Subwoofer setup and MultEQ

Many powered subwoofers have controls that are set manually.  It's important to follow some simple guidelines to avoid having these controls interfere with proper subwoofer calibration and integration with the satellite speakers.

  1. If the subwoofer provides a direct input (sometimes called LFE input) then it should always be used.  That input bypasses the filters in the subwoofer and allows the bass management system in the AV Receiver to operate properly
  2. If there is no direct input, then the lowpass filter knob on the subwoofer should be permanently set to the highest frequency it allows.  That way it will not interfere with the MultEQ measurements and bass management
  3. The level control on the subwoofer is often set too high.  This can cause the AV Receiver to run out of level correction range when MultEQ tries to set the subwoofer to reference level.  Set the subwoofer level control to the midpoint.  If MultEQ reports high negative trims (e.g., –12 dB) for the subwoofer, then you should turn the level control further down and run MultEQ again
  4. If there is a Phase control on the sub it should be set to 0°

If you have a subwoofer with room EQ, then you should run that first in the subwoofer and then run MultEQ in the AVR

If you have an external subwoofer processor (such as the SVS AS-EQ1 or the Audyssey Sub Equalizer) you should run the calibration in that processor first and then run MultEQ in your AVR

If you have two subwoofers, there are some additional steps to take:
  1. Place them at equal distances from the main listening position
  2. Set the level controls on the back so they both play at the same level
  3. Connect a y-cord to the sub out of the AVR and then connect to both subs
  4. Turn off processing in the subs as it will not be able to give you the same resolution that you will get from MultEQ (thousands of points vs. a few parametric bands)
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399 Comments

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  • 0
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    Mike Phillips

    Hi Chris,

    I've had an Onkyo 5008 amp for a couple of years and been using it with a 9.1 speaker configuration with a single sub.  Late last year I changed the sub for a larger unit (a BK XXLS400) so I re-ran the MultEQ set up using 8 mic positions. The sub has a switch described as a 'Filter Bypass' which, according to the manual, should be set to 'out' when using an amp that manages the bass frequencies. Consequently, before running MultEQ I set this to 'out' and after the process all seemed fine. However, over a few weeks when playing back movies with an LFE track I thought I noticed some occasional distortion on some very low frequencies, so I downloaded some test tones to check the sub out.

    Running the tones there is noticeable distortion on frequencies around and below 40Hz when played back at volumes approaching and above reference level. It is quite alarming as, at first, it sounds like the speaker cone is vibrating uncontrollably. However, on closer listening the bass note actually starts to change its tone as the volume increases; when getting towards reference level it is no longer a steady note but what sounds like a variable tone, like a deep 'warble'.

    I assumed that there was some fault with the new sub so reconnected my old unit and ran the test tones, which played perfectly. Both the new and old sub are made by BK so have the same control panel and the same 'Filter Bypass' switch but noticed that on the old sub, I'd inadvertently left this turned to 'In', despite the instruction to set it to 'Out'. Reconnecting the new sub I then turned the Filter to In and played the test tones, which were perfect. Switching it to Out reintroduces the distortion.  However when its 'In', playing back movie soundtracks have no distortion at all and the system sounds great.

    The easy solution is, of course, to leave the Filter set to In and re-run the MultEQ set up. However I'm baffled by why selecting what is apparently the right setting introduces distortion and would be very grateful for your input. I'm more than happy with the sound of my system with the switch in the wrong position, so if you advise to leave it like that, I'll just run the EQ again and sit back and enjoy it!

    Many thanks

    Mike.

  • 0
    Avatar
    Audyssey Labs

    Hi Mike,

    The notation is confusing.  I would think that in order to put the Sub in Filter Bypass mode you would have to set the switch to "in".  You should check with the manufacturer to be sure.

  • 0
    Avatar
    Mike Phillips

    Thanks for your quick response Chris. I'll ask BK for their advice and meanwhile I'll re-run the EQ set up with the switch in the 'in' position.

  • 0
    Avatar
    Varinderpal Choat

    Hi,

    please can you kindly check what I'm about to do is correct. 

    A rear picture should help: http://imgc.classistatic.com/cps/blnc/120418/082r1/4895c7c_20.jpeg

    I am going to set the crossover knob to av/lfe (as opposed to 80hz or 120hz).

    & please you clarify what to do with the knob next to it ( the Level AV/LFE knob).

    thanks.

  • 0
    Avatar
    Audyssey Labs

    Yes, the crossover knob should be set to LFE so no filter is applied.  The Volume knob next to it should be set to just under the midpoint so that the AVR has enough range to set the proper sub level.

  • 0
    Avatar
    HT

    Chris,

    My sub (and many others) has the crossover nob from 80 to 120hz instead of what in the picture.   Should I change it to 120hz?

    Thanks

    HT

  • 0
    Avatar
    Audyssey Labs

    Your sub should never ever be in charge of the crossover.  The analog filter in the sub is not even a real crossover.  It's just there for people with old analog gear that have no bass management.  If there is no setting that turns off the sub filter, then you should set it to the highest available frequency so that it's out of the way and doesn't interfere with proper operation.

  • 0
    Avatar
    Varinderpal Choat

    Another question I have is more concerned with room dimensions & mic positioning.

    The problem is where the sofa is situated (right up against the rear wall). Our ears are 30-35cm from the rear wall and of those 30cm the rear speakers protrude 12cm of this space.

    Should I take measurements at normal ear height since the chair is hardly far from the wall or raise the mic above the chair?

    Could you advise me how to make the most of the situation at the rear of the room & your thoughts on which positions from the respective diagram would serve best.

    http://www.audyssey.com/audio-technology/multeq/how-to

  • 0
    Avatar
    Audyssey Labs

    I suggest using the pattern shown in the diagram.  However, move mic positions 7 and 8 forward so they are 40-50 cm from the back wall.

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