LFE Vs LINE IN? - AVS Forum
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post #1 of 7 Old 11-28-2011, 06:16 PM - Thread Starter
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hey guys whats the diff about line in and LFE inputs on a amp? i orderd a A7-650 for my small room . i have one concern is that eD didnt have there LT1300 plate amp. so i got the behringer amp. i dont believe it has LFE input. will this make a diff and should i be worried. pls help clarify this for me.
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post #2 of 7 Old 11-28-2011, 06:39 PM
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Quote:
Originally Posted by frankie2075 View Post

hey guys whats the diff about line in and LFE inputs on a amp? i orderd a A7-650 for my small room . i have one concern is that eD didnt have there LT1300 plate amp. so i got the behringer amp. i dont believe it has LFE input. will this make a diff and should i be worried. pls help clarify this for me.

On sub amps that are equipped with both, the 'LFE input' USUALLY bypasses the sub's own low-pass filter (sometimes called its 'crossover'), completely. And the low-pass filter setting WOULD be applied to the other pair of inputs. When connecting a sub conventionally, to an AVR's sub out, the 'LFE input' would be the preferred connection on a so-equipped amp.

But if your amp doesn't have this sort of 'LFE input', and it has no sort of low-pass filter bypass switch, and you are connecting the sub conventionally to your AVR's sub out, then set the amp's low-pass filter setting to the highest possible setting.

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post #3 of 7 Old 11-28-2011, 06:46 PM
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I'm going to attempt this and if I'm incorrect, please ppl chime in to correct me,

When using LFE, the receiver will send all the low frequencies to the subwoofer. You will have to set the xover frequency on your receiver to achieve this. So if you set it at 80hz (wich is the recommended setting for use with towers) anything under that 80hz will be handle by the sub. You have to make sure your speakers are set to "small" for this application.

When using "line in" all the low frequencies that would normally go to your L / R, speakers, will be "intercepted" by your sub. You will have to use the xover frequency directly from your sub to achieve this. You have to make sure your speakers are set to "large" for this application. This method although not as popular, tend to have the same effect as not much content under 80ishHz (from a movie soundtrack for instance) would be directed to your surround back and or your center.

this is to the best of my knowledge.

cheers.
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post #4 of 7 Old 11-28-2011, 07:13 PM
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Quote:
Originally Posted by jproy13 View Post

I'm going to attempt this and if I'm incorrect, please ppl chime in to correct me,

When using LFE, the receiver will send all the low frequencies to the subwoofer. You will have to set the xover frequency on your receiver to achieve this. So if you set it at 80hz (wich is the recommended setting for use with towers) anything under that 80hz will be handle by the sub. You have to make sure your speakers are set to "small" for this application.

When using "line in" all the low frequencies that would normally go to your L / R, speakers, will be "intercepted" by your sub. You will have to use the xover frequency directly from your sub to achieve this. You have to make sure your speakers are set to "large" for this application. This method although not as popular, tend to have the same effect as not much content under 80ishHz (from a movie soundtrack for instance) would be directed to your surround back and or your center.

this is to the best of my knowledge.

cheers.

Well, what goes to the sub is dictated by which outputs you use on the AVR and how the AVR is configured, exactly. But, yes, a so-equipped sub's 'LFE input' is for connecting it, conventionally, to an AVR's sub out regardless, though, of the exact bass management scheme being used (i.e LARGE vs. SMALL speakers). With this sort of conventional connection the AVR will send to the sub's unfiltered 'LFE input' a signal that is dictated by how the AVR;s bass management settings are configured. It is up to the user to either configure manually or ensure that his auto-EQ/calibration configures his AVR's bass management settings properly.

And, yes, generally, on a sub that is equipped with both filtered and unfiltered (LFE) inputs, the filtered, line-level inputs would be used to connect it to either the front R/L channel pre-outs of an AVR or pre/pro or to the R/L channel pre-outs of a 2-channel receiver or pre-amp. And, yes, generally, if connected this way to an AVR or pre/pro, the front channels would probably be set to LARGE and the sub's own low-pass filter setting would be used to adjust the sub's output to the front speakers' low-end capability.

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post #5 of 7 Old 11-28-2011, 08:55 PM
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Quote:
Originally Posted by sivadselim View Post

Well, what goes to the sub is dictated by which outputs you use on the AVR and how the AVR is configured, exactly. But, yes, a so-equipped sub's 'LFE input' is for connecting it, conventionally, to an AVR's sub out regardless, though, of the exact bass management scheme being used (i.e LARGE vs. SMALL speakers). With this sort of conventional connection the AVR will send to the sub's unfiltered 'LFE input' a signal that is dictated by how the AVR;s bass management settings are configured. It is up to the user to either configure manually or ensure that his auto-EQ/calibration configures his AVR's bass management settings properly.

And, yes, generally, on a sub that is equipped with both filtered and unfiltered (LFE) inputs, the filtered, line-level inputs would be used to connect it to either the front R/L channel pre-outs of an AVR or pre/pro or to the R/L channel pre-outs of a 2-channel receiver or pre-amp. And, yes, generally, if connected this way to an AVR or pre/pro, the front channels would probably be set to LARGE and the sub's own low-pass filter setting would be used to adjust the sub's output to the front speakers' low-end capability.

lol, thanks. Your explanation makes my explanation look like a child wrote it
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post #6 of 7 Old 11-22-2014, 09:56 AM
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I realize this post is several years old, but I found it by good ol' Google. I thought it was quite helpful. Thank you guys! Another question on a related topic: Is there any advantage in having 2 subs, 1 connected line level to handle the lower frequencies of the L/R fronts plus 1 other sub connected as an LFE? I bought Mission speakers (including EAS1 (10")and EAS2 (12") subs) a number of years ago from an AV store in Chicago and have had my system configured in this 5.2 way using a Denon AVR-4308 receiver. From the get-go I had constant problems with the two subs and have had each repaired a couple times; given my listening volumes I highly doubt they were over-driven. In any case, I want to upgrade and am considering a Velodyne DD-15+. Do I really need a second sub run line-level, or will a single sub run as LFE work just fine with crossover set on my AVR to 80Hz? Any feedback is appreciated!
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post #7 of 7 Old 11-22-2014, 10:05 AM
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Sorry, let me clarify/re-word. Do I really need a second sub run line-level, or will a single sub run as LFE+Main (setting on my Denon AVR) work just fine with crossover set on my AVR to 80Hz? Will there be any noticeable difference in sound quality by having 2 separate subs, one for the L/R front lows and one dedicated sub for LFE only?
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