@Scottmoose
Hmmm... from my chair you shoulda quit while you were ahead. (Although it's clear we are each holding a different end of the stick.)
Whether or not Bailey was 100% successful in reaching his aspirations for the non-resonant transmission line is immaterial. Indeed, he presented a second design that he felt did better than the first... and stated why he believed it was better. One could surmise that had he continued to work at it he would have gotten even closer to the bulls-eye in the approach he was taking.
On the other hand you offer that you've just designed a similar "line"... which turns out to be an acoustical labyrinth that you yourself wouldn't term a transmission line...either. Read what Bailey replied to Mr. Barlow.
One can play with the configuration of the transmission line a fair bit with the approach and objectives firm and still not wind up with a labyrinth or a multi-resonant closed box. I guess you would term each configuration an alignment. I'm trying to use the language you're using.
Let me use an analogy to get at what I'm trying to express. NB: I'm not arguing politics here. In electoral representative democracy one ideal would be that every voter gets a rep that he voted for and every sitting rep represents the same number of voters. Inclusivity and equality both... equal legislative power for all voters. That's the ideal, the bull's eye on the target.
It's an ideal that for all intents and purposes can never be achieved... but we can get close and have a path that takes "close" even closer. There is a design family that produces implementable instances that look squarely at the bull's eye and can take you as close as practicable in a particular way. Each implementation will be different... but the essential character will be consistent across implementations. It's called the single transferable vote (STV). It does a lot of other good things -- for very good reasons -- which factor into its appeal too.
Now all electoral systems can be also classified on the basis of certain characteristics and one popular classification pigeon-holes systems on the basis of party proportionality. Proportionality has nothing to do with equal legislative power for voters. STV is "proportional" but no other system has the design objectives (intent) or approach or mechanisms of STV. Proportionality isn't its defining characteristic... or even its mist important one.
If "quarter wave" (or whatever you want to call it) is proportional representation then the non-resonant transmission line --- aka, what Bailey intended to build -- is STV. As far as I know STV has no competitor. There may be one. There may be a new system come along that takes a look at the ideal and "does it better". In the final analysis the non-resonant transmission line might be a dead end. Maybe multi-resonant is the way to go.
One more thing. Words matter. They mean something agreed upon... or should. Otherwise we live in Trumpian world not the real one.
Names matter too but in a differnt way. You don't want me representing myself around town as Scott Lindgren.
Hmmm... from my chair you shoulda quit while you were ahead. (Although it's clear we are each holding a different end of the stick.)
Whether or not Bailey was 100% successful in reaching his aspirations for the non-resonant transmission line is immaterial. Indeed, he presented a second design that he felt did better than the first... and stated why he believed it was better. One could surmise that had he continued to work at it he would have gotten even closer to the bulls-eye in the approach he was taking.
On the other hand you offer that you've just designed a similar "line"... which turns out to be an acoustical labyrinth that you yourself wouldn't term a transmission line...either. Read what Bailey replied to Mr. Barlow.
One can play with the configuration of the transmission line a fair bit with the approach and objectives firm and still not wind up with a labyrinth or a multi-resonant closed box. I guess you would term each configuration an alignment. I'm trying to use the language you're using.
Let me use an analogy to get at what I'm trying to express. NB: I'm not arguing politics here. In electoral representative democracy one ideal would be that every voter gets a rep that he voted for and every sitting rep represents the same number of voters. Inclusivity and equality both... equal legislative power for all voters. That's the ideal, the bull's eye on the target.
It's an ideal that for all intents and purposes can never be achieved... but we can get close and have a path that takes "close" even closer. There is a design family that produces implementable instances that look squarely at the bull's eye and can take you as close as practicable in a particular way. Each implementation will be different... but the essential character will be consistent across implementations. It's called the single transferable vote (STV). It does a lot of other good things -- for very good reasons -- which factor into its appeal too.
Now all electoral systems can be also classified on the basis of certain characteristics and one popular classification pigeon-holes systems on the basis of party proportionality. Proportionality has nothing to do with equal legislative power for voters. STV is "proportional" but no other system has the design objectives (intent) or approach or mechanisms of STV. Proportionality isn't its defining characteristic... or even its mist important one.
If "quarter wave" (or whatever you want to call it) is proportional representation then the non-resonant transmission line --- aka, what Bailey intended to build -- is STV. As far as I know STV has no competitor. There may be one. There may be a new system come along that takes a look at the ideal and "does it better". In the final analysis the non-resonant transmission line might be a dead end. Maybe multi-resonant is the way to go.
One more thing. Words matter. They mean something agreed upon... or should. Otherwise we live in Trumpian world not the real one.
Names matter too but in a differnt way. You don't want me representing myself around town as Scott Lindgren.
No. I said that in usage it's an acoustical labyrinth because it's a lagged pipe. It's designed (as you can see per the graph) as a near-aperiodic line with a uniform damping density throughout, and tracking a very similar alignment (frequency / amplitude response, impedance response, impulse response, GD etc.) to that used in Augspurger's alignment tables, and also close to what Bailey employed. For most users however, that is not practical given the type of drivers used in those desktop enclosures, so the damping scheme provided is adjusted to that lighter level shown in the sketch & notes, shifting it to a more useful higher gain alignment. Builders are of course free to use the higher damping quantity (complete uniform fill) if they wish to do so.
I don't like to sound discouraging, but since you are a bit hazy on the basics of what 'alignment' even means, you're not ideally placed to be trying to lecture me on the subject or announce rigid rules on it either. 😉 As noted, a 'labyrinth' is not an 'alignment', any more than, say, a sealed box or open baffle is: alignment is something an enclosure possesses, and it varies according to the design objects. For e.g., a vented box isn't an 'alignment'. It's a vented box. 'Alignment' refers to the particular characterisics a given example tracks. Some of the better known / specific types are QB3, B4, SBB4 and so on.
I've no interest in being drawn into politics, so I won't be baited into doing so, but since you've avoided the factual information I've given you several times on how the name relates to operating physics and instead tried to divert into political analogies, there's no point in discussing it further until you've read and understood what it means.
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I'm not trying to lecture... far from it.
I'm trying to have a discussion to obtain understanding.
The electoral mechanics was simply an analogy with which I am familiar... maybe as well versed as you are in speaker design.
But when you say a vented box is a vented box and an acoustical labyrinth is an acoustical labyrinth that's what I've been trying to get across. A TL is a TL and it was Bailey's approach in the same way.
I've understood "alignments" to be particular instances of solutions to whatever parameters you feed in. if you plugged in Bailey's two instances of TLs the calculations would provide alignments. they'd be TLs... but not something else. Nor would something else be a TL.
But I admit I find your usage of a lot of this
language vague and hard to come to grips with.
Got a reference I could read?
Thanks again.
I'm trying to have a discussion to obtain understanding.
The electoral mechanics was simply an analogy with which I am familiar... maybe as well versed as you are in speaker design.
But when you say a vented box is a vented box and an acoustical labyrinth is an acoustical labyrinth that's what I've been trying to get across. A TL is a TL and it was Bailey's approach in the same way.
I've understood "alignments" to be particular instances of solutions to whatever parameters you feed in. if you plugged in Bailey's two instances of TLs the calculations would provide alignments. they'd be TLs... but not something else. Nor would something else be a TL.
But I admit I find your usage of a lot of this
language vague and hard to come to grips with.
Got a reference I could read?
Thanks again.
The issue with that is that 'transmission line' is not actually a synonym for 'Bailey's approach'. It's just a technical name for a structure long enough that wave behaviour needs to be accounted for, and in acoustics another term for 'quarter [or half] wave' enclosure. Arthur had a general set of goals within this category of enclosure, but he never claimed they were the only ones, let alone defined the term itself, which comes from wider physics. It's been other people who have for their own reasons decided to try to apply it narrowly. And that literally is 'it'. Many of us for convenience tend to apply it to relatively well-damped pipes, but it's typically a brevity / convenience, not a requirement.
More or less.
It depends what 'calculations'. You can measure (or model) the response of his enclosures, and by definition they each possess some kind of alignment because it's physically impossible for a speaker not to. They don't 'provide' alignments though. They simply show the response characteristics of the measured or defined speaker.
It's technically possible, if you know the LF characteristics of the drivers Arthur used, to take those, his enclosure dimensions and a near-approximate for the damping, then empirically work out a set of formuas that will allow you to consistently achieve the same alignment* across a range of suitable drive unit characteristcs. And somebody has done that: they did 24 years ago. That's roughly the starting point George Augspurger's extended alignments. Not identical, but similar. With a bit more time available, we can probably come up with something even closer. But there's a caveat to that, which is the reason for the asterisk above and below. 😉
*Arthur was general, rather than specific. His two WW articles were 6 1/2 years apart, and the two nominally completed speakers presented actually had two different responses, so there wasn't a great deal of consistency there, and while it's technically possible to work out and therefore repeatably track the alignment of one of his offered designs, you can't do both at once because they're different. Name your poison, as they say.
A couple of other points on his '65 WW article that often get overlooked are worth noting. Arthur's experimental folded pipe (Figure 5 in his '65 article) had an adjustable terminus flap, so it could be run closed (a 1/2 wave pipe), or open (a 1/4 wave). He settled on the latter for the production speaker design, mainly because of the bass reinforcement from the mildly resonant line. He was also very careful, when presenting the data and stressing the low pass nature of the pipe, to show a graph (Figure 6 in the same) indicating its behaviour when the pipe was run as a sealed 1/2 wave type (terminus closed) rather than open, since this naturally shows a more effective / rapid acoustic LP. 😉 His exploding wire impulse response is often (rightly) lauded as one of the earliest examples of such measurements -but even then we need to be careful because the comparisons are loaded: the pipe was run in its closed not open form, unlike the two bass reflex enclosures, automatically biasing the results in its favour, because a sealed system, being 2nd order, will almost invariably have superior performance in this regard to a 4th order system -whether Helmholtz or 1/4 wave based. This wasn't deception, since he does state what it is, but it's certainly presentational sleight of hand as it isn't stressed, and many at the time (and even more since) have missed this aspect as a result. I don't blame him, as he had a modest financial 'interest' in the matter, but it's a significant detail that's best kept in mind.
This is also why you see the deviations in the FR of his production speaker in the 2 octaves above Fb (Fp), because the LP effect isn't as rapid as with a sealed pipe for obvious reasons. Not unless you rammed it so full of damping there was no usable output from the line (which is what he was after) and risk mass-loading the cone / suspension, which he also refers to, albeit in slightly different terms.
Yes, because they're pipes / structures long enough that wave-behaviour has to be accounted for.
Wrong, for the reasons already given multiple times above. The term is a technical one in the laws of physics / engineering which you can find in any decent textbook on the subject, and applies to any structure long enough that wave-behaviour needs to be accounted for, be it electrical or its acoustic analogues. I know that many people have really wanted it to mean something narrower, but unfortunately (since I don't like to disappoint) that isn't actually the case. Sorry, but hope it helps a bit.
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That sentence applies to pretty much all audio "discussions" that I have seen/read. 🙂
...not a synonym... a name.
...not a technical name... a name.
...like Mark. Or Scott.
Maybe as a historian you can tell me... back in the day, were there technical transmission line equations that Bailey could have applied to sound waves... maybe that he didn't present?
Are these embedded in the software today?
Resources?
...not a technical name... a name.
...like Mark. Or Scott.
Maybe as a historian you can tell me... back in the day, were there technical transmission line equations that Bailey could have applied to sound waves... maybe that he didn't present?
Are these embedded in the software today?
Resources?
Well, you can't have it both ways: right now you're on the one hand claiming that only Bailey's enclosures can be called transmission lines, and on the other hand stating it's just 'a name'. 😉
Except it is a technical term. Sorry, but that's just the fact of it.
There were, but beyond what's available in the articles, there's no way of knowing if he used any, and if so, what. We do know he states an 8ft pipe for his test box, and roughly that for the commercial design he did for Radford in Figure 8 of his '65 WW article; accounting for the geometry & the damping type / quantity, that corresponds roughly with the Fs of the KEF B139 units most commonly associated with them. Beyond that, we don't know, unless Arthur left an archive of notes, materials etc. If he did, I've never heard of it, although if time allows I might contact Bradford to see if their library holds any of his materials (I doubt it, but stranger things have happened). He was a very good engineer, that much we do know, so he will have indirectly applied aspects he knew as a matter of course, but there doesn't appear to be anything particularly significant beyond adjusted pipe length & tuning relative to Fs; he even said outright he didn't think other aspects were especially critical. That could have been a deflection, as he did have some commercial involvement with Radford, latterly IMF, and Ferrograph's monitor's were obviously at the very least influenced by his '72 WW article (although I've no idea if he had any involvement with them), or it could simply have been a genuine statement. If you want an opinion, it was probably a bit of both, with the latter taking the bulk given the date.
WRT to naming. I've been saying the problem is one of semantics.
But that's just what we have -- a name of a particular approach and a technical term both. We wouldn't be having this discussion if Bailey had named his design "Jennifer" or the "nearest approximation" -- the NATL. Can we agree that "Jennifer" is distinct in intent and purpose from, say, a "multi-resonant TL" ? And even if you're using "TL" tools, it doesn't necessarily mean you're designing a TL. As you and Dave keep pointing out the software exploits a large and richly-varied field. Not all of them can realistically called TLs... even using the expanded technical definition. Like the Hegeman.
I swept through Augspurger this morning. Locanthi published in 1971. That seems to be the first tool of the kind we're discussing. Bailey predates this for all intents and purposes.
Dave characterized Jennifer as a "sledgehammer" and that might have been part of the notion. Bailey opined that early reflection and resonances were an anathema but that measures to mitigate these -- such as the reflectors in his second (published) line -- didn't make that much difference. Other builders thought they were important in their builds. For someone working essentially empirically he showed no inclination to do what Locanthi was doing for instance (or Augsburger later). Both his articles were in the nature of "here's an idea... this is what I learned when I looked into it" (probably on Radford's dime of course).
You have a brilliant idea in contacting Bradford. Long ago -- but long after I saw the articles -- I'd thought of writing to Bailey but could never see an address. I'd never considered writing to the school. Let us know what you find out. Maybe his kids have some boxes in the attic... maybe some subsequent enclosure refinements!
But that's just what we have -- a name of a particular approach and a technical term both. We wouldn't be having this discussion if Bailey had named his design "Jennifer" or the "nearest approximation" -- the NATL. Can we agree that "Jennifer" is distinct in intent and purpose from, say, a "multi-resonant TL" ? And even if you're using "TL" tools, it doesn't necessarily mean you're designing a TL. As you and Dave keep pointing out the software exploits a large and richly-varied field. Not all of them can realistically called TLs... even using the expanded technical definition. Like the Hegeman.
I swept through Augspurger this morning. Locanthi published in 1971. That seems to be the first tool of the kind we're discussing. Bailey predates this for all intents and purposes.
Dave characterized Jennifer as a "sledgehammer" and that might have been part of the notion. Bailey opined that early reflection and resonances were an anathema but that measures to mitigate these -- such as the reflectors in his second (published) line -- didn't make that much difference. Other builders thought they were important in their builds. For someone working essentially empirically he showed no inclination to do what Locanthi was doing for instance (or Augsburger later). Both his articles were in the nature of "here's an idea... this is what I learned when I looked into it" (probably on Radford's dime of course).
You have a brilliant idea in contacting Bradford. Long ago -- but long after I saw the articles -- I'd thought of writing to Bailey but could never see an address. I'd never considered writing to the school. Let us know what you find out. Maybe his kids have some boxes in the attic... maybe some subsequent enclosure refinements!
Like the term “phase plugs” (in cone drivers), “transmission lime” is a convienient term that actually has little meaning relative to the originating use. Phase plugs are actually in compression drivers, and transmisison lines ar along long wires. Audio borrows many terms whos use is realy just convenient.
dave
The response of the TTL is not great by his measures (the significant step at teh bototm does not look like step=-loss:
dave
Time-smeared stuff coming from the back of the cone is an issue in every loudspeaker. Martin at some point showed that the deflectors in the corners of a line are actuallu counter-productive.
dave
I believe the time smeared stuff coming back to (and through) the cone from the enclosure were of prime concern to Bailey. Less so the bass augmentation.
I seem to remember hearing that about the reflectors. Any idea why? At first blush they made sense (at least to try).
Notionally, I always thought of Jennifer as a lobster trap... what goes into the line doesn't come back up -- a ratchet. Maybe an asymmetrical "saw tooth" wall would perform better than the simple reflector that works as well in both directions.
Yes.
The expansion in the line if the deflectors are left out creates an acoustic low pass filter, killing more of the top you do not want out the terminus.
The function of the line & terminus is to be a sufficient low pass to filter out the unwanted harmonics and preserving th efundemental (if your goal is extended bass/more bass gain)
What, who is Jennifer?
dave
OK, so you said it, not me ;^)
We give our designs name (as do many others)… after awhile you have to get creative.
dave
We give our designs name (as do many others)… after awhile you have to get creative.
dave
Up from the ashes grow the roses of success.
I can only take computer modeling so far, then I have to actually build a prototype, listen, and start gathering data. I don’t care so much what the simulation says, if it sounds bad it is bad. Many builders obsess over damping material, structural materials, roundovers, gasket material, what kind of wire to use, etc. they have no idea what the ‘box’ is going to do. They are armed with a simulation and off they go to their CNC. Actual, for real, measurements instead of one particular model‘s simulation hold far greater weight in my design process. Your experience may differ, and that’s OK too. Besides, as you pointed out, MDF burns well.
My approach comes from my age, I guess. When I started out building loudspeakers, last century, there was very limited information on the Internet. Come to think of it, there was no Internet. If your library had an acoustics or loudspeaker book you had it made. We had one phone and one TV for the whole family. My home computer was a pad and pencil. I didn’t even have a calculator. (My neighbor had a Sinclair!) Most everything about the design process was a huge guess. Intuition, and who you knew, played a large part in loudspeaker design. So, I always made several prototypes before settling on a final design, and often scratched projects that simply didn’t work.
This was a crazy time for audio, many new ideas were being marketed before being fully thought out. It was the time of Kenwood amps and Jensen coax 6x9’s in a Chevy Nova that got 12mpg. I had to try things out myself and listen. I had no measuring capability except for my ears, which were very good but untrained. I made a lot of mistakes, and consequently had a lot of firewood to keep me warm, but it was fun. I still listen to the first t-lines I ever built. They are pretty good for no computer help. They are great for jazz.
Bottom line, don’t be scared to try something new. Don’t be deterred by your failures, it’s how you learn. Well, it’s how I learn.
Built my first loudspeaker in 1966. Got seriously into experimenting in 1974.
Since Y2K I designed (& Scott) and Chris built 100s of designs. Rarely did we have to build more than the first one.
A skilled and experienced designer can often nail it on the first try. If you have XOs it is often harder.
dave