Ok, it involves the damping, thanks for clearing that up, "sucked into the line" conjured up a different image for me.
"and Bailey (God help us... the 'transmission line', despite the fact that the example he presented wasn't really a TL)... I sometimes wish Bailey had never coined the term."
About that. In his initial article, "A Non-Resonant Loudspeaker Enclosure Design", (spoiler alert -- the title is a dead giveaway) Bailey argued:
It is now apparent that it is the sound waves produced at the rear of the cone that have to be absorbed is delayed output and resonances are to be avoided.
Acoustic labyrinths have been used in the past in an attempt to "lose" the sound down multiple paths. Such an enclosure is shown in Figure 3, but the size needed is excessive. Unless there is adequate internal lagging, then these cabinets will also possess pronounced energy storage and the consequent lack of sound clarity.
The only safe method of removing the rear cone sound energy is by transmitting it down an infinite transmission line. This is obviously impracticable so the nearest approximation was examined."
So before the TL moniker was attached to his design intent -- and the intent is more important that the name, right? -- Bailey declared that he wasn't implementing an actual transmission line, only a first approximation. And the central point of the update article that gave us the name, Bailey's focus was (still) on lowering cabinet effects on driver performance.
Actually Planet10's more modern observation "...if the line is done right… all the mids get sucked into the line and absorbed so one can get less time-smeared midrange coming back thru the cone" is actually close to what was of prime interest to Bailey... his key objective. Bailey believed that that objective couldn't be usefully achieved with short lines.
However, I'm curious: if Bailey's designs were not really a real TL (as Bailey himself admitted anyway) then in what way are the more recent constructs "real" or actual transmission lines that completely remove the deleterious sound energy? Maybe the AB problem (After Bailey) is that the name has nothing to do with the actual intent or action of the enclosures. Maybe what's needed is a more clear statement of intent... and a name to match?
Just sayin'.
About that. In his initial article, "A Non-Resonant Loudspeaker Enclosure Design", (spoiler alert -- the title is a dead giveaway) Bailey argued:
It is now apparent that it is the sound waves produced at the rear of the cone that have to be absorbed is delayed output and resonances are to be avoided.
Acoustic labyrinths have been used in the past in an attempt to "lose" the sound down multiple paths. Such an enclosure is shown in Figure 3, but the size needed is excessive. Unless there is adequate internal lagging, then these cabinets will also possess pronounced energy storage and the consequent lack of sound clarity.
The only safe method of removing the rear cone sound energy is by transmitting it down an infinite transmission line. This is obviously impracticable so the nearest approximation was examined."
So before the TL moniker was attached to his design intent -- and the intent is more important that the name, right? -- Bailey declared that he wasn't implementing an actual transmission line, only a first approximation. And the central point of the update article that gave us the name, Bailey's focus was (still) on lowering cabinet effects on driver performance.
Actually Planet10's more modern observation "...if the line is done right… all the mids get sucked into the line and absorbed so one can get less time-smeared midrange coming back thru the cone" is actually close to what was of prime interest to Bailey... his key objective. Bailey believed that that objective couldn't be usefully achieved with short lines.
However, I'm curious: if Bailey's designs were not really a real TL (as Bailey himself admitted anyway) then in what way are the more recent constructs "real" or actual transmission lines that completely remove the deleterious sound energy? Maybe the AB problem (After Bailey) is that the name has nothing to do with the actual intent or action of the enclosures. Maybe what's needed is a more clear statement of intent... and a name to match?
Just sayin'.
It is not that he did not design a TL, just that the title had little to do with the actual example presented which has caused considerablt confusion amoungst many of what a TL is.
The work by King and Augspurger, modesl that fairly accurately modeled TLs, much “common TL knowledge” was trashed and the work carried on by King, and others following in his footsteps.
TL-space (the universe of possible TL/quater-wave/half-wave designs) has been dramatically expanded. And that has brought a richness to the diy community that we did not have in the past. A few commercail companies are paying attention too.
dave
...anyway all methods of bass extension or boost by acoustical means are obsolete these days, days of common availability of active digital correction (and cheap amp power)
OTOH "A Non-Resonant Loudspeaker Enclosure Design" is still a valid challenge
OTOH "A Non-Resonant Loudspeaker Enclosure Design" is still a valid challenge
Only, graaf, if you can live with the downsides of DSP.
And one still needs to pay attention to alignment. Sure one can DSP really low bas sout of a sealed box, but at teh expense of needing much greater xMax in the bass driver and way more power.
dave
And one still needs to pay attention to alignment. Sure one can DSP really low bas sout of a sealed box, but at teh expense of needing much greater xMax in the bass driver and way more power.
dave
yes, that is true, besides it is still an art, after all, mechanical watches are obsolete too
some bass systems, especially bass horns are just outright beautiful
some bass systems, especially bass horns are just outright beautiful
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I would argue, then, that King and Augspurger designs have even less to to with "transmission lines" than Bailey's.
So... what are their designs actually doing -- since Bailey's evidently didn't -- and what name should they obtain that relates to that operation?
How about a completely unconnected name to help clarify things? How about "Jennifer"? Jennifer is a nice name. (Yes, my tongue is firmly in my cheek but you get my point...)
Seriously, these modern quarter-wave pipe designs should just drop the "transmission line" part. Bailey's non-resonant design -- with it's more aperiodic intent -- might do the same.
And, perhaps, if Bailey failed in his first approximation maybe a second approximation would be worth pursuing... if the goal of the transmission line ideal as he stated it is worthwhile.
So... what are their designs actually doing -- since Bailey's evidently didn't -- and what name should they obtain that relates to that operation?
How about a completely unconnected name to help clarify things? How about "Jennifer"? Jennifer is a nice name. (Yes, my tongue is firmly in my cheek but you get my point...)
Seriously, these modern quarter-wave pipe designs should just drop the "transmission line" part. Bailey's non-resonant design -- with it's more aperiodic intent -- might do the same.
And, perhaps, if Bailey failed in his first approximation maybe a second approximation would be worth pursuing... if the goal of the transmission line ideal as he stated it is worthwhile.
The non-resonant line is much more like Onley’s Labyrinth. And modern aperiodic midTLs. Very few aperiodic TLs other than that, and that is what you seenm to be pidgeon holing the TL, as in the only real TLs are aperiodic TLs.
http://p10hifi.net/planet10/TLS/downloads/Acoustic-Labyrinth-Olney.pdf
You are really limiting yourself.
dave
http://p10hifi.net/planet10/TLS/downloads/Acoustic-Labyrinth-Olney.pdf
You are really limiting yourself.
dave
What I'm saying is that if Bailey's isn't "really" a transmission line where the name has some semblance of a connection to the intent then the others are less so.
Unless you'd like to argue that they do have some resemblance to electrical transmission lines that inspired Bailey?
Unless you'd like to argue that they do have some resemblance to electrical transmission lines that inspired Bailey?
Yes Bailey’s line is a transmission line as we define it today. And that was also, i believe, when the term was coined.
So even just given that he invented the term, if he called his box a TL then it was.
dave
So even just given that he invented the term, if he called his box a TL then it was.
dave
Isn't the idea that it's related to an electrical transmission line in the sense that there are no reflections?
You're sidestepping the question.
If the name is not a misnomer then what are the real objectives of the current, broader class and what would be a more appropriate descriptive name that wouldn't confuse or mislead people.
(And actually I suspect that it was readers who latched onto the name rather than Bailey. Otherwise he would have called it that in the first article)
What we call things matters especially if those names serve to undermine understanding and thwart constructive discussion. I see that in other endeavors and they have been crippled by it.
If the name is not a misnomer then what are the real objectives of the current, broader class and what would be a more appropriate descriptive name that wouldn't confuse or mislead people.
(And actually I suspect that it was readers who latched onto the name rather than Bailey. Otherwise he would have called it that in the first article)
What we call things matters especially if those names serve to undermine understanding and thwart constructive discussion. I see that in other endeavors and they have been crippled by it.
Sort of. I expect that is where the name was pinched from. The analogy thou is tenuous.
dave
A quarter-wave or half-wave resonator. An aperiodic line tries to kill all the harmonics, most try to capture just the fundemental, and kill all the rest. Modern TL modeling has shown us a few more tricks to deal with those unwanted resonances so we no longer have to rely on volume damping.
And “TLs” also include voigt pipes which can also be classified as a horn (not a very good one in most cases, so most often mass loaded).
As bass reflexes transition into mass loaded TLs as one dimension starts to exceed the others significantly, so too does a “TL” transition into a horn as the flare increases from conical. Horns that are not long enuff or have a big enuff mouth area to fully support the bass cutoff, it starts behaving as a TL, and with no damping, one gets TL ripple.
dave
Without getting hung up on terminology, I feel the various enclosure designs draw on various physical principals to achieve certain goals. Some of the goals include; bass extension, woofer cone control (ie. reduction of cone movement at the driver Fs), reduced distortion due to internal box reflections, reduce distortion due to panel resonances, etc.
Acoustic suspension (sealed enclosures) and bass reflex (ported enclosures) rely on mass/spring/damper principals to achieve their goals where as transmission line (1/4 wave rectifiers) and horns use sound wave reflection principals in their designs. I believe the reflected wave principal is much faster response than the mass/spring/damper resonance principal and this helps gain better woofer cone control through transients (less bass distortion). Also the tapered and stuffed line helps reduce the internal reflections and harmonic distortions prevalent in TL enclosures. TL designs are also inherently well braced internally which doesn’t hurt.
Acoustic suspension (sealed enclosures) and bass reflex (ported enclosures) rely on mass/spring/damper principals to achieve their goals where as transmission line (1/4 wave rectifiers) and horns use sound wave reflection principals in their designs. I believe the reflected wave principal is much faster response than the mass/spring/damper resonance principal and this helps gain better woofer cone control through transients (less bass distortion). Also the tapered and stuffed line helps reduce the internal reflections and harmonic distortions prevalent in TL enclosures. TL designs are also inherently well braced internally which doesn’t hurt.
Terminology aside my interest is what are the advantages and disadvantages of regular tapered TL and MLTL? Also are all MLTLs straight pipe or can a tapered pipe also use the mass loading technique?
You can add a mass-loaded terminus to any TL/Voigt. Derigor for any voigt.
The first exploration of a mass-loaded vent was by Augspurger (restricted terminus was his term) and well documented in Martin Kings FE164 ML-VOigt.
dave
The first exploration of a mass-loaded vent was by Augspurger (restricted terminus was his term) and well documented in Martin Kings FE164 ML-VOigt.
dave