Directional Bass – Achieving Even Coverage


Denon and Marantz have released Directional Bass for their new line of receivers. We discussed this briefly in our Denon and Marantz receiver comparison articles.

As Tyler discussed in our Directional vs Mono bass article, one of the main issues with Directional Bass is the lack of even bass coverage and response within the room.

To achieve an even coverage and response for multiple listening positions in a room, you normally need multiple subwoofers playing the exact same signal and equalised across the listening space. This is what a manual calibration, a calibration with Multi-Sub Optimiser, Audyssey’s MultEQ HT and Dirac’s Bass Control are all trying to achieve.

Now along comes directional bass. The whole idea behind directional bass is that the room is split up into zones and bass from the main speakers (that are not set to full range) is re-directed to the closest subwoofer.

The LFE information – the .1 in 5.1, etc. – is being played back across all the subwoofers even if set to directional bass, so in theory you could still equalise the subwoofers for even coverage for the LFE signal.

Unfortunately, this is not the case for bass from the main speakers, as the bass signal only played by a single subwoofer would be unfavourably affected.

The Solution

One possible solution to this problem would be to use multiple subwoofers per zone and equalise each set of subs for a zone together. To do this with 4 subwoofers, for example, you could

  1. Set your AVR for 2 subwoofer outputs (2 subs)
  2. Set directional bass to on
  3. Set up two zones: either LEFT / RIGHT or FRONT / BACK
  4. Feed the two independent subwoofer signals (one for each zone) into a 2x4HD MiniDSP unit. Then within the unit, you split the signal across two subwoofers per zone and equalise each pair of subs / each zone for even coverage across the room using Multi-Sub Optimiser (MSO). This is possible as the 2x4HD has two inputs and four outputs.
  5. If you need more subs (for example because you are using four zones), you could use a larger MiniDSP unit (although the 4x10HD is out of production now) or multiple 2x4HD units

This way, you COULD have your cake and eat it too: directional bass, but also even coverage.

To learn more about MSO, see our article about it here.

Closing Thoughts

I am not fully on-board with Directional Bass, simply because the research isn’t there to support that we can hear bass direction in our normal listening rooms. This of course may change once the time-domain issues are fully controlled using active room treatment.

However, as it stands today, that isn’t the case. So when a system is fully in phase, our brains interpret anything under 80Hz (possibly even higher) to come from the direction of the main speakers – as long as the higher-frequency cues are delivered with correct timing and phase.

However, for larger listening rooms with multiple rows of seats, this might be a bit more difficult to achieve if the bass waves only originate from the front of the room, since cues coming from the surround speakers may not be in time and at the correct phase for all listeners, as the direction of sound comes from two different locations.

While this might not be a limiting factor in performance currently, it might be in the future. Especially as Room Correction systems such as Dirac’s Active Room Treatment achieve better time and phase-alignment, along with lower ringing, these time and phase-alignment issues across the listening space might be easier to hear as residuals.

In such a case, front to back – and left to right – directional bass might be appropriate, as long as they are delivered by groups of subs equalised together, as discussed in this article.

That is unless Dirac’s Active Room Treatment can achieve both without doubling up on subs per zone. We will wait and see!

Leave a Reply

Up ↑

%d bloggers like this: