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Polar response is not the key

restorer-john

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Did you know the Q Acoustics 3050i comes in Arctic White? I bet it has a good Polar response....

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Audiojim

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But basically the possible range of dispersion patterns is baked in through the choice of driver dimensions and baffle size..?

I doubt it. This is basically a rehash of the idea that only the frequency response matters and the price and cone materials and other specifications don't matter. I disagree.
 

Cosmik

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I doubt it. This is basically a rehash of the idea that only the frequency response matters and the price and cone materials and other specifications don't matter. I disagree.
Do you know how and why 'beaming' occurs? Look it up.
And then look up 'baffle step". It might explain a few things.

Edit: and have a look at this https://www.grimmaudio.com/site/assets/files/1088/speakers.pdf
It explains quite lucidly why the Grimm LS1 is designed as the seemingly odd shape it is. The designer really did think that dispersion matters and consciously created a speaker with the dispersion pattern he wanted (in the process going against convention, or as I believe it to be, 'fashion').

Also, read this: http://www.regonaudio.com/Audio in Modern Times.pdf
 
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edechamps

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Phase is important, but not because phase in itself is audible. It is important because the low frequency driver and the high frequency driver must sum up correctly around the crossover frequency, where both drivers emit sound simultaneously. Any time offset between the drivers makes it more difficult to get this summation correct.

I agree, and I will add, as I did in my previous post, that this problem will show up on frequency response measurements, not just phase response response measurements, as interference will cause frequency response deviations. Which is why there's usually little point in looking directly at the phase response (or "time coherence" as @Audiojim calls it).

Hi. Would you say that for a particular combination of driver sizes place on a baffle of a certain size, there are going to be 'no surprises' whoever is doing the designing? i.e. if you have a 6" woofer and a standard 1" tweeter on a baffle 8" wide, there's only so much difference in polar response you can achieve, whether it's $10 drivers, or $1000 drivers?

I disagree. The design of the enclosure can make a difference, and not just because of its size. For example the waveguide used (if any), edge diffraction. An LSR305 is just boring drivers in a rectangular plastic box - I suspect it's the waveguide that makes it measure so well. Maybe people more familiar with speaker design can pitch in.

This is basically a rehash of the idea that only the frequency response matters and the price and cone materials and other specifications don't matter. I disagree.

The "cone materials and other specifications" do often affect the frequency response (or other basic metrics like maximum output level), so I don't see what your point is. It's a false dichotomy.

As for the price, well, I'm not sure what you mean by that. Are you saying that if I take a $300 speaker, and change its price tag to $3000, then it's magically going to sound better? That might very well be true in sighted listening (due to bias, if the listener knows the price), but certainly not in a double-blind test.

You said you disagree, but so far we have seen exactly zero evidence from you backing up your reasoning as to why you might disagree. It would help if you could provide links and references to sources that seem to contradict our claims, so that we have something concrete to respond to, instead of blanket, sweeping statements like "I disagree" with no details whatsoever. It's difficult to debate with someone if we don't how that person arrived at their conclusions. Right now all I can tell is that you seem to believe that audio quality is strongly correlated with the price tag of the equipment, an assumption that has no basis in fact, as has been shown countless times (e.g. @amirm's numerous reviews on this forum, obviously bogus products like overpriced cables, etc.). If you were to let go of that baseless assumption, you might find it easier to make sense of the data and the research.
 

maty

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Talking about the phase, the phase shift.

Imagine you are listen to very good recordings with high dynamic range (DR) and... with a majority of acoustic instruments and natural voices without autone (vade retro satana) like as it is usual in my auditions.

How affect the phase shift at HF, aka tweeter? From Class D amplifier and the room.
 
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Cosmik

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I disagree. The design of the enclosure can make a difference, and not just because of its size. For example the waveguide used (if any), edge diffraction. An LSR305 is just boring drivers in a rectangular plastic box - I suspect it's the waveguide that makes it measure so well.
I wasn't really talking about waveguides and horns, just about generic direct radiator speakers that feature the same driver configuration as each other.

But on this topic, and the notion of "well-engineered", I see a paradox (or whatever the right word would be). We are led to believe that designers are using science and engineering to achieve miraculously different measurable results compared to the next designer (or why bother?), but aren't they all using the same science and engineering?

And if it really is science and engineering, why do you need a designer at all? You really could just program the known objective characteristics of the drivers and box into a computer (because the designers are doing it with science and engineering, right? Not intuition, feelings, guesswork) and model the result. And you could set the computer off finding the optimal arrangement of drivers, box, waveguides, crossovers that would give the designer the 'best' result. Then order the bits and glue it all together.

If this isn't possible for some reason, then I call the bluff of the designers: they're still relying on convention, fashion, guesswork and intuition, not 'science'.
 
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Audiojim

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No designer designs a speaker without extensive listening which proves my point that it's all unknown. Frequency response is not the final arbiter all it does is tell you how bright or low different frequencies are. Which is just matter of preference anyway.
 

jazzendapus

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And if it really is science and engineering, why do you need a designer at all? You really could just program the known objective characteristics of the drivers and box into a computer (because the designers are doing it with science and engineering, right? Not intuition, feelings, guesswork) and model the result. And you could set the computer off finding the optimal arrangement of drivers, box, waveguides, crossovers that would give the designer the 'best' result. Then order the bits and glue it all together.
One can dream...
As it is now this field is closer to some vague pseudo-artistic woodwork fetishism that's somehow related to sound rather than something with clear goals about what speakers are supposed to do. Personally I believe speakers are supposed to be neutral mediators between myself and the artists, and simply give me what they want me to hear. Once this is achieved I see no reason for mucking about anymore, the mission would be accomplised. But obviously a lot of powerful people in the biz would lose a lot of money if things were going according to this ideal, and that's imo is one of the biggest reasons it's not happening.
 
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edechamps

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But on this topic, and the notion of "well-engineered", I see a paradox (or whatever the right word would be). We are led to believe that designers are using science and engineering to achieve miraculously different measurable results compared to the next designer (or why bother?), but aren't they all using the same science and engineering?

If this isn't possible for some reason, then I call the bluff of the designers: they're still relying on convention, fashion, guesswork and intuition, not 'science'.

I don't think your reasoning makes sense, for a number of reasons.

First, not all designers are trying to optimize solely for sound quality; most designers are also concerned about other aspects of the product, such as maximum output level, size, cost of materials, aesthetics, etc. Optimal designs can differ based on these factors.

Second, even if we consider designers that are all trying to optimize purely for sound quality: while competent designers will agree on the science of what makes a speaker sound good from an external perspective (e.g. on-axis and off-axis frequency response, reasonable THD), they do not necessarily have to agree on the best way to design a speaker that fulfills these external criteria. Yes, that could mean they're relying on "convention, fashion, guesswork and intuition", but that doesn't matter as long as the goal is correct (and backed by science). As consumers we don't care how the designer made a speaker sound good, as long as it sounds good.

Here's a different phrasing on that second point: imagine a designer who's not sure what the best approach is. The designer tries a number of potential speaker designs using "convention, fashion, guesswork and intuition", measures them, and only keeps the one that science says measures best. Is that designer "relying on science"? I would say yes, because they're ultimately relying on science to determine what designs sound best. In other words, it doesn't matter much what process they're using to design the speaker - all that matters is the end result, i.e. the finished product.

Now, of course, some designers might be able to reach that goal more quickly, more cheaply and more effectively by using better, science-backed design methods, and the market will reward them for that since such designers will be able to produce better speakers at lower cost. (Assuming that the market is perfectly rational, of course. Sadly, in audio, it's really not.)

And if it really is science and engineering, why do you need a designer at all? You really could just program the known objective characteristics of the drivers and box into a computer (because the designers are doing it with science and engineering, right? Not intuition, feelings, guesswork) and model the result. And you could set the computer off finding the optimal arrangement of drivers, box, waveguides, crossovers that would give the designer the 'best' result. Then order the bits and glue it all together.

I don't think we're there yet in terms of the state of the art in speaker design processes. I believe we are making progress towards what you're describing, especially with the advent of physics simulation techniques like FEM or BEM (which are now used routinely by companies like JBL or Genelec), but I think we're still a long ways away from being able to input some constraints, let the computer do the work, and have it come up with a fully optimized speaker design. Maybe if you fast forward 20 years, you'll live in the world that you're describing :)

No designer designs a speaker without extensive listening which proves my point that it's all unknown. Frequency response is not the final arbiter all it does is tell you how bright or low different frequencies are. Which is just matter of preference anyway.

That's it. I'm done responding to you. You still persist in making baseless, unsubstantiated statements that research and rigorous studies have thoroughly debunked many times, and I have pointed you numerous times to literature that explains why such statements are wrong and describes the relevant research in great detail. From this point on I'm just going to assume you're acting in bad faith. Please don't come back until after you're read the relevant research so that we can have a productive discussion, instead of wasting everyone's time.
 
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solderdude

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Frequency response is not the final arbiter all it does is tell you how bright or low different frequencies are.

No it isn't, nobody here says it is. Nor that polar response is the only important aspect, nor do 'we' think used materials, geometries and other aspects are solely important factors. All factors matter and 'we' can measure a few of them with a reasonable tolerance.
Nor do any of us here believe they can accurately predict HOW a speaker will sound EXACTLY in any random room from any random amplifier.
Some folks here CAN actually make educated guesses as to how a speaker with certain measurements may sound in a room and how to improve the sound based on knowledge of room conditioning, EQ, and a set of measurements.
If you can't then I don't see the reason to crap on measurements and experiences of others (other than trolling)

What frequency response plots show is how the speaker measures in certain conditions.
What polar response plots show is how certain frequencies spread out under horizontal angles.
What CSD's show is how long certain frequencies continue to ring.
What phase measurements show is either electrical phase (important for amp loads) or acoustical phase in one specific point in a certain space.
What step response plots show is how the phase response of driver units 'combine' in one specific point in a certain space.

When the conditions are similar during measurements you can compare certain aspects. It won't tell you exactly how those speakers will actually sound in each room at a random position between the speakers and room.

That last part seems to be your gripe with measurements. They don't seem to tell you anything. For that reason you find the measurements irrelevant.
That's O.K. ... then stop arguing about it and either learn something from others here, articles, or whatever or... ignore measurements and those that place a certain value to them.
 
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Cosmik

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As it is now this field is closer to some vague pseudo-artistic woodwork fetishism that's somehow related to sound rather than something with clear goals about what speakers are supposed to do.
A good way of putting it!

My suspicion is that while materials and so on have improved over the years, the necessity for that has been short-circuited by the development of DSP and practical active amps. So while 'designers' are fetishising the latest high tech woofer that can work up to 5 kHz or whatever, and using their golden ears to tune their first order crossovers with it - generally being 'artists' - they could simply have added a low cost third 'way' using DSP and solved all their problems at a stroke. And it could have been a more-or-less automatic process that required very little in the way of artistry.
 

Cosmik

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As an aside, I can do a 'party trick' with my three-way active speakers and software:

I can show that if the three drivers are phase corrected and time aligned (which they are, pretty well), it is possible to switch between vastly different crossover points and slopes while playing music 'live' and hear virtually no audible change. If you listen to an individual driver (which I can also demonstrate with the software), there is an obvious large change.

The point? Well, it is suggestive of the idea that there is no need to be an 'artist'. If you have three drivers (it might not be so easy with a two-way) mounted on a certain baffle, and basically-correct DSP, there's very little you can (or should be able to) do to the sound beyond that. The sound of the speaker will (should) be defined by the sizes of the drivers and the dimensions of the baffle.

For sure, rounding of the edges will help with the measurements, but Mr. Linkwitz thought that that aspect was overplayed.
While I try to minimize visible diffraction ripples in the frequency response for good measure, I have no evidence that even strong diffraction effects have significant audible consequences...

Waveguides and horns are another factor, but don't they fit into the 'science'/mathematics category where no artistry is needed in order to achieve a certain measured characteristic? (That is not me saying that I approve of their use, though :)).
 

edechamps

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So while 'designers' are fetishising the latest high tech woofer that can work up to 5 kHz or whatever, and using their golden ears to tune their first order crossovers with it - generally being 'artists' - they could simply have added a low cost third 'way' using DSP and solved all their problems at a stroke. And it could have been a more-or-less automatic process that required very little in the way of artistry.

DSP can't fix everything. In particular, it can't fix directivity (so, for example, you can't tell it to fix something in your off-axis response without altering the on-axis response too, at least not in the general case). It also can't make your speaker play louder (quite the opposite, in fact). These kinds of acoustic problems still have to be solved the old-fashioned way, by playing with various transducers, materials, enclosure shapes, etc.
 
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daftcombo

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DSP can't fix everything. In particular, it can't fix directivity (so, for example, you can't tell it to fix something in your off-axis response without altering the on-axis response too, at least not in the general case). It also can't make your speaker play louder (quite the opposite, in fact). These kinds of acoustic problems still have to be solved the old-fashion way, by playing with various transducers, materials, enclosure shapes, etc.

Is it possible to tell, from a polar graph, how much one should toe the speakers in?
 

Cosmik

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DSP can't fix everything. In particular, it can't fix directivity
I didn't say it did. I said that it allows you easily and transparently* to add another 'way' to bridge the yawning chasm between your 8" woofer and 1" tweeter. And that will certainly allow it to play louder.

* of course you can argue about perfection
 

sergeauckland

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Is it possible to tell, from a polar graph, how much one should toe the speakers in?
Yes, but together with the on-axis anechoic response graph. One without the other won't tell you at what angle the response is flat, if it ever is, of course.

S
 

edechamps

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Is it possible to tell, from a polar graph, how much one should toe the speakers in?

Most speakers are designed so that the best possible response is obtained directly on-axis. So the answer is simple: the speaker should be facing the listener.

If there are multiple listening positions, then yes, I guess off-axis response could be used to inform the choice of angle. In fact, GedLee has a paper describing exactly that.
 

sergeauckland

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Most speakers are designed so that the best possible response is obtained directly on-axis. So the answer is simple: the speaker should be facing the listener.

If there are multiple listening positions, then yes, I guess off-axis response could be used to inform the choice of angle. In fact, GedLee has a paper describing exactly that.
Many modern 'speakers have a response that rises at HF. This is both because they stand out on dealer demos (listen to all that detail) and because many people prefer to have the 'speakers pointing straight on rather than angled, for aesthetic (WAF) reasons. If that's the case, then to achieve a flat response at the listening position they need to be toed in, by an amount that can be seen from the polar diagram and anechoic on axis response.

S
 
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