FYI
source from
相信係前文嘅英文版本
以上文中提及
如果唔用sub-woofer ...
chhanthony 發表於 2011-3-15 19:46 http://www.post76.com/discuss/images/common/back.gif
師兄呢段英文既意思，只是講LFE唔一定由subwoofer出，可以由FL,FR出。呢個問題大家都無爭議。但係上面師兄所講的例子，是有開subwoofer，只是subwoofer的響應只在20-80HZ，所以80-120HZ流失是無錯的。因為當Amp設定subwoofer為on時，所有LFE的是交給subwoofer的。只有在amp的subwoofer設定為off，才會把LFE的訊號交比其它喇叭出的。謝謝！ 本帖最後由 Big_McIn 於 2011-3-17 10:34 編輯
subwoofer的響應只在20-80HZ，所以80-120HZ流失是無錯的。因為當Amp設定subwoofer為on時，所有LFE的是交給subwoofer的。只有在amp的subwoofer設定為off，才會把LFE的訊號交比其它喇叭出的。
maskedtsang 發表於 2011-3-17 00:03 http://www.post76.com/discuss/images/common/back.gif
LFE does not equal subwoofer
Dolby Digital programs may include a bass-only LFE channel, but this channel does not correspond directly to a subwoofer output. It is possible for a program to contain an LFE channel, but a decoder may provide no subwoofer output because all of the bass information in the program, including the LFE channel, can be reproduced by the main speakers. The opposite is also true: it is possible for a program to not contain an LFE channel, yet a decoder may provide a subwoofer output because some or all of the main speakers are unable to reproduce the bass information in the program. The difference between the LFE channel and the subwoofer output is that the LFE channel is used to carry additional bass information in the Dolby Digital program while the subwoofer output represents how some or all of the bass information will be reproduced.
1. 以上說明在無Subwoofer環境下，LFE可以由優質大型前、中置(或稱主要喇叭)重播。
2. 但當選用subwoofer時，是否意味LFE就完全交由Subwoofer重播，以Onkyo為例，說明書並無交代清楚，以Onkyo 5508為例：
■LPF of LFE
(Low-Pass Filter for the LFE Channel)
80Hz, 90Hz, 100Hz, 110Hz, 120Hz
With this setting, you can specify the cutoff frequency
of the LFE channel’s low-pass filter (LPF), which can
be used to filter out unwanted hum. The LPF only
applies to sources that use the LFE channel
它只說LPF可濾除討厭HUM聲，所以Subwoofer 80Hz設定，並非100%確定LFE內81~120Hz訊息會消聲匿跡，要視乎廠家firmware設定，消費者很難查核。 師兄呢段英文既意思，只是講LFE唔一定由subwoofer出，可以由FL,FR出。呢個問題大家都無爭議。但係上面師兄 ...
maskedtsang 發表於 2011-3-17 00:03 http://www.post76.com/discuss/images/common/back.gif
呢段已有提及
Some less expensive consumer receivers offer only a fixed bass-management
crossover frequency (often at 80 Hz) using one filter after the summation of the LFE
and the main channel information (see Figure 4-6). This results in a situation where
bass content between 120 and 80 Hz in the LFE channel is lost.
出唔出到LFE中80-120hz應該係睇AV AMP內嘅bass-management中LFE crossover，而唔係睇sub-woofer，
如果只係睇sub-woofer嘅spec，AV AMP內應該唔需要有LFE crossover呢個setting，將整條LFE交由sub-woofer去handle就得。
以我估計係
1) 如果AV AMP無得校LFE crossover只係統一地可以set一個crossover frequency +
2) 將crossover frequency set 80hz
= LFE 中80-120hz 會消失
1) 如果AV AMP有得校LFE crossover +
2) 將LFE crossover frequency set 80hz
= LFE 中80-120hz 會交由主聲道處理 本帖最後由 maskedtsang 於 2011-3-17 14:09 編輯
LFE does not equal subwoofer
Dolby Digital programs may include a bass-only LFE channel, but this...
Big_McIn 發表於 2011-3-17 10:26 http://www.post76.com/discuss/images/common/back.gif
多謝師兄回應！上述師兄引述的說明書，我也在Onkyo 708的說明書睇過。以我有限英文所理解(哈！)，Low pass filter for LFE是決定LFE channel內的音訊由幾多HZ以下會分去給subwoofer 工作。而default 都是120HZ的。但呢個設定同其它speaker channels的crossover 設定是不同的，crossover的設定，從英文亦可得知，是從分頻點以下的都交給subwoofer。而Low pass filter for LFE是把分頻點以上的音訊 filter out 的，雖然說明書並無指明，但照英文用字filter一詞可以明白。上述只是推測，要找人問下Onkyo 好D！ 呢段已有提及
出唔出到LFE中80-120hz應該係睇AV AMP內嘅bass-management中LFE crossover，而唔係睇sub ...
chhanthony 發表於 2011-3-17 11:10 http://www.post76.com/discuss/images/common/back.gif
第一個情況，同意！
第二個情況，有保留！
■LPF of LFE
(Low-Pass Filter for the LFE Channel)
80Hz, 90Hz, 100Hz, 110Hz, 120Hz
With this setting, you can specify the cutoff frequency
of the LFE channel’s low-pass filter (LPF), which can
be used to filter out unwanted hum. The LPF only
applies to sources that use the LFE channel
從字面上理解，是設定謀一點cutoff，而不是crossover to.....。佢用既字眼亦不是LFE crossover，而是 Low pass filter for LFE channel，所以有保留！謝謝！ 本帖最後由 Big_McIn 於 2011-3-17 17:25 編輯
多謝師兄回應！上述師兄引述的說明書，我也在Onkyo 708的說明書睇過。以我有限英文所理解(哈！)，Low pass ...
maskedtsang 發表於 2011-3-17 14:08 http://www.post76.com/discuss/images/common/back.gif
1. 但當選用subwoofer時，是否意味LFE就完全交由Subwoofer重播，以Onkyo為例，說明書並無交代清楚。
Subwoofer 1ch: Audio signal is outputted from SW1 jack only.
2ch: Audio signal is outputted from SW1 and SW2 jacks (default).
No: Select if no subwoofer is connected.
Front*1 Full Band, 40Hz, 50Hz, 60Hz, 70Hz, 80Hz(THX) (default), 90Hz, 100Hz, 120Hz,
150Hz, 200Hz
因當選用Subwoofer時，Front Spk and center均可選Full Band，那是否意味有LFE呢？Onkyo無交代。
2. to filter out unwanted hum。
a. 那又是否意味81~120Hz是討厭的Hum。
b. 假設Front and center選Full Band時有LFE，此filter是否濾去LFE source或只是在subwoofer ch 的LFE。
以上a.和b.又是謎。
所以Subwoofer 80Hz設定，並非100%確定LFE內81~120Hz訊息會消聲匿跡，要視乎廠家firmware設定，消費者很難查核。
以上两點是我想說的。 1. 但當選用subwoofer時，是否意味LFE就完全交由Subwoofer重播，以Onkyo為例，說明書並無交代清楚。
2....
Big_McIn 發表於 2011-3-17 16:49 http://www.post76.com/discuss/images/common/back.gif
可能我的表達能力不足，但我好似無話subwoofer set 80HZ，就令LFE 內的 80-120HZ消失。而係話Low pass filter for LFE 如果設定在 80HZ，LFE channel的 80-120HZ會消失。而現在問題的要點是如果 Low pass filter for LFE set 80HZ，LFE 80-120HZ果段，Amp 會點樣處理？
1. Amp會把 80-120HZ cutoff，禁LFE channel 的 80-120 HZ 會消失，即係無左！
2. Amp 會自動把80-120 HZ 交比其它 speaker 處理！禁LFE channel 80-120HZ 只是經由其它 speaker 出，並非無左。
禁樣講有無問題？
剛才寫了封電郵問香港Onkyo，估唔到佢禁快覆我！但可惜佢只是電話回覆！而佢既回覆係如果Low pass filter for LFE set 80HZ，禁 80-120HZ是會無左，而不會交給其它speaker 工作！謝謝！
回覆: 調校分頻點一問。
謝謝資料發送自我的 HTC Wildfire 大板凳 我用緊部AMP係咁{:1_256:}
11. Set Crossover Points
During Set Crossover Points testing, the following appears on the VFD display and checks
are made to detect the test sound in the listening room (whether there are speakers
connected to each channel or not) and the polarity of the speakers as they are
connected.
Set Crossover Points
FL ........ Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
CEN ..... Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
FR........ Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
SR ....... Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
SBR...... Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
SBL ...... Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
SL........ Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz
SW....... Full Full, 40Hz, 40Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz, 110Hz, 120Hz, 130Hz, 150Hz