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.
HB-1's cross section
[dB]
110
100
90
80
70
60
50
Frequency-to-SPL relationship (1 W 1 m, 1/2 free sound field)
20 | 50 | 100 | 500 | 1k | 5k | 10k | 20k |
| | | | | | | [Hz] |
•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:
High-pass filter (– 12 dB/oct): Cut-off frequency=40 Hz, Q=1.0
Low-pass filter (– 12 dB/oct): Cut-off frequency=100 Hz, Q=1.0
Frequency-to-gain relationship
20 | 50 | 100 | 500 | 1k | 5k | 10k | 20k |
| | | | | | | [Hz] |
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.
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.
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.
•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.)
