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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    Andy Hill

    Hi Chris,

    Thanks for this, very enlightening!  I have noticed that the sub is better when left with the gain near 12 o'clock and it is within the range you stated. 

    But as far as my second point, if bass is a little quiet, would you recommend adjusting the AVR dB setting for the sub or adjusting the gain on the sub?

    Also, by adjusting the sub am I right in thinking this does not affect Audyssey 2EQ.

    Cheers

    Andy

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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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    Andy Hill

    Hi Chris,

    Thanks very much for your help.

    Excellent product!

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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

    Do you mean that the upper frequency of the sub is 85 Hz?  Seems unusual... But, yes, if that is the case then you would be missing anything in the LFE track that is between 85 Hz and 120 Hz.

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    omkar

    yes the Wharfedale Diamond SW150 subwoofer  i have has a a knob which you can select crossover from 35hz to 85hz, so does  this mean i can set the LFE on my onkyo to 90hz instead of 120hz?  which will help the sub crossover do less work?  thanks chris

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    Barnet Feingold

    Hi Chris,

    I have Audyssey 2EQ in my Onkyo receiver. I've been using left and right speakers that are flat to 58 Hz. anechoically and allegedly reach -3 db. at about 42 Hz. in domestic environments like mine. (I don't have a powered subwoofer.)

    I recently acquired an (unpowered)  B&W Acoustitune subwoofer, which is designed to be driven by the same amplifier(s) as the speakers whose bass it extends. I'm thus connecting my left and right speaker outputs to the Acoustitune's input terminals, and connecting the left and right speakers to the Acoustitune's output terminals.

    The Acoustitune comes with four ports that differ in length. The shorter ports render the subwoofer more efficient but "roll off" more steeply in the deep bass (relative to, say their output between 80 and 100 Hz.). The longer ports yield flatter overall frequency response. (All ports yield have similar absolute deep bass output; they differ most strongly around 80 Hz. with reduced differences in output at lower frequencies.) 

    If I were not using the Audyssey EQ, I would have to decide whether the additional output below between, say 20 and 58 Hz. that a shorter port can provide justifies  the additional "overlap" (and emphasis) in the higher frequencies. 

    How do you suggest I choose the port, given that I'll be using Audyssey 2EQ?

     

     

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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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    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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    Audyssey Labs

    2EQ was designed for AVRs that don't have enough processing power to run higher versions of Audyssey room correction.  So, unfortunately, 2EQ does not apply filters to the subwoofer.  In the main speakers it will apply correction, but the amount depends on the speaker response.  It can make adjustments to some problems, but does not have enough resolution to catch narrow peaks and dips.  You can see the relative resolutions of each version of Audyssey here.

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    Barnet Feingold

    Thanks. I hadn't realized how limited my EQ was. I'll seriously consider a receiver that incorporates more sophisticated Audyssey circuitry. 

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    Kraig L. Tytus

    Hi Chris,

    I'm pretty new to the game, and would like your advise on a setup that will best utilize both my Denon AVR-1913 and the Audyssey.

    1.I have the Definitive Technology ProCinema 600 system, DT recommended that I run my R/L front speakers into the sub then back out to the receiver for "better sound quality". Do you think I should do this or should I just go back to the standard setup of running my R/L front speakers directly into the receiver.

    1. DT also recommended that I set the crossovers for my Center, Front R/L and Rear R/L at 150hz. Not sure what I should set my sub crossovers at. What do you think?

    2. I have all my speakers set to SMALL and DT told me to set the sub to LFE+Main.

    Any other suggestions are welcome. just looking for a little clarity from a Pro.

    Thanks

    Kraig

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    Audyssey Labs

    Hi Kraig,

    1. If you want to take advantage of the higher resolution filters in the subwoofer channel that MultEQ provides then you should not connect this way.  If you do, the system doesn't know that you have a sub connected.  We recommend connecting the subs via a y-cord from the Sub out of the AVR.

    2. The crossovers for each speaker should be set based on the in-room measurements.  That's the whole point of measuring: to find out the performance of the speakers in your room.  Keep in mind that there is no such thing as a "sub crossover".  The crossover is set between each speaker and the sub.  In other words it requires two speakers: one for the high frequencies and one for the low frequencies.  The silly analog knobs on the back of subs are not crossovers.  They are there to provide some ability to extract bass from old analog preamps that have no bass management.  Not the case here.

    3. Small is the correct choice after you connect the sub as mentioned in #1 above.  LFE+Main is the wrong choice.  It should be LFE only.  

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    Mike Vlasenko

    I have avr 1713 and 2 infinity IL40 speakers. when i had that connected to sony ste-de197, the bass sounded so nice and deep, but now in this 1713 its much weaker, and i cant find a way to adjust it for more bass. I do not have a subwoofer on the side. Any thoughts? Thank you so much.

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    Audyssey Labs

    Hi Mike,

    Very often a boomy room mode is thought to be "more" bass.  MultEQ is making the bass response flat and smooth and so the lack of that boom note may take some getting used to.  I suggest you listen that way for a while to see if more notes in the bass are revealed.

    Also, please make sure you are following the instructions for mic placement here.

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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

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

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    HT

    Thanks Chris.  One more thing.  I read the guide and it states:

     

    After MultEQ is finished, check your speaker settings in the Setup Menu. If your AVR has set any speakers to “Large” or “Full Range”, change them to “Small”.

     

    Mine is currently set to Full Band and I still have bass coming out to my sub.  I don't have "Small" setting. 

    First of all, should I change it from Full Band.  If so, what number should I change it to?  The value is ranging from 40Hz to 200Hz.

    THanks again Chris.  You are awesome.

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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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    HT

    Thanks Chris.

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    WW

    From the 1st post in this thread:

    "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."

    Can a case also be made for setting the crossover frequency higher than the natural low-frequency cutoff frequency of your speakers? This would mean that the speakers would be relieved of some of their bass reproduction load, with the subwoofer taking over some or most of the bass reproduction duties. A crossover frequency of about 80 Hz would likely work quite well with many floor standing or larger bookshelf speakers. Smaller satellite speakers would need a higher cutoff frequency, of course.

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    Audyssey Labs

    Yes, such a case can be made for the reasons you state.  

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    VK

    Chris 

    Thanks for all ur assistance.

    I need some clarifications . Sorry if these are very naive questions..new to all this.

    My Onkyo 608 Multi EQ configured the speakers (Def Tech 60 series) fronts to 150Hz, Center to 120 and Surround to 100 . My sub is connected via LFE port from Onkyo . Sub is set to "yes". I understand the THX mode sets up everything to 80Hz. I was wondering considering the setup which came up ...are there any frequencies which are missing from between 130-150 (from center/fronts) which are not send to the sub.

    I have noticed that setting the fronts and center channels to Fullband makes sound richer. 

    Also , is LFE to connect the sub. I managed the bass via the bass management options to set different levels. 

    Is there a optimal way to set it this setup.

    Thanks

    VK

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    Audyssey Labs

    There are no frequencies missing.  The crossovers set for each speaker make sure that everything below the crossover frequency is sent to the sub.  If you set speakers to Full Band then no bass from those speakers is sent to the sub!

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    VK

    Thanks Chris 

    LFE to connected to the sub. I managed the bass via the bass management options to set different levels.Is this correct .

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    Audyssey Labs

    Yes, this sounds correct.  Make sure all speakers are set to Small and there is a crossover frequency set for each one.

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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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    Audyssey Labs

    Hi Matt,

    Increasing the level of the sub above the reference level set by Audyssey is a personal preference.  It's really up to you.  There is no risk to your sub as most have built-in protection.

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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

    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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