At -40db ref 1w on this low efficiency pc83-8 you are no longer really listening. It is a faint sound, so there is real no point in measuring further. At some level the friction will prevent the speaker from even moving and you will have a "stuck" motor with probably 100% distortion.
If the system sounds bad, they are probably overdriving the speaker, or the amp may have excessive distortion, and you are finally hearing it. Hard to tell without a measurement.
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I would expect any machine to have a design range. Spec'd at 1w is probably a sweet spot for measurements and I would expect it to get worse at the extremes of too little or too much power. I'm still experimenting (learning) with these pc83-8's otherwise I might try the "too much" end of the spectrum
Zarathu
1) No extrapolation- the frequency response of the hundreds of properly working transducers I have tested does not change when operated in their linear range, which can be anything from 0 watts to over a 1000, depending on the transducer.
2) To make the math easy, start with a single driver with 83 dB 1 watt one meter, drop it 3 dB, .5 watts =80 dB, drop it 10 more dB to .05 watts and SPL is 70 dB, a conversational level that anybody with "normal" hearing has no problem hearing. At 60 dB, the speaker sees only .005 watts, but is still quite audible in a quiet location. With a dozen drivers in a line array that 83 dB sensitivity rises almost 10 dB, "twice as loud" sounding as a single driver, but each driver in the array using less than 1/100th the power as one at the same level, some comparisons here:
Dirty Dozen Line Array
For "average" music levels each driver in the "Dirty Dozen" seldom sees even .005 watts peak, though their subs might see a few watts.
3) Your "someone" made a statement that is simply not true, and inconsistent with thousands of multi-level distortion tests posted by hundreds of individuals, both DIY and commercial, as DonVK's post #21 here has shown.
4) Manufacturers have attempted to produce speakers with flat frequency response for over a hundred years now, and you still won't find any cheap speakers with flat response, though with a global economy and design "secrets" widely available cost is no longer as indicative of quality as it used to be.
Transducer costs on a speaker retailing at $8000 will be a small fraction of that cost.
A rising upper response is actually preferable to "flat" for "full range" line arrays if EQ won't be used.
Cheers,
Art
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I have listened to several, and I disliked all of them. I'm guessing that doesn't count, either.
Tiny little 2" and 3" drivers make very poor woofers (f0 too high, too little cone area), and they also make very poor tweeters (they're too big to disperse treble.) They can make decent midranges.
But stringing a lot of midranges in a line array doesn't fix the severe treble dispersion problems, and often adds a lot of "boxiness" from the long tubular enclosure. Meantime the ragged vertical and horizontal dispersion patterns typically make the midrange sound screechy and unpleasant.
In simplified theory the cone areas add to improve low frequency response compared to one 2" or 3" driver, but the f0 is still usually too high, enclosure volume is still too small, and bass is rarely as good as that from a single 10" or even 8" woofer.
And that's how every line array I've heard sounds to me - it suffers from some or all of the following: limited bass, boxy midrange, screechy high midrange and treble.
The best-sounding (i.e. least unpleasant) line array I've ever heard was an ancient Phillips model that used no tweeters, but instead, an array of elliptical full-range drivers. It sounded like a loud AM radio: no deep bass, no high treble, but reasonably pleasant midrange response.
That old Phillips array did not cause rapid and severe ear-fatigue, in other words, in the way that the contemporary Fishman SA220 and Bose L1 do.
Huge line arrays are very common in huge music festivals and stadium-sized sound reinforcement systems. They also have the same problems with sound quality, but in those environments, they are about the best one can do.
While trying to avoid one assumption, you seem to be making another assumption instead: that speakers actually do something bizarre that causes the frequency response to be different at all power levels.
There is no physical explanation for the mysterious constantly-changing frequency response, so why do you suppose this is a better assumption to make?
Keep in mind the Internet is mostly filled with nonsense. When confronted with a claim like this, the first thing to do is ask for evidence, and plausibility. Both trustworthy measured data, and a good scientific physical explanation for the claimed effect.
The famous cold-fusion fiasco of 1989 ( Cold-fusion Fiasco Not One Of Science's Finer Moments - tribunedigital-chicagotribune ) is a good example of the dangers of ignoring this advice. The original proponents had some measured data (which turned out to be both inaccurate and incomplete), but they had no scientific / physical explanation. They called the newspapers and TV crews anyway. Unfortunately for them, their measurements were faulty, their claims were false, and they ended up losing their scientific reputations and careers entirely.
As Chris661 explained so beautifully a few posts ago, there certainly are mechanisms that alter the frequency response of a loudspeaker driver at extremely high power levels. But there aren't any known ones that magically turn invisible tone controls with every slight change in drive power. That's a pretty ridiculous claim, on the face of it.
It helps to have at least a basic understanding of how solids behave. Look up Hooke's law; most materials - paper, wood, steel, plastic - are linear up to a limit, then start to become nonlinear, then fail altogether (break). This is not an assumption, but is supported by thousands of measurements - and billions of working devices.
Loudspeakers are no exception. They're most linear at very low power levels. Beyond some power level, they start to get nonlinear. Beyond that, they fail.
Incidentally, your hearing does change a lot at low SPL levels: if you aren't familiar with the Fletcher-Munson equal loudness contours, do a little research on the topic. If you turn down the SPL of a loudspeaker system until it's very quiet, you will certainly hear a very different frequency response - but it's not coming from the speakers, it's coming from your ears and brain!
0.04 watts is quite a lot of power - only -14 dBW. When you feed -14 dBW into a speaker with a sensitivity of, say, 84 dB@1W@1m, you get an SPL of (84 - 14) dB at a distance of 1 metre.
In other words, your 0.04 watts, fed into a rather insensitive 84 dB/W @1m speaker system, creates an SPL of 70 dB at a distance of 1 metre.
Is 70 dB incredibly quiet, so that you "might not even be able to hear it"? No, 70 dB is quite loud. It is about the loudness of a typical household vacuum cleaner, or a shower. See these references of typical SPL levels of common sounds: Table chart sound pressure levels SPL level test normal voice sound levels pressure sound intensity ratio decibel comparison chart conversion of sound pressure to sound intensity noise sound units decibel level comparison of common sounds calculation , Noise Level Chart: dB Levels of Common Sounds ).
A few years ago, I fed 10 microwatts (0.00001 W, or 0.01 mW) sinewave power at 1 kHz to a guitar speaker, and found it quite audible from several feet away. This surprised me at the time, but when you calculate the numbers, it makes total sense: 10 uW is (-50) dBW. Drive that into a speaker with a sensitivity of 95 dB@1W@1m, and you can expect an SPL of (95-50), or 45 dB at 1 metre.
According to the references I listed above, 45 dB is about as loud as a babbling brook, or light traffic. Quiet, but very definitely audible.
That is complete and utter nonsense. Ask yourself what physical mechanism could possibly cause every crappy loudspeaker on earth to magically become perfect at very low power?
Artifacts from bad loudspeakers are usually much worse than artifacts from passive crossovers. Yet this fellow apparently came to the conclusion that the speakers will be perfect at low power, but the crossovers won't? Does that sound even remotely plausible?
-Gnobuddy
Most comments are very positive, from people who have owned or listened to LAs, and I believe them. There is something in the sound field created, but it is not super low distortion. The LA crowd seem to spend a lot of effort measuring their systems and they provide a lot of useful data from them. This one Full Range TC9 Line Array CNC Cabinet is (I think) typical and its distortion at -30db from the fundamental is not superlow.
We have to distinguish between very low in measurements and very low in hearing. 30 db down is un-hearable by most anyone.
If you owned a line array you would know that one of the characteristics is that you cannot tell how loud it is playing. The reason for this is that the human brain-ear distinguishes different loudness levels in speaker systems by the levels of distortion. Of course if its very soft, or very loud, of course you can tell this--so lets be practical, and linearly literal.
Measurement and actual hearing are two different things. You can measure comb distortion, for example, but unless you are moving while you’re listening, instead of sitting still, as Don Keel has shown, you won’t be able to hear it.
Engineering types spend too much time, IMO, measuring things that simply cannot be heard.
That would be true, since this is my thread, not yours.
People who like listening to miniature pianos and dislike the large sound stage of a line array are always looking for more reasons why miniature sound is better.
And they will find it. But they are also people who, while they have listened to a couple of line arrays, don’t actually own one in their house. So they are not like people who have both miniature sound and full sound stage in their houses. And then there is the question as to whether they listened to a home audio line array in the nearfield, or one in a a church or music establishment.
But in any case, I was certainly not looking for thoughts from someone who hates the whole concept.
You're coming up with a hypothesis and asking us to disprove it, while you haven't actually provided any evidence to support the hypothesis.
My hypothesis: today, the sky is green.
I refuse to go and look, but someone once said it looked kinda green once and I'm going to base my hypothesis on that.
So far, there's been a good amount of evidence presented that your hypothesis needs a little more thought, and yet you're having a go at people because they don't own line arrays.
This is a strange thread.
Chris
If you wanted no input from other people, why post to a public forum? Why not just make an entry in your private journal?
This response is utterly irrelevant to what I posted - this is a general opinion (yours) about some group of people you chose to lump into a very odd category (people who like miniature pianos.) I also note that you made no attempt to address the criticisms I leveled at line array speakers: that the use of a number of small drivers usually produces weak bass, boxy sound due to organ-pipe resonances in the long thin enclosure, and poor treble dispersion because the drivers are too large compared to high frequency sound wavelengths.
So let's forget about pianos, big and small. That is another discussion entirely. I dislike line arrays because all the ones I've heard have some or all of the following problems: weak bass, poor treble dispersion, boxy midrange, and screechy upper midrange.
When I thought about this and did a little research, I found some of those weaknesses come with the concept of using a large number of drivers that are too small in size to make good woofers, and too big in size to make good tweeters. Others come from the use of a long, narrow enclosure, which has a tendency to suffer from numerous organ-pipe acoustic resonances which cause the "boxy" sound.
You can take a line array speaker and improve the bass by bolting on big woofers in conventional box enclosures. You can take a line array and improve the poor treble dispersion by bolting on proper tweeters. But each of these additions takes you further away from the original "pure line array" concept; you end up with a speaker that is good not because it is a line array, but because it uses woofers, midranges, and tweeters, just like the vast majority of speaker-in-a-box systems sold over the last seventy years or so.
There are some things that line arrays are good at, such as being louder than a single driver of the same size (no big feat, since multiple drivers of the same size will obviously be louder than one.) So when one wants loud, but mediocre, performance, line arrays are excellent choices.
This is why big line arrays, usually made up of multiple large horns strapped together, are so commonly used for sound reinforcement in very large venues. In that situation, you have to use a lot of drivers to get loud enough, and if you have to use a lot of drivers, putting them in a line array is less-bad than the alternatives.
Line arrays are also used by some musicians who care mostly about minimizing setup time, or who bought into the Bose advertising rather than listening critically.
And there are also some people who like the sound of a line array. Not because line arrays are the best kind of loudspeaker, but because the peculiarities of line arrays happen to suit their personal taste. Some people also like kiviak, which is a food consisting of lots of little auks stuffed into a sealskin bag and left to decompose before being eaten.
In the same way, I have also met a few musicians who are not bothered by the screechy sound of a Bose L1 or Fishman SA220, and are quite happy with the way they sound.
Firstly: what were you looking for - only opinions that agreed with your own, disregarding the actual realities of acoustics? That's not the way public discussion forums work (not the ones with any shred of integrity, at any rate.)
Secondly: "Hates the whole concept" is your words, not mine. In fact, I don't hate the concept at all - I found the concept quite fascinating when I first encountered it, several decades ago.
Unfortunately, like the concept of car engines made out of Jello, the line array speaker sounds much better in the imagination than it turns out to be in reality.
In other words, the trouble isn't the concept. The trouble is reality.
Perhaps we should start a thread on the merits of car engines made from Jello. No disagreement permitted, all posters must agree to agree!
-Gnobuddy
Well we do have a thread about line array theory that's pretty decent. It might not be about the type of arrays you've heard personally but it's quite entertaining to read:
Infinite Line Source: analysis
Your previous post seemed familiar though.
Infinite Line Source: analysis
Your previous post seemed familiar though
.Of course. My opinion isn't based just on a whim, but on both experience and technical analysis, so it's not going to suddenly change for no particular reason. I haven't changed my opinions about gravity lately, either.Your previous post seemed familiar though
-Gnobuddy
I was actually getting at the cold fusion part of it. Resembling some remarks you made about a picture of my arrays some time ago.
The link I posted actually has pretty well balanced information why arrays might get ahead of that cold fusion fiasco after all. At least, when setup with some care.
How would we know the quality of the arrays you have experienced? I'd love to hear more about them. They seem to have made a lasting impression. A bad experience with some of them would not say much about all of them in my opinion.
I do wonder why you're so vocal about your dislike of the basic principle of arrays.
The thread I linked has a lot of technical analysis that explains why I like them so much.
The link I posted actually has pretty well balanced information why arrays might get ahead of that cold fusion fiasco after all. At least, when setup with some care.
How would we know the quality of the arrays you have experienced? I'd love to hear more about them. They seem to have made a lasting impression. A bad experience with some of them would not say much about all of them in my opinion.
I do wonder why you're so vocal about your dislike of the basic principle of arrays.
The thread I linked has a lot of technical analysis that explains why I like them so much.
The cold fusion comment wasn't about line arrays, but about the OP's belief that loudspeaker frequency responses varied continuously with every slight change in driver power. There was no explanation offered as to what mechanism was causing this mysterious frequency response change. So I made the comment that it's dangerous to believe technical claims that have no scientific explanation behind them.
I made a comment that they were like experimental flying cars, if I recall correctly.
Agreed. Every line array I've heard has been in the mediocre to bad category. That doesn't prove it is utterly impossible to make a line array that isn't horrible - but it does show that, at the very least, it is not the typical result of this particular speaker design.
I know you've put a lot of time, effort, and money into your own line array design. I haven't heard it, and therefore, have formed no opinion about it's sound quality.
I do, however, have a strong suspicion that if you had put equal amounts of time, money, and effort into a design that was NOT a line array, it would have sounded better...
I studied classical optics in college, which includes a lot of the math that describes line array speakers. That includes the mathematics of wave propagation and diffraction itself, and also the mathematics of diffraction gratings. So I do know some of the relevant math.
I'm sure you know that a line-array speaker is almost identical, mathematically, to a short, one-dimensional, optical diffraction grating.
I'll take a longer look at that thread to see if I'm missing something, but I can't do it right now.
-Gnobuddy
I can agree with that.
I made a comment that they were like experimental flying cars, if I recall correctly.
Yes, it came back to me... I'm pretty sure they are going to try and resurrect that flying car idea very soon though
It was worth it to me to try, for the reasons that are outlined in the thread.
For me, it remains the only valid solution I saw available to me with my specific set of compromises in my living room.
I'm not that versed in optics, but I'm not surprised by any commonalities either. I'll be sure to look into it.
I continue to believe that extrapolation to a linear response of speakers based on one measure at 1 watt/1 meter is not science. There is no scientific expectation that we are dealing with a linear system since there is no research to show that we are. There is research to show that the frequency response changes as the volume to the speaker increases and the voice coil heats up, and the research on that has shown that its not a linear relationship.
I never said the FR changes with each tiny little change in power to the speakers. I said it wasn’t a linear change, and that we needed multiple measures at different power levels with different speakers.
I do not have the funds, the equipment, or the knowledge to do this.
I stand by this belief until I am presented by research that shows me to be wrong. Produce the research, not authority.
I never said the FR changes with each tiny little change in power to the speakers. I said it wasn’t a linear change, and that we needed multiple measures at different power levels with different speakers.
I do not have the funds, the equipment, or the knowledge to do this.
I stand by this belief until I am presented by research that shows me to be wrong. Produce the research, not authority.
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