Bass integration guide

aeroash

Well-Known Member
Joined
Oct 11, 2010
Messages
647
Points
93
Location
Mangalore
While testing and calibration with proper measuring equipment will always remain the ultimate way, for those without any measuring equipment, this guide from JL Audio is simple, effective and has helped me immensely.

"Most" subwoofer "issues" stem from the subwoofer being out of phase. The first step will always be to find the best location for the subwoofer, achieved through the sub-crawl procedure.

Note: edited original JL Audio text for clarity.


Adjusting Phase Alignment between the Main Speakers and Subwoofers
When adding a subwoofer to a home theatre system or two-channel audio system, adjustments of the subwoofer’s level and phase settings are critical to achieving optimum performance. When performed properly, perceptible improvements in frequency response, imaging, dynamic range, and impulse response can be achieved, with distinctly audible results.


Initial Setup
Set the desired low pass crossover frequency to be used on only ONE of the following:
  • The bass management controls on the receiver or preamplifier/processor
  • The crossover settings on an outboard active subwoofer crossover

Adjust the settings for the subwoofer:
  • Set the Level Mode to the Variable position, if equipped. Turn the master level all the way down.
  • If using the bass management crossover in a receiver, preamplifier/processor, or outboard crossover, set the LP Filter to Off.
  • For home theatre systems, temporarily set the receiver or preamplifier/processor to Stereo mode.
  • Set the ELF to 0, if equipped.
  • Turn the Phase knob fully counterclockwise to 0.
  • Set the Polarity switch to the 0 position.

Adjustments
Perform the following procedures in order, one channel at a time:

Level match the volume of the main speakers and subwoofer
  1. Disconnect the main speaker that is furthest from the subwoofer. For a system with two subwoofers, disconnect one main speaker and turn off the subwoofer on the same side.
  2. Play a test tone of the selected crossover frequency or low pass filter setting at a medium volume level. Link to TEST TONES
  3. Sit at a centre position in front of the main speaker and subwoofer. With your head placed equidistant from each, slowly adjust the subwoofer's level control and notice the tone level transition from the speaker to the subwoofer, and back.
  4. Set the subwoofer level control at the position where the speaker and subwoofer appear to have the same volume.

Align the phase of the main speakers and subwoofer
  1. Reverse the polarity of the speaker by connecting the positive speaker wire to the negative terminal and the negative speaker wire to the positive terminal.
  2. Return to the centre seating position in front of the main speaker and subwoofer. With your head placed equidistant from each, slowly rotate the subwoofer's phase control knob clockwise and notice the bass drop off significantly, then begin to rise. With the speaker and subwoofer playing the test tone at the same level, but 180 degrees out of phase, a null point is created, and the bass cancellation should be easily discernible.
  3. Set the subwoofer's phase control at the position where the bass appears to have the LEAST amplitude.
  4. Reverse the polarity of the speaker again by connecting the positive speaker wire to the positive speaker terminal and the negative speaker wire to the negative speaker terminal.


Repeat the process for the opposite side if a second subwoofer is being used.

Ideally, if you have a friend available to assist with this procedure, you can improve the outcome by listening from your favourite chair while the volume and phase adjustments are made, as the results might be slightly different between the two locations.

Upon completion of the phase alignment procedure, the subwoofer's level control can be adjusted to the desired position.
 
Last edited:

liverpool_for_life

Well-Known Member
Joined
Feb 2, 2015
Messages
1,036
Points
113
Location
Madras Nalla Madras
While testing and calibration with proper measuring equipment will always remain the ultimate way, for those without any measuring equipment, this guide from JL Audio is simple, effective and has helped me immensely.

Fair enough. No issues with your experience. Any improvement to the bass contributes to an enriched audio experience.

However, I'm of the opinion that anyone that has a subwoofer (or two or four) in their room needs to have measuring equipment of some sort just to see how the room affects what they're hearing in the modal region. "By ear" may well get one to non-offensive or even pretty decent bass. Ultimately though, in the absence of a processor with Harman's SFM or Dirac's DLBC (not sure if the issues with this have been resolved yet), a procedure like the one linked to is effectively mandatory for great/exceptional bass.

When I hear folks say that their subs and mains integrate seamlessly and have no measurements to back it up, I tend to discount those opinions pretty significantly. The oft-mentioned "test" for this integration (other than not being able to localize the sub) is to turn off the sub(s) and hear if you miss it. If any time has been spent on the integration (the procedure you'd posted or something similar), of course you will. You just removed the bass source(s), so sound is going to be thinner/anemic/lack body/lack weight. A better test is to run your mains full range and compare that with the mains crossed over to the subs. This is still a relative comparison, however. Measurements will give you a much better picture of the subs-mains integration. As always, YMMV.
 

aeroash

Well-Known Member
Joined
Oct 11, 2010
Messages
647
Points
93
Location
Mangalore
However, I'm of the opinion that anyone that has a subwoofer (or two or four) in their room needs to have measuring equipment of some sort just to see how the room affects what they're hearing in the modal region.
Agreed. A subwoofer is one of the hardest components to integrate seamlessly. Having more than one is even more painful. The guide I have posted is just a start to help a novice. Ultimately one has to rely on proper tools to measure and calibrate to realise the full potential of their equipment.

For now, I use Anthem Room Correction, which has helped flatten and smoothen the lower frequency curve. It has its limitations. I've been eyeing the miniDSP DDRC-24 to tune them further.
 

liverpool_for_life

Well-Known Member
Joined
Feb 2, 2015
Messages
1,036
Points
113
Location
Madras Nalla Madras
For now, I use Anthem Room Correction, which has helped flatten and smoothen the lower frequency curve. It has its limitations.

As does any system that measures and corrects loudspeaker responses individually. One can either go with the "subwoofer distance tweak" or the procedure you'd posted (or something similar) to allow for better combination of the subs and mains to improve things over and above what these systems give you, but that's merely a warm-up, if you will.

I've been eyeing the miniDSP DDRC-24 to tune them further.

Welcome to the rabbit hole, and better bass;)
 

aeroash

Well-Known Member
Joined
Oct 11, 2010
Messages
647
Points
93
Location
Mangalore
@liverpool_for_life I just read your thread on room treatment.
I now understand where you’re coming from with regard to Room Treatment and Measurements. That’s a monumental effort!

And I concur, getting the lower frequencies to wear tight pants and move in unison can greatly enhance the SQ.

I have recently learned that “time delay” plays a massive role and “time aligning” the speakers can fix issues aplenty!

Cheers!
 

ankitbhargava

Well-Known Member
Joined
Oct 29, 2012
Messages
1,166
Points
113
Location
Udaipur
@liverpool_for_life I just read your thread on room treatment.
I now understand where you’re coming from with regard to Room Treatment and Measurements. That’s a monumental effort!

And I concur, getting the lower frequencies to wear tight pants and move in unison can greatly enhance the SQ.

I have recently learned that “time delay” plays a massive role and “time aligning” the speakers can fix issues aplenty!

Cheers!
Time aligning mains and Sub/s has such an impact sometimes that you may feel as if you have upgraded to a new setup.

There is a scene from Movie "Arrival" where the lead characters meet in Helicopter. The whirring blades of Helicopter for 40 seconds is such an opportunity to time align your mains and the subs itself (if more than one). Your ears in this scene can tell you a lot.
 
A beautiful, well-constructed speaker with class-leading soundstage, imaging and bass that is fast, deep, and precise.
Top