Bass Management and LFE: NOT the same thing!

Should I use bass management in my AVR? What's the difference between the Subwoofer signal and the LFE signal?

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92 Comments

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    Matt Williamson

    Thanks Chris,

    If I set the sub 5db hotter in the trim after running audyssey, does this mean that the sub is then sitting at around 80db instead of 75db when the receiver volume is at 0? The specs on my sub rate it at 115db subject to room placement, so just trying to make sure that I don't reach that level and bottom it out.  I know you stated that most have built in protection, but I have been recently reading that a few people managed to bottom their subs out after increasing the trim in the AVR. 

    Thanks

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    Audyssey Labs

    Small means: set a crossover frequency and send the bass to the sub

    Large (Full Range) means: don't send bass to the sub ever

    Onkyo doesn't use the word "Small".  If you have a crossover set then you have designated the speakers as "Small" correctly.

    Double Bass is a terrible setting because it sends bass to the speaker and the sub and results in muddy bass in the overlap region.

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    scott benson

    @Chris. I have set my onkyo 875 up using the audessey 8 positions but it still sound better with out audessey on which is weird because the onkyo 606 with audessey sounded awesome.
    I have been told that my leather sofas could be the problem and to place the Mic in the center of the room instead and enter the distances and levels manually after.
    I understand the that i can do the distances but how would i enter the levels, should i just enter the levels it has set this time that doesn't sound right or get a meter and do it that way.

    Scott

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    Audyssey Labs

    Hi Andy,

    If you have a preference for higher-than-reference bass levels then it's best to do that in the AVR.  That way you can always go back to the original level.  2EQ will not be affected by changes in the sub level.

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    Audyssey Labs

    Hi Danny,

    If your product has MultEQ or MultEQ XT then we recommend connecting all the subwoofers (the ones in the speaker cabinets and any external ones) to the line level Sub Out of the AVR.  You will need to use y-cords for this.  The benefit of doing that is that the subwoofer channel filters in MultEQ and MultEQ XT have much higher resolution and so you will get smoother bass response.

    You will have to make sure that all speakers are set to Small for this to work correctly.  Audyssey is not allowed to make this determination.  The AVR manufacturer makes it based on the info it receives from the Audyssey measurements. 

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    Audyssey Labs

    Yes, you should change from Full Band to Small.  Onkyo doesn't use the Small notation.  You simply select a crossover frequency and that's how speakers are set to Small.  In your case I would suggest 60 Hz as a starting point.  80 Hz is also a good choice.

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    Audyssey Labs

    It will make no difference whatsoever.  If you turn it up on the back of the sub and run Audyssey again then it will turn it down in the AVR for you.  No matter where you set the volume on the sub Audyssey will always give you the same bass level.  That's what Reference means!  It's the level they were using in the studio where the content was mixed.  If you want more bass than reference then you have to turn up the sub level after Audyssey is finished.  I suggest doing that in the AVR menu so that you can always go back to the reference level any time.

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    Matt Williamson

    Hi Chris,

    I have the gain on my Outlaw LFM Plus subwoofer set to about 3.5 on the back of the sub.  I ran Audyssey several times on my Denon 591 and it sets the AVR trim to -8.  If I want to increase the volume of the sub, how many db hot can I run the AVR trim before risking my sub?  I currently am running it about 6-8 db hot in the AVR trim settings (which puts it at about 0 in the AVR).  What if I went as high as 12 db hot from where it was set by Audyssey, and the AVR trim level was up to +4, would this risk my sub?  I have scoured the internet for answers on how high I can turn the sub trim without risking my sub, but haven't found any answers.  Thanks!

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    scott benson

    hi chris, i have all my speakers bar the ffornts set to 80hz, my fronts audyssey set them as full, i have a 15" 300w rms sub and double bass selected. so the bas that the rears can cope with under 80hz will be sent to both the sub and fronts is that right.

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    Audyssey Labs

    Audyssey is not in charge of the Large/Small setting. That's up to the AVR maker.  They use 40 Hz as the decision point, so if Audyssey reports a roll off below 40 Hz the AVR sets the speakers to Large.  It's a bad idea to do this if you have a sub.  The sub is better equipped to handle the lower octave and you also get higher resolution filters in the sub channel with MultEQ and MultEQ XT.  So you should change the setting to Small after the calibration is finished.

    LFE+Main is another bad idea.  It doubles the bass by sending it to the speaker and sub even if the speaker is set to Large.  That can cause boomy bass in the overlap region.  You should only use LFE mode.

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    Barnet Feingold

    Thanks, Chris. I figured as much. That's why I wrote to you. Perhaps an answer to another question might help me choose the best way to blend my passive subwoofer with my L and R speakers.  Does 2EQ adjust at specific bass frequencies? If so, what are they? 

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    Danny

    Hi Chris,

     I have Definitive Mythos ST - Floor Standing speakers and it comes with built-in subwoofer and I dont have a separate subwoofer. Definitive suggests that the sepaker setting should be large/full band and subwoofer setting to be set as Yes in the receiver. I updated this and once I finish running the Audyssey calibration, it updates the Subwoofer setting as "No". Can I turn them back on. Whats your advise.

    Also, during movie watching, I wanted to hear the dialogue louder from the center speaker. Can these be tweaked once the setup is completed. 

    Please advice.

    Thanks,

    Danny

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    HT

    Hi Chris,

    Thanks for being very responsive all this time.

    I have a TX-SR805 and after running the Audyssey setup and it set (or maybe it's the default) the LPF of LFE to 80Hz (THX) under Speaker Config.  I know you mentioned above the LFE should be set to 120Hz.  Since this is LPF to LFE, I am not sure it is the same thing or not.  Anyway, should I override this setting and set it to 120Hz.?

     

    Thank much

    HT

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    Audyssey Labs

    You are fine.  This is still in the range that the AVR can compensate.  You only need to turn down the sub level (and run MultEQ again) if the reported level is –12 dB.  Then you are at the limit of the AVR range and don't know if more adjustment may be needed.

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    Audyssey Labs

    Yes, that's what it means.  The sub will also be 5 dB hotter than the other speakers (i.e. not how the content was mixed).

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    scott benson

    what even if my main speakers have 15" drivers.

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    Robert M. Bridi

    Thank you very much Chris.  This is very helpful.

    By the way, Audyssey in general has greatly improved the sound in my room.  Thank you for this excellent product.  I will not buy a receiver without Audyssey.

    Rob

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    Audyssey Labs

    If you have a subwoofer in your system, you should always use bass management in the AVR.  Unfortunately this is not always the default setting and several manufacturers still insist on setting speakers to “Large” or “Full Range”.  Doing so will prevent bass from being redirected to your subwoofer from the satellite channels.  Audyssey recommends to manually change all speakers to “Small” (i.e. set a crossover frequency for each speaker in the manual settings menu) thus enabling proper bass management.  This has the additional benefit of much better low frequency correction because MultEQ uses filters with 8x more resolution in the subwoofer channel.  More information about this can be found on our blog post here.

    The LFE signal and the bass management crossover are two different things.

    The crossover is responsible for taking the bass from the speakers and sending it to the subwoofer.  That should be set at around the frequency where your speakers are no longer able to reproduce bass.  This is called the crossover frequency.

    In 5.1 content, there is an additional bass-only track called the LFE track.  This is not played from the main speakers, but only from the subwoofer.  This track is authored to have content up to 120 Hz and so the filter in the AVR called LFE Lowpass should be set to 120 Hz. Always.  It is a mistake for AVR makers to even make this an option as it has nothing to do with bass management.

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    Audyssey Labs

    Hi Barnet,

    When connecting the speakers to the sub, the AVR doesn't know there is a sub in the system and so it can not perform bass management.  This can be a drawback because the analog filters in the sub that are now in charge of blending with the main speakers are usually not of sufficiently high order to perform a proper overlap.

    In any case, my preference is always for the deepest possible bass extension.

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    Danny

    Chris, 

    Definitive advises to set speakers to Large/Fullband for MYTHOS ST. Is it Ok to set them as small.

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    Audyssey Labs

    Yes, you should override and set to 120 Hz.  In fact, this should not even be a setting in AVRs...

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    ashley ashna

    So if I wanted, I could actually turn it up a bit more and run Audyssey again?

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    Audyssey Labs

    Hi Matt,

    I'm sure Ed is concerned about feeding the sub too high of a signal.  I've never seen this as a problem and always prefer the convenience of being able to precisely control the sub level from the AVR.  But, the other way is fine too.

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    Audyssey Labs

    It's up to you.  Sending bass to the sub has two benefits: (1) you get more headroom by using the sub amp for the low frequencies and more importantly (2) you get much higher MultEQ filter resolution in the sub channel so this will give you smoother bass.  Audyssey recommends against setting speakers to Large/Full Range if you have a sub in the system.

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    Audyssey Labs

    Scott, levels and delays are an insignificantly small part of what Audyssey does. There is no rocket science there. Anybody with a tape measure and an SPL meter can do it.  The trick is in the acoustical correction.  In the 875 you have much higher resolution filters than the 606 so you should be getting much closer to reference.  But, maybe your own preference is different. Audyssey can't really help with that... 

    If you are placing the mic at ear level in the positions specified (all of them--not just 2 or 3) then you should be getting the correct acoustical calibration.  The leather sofas are not an issue.

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    John Raines

      I currently do not have a subwoofer.  Because of this I'm wondering if MultiEQ will still run or do I need to do manual settings.  Also, should I run my L & R mains as "large" or "full range" (not sure which term my AVR uses yet) to have the bass ran through them?  Any help is appreciated.

     Thanks,

    John

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    omkar

    hi chris,   so if i have a subwoofer that can only go to 85hz and i set my onkyo 607 LFE to 120hz,  am i missing some of the sound track in a 5.1 movies?  is it better  to buy a sub that goes to 120hz or am not missing much?

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    Audyssey Labs

    Small only has meaning if you have a subwoofer in the system.  If you have a system with MultEQ or MultEQ XT then we strongly advise to connect the woofers as subwoofers.  In other words, connect them with a y cord to the Sub Out of the AVR and make sure that the speakers are set to Small once the calibration is finished.

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    HT

    Thanks Chris.

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    Audyssey Labs

    Hi Mark,

    Audyssey doesn't set Large and Small.  Denon does.  They use 40 Hz as the decision point and so if the speaker was measured to roll off there (or a little below due to wall proximity) then Denon sets it to Large.  We disagree because then no signal goes to the subwoofer. So, yes, after the calibration is finished go ahead and set it to Small.  That way the content below the crossover point will be sent to the sub where the MultEQ filters have 8x higher resolution.

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