ELAC Bass 130 Active Safety Instructions page 29

Acoustical Setup Reference
distance between parallel walls
10 m
8
6
5
4
3
2,5 m (room height)
Thus under practical conditions the effect appears exactly in the range where a Subwoofer should show his strength. It is
valid for all boundary planes, even between floor and ceiling, if they are of solid construction.
But the remedy is simple: A slight moving of about 50 cm out of the center is sufficient to hear the low bass again.
If the listener is sitting directly in front of a wall (the other extreme), bass reproduction is often too heavy. This can be
balanced by reducing the Level and Crossover Frequency at the subwoofer. For all higher frequencies and a more natural
space impression however, it is better to move the listening position into some distance from all walls.
Acoustical theory of low frequencies in small closed rooms tell us, that the location of listener and subwoofer could be
exchanged against each other. The same rules apply; for example, you can place the speaker at the preferred listening
position, then move around to look for the location with the "best" bass sound and finally place the speaker there.
Under real world conditions this is only partly true (and you should never try to judge bass sounds without main speakers),
but, as for the listener, also for the Subwoofer himself exact center positions in small closed rooms should be avoided.
Because of adjustability and a clean cut frequency range the ELAC Bass 130 Active can make full use from the practical
benefits a location near a wall or into a corner has to offer. The necessary free rear space for cooling and cabling is 10 cm
minimum. A move much farther away from the wall is recommended only, if the polarity alternative (see there) shows no
definite advantage for either plus- or minus-position.
Good bass sounds can be attained in breached, open rooms and slightly asymmetric placements. Each somewhat larger
irregularity of the building, sometimes an open door, can have a surprising, mostly positive effect.
Under practical conditions the ELAC Bass 130 Active will not be localized by ear and therefore has not to be placed exactly
between the main speakers.
A position at one side wall, even behind the listener, is no general problem, especially if the crossover frequency is low.
The freedom of Subwoofer placement has only one serious limit: The Subwoofer should not be much nearer to the listener
than the main speakers (max. 1 m). Rather a larger listener distance is preferable, i.e. a position behind the main speakers
up to ca. 1 m, from special Subwoofer outputs and reproduction of Surround Video effects up to 3 m.
Not only the max. sound pressure, but also the bass quality can still be improved by using a pair of Bass 130 Active.
If both Subwoofers are working from one source (Mono), it has benefits to place the second unit not directly beside the
first, but as asymmetric as possible to all other speakers. In this way especially small rooms gain a smooth, less resonant
bass quality, which otherwise is a feature of larger, more open rooms.
On the other hand, with two Subwoofers in a true Stereo mode, it is better to keep similar distances to the main speakers
and the listener; difference in listener direction: max. 0.5 - 1 m, depending on Crossover Frequency.
If two Bass 130 Active work in parallel (or Stereo), both should run with the same adjustments.
According to the newest, digital Home Theater standards (e. g. AC3), effect speakers in Surround sound systems have
to reproduce signals with full dynamic and full audio bandwith. If you really like to have the perfect impression of a
helicopter crossing through the room, you should have a subwoofer for the rear channels too. If a second (or third) Bass
130 Active (Crossover Frequency approx. 100 Hz) seems to be a little bit overqualified for that purpose, ELAC's passive
subwoofers will do a fine job. Recommended combinations with ELAC effect speakers:
Bass 2-50 or 2-60 with Dipol 40
Bass 2-80 with Dipol 60/Dipol 60 II, Dipol 60/4
m
m
m
m
m
frequency of pressure minimum exactly
midway between the walls
29
17 Hz
21 Hz
29 Hz
34 Hz
43 Hz
57 Hz
68 Hz