Thats my point. Almost like a different vented alignment, if no stuffing is included. After all you can make any shape cavity resonant in this way. A pipe just adds predictable harmonics, maybe im being a little simplistic though. If thats right, then Im annoyed it took me so long to realise. What advantage remains then for using a pipe at all? ANy also, surely then, a vented 'box' can be made to follow similar rules, if vent and driver position is optimised in a similar way.
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In playing around with Martin's MLTL worksheet, I have noted that moving the port up close to the woofer (classic reflex box style) considerably increases its Q factor, but the port resonant frequency stays much the same. The overall response then has a noticeable peak at the port resonance which isn't there with the MLTL.
Absolutely; a vented system can be optimized in the same fashion, but most vented boxes do not have an internal dimension, like the height, that is long enough to allow the overall tuning to benefit from the 1/4-wave resonant frequency of that dimension, and the pipe's dimensions are calculated based solely on the box's volume. When the box becomes a tall(ish) floor-stander, its internal height becomes long enough to have contribution of its 1/4-wave resonant frequency to the overall system tuning, and less from the port. TLs and vented boxes are cousins in the same family, all inherently 4th-order at their roots. An ML-TL is a close cousin, whereas a really long, non-tapered TL or a shorter but tapered TL are often more like a distant cousin. Frankly, the best application of a TL is in a 2-way system, either a TM or MTM or 2.5-way TMM, where the "M" drivers cover both bass and midrange. The TL provides bass reinforcement as well as virtually eliminating reflections back through their cones by the stuffing absorbing them.
Paul
Paul
Without stuffing I don't think there's any advantage, in fact, there's the added of problem of pipe resonances.
Someone, it might have been Martin himself (though I can't find the quote), said that the only advantage to using TL software or speadsheets was that in designing a tall, thin bass reflex you would get resonances, and with a standard BR analysis, these would be overlooked.
When you start adding stuffing, then you're moving from a bass reflex to an aperiodic design. (Edit: The transition can be noted by the loss of the second hump in the impedance curve.)
That is, I think any empty TL response can be duplicated by a "golden section" bass reflex design, and any stuffed TL can be duplicated with an aperiodic box.
Still, it sure is easier to fit tall, thin cabinets in my crowded living room.
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No, I was saying that I wouldn't recommend not using multiple subwoofers in a primary listening system.
And that's unfortunate. Because full range box speakers will always have bass response dictated by placement and room.
Nothing at all unfortunate about it. My full-range speakers sound just fine in my room and definitely don't need any assistance from a bunch of subwoofers.
Not sure what you mean by a well designed/well tuned TL especially as compared to an MLTL (which apparently isn't well designed or well tuned)?
Paul
Paul
Thanks for answering Paul
Sorry I didn't mean that at all, just tired when I wrote it last night!
I remember reading that a Transmission line, when properly designed, can really help control cone movement. I'm not sure if this cone control carries on below the tuning frequency or not. I'm just wondering if a (well designed) MLTL behaves in the same way, or if things fall apart abit below tuning frequency a la Bass reflex.
Sorry I didn't mean that at all, just tired when I wrote it last night!
I remember reading that a Transmission line, when properly designed, can really help control cone movement. I'm not sure if this cone control carries on below the tuning frequency or not. I'm just wondering if a (well designed) MLTL behaves in the same way, or if things fall apart abit below tuning frequency a la Bass reflex.
Well, as you know, all TLs are inherently 4th-order systems because there's a driver near the closed end and there's an opening or port near the open end. A TL, then, will have a double impedance peak and the driver's excursion will continue to increase below the system tuning frequency. That excursion can be reduced, the magnitude of the lower-frequency impedance peak can be reduced or even essentially flattened, and the bass response can be made to roll off almost at 2nd order by the design details. When you do that, though, the line's exit (terminus or port) will have less output, maybe essentially none, and the system bass response where there is actual important content will be negatively affected, like a (much) higher f3.
Paul
Paul
It only flattens it if designed to do so, typically Fp = Fs/Qts', the TL version of a T/S max flat vented alignment.
Qts' = mh-audio.nl - Home
GM
Qts' = mh-audio.nl - Home
GM
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