Do you have a question about the Altec 815A LF SPEAKER CABINET and is the answer not in the manual?
Details the ALTEC 815A Low-Frequency Horn's design for directivity and uniform response.
Technical details for the ALTEC 815A horn paired with ALTEC 421A speakers.
Technical details for the ALTEC 815A horn paired with ALTEC 515B speakers.
Recommends an 18 dB/octave high pass filter with a cutoff frequency of 70 Hz.