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Discussion Starter #1
I have a Sony DA4ES reciever and I'm playing with the crossovers between my DIY tempest and paradigm monitor 7/mini monitor system. I have the crossover for all the speakers set at 80hz right now but there is another thing I can adjust in hz thats called the "L.F.E High Cut" Does this allow frequencies above or below whatever I set to pass? Please help me understand what this does and if it can be used to my advantage.


One quick thing. I have a crossover on my sub amp as well that goes from about 40hz-140hz. To defeat this crossover and let set the crossovers in the receiver do I turn the crossover all the way to 40hz or 140hz. I used to know this but I forgot.
 

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The Low Freq Effect only has a high cut (off), then lets the driver in the sub play as low as it can go. In passive crossover networks a "low-pass" would be some coils and a cap that would limit the high cut crossover point of 100HZ, etc. Bandpass could allow 100HZ to 350HZ to be heard, maybe another 350HZ to 3.5KHZ, and a high-pass for the tweeter starting at 3.5KHZ and playing to the human range of hearing.


With home theater the LFE is set when the Bass Management feature is implemented. You can set the sub to what cut off point you desire. THX got famous by setting it to 80HZ. Here is a great article that makes Bass Management clear.

http://www.mkprofessional.com/bass_mgmt.html
 

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Discussion Starter #3
thanks for the article. So the high cut doesn't allow frequencies above it to be played by the sub. If I set the high cut to 80hz would that mean that nothing would be played by the sub over 80hz, or does it mean that it would just be rolled off above 80hz? Basically I'm just not sure where to set it.
 

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True, it is a filter that does not let frequencies above 80HZ pass through. Basically Bass Management, a electronic crossover manages the frequencies so only 80HZ and below are played by the sub, then tones above 80HZ are played by the other speakers. With Bass Management 20HZ to 20KHZ is heard from all 6 speakers, even though the sub plays the lows and the satellite's play the mids and highs.
 

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Quote:
Originally posted by KingofOld
thanks for the article. So the high cut doesn't allow frequencies above it to be played by the sub. If I set the high cut to 80hz would that mean that nothing would be played by the sub over 80hz, or does it mean that it would just be rolled off above 80hz? Basically I'm just not sure where to set it.
Highs are rolled off.

Depending on the slope of the crossover (also refered to as order) it will be either 6dB/octave, 12dB/octave, or 24dB/octave.

This means (for example using a 12dB/octave slope) that if your high cut is set to 80hz, your sub would be outputing (just for example) 100dB at 80hz, then at 160hz (next ocatve up) would only be 88dB (12 dB's lower).


This of course is very simplified, as your room and setup also affect output.


To set it, depends on your main speakers. If they have usable output down to 80hz, by all means set it there. Try it and see. It will take some experimenting to get it just right.

I set the cross over at a certain level, then play a couple chapters from a familiar dvd, then try a new setting, play same chapters. I repeat this until I find what sounds best for me.
 

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Discussion Starter #6
I get it now I believe. Thanks for the explanations. Only thing I'm trying to figure out now is how is this different than setting the 80hz crossover for all the speakers (not the L.F.E. high cut). I mean when you set the crossover isn't everything above 80hz getting rolled off already. What purpose does this high cut have. I mean what if I set the crossover to all speakers at 80hz and then I set the LFE high cut to 120hz...what effect would this have. I guess I just don't understand the interaction between these two settings.
 

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Depending on where your decoder is, pre/pro, receiver, or DVD player setting your sub/LFE to"ON" and setting your smaller satellite speakers to "SMALL" this implements the Bass Management feature of the decoder/processor. Sometimes the LFE cut off is fixed in a Sony DVD player at 100HZ. Other pre/pros have adjustable crossover points for LFE). When you activate Bass Management the sub would stop playing at 100HZ and the smaller speakers would start from there and play to the range of human hearing.
 

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Discussion Starter #8
ok got it. Right now I have all my speakers set to small, the crossovers set at 80hz, and the LFE High Cut also at 80hz. The crossover on my sub is turned as high as it will go essentially defeating it...correct?
 

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The crossover on the powered sub may go higher than 80HZ, it may go to 120HZ, or so. I would try not to crank it up to the full right, but try and keep it in the 80HZ range if you can judge it. You only need one crossover, but in most cases two are there with the use of a pre/pro. I adjust my setting on may sub to 80HZ and the setting for the LFE in the pre/pro at 80HZ. Some powered sub allow the user to turn off the internal crossover in the plate amp.
 

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You are correct KingofOld. With all your speakers set to small and the pre-pro's crossover set to 80 (or whatever). You should absolutely crank the sub's crossover to it's maximum setting to keep it out of the way. Anything else and you'll only risk gaps in your bass response.
 
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