http://www.mh-audio.nl/ob.asp Also called a dipole speaker. Used very commonly up until the 60’s in hifi applications, so probably why its not “heard of”, But modern high end open baffle designs are around and theres plenty of people that enjoy diy’ing them. They’re simply just a baffle with no enclosure. Out of phase Highs and mids are directional and pointed away, so with proper positioning, they blend in nicely with the liveliness of a room. Although stereo imaging takes a hit (worked plenty well in the mono days). The folded version was just to conserve space and common to table radios, although too deep the box acts like a horn on mids.
Lows will bend around the baffle and interact with front of the speaker, but the size of the baffle influences what size wavelenths shift enough in travel to not cancel out. The floor itself acts as a baffle extension, and having just one dimension large enough (usually height) to shift the desired lowest frequency works well, as it negates the other dimension’s cancelling shortness. So they can actually have good low frequency response when done well.
As to the speakers, at one point in time speakers were speakers. They weren’t engineered for a flat response, commonly stiff suspension (work great for open baffles, usually best without the air spring in a sealed enclosure), accordian surrounds for excursion, and they had all kinds of distortion modes and breakups characteristics up and down the frequency range and at any volume. Leo fender pulled regular speakers off the shelf to make his first amps, and their poor design by modern hifi standards made them perfect to fill out and color the voice of a guitar. In fact regular woofers back then had high mid bumps that accentuated guitars, and roll offs that killed unpleasant high frequencies and low rumbles. They distorted, making the thin guitar output sound full.
Eventually hifi became a real science towards the 70’s, T/S parameters were introduced, and hifi speakers diverged. Guitar speakers retained those early designs, optimizing them to handle extremely high wattages. So vintage speakers are just fine for low wattage amplified instruments. Generally you want some headroom in the wattage to accomodate sustained musical tones, vs the occasional transients in music reproduction the wattage rating is generally meant for. Theile paramaters are only relevant to bass, which these 6” phillips speakers pleasantly roll off. The low mids are more of a sensitive area.
The 12” version of my speaker were actually used in a guitar cabinet, and fetch incredible prices on ebay. Mine are pulled from a poorly designed bookshelf enclosure, and the 6” isn’t valuable, but works great for my needs.
Anyways TL enclosure design is relevant to the depth of a folded baffle acting like a horn, so it helps immensely that you suggested that, thank you.
