Acoustic column speakers?

[walpurgis]

Has anybody experimented with folded acoustic column loudspeakers? NOT transmission lines, tapered or otherwise. I'm referring to 'organ pipe' type designs.

I'm interested in line lengths and what happens at what frequencies. I can't find any info on the net, but do recall reading about this years ago.

Obviously, full wavelength lines would be too big, but is there a way of tuning shorter lengths to partly match the phase of fundamental bass frequencies?

And no, I don't want to build a 'reflex' phase inverting box :).

[walpurgis]

Any thoughts anybody?

[Macca]

It's not a concept I'm familiar with

Your talking about a pipe, like an organ pipe, driven by backward pressure from a driver, to produce a single low frequency note, but with multiple pipes to cover all the LF?

[walpurgis]

Your talking about a pipe, like an organ pipe, driven by backward pressure from a driver, to produce a single low frequency note, but with multiple pipes to cover all the LF?

Correct, But a single pipe. I know it's been done, I read about it years (and years) ago. Obviously, a full wavelength pipe with the same cross section area as the bass cone would be huge. I'm wondering how it was done to fit in a usable sized box. Small bore pipe perhaps? Using a half wavelength pipe would double the line resonance frequency, so that's no good.

I assume the best would be for the line resonance to be slightly lower than the natural resonance of the driver, that way the line resonance can be placed in the low frequency roll-off of the driver avoiding a big bass hump and still producing sufficient energy to excite the line .

[Barry]

The only thing I can think of is the Voigt tapered quarterwave line: http://janbatist.narod.ru/Sound/4SubwofersRouporsFaziki/ExperimentswithTaperedQuarterWavePipes.htm , but part of it is loaded with absorbing material, and uses more than one driver.

Or there is this: https://www.ejjordan.co.uk/project-bib/ , again a folded tapered horn, but with only one driver and the addition of absorbing material is "stuff to taste" (?!!!).

[narabdela]

These used to discussed, and plans published, in Hi-Fi mags back in the golden age before the Linn/Naim coup d'etat.

[walpurgis]

These used to discussed, and plans published, in Hi-Fi mags back in the golden age before the Linn/Naim coup d'etat.

I know. I do remember seeing this type of speaker discussed, I may even still have relevant articles somewhere. Still looking.

And it wasn't a quarter wave horn. That was a very popular type in the fifties and sixties and before.