Saturday, August 15, 2015

HIFI Near field listening

Are you listening to your room, when you should be listening to your speakers?

I pose this question, because I believe many music lovers/audiophiles make the mistake of selecting a far-field listening position, which forces these individuals to listen to more of the room than necessary.

For me near-field listening offers many sonic and acoustic advantages over and above far-field listening. However we need to realise that not all speaker systems lend themselves to a near-field listening scenario. Typically speakers which don't work well in near-field setup exhibit the following characteristics:

  • Large physical size 
  • Larger than normal distances between drivers
  • Reduced high frequency dispersion patterns
  • Speakers which require +2m from listener to speaker to achieve driver coherence. 

On the flip side speakers which exhibit wide dispersion, decent driver integration/cohesion and imaging, open up the possibility for near-field experimentation.

So what is near-field listening?

Near Field Listening can generally be described as a listening position relative to your speakers of less than 2-1.5meters. NFL promotes an acoustic listening scenario in which "the room" is less likely to impact on your aural experience when compared to traditional far-field positions.

Its important to note, NFL still requires careful consideration and application of acoustic treatment/principles to achieve best outcomes.

NFL is not a substitute to room acoustic treatment and optimisation.

Although the definition above is probably an acceptable technical definition, I take a slightly more "liberal" approach and application of the definition. I like to describe NFL as a listening position of less than 2meters which is equal distance to both left and right speaker positions, and the same distance again exists between each speaker (equilateral triangle). In this listening position you are also ideally closer to the speakers than you are to their nearest primary reflection point. 

Traditional Equilateral NFL Positioning..  

As you can see in the below NFL diagram, the listener and speakers form an equilateral triangle, which aims to organically optimise soundstage composure, soundstage depth and musical imaging.

Nearfield listening - Grizzlyaudio

Treating primary & secondary reflection room points to improve NFL acoustics. 
The point of this blogpost is not to provide an acoustic treatment lesson, however some basic principles need to be covered. The image below details a "standard" listening room, which has acoustic optimisation. 

Take particular notice of the primary reflection points, which occur at the mirror points between the listener and the speaker (both walls and ceiling points). Its always important to note, in near field listening scenario we are trying to position ourselves and our speakers, at a distance closer than that of the first primary mirror/reflection points, but these points need either absorption of diffusion treatment to manage acoustic reflections and bass anomalies. 

In a near-field listening scenario I suggest the following acoustic treatment be considered as a minimum, to help control primary reflections.  

  • Front wall panels directly behind each main speaker. A mix of absorption and diffusion are suitable
  • Bass Traps. Bass needs to be controlled! More bass is not necessarily the best medicine. Controlled taught and defined bass is what you are after. Try using bass traps in the corners of your space. Full height floor to ceiling and at least 600-800mm wide. 
  • Side walls @ primary reflection points, Absorption at primary reflection / Diffusion also suitable to retain air, space and life in the room
  • Back wall for primary reflection point, Combination of absorption /diffusion 
Note, NFL success will also be impacted by environmental factors including:
Room shape, ambient room noise (noise floor), room dimensions, furnishings, location of these furnishings, Floor finish, Windows? V's Plaster, etc..... Everything needs consideration ;)

Near-field listening Pro's & Con's 

In a nut shell near field listening has the following benefits over more traditional far field listening.

Higher sound pressure level per amplifier wattage (Headroom)

Inverse square law tells us, for every doubling of listening distance, there will be a corresponding SPL loss of 6db. The reverse is also true, the closer one listens to the point source the louder it will be for any given input power. This fundamental truth organically provides reduced system distortion on application.

A good link comparing listening distance to SPL

Amplifier power requirements V's distortion 

Expanding on the point above. Reduced SPL requirements, equates to reduced load both constant & transient on amplifiers. Potentially reducing amplifier distortion. Obviously not true in all scenarios.

Speaker Distortion 

Speaker driver excursion is reduced as SPL requirements are lessened for the same frequency response. Organically this limits the amount of transducer electro-mechanical distortion induced into the music reproduction.

Room Distortion | Acoustic Interaction Minimisation 

Measured at the same frequency & location, the lower a sources actual SPL, the less acoustic energy produced. This equates to less acoustic/room overlay/distortion due to less acoustic/room interaction.

Acoustic reflections at primary and secondary locations still need to be addressed (at a minimum) for best acoustic performance, but near-field listening by its very nature positions the listener directly in the source emitted sound wave for direct and reflection "minimised" listening.

Better stereo separation 

The further a listener sits from the source (speakers) the more potential for breakdown in stereo image projection/presentation.

NFL naturally promotes excellent stereo imaging/separation and arguably presents a signal which is more immediate and heightened in its detail presentation and retrieval, when compared to the same signal at a far-field listening position.

Disadvantages include: 


Depending on your room setup and furniture arrangement, a near field setup may not be possible. The wife approval factor (WAF), such a inconsistent and formidable power.

NFL requires speakers which have good/great driver integration & frequency coherency 
Speakers which have poor driver integration due to design or driver placement may not lend themselves to near field listening. This is really something that must be subjectively tested. I know from experience large JBL style monitors 43/44 series do not lend themselves to near field listening, and to be fair this was never a design intention, but this example makes my point nonetheless.

In general terms, smaller speakers with close proximity drivers work best in near-field applications. These speakers tend to have high frequency drivers with wide dispersion wave guides and/or soft dome style drivers which promote wide dispersion in the applicable driver frequencies.

Less bass due to less acoustic loading & help from your listening space   

Some users report less bass energy in near-field listening applications. I can't really say I have found this to be true, as I use dual subwoofers firing into the near-field listening position. Each subwoofer offers full manipulation of phase, polarity and Parametric frequency equalisation making mains to subwoofer phase alignment and frequency crossover much simpler. I believe this negates any potential loss of bass at NFL ranges.

I will however concede that many audiophiles may find by moving away from the traditional corner/wall loaded speaker setup, bass will be reduced. Personally, I have never been one to place speakers close to a wall or corner to enhance bottom end, as I believe soundstage and mid range clarity suffers, but nevertheless a bass reduction in this instance would be highly expected & likely.

That's enough from me,

Try NFL for yourself.....

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