THX ARENDAL, Handbook

Page: 32 / 48

Positioning - How to cope with walls and
fl oors
We recommend a minimum 20-30 cm between the
front wall and the rear of the speakers. Any closer than
this will make the speakers sound muddy in the lower
midrange and thicken the upper bass, making voices and
instruments generally sound congested and indistinct.
Although Arendal Sound speakers are engineered to
ensure a reduced amount of upper frequency energy is lost
sideways and that which is, is engineered to be of equal
power across as wide a range of frequencies as physically
possible, further from a sidewall is always better. The
energy refl ected from the sidewall effectively creates a
wider phantom speaker between the point of refl ection
and the real speaker. If you add that time delayed version
of the sound to that arriving direct from the loudspeaker,
it will not only make the sound busier and less clear, it
will blur the size and positioning of images across the
soundstage, as well as making the extreme left and right
of the soundstage dominate over the central images.
One set of refl ection points you really can’t avoid,
wherever you point your loudspeakers, is the fl oor. We
strongly recommend a rug positioned across the fi rst
refl ection points. If you wish to know where these points
are, place a mirror on the fl oor and the point at which you
see the tweeter refl ected in the mirror when seated in the
listening position, is it. Use a bit of tape to mark the point
and repeat for any of the other listening positions and for
all of the front speakers. You will then see the area that
needs covering and add 30cm in all directions for good
measure.
Of course, this ‘good practice’ of soft furnishing the fl oors
fi rst refl ection points, also applies to the walls we’ve
previously mentioned. However, hanging rugs or other
soft sound absorbing items on walls is rather a matter of
taste; or lack of, depending on your point of view.
None the less, the methods described for the fl oor apply
equally to the walls and at least one wall will generally
have a window, that is even worse in acoustic terms than
a painted wall. If that window has curtains, then the
room will sound better with them closed. Whilst we’re
getting picky - are you sitting on a leather sofa? If so, the
hard surface of the leather places a mid-high frequency
refl ection point right behind your head. Cover it with
something soft and it will have a positive impact.
If you’re lucky enough to have a dedicated room, then
easily one of the biggest upgrades you can make to any
system, is to add proper room treatment. It’s slightly out
of the scope of this guide, but there is a massive range
of pre-made and DIY solutions available. Backed with
research and/or professional guidance, engineering the
correct blend of absorption, diffraction and refl ection
can have an absolutely staggering effect on the quality of
reproduction of even modest systems.
Getting back to the speaker positions; One fi nal
consideration, is try and ensure that ideally, the relative
distance from the fl oor to the centre of the bass drivers, is
not equal to the distance to the front wall behind and in
turn, that the distance from that point to the sidewalls is
different again. This has to do with the way bass refl ects
and reinforces/cancels within a room and by randomizing
these distances, you are helping to spread out and reduce
the impact of these room (not speaker) related artifacts.
It’s just a logical extension of the golden ratios employed
in ideal listening room dimensions to achieve exactly the
same end.