I bought this Argosy enclosure a while back. Someone put a small speaker in it using a baffle. I am putting in this 12" Utah coaxial. The rectangular hole at the bottom of the enclosure makes me wonder what it is for. Is it a port or an opening for a horn speaker? What puzzles me is that the hole is at the bottom of the enclosure, to me indicating a port. Most midrange or tweeter speakers seem to usually be situated toward the top of the enclosure. Can anyone set me straight?

Most likely a port. It wouldn't do very much as most ports require a tuned duct to properly radiate bass notes. Thats a simple explanation. I'm sure more learned members can expound on it.

https://en.wikipedia.org/wiki/Bass_reflex

Early incarnations of this speaker concept didn't use an internal tube. I have a 1937 Motorola 10Y1 with nearly
exactly the same configuration: sealed speaker enclosure, with 12" speaker above a rectangular port cut in the sound board below the speaker.

I too have a few enclosures that have this rectangular "port".

steve

No horn has been there due to the absence of mounting holes visible. I would say that after you put in the damping materials you could always experiment and see if it sounds better with the hole covered or open. But also if it was scientifically designed it's size might have been determined with a specific driver in mind. But the fact is that alot of old speakers were cut and try or a compromise design, anyway.

Ya, port is most useful so long as the enclosure is sealed. If the enclosure has an open back there may be slight loss in bass response. probably not even noticeable.

In my teens I made enclosures for friends. Fully enclosed, fiberglass lined had a port opening based on the remainder of sq.in. of the speaker diameter incised into the square of the speaker diameter. about 31 sq. in.They were quite effective using cheap 10-12" speakers. Friends had only 5 watt amps so it worked well.

YMMV

The enclosure has a back, and also fiberglass insulation.

When the port works right, the sound from it reinforces the sound from the cone.
You can play with the port size making a sliding panel that changes the area.

My 12Y1 has the same thing. A previous owner replaced the grill cloth and backed it with cardboard. They didn't cut holes for the speaker and port.

I have a mid 50's Zenith console that has one of those ports which I bought several years ago.

Original speaker was shot so I put in a vintage 12" speaker (forget brand, but it isn't one of the well known ones) and a better cone tweeter.

The speaker when driven by an external amplifier (amp section being reworked into a higher powered amp while keeping the tuner fully functional) sounds great with excellent bass response.

Sorry, broken link. Please remove this post, thanks.