝擊搎〝,音箱所標靈敏度是正前方1M處,實際聆聽位,常常大於1M,而且不在正前方,這時所聽到的靈敏度就會下降,也就是在實際聆聽位要聽到相同的靈敏度,輸入必v就要增加,再有就是,輸入必v和音壓值是對數關係,也就是音壓值每增加3 dB(也就是聲音響度增加一倍),輸入必v要增加10倍.
當然,87dB絕對不是一個參考值,有些比它更低例如Chord 5/12A=81.5dB,Chord 5/12B=83dB,Celestion 600…..或更多.
多謝指教! - #19 [kcm], 01-10-21 10:21行內人
Oh don't use the word 指教, I learnt from you!
BTW, any comment on the following:
For sensitivity 87dB, 1W spk, then
when 0.5W input, we got 87-3=84dB (-3dB)
0.25W input, we got 81dB (-6dB)
0.125W input, we got 78dB (-9dB)
Seems it is not so correct to use 87dB as reference point for calculating dynamic range because below 1W, we still have 0.5, 0.25, 0.125W.... - #18 [行內人], 01-10-21 01:08kcm
1)多謝朋友指導,但我真沒有膽量對人客說一對power handling 50-1000W喇叭,最小用50W就能用,想更好就改用1000W推動的說話,想必總公司的投訴電話就馬上響起,一時間用50W,一時間又話1000W,有點像氣弄客人之意思(起碼對方會有這樣想法).
當然,實話實說是對,但生意好可能會跑掉,問題就好似一對四路電子分音喇叭一樣,買它,請同時買8部Mono block or 4部stereo power amp,容易賣嗎?依我愚見,提議配一部500W又如何?(500logx10=27dB,1000logx10=30dB),27跟30好似近一點吧,500跟1000W差一倍,犧牲3dB可行嗎?另外,相同品牌中的擴音機500W跟1000W輸出,無論價錢、體積都一定相差得很遠,對嗎?我做得成生意的機會高一點嗎?
2)又是一個兩難問題,3000cc與5000cc的車在塞車時效率是相差不遠(常理),但同時要跑一轉舊山頂道,相信一部較有寬餘度的車在斜坡上行走會較輕鬆吧!
我時常指出hifi綜合性係好重要,器材配搭得好,比找一位知心人伴侶更難,但針對性選擇可縮小購買範圍,你行進店內大大小小擴音機,你會怎選擇?
多謝指教! - #16 [kcm], 01-10-20 13:46I think the problem is we shouldn't take sensitivity as zero point for calculating dyanmic range.
Because for sensitivity 87dB, 1W, then
when 0.5W input, we got 87-3=84dB (-3dB)
0.25W input, we got 81dB (-6dB)
0.125W input, we got 78dB (-9dB)
and so on until we cannot hear anything, then we got background noise only, around 40-50dB. - #15 [kcm], 01-10-20 12:48One more point to add, even your speaker and amp can output 120dB, it doesn't mean your room can withstand this level without distortion.
- #14 [kcm], 01-10-20 12:38TEric
From cdp 100dB to speaker 20-30dB(?), this is exactly I'm skeptical about the dynamic range calculation method.
By definition, dynamic range is the difference between the quietness and loudness, in dB. So, if a speaker can achieve 120dB, and the quietness we can hear, say 40dB-50dB (40-50dB because it is the general background noise level in "silent" area), then dynamic range should be
120dB-40dB=80dB!
Again, it shows that dynamic range is related to environment, depends on how quiet your room is. And it is also why spk manufacturer can't show it at the spec.
All above are only my educated guess, any comment/correction is welcomed. - #13 [TEric], 01-10-20 12:10kcm,
我諗行內人想講出一點,
動態表現越好, 樂器的質感表現就越好,
音質表現就會較好. 音質同音色唔同, 不過
好多人都混淆了.
由CDP 一般都有100db 動態範圍去到
喇叭(就算在full power output) 時
可能得番20-30db, 已經衰減三份之二有多,
如果連呢個有限動態都表現不足,
咁音質又再降底.
至於最大聲壓問題又是另一回事,
因現在祇談論必v放大器與喇叭之關係,
空間能受幾大的聲壓並不在討論之中.
因要趕往銀行, 祇能討論到呢度,
呢個係一個十分之好的話題,
我相信如能正面地討論,
大家會得益不少. - #12 [hifi oldman], 01-10-20 12:07kcm, the things listen to your ears and are related in too many factors, in the wordings , they are difficult to separately consider, eg, a very strong power supply play and important role in dynamic and details in the amp performance , although they are part of it, it don't think a weak power supply amp can produce good sound except some very econmonic and high efficient amp eg . qual 405 ! therefore normally every part are related,eg, the transitors, or mosfet, as result, use the ear and price for judgement may be better, in wording explaination may be only partially, have you remember the topic bi amp, a VERY BIG AND WIDE TOPIC, the content is too big and not easily to discuss with good conclusion therefore i didn't say too much !!
- #11 [kcm], 01-10-20 11:55hifi oldman,
Well, frequency response shouldn't be confused with dynamic range.
Freq response is referring how low and how high freq the amp can reproduce.
Dynamic range is referring the difference range between quietness and loudness, something related to sound ampitude not frequency. - #10 [hifi oldman], 01-10-20 11:47kcm, what i point out and is a normal case about the dynamic, and details, compare within the same design , of course , different brand, different price, different grade of parts and design may also greatly affect the sound quality. spec. base on wrong measurement and misleading information are sure incorrect, but wide 5-50000hz compare 20-20000hz in the same above factors, sure better, i am trying to explain the dynamic related to these factors.
- #9 [kcm], 01-10-20 10:46hifi oldman,
I don't quite agree that 5-50khz must be better than 20-20khz.
yes, 5-50khz is more extended in both extreme, but it doesn't tell you how is the quality within more important 20-20khz range. If all of us only look at this figures, manfacturers can easily achieve high bandwidth by incresing NFB.
Typical example is tube preamp, if manfacuturer just want to have better figures, they can just use more NFB, but the result is frequency is extended but doesn't sound good. - #7 [hifi oldman], 01-10-20 10:37kcm and hifi insider, besides, rms, current, ohm ,i think the 5-50000 is better than 20-20000, the amp has 5-50000hz 100W is much better than 20-20000hz, 100W , it may be have more dynamic and details normally ensure that the figure is accurate, expensive amp has better and higher range !!
- #8 [hifi oldman], 01-10-20 10:37kcm and hifi insider, besides, rms, current, ohm ,i think the 5-50000 is better than 20-20000, the amp has 5-50000hz 100W is much better than 20-20000hz, 100W , it may be have more dynamic and details normally ensure that the figure is accurate, expensive amp has better and higher range !!
- #6 [kcm], 01-10-20 09:25TEric, for hifi discussion, why don't come out here? This forum is getting bore and bore without real hifi discussion.....
Certainly some energy are lost in crossover, coil, etc. But it is already stated in the efficiency rating, otherwise speaker will have 100% efficiency. But it is not related to the subject. - 下一頁 (2 of 3)
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最後修改時間: 2018-09-16 13:02:39