I didn't mean any disrespect to anyone, the designer, end user, or the manufacturer. In those days T/S parameters and horn design wasn't as well understood compared to what designers have at hand today. Computers have little to do with anything, except speeding up the design calculations.
When settling on a horn design, it should be tailored to the bandwidth of interest. To work low, the horn path would have to be considerably larger than what those boxes have, and additionally the horn path is going to limit any higher frequency ( 1-4 Khz) extension. Because of this, what is coming out of that enclosure is a compromise, likely a large, low mid bump with considerably less upper end detail. it may be loud, but for the purposes of micing a cabinet especially for recording, there is going to be considerable gaps in the audio spectrum relevant to bass guitar.