TOA hb-1 Manuel D’Utilisation
10
8. CROSSOVER CONNECTIONS WITH A FULL-RANGE SPEAKER
8.1. Recommended Filters for the HB-1
• Because the HB-1's enclosure construction is designed to create an acoustic band-pass filter, the mid and
high frequency audio ranges are cut even if the input signal band is not limited with a low-pass filter.
Therefore, the HB-1 functions as a sub-woofer with no filtering.
Therefore, the HB-1 functions as a sub-woofer with no filtering.
• The speaker driving efficiency can be increased by inserting a low-pass filter before the power amplifier to
cut the mid and high frequency components of the input signal to the sub-woofer.
• The following filter settings are recommended
when using a digital signal processor for the
HB-1's signal system:
HB-1's signal system:
High-pass filter (– 12 dB/oct):
Cut-off frequency=40 Hz, Q=1.0
Cut-off frequency=40 Hz, Q=1.0
Low-pass filter (– 12 dB/oct):
Cut-off frequency=100 Hz, Q=1.0
Cut-off frequency=100 Hz, Q=1.0
8.2. Level Balance and Polarity
When using the HB-1 in combination with TOA's F or H series Full-Range Speakers, adjust their level balance
or polarity depending on the conditions of the installation location.
or polarity depending on the conditions of the installation location.
8.2.1. Level balance adjustment
Adjust the level of the sub-woofer or full range speaker depending on the number of units to be installed or
installation conditions.
installation conditions.
8.2.2. Polarity adjustment
• Acoustic energy increases at the crossover band for the sub-woofer and full-range speaker if the two
speaker are in phase with each other, and decreases if out of phase. Because the phase characteristics of
both the sub-woofer and the full-range speaker vary continuously depending on frequency, simply matching
the connector polarities of the sub-woofer is not always the best procedure.
both the sub-woofer and the full-range speaker vary continuously depending on frequency, simply matching
the connector polarities of the sub-woofer is not always the best procedure.
• To confirm how much the acoustic energy increases or decreases, reverse the polarity of the sub-woofer's
"+" and "–" connectors and select the connection polarity that results in the largest output of acoustic energy.
(The use of a real-time spectrum analyzer to check the degree of energy increase is highly recommended.)
(The use of a real-time spectrum analyzer to check the degree of energy increase is highly recommended.)
[dB]
+20
+10
-10
-20
-30
-40
0
20
50
100
500
1k
5k
10k
20k
[Hz]
Frequency-to-gain relationship
HB-1's cross section
[dB]
110
100
80
70
60
50
90
20
50
100
500
1k
5k
10k
20k
[Hz]
Frequency-to-SPL relationship
(1 W 1 m, 1/2 free sound field)