Here's a very good extended argument at Parts Express that you may be thinking of:
ML transmission line vs. Bass reflex - Techtalk Speaker Building, Audio, Video Discussion Forum
As with the other thread about a JBL 18-inch behemoth TL, the question of 2- versus 4-order really is important in terms of extending f3 bottom end.
I think the "naive" theory TL would probably be 2-order (if it exists at all) but the King-type design definitely is 4-order. So as in the JBL thread, it makes sense to head towards 2-order design.
B.
PS King's reports are good stuff; solid engineering and not the least bit cult or faddish. But to read comments from his adherents, they sound like "true believers" who have seen the light rather than folks stumbling around in the dark like the rest of us
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Nicely put although many builders of IBs, aperiodic boxes, and leaky sealed boxes wouldn't take "oblivion" in a pejorative sense.
But what about Linkwitz's Pluto and a legion of sewer-pipe sub builders using Voigt pipes? Would those be considered "naive" TLs or how to characterize them?
B.
It was meant in a positive sense. It is a good thing. Some TL advocates — and they are hard nosed & will not bend to reality — think that this & bass reinforcement can be had.
Hard to build a Voigt pipe from a sewer pipe, and it has been shown that the ripple inherent in a Voigt can be greatly reduced by Mass loading it.
Many sewer pipe TLs are not near big enuff to be a proper TL, the LX-mini likely in that niche.
dave
All of this is actually for naught. You can't build a TL and terminate with a PR. It won't be an MLTL. It won't be a TL. It won't be ported box. It will just be a plain-Jane PR alignment. This is because the PR works off the pressure wave of the active driver. You cannot include the pipe resonances of the box as in a TL, if the PR just ignores them.
Sorry, but this theory just does not work.
Wolf
Sorry, but this theory just does not work.
Wolf
What you say seems cogent to me*. But what about the respected persons (King and McBean) who seem think it can be modelled within a T/S TL framework? Or am I misunderstanding everybody.
B.
* I'm pretty close to giving up my "naive" daydreams about a PR design or even a Voigt-pipe solution.... unless detuned as per Augspurger and damped to aperiodic status
T/S theory generally assumes that box dimensions are <1/6 wavelength. A 1/4 wave box with a PR at terminus will not be a plain jane PR box, but whether the line does anything useful is debatable.
It's fairly simple to model in Hornresp. bentoronto, I'm sure if you ask nicely "Just a Guy" will model it up for you...all you have to do is say pretty-please
What makes you think that the passive radiator ignores the "pipe resonances"?
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I don’t think it can be looked at like that. I am no expert on bandpass boxes but i suspect it is something like: the box has a 2nd order roll-off, add a hole and you get 2 more poles, and then, when configured like a bandpass, the 2nd hole adds 2 more poles, yielding 6th order/6 poles.
dave
dave
The speaker is 2nd order. The box on each side is second order. Combined they are 6th order. Each unique mass (port or diaphragm aperture) and compliance (spider or box) combo adds two energy storage elements. The number of energy storage elements is the order.
Might I ask a simple, maybe silly, but practical question?
Say there's a cylinder-shaped speaker, with diameter of about 120mm and height about 250mm. On the one end it has 3' woofer, and two long sides have passive radiators with double amount of surface that woofer has. If I add inner labyrinth in a such way, that air has more distance to travel before it reaches passive radiators, will I get better lower frequency response?
Say there's a cylinder-shaped speaker, with diameter of about 120mm and height about 250mm. On the one end it has 3' woofer, and two long sides have passive radiators with double amount of surface that woofer has. If I add inner labyrinth in a such way, that air has more distance to travel before it reaches passive radiators, will I get better lower frequency response?
Thanks. I'm trying to design a portable speaker with good bass, and have no idea how they do it. For example, Aukey Eclipse bluetooth speaker has inner volume approximately half o what I've described, and it has two 2' drivers and 2 passive radiators. Believe or not, but to approximately 40% volume level, it sounds like pair of good bookshelf speakers with 6.5 woofers at least!
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