The Talking Machine Forum — For All Antique Phonographs & Recordings

You know the re-entrant horn technology is still used in speakers such as the Klipschorn, but only for low frequencies.

The Bose "soundwave" speaker system is not an exponential horn. It most closely approximates the "transmission line" type of speaker enclosure. This technology predates Dr. Amar Bose by decades, so he didn't "invent" it, either. The idea is that the mass of the air in the transmission line (similar to a ducted port) loads the speaker cone and reduces the system resonance to increase the bass performance. That, plus GOBS of electronic equalization and a big power amplifier is the basis of the new Bose system. The earlier Bose "direct/reflecting" systems, most notably the model 901 were merely lots of little speakers in a smallish box that achieved bass purely by the application of GOBS of electronic equalization. Listen to a 901 system without the external equalizer and it sounds like a table radio - there's nothing special about the acoustics.

I can add a new entry into my book of things I didn't know that I didn't know.

Shane,

that is a great cutaway re-entrant horn you have! Where did you ever find that?

Regards, Glenn.

It's from the EMI site.

I understand the basic idea of how these horns increase in width as they progress away from the sound source, and how they are folded up to conserve space, but I never understood the reason why they are called "reentrant" per se.