Crossover Frequency, Polarity - ELAC Bass 130 Active Safety Instructions

Crossover Frequency, Polarity

The Crossover Frequency defines that point in the sound spectrum, below of which the Subwoofer responds and above which
his response is increasingly reduced. The adjustability of this point (together with the Level) allows a harmonic tuning of the
complete system including personal preferences.
In order to have a good start during hookup, you can use the following table as a preset:
main speakers
a) miniature or general purpose (not HiFi)
b) small satellite speakers
(like ELAC M Sat 40, COOL, Dipol 40,
M Sat 60 (60 II), Dipol 60 (60 II), Dipol 60/4)
c) larger bookself speakers,
smaller floorstanding models,
most ELAC models
incl. Elegant 305 (305 II), Little Wonder
d) state of the art audio system
under favorable room conditions
e) Surround system, Bass 130 Active
parellel to the main speakers
f) Surround system, Bass 130 Active
at specific subwoofer output
These recommendations give hints for typical conditions. Following detailed listening tests with the actual system, any better
working adjustment can be choosen.
The "POLARITY" (or: relative phase) has a similar important effect on the harmonic combination of main speakers with a
Subwoofer.
In order to benefit from the more favorable of the two Polarity choices, the small sliding switch on the back of Bass 130 Active
should be switched at least once during the hookup phase. If this procedure seems to be questionable at first sight, one
should know that there are many sources for difficult to predict phase relationships:
* Many different design, tuning and filtering variants of low freqency drivers + cabinets
* the absolute and relative position of main speakers and subwoofer
* the individual room character acting on these and the listeners position
Important is the impression at your preferred listening place. It is nonsense to make decisions on the sound as perceived
directly behind the Subwoofer during switching. At this stage it is fine to have a second audiophile person for help.
Music or sound tracks with a broad and even distribution throughout the bass and lower midrange are best suited as program
material for alignment purposes. Short bursts (like isolated percussion or explosions) or low bass only are less helpful. Test-
CD's with low frequncy noise signals will make the Polarity alignment most easy. Ask your audio specialist.
In the ideal case one of both polarities will give the clearly stronger reproduction of all low frequencies so that the decision is
easy. You should fix the found switch position against further misplacement for example with adhesive tape. Later small
adjustments of Level and Crossover will not have much influence on the phase relationships.
But sometimes the difference between both polarities will be smaller and the choice becomes a matter of taste, for example
a stronger bass but less "warmth" in the lower voice range (and reverse). If you have the space and like to offer your ears the
absolute maximum additon of Subwoofer and main speakers (what is not always the optimum), you should move the
Subwoofer -- starting from the original location -- about 0.5 - 2 m (depending on crossover) forward or backward relative to
the main speakers, so that one of both polarities will become the unquestionable "better" one.
The antipathy among purists against "wrong" polarities (signal inversion) has to be overcome, it is not justified in our case of
single, bandlimited units playing within a multiway speaker system. By inversion of a single unit (or two in stereo) the music
will not play abruptly "the wrong way round", at least not less correct as in the plus polarity.
Long experience seems to confirm more the contrary: In about 60% of all real situations a signal inversion produces the more
effective teamwork.
Crossover Frequency at ELAC Bass 130 Active
32
180 - 125 Hz
125 - 80 Hz
80 - 50 Hz
50 - 40 Hz
as b) or c)
180 - 100 Hz