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Author Topic: Understanding speaker specs  (Read 3381 times)

Ivan Beaver

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Re: Understanding speaker specs
« Reply #20 on: January 27, 2013, 12:06:26 pm »

Ahh....

It would be my conclusion then that the curve should be published without any "smoothing".  It is simply becoming "not accurate" and certainly not representative in any way.
Good luck finding any of those out there.

And remember that our ears do not hear "unsmoothed".  We have a built in "smoothing mechanism" that helps.

The example I posted was of a single driver-a multiway speaker is going to look a lot worse.

And even if you said "unsmoothed"-how many data points would you want?  that is a different way of smoothing.

You will never get a "standard" that everybody uses.  That is why it is important to be able to look at various graphs and try to recognize what is the same-what is different and what is important.

There does become a point at which unsmoothed data is almost useless-as there is to much detail.

Now if you are looking for a SPECIFIC thing in the data-then unsmoothed in a particular freq range can be a GOOD thing-but not overall across the full freq spectrum
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Ivan Beaver
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Jonathan Johnson

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Re: Understanding speaker specs
« Reply #21 on: January 27, 2013, 10:42:29 pm »

The example I posted was of a single driver-a multiway speaker is going to look a lot worse.

I'll also point out that no single test of a single speaker is representative of the whole production of that model. A graph representing the response curve as included in product literature should be an average representation of several samples. The more samples you have, the smoother the graph will become. Even so, if every unit of a particular model exhibits a deep, narrow dip in response at 12 kHz for example, it is important to display that on the graph; overzealous smoothing may cause that dip to appear as an insignificant ripple.

The best we could hope for is a graph that presents an average response curve with dips and spikes typical of the model, and also includes curves representing deviation. Of course, now we have to understand what those high and low deviation curves mean, and that may be much more difficult to represent and interpret. Marketing people don't want customers to have doubt, and deviation specs create doubt (at least in the minds of the marketers).
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AllenDeneau

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Re: Understanding speaker specs
« Reply #22 on: January 28, 2013, 04:54:47 pm »

great explanation guys. Is it safe to assume that what's being said is every manufacturer has their own test methods and publish what they wish to publish and it's up to us to discern it's validity?

Brand A may do multiple tests and then average their results and present it in a non-smoothed fashion but, brand B may only do 2 tests and then use the most beneficial smoothing results and, brand C takes the data straight from the manufacturer of their components and publishes them without ever testing them in their box design and so on with each different speaker brand?

You will never get a "standard" that everybody uses.  That is why it is important to be able to look at various graphs and try to recognize what is the same-what is different and what is important.

So that's my next new quest, how to determine the above... The answer was presented to my original question, now how do I interpret the results? I believe the best case scenario is to be able to audition each "box" myself and measure them out but, what if you don't have that luxury? Can you really hold the plots as useful and beneficial info as a whole?

Thanks for the info guys, it's been a real learning experience and I truly love to learn. Now I'm trying to understand why I avoided this learning for so long  :-[
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Ivan Beaver

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Re: Understanding speaker specs
« Reply #23 on: January 28, 2013, 08:20:29 pm »

Here is an example of using no smoothing-but changing the 'data points".  I am showing 2 graphs.  The first one is just a few samples and one with more samples.

The second graph still shows both of those-but also has one with a lot of samples.  Notice how "cluttered" it gets.

I have never seen any manufacturer show data that looks like that-even though it is the most accurate.

Sometimes to much information is not a good thing.
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Ivan Beaver
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Scott Bolt

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Re: Understanding speaker specs
« Reply #24 on: January 29, 2013, 10:44:30 pm »

Here is an example of using no smoothing-but changing the 'data points".  I am showing 2 graphs.  The first one is just a few samples and one with more samples.

The second graph still shows both of those-but also has one with a lot of samples.  Notice how "cluttered" it gets.

I have never seen any manufacturer show data that looks like that-even though it is the most accurate.

Sometimes to much information is not a good thing.

Sure, but both of these sets of graphs show the data I would look to see.  They show the peaks and valleys in the response clearly.  Taking this graph and showing anything that looks "flat" would simply be bogus.
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Ivan Beaver

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Re: Understanding speaker specs
« Reply #25 on: January 30, 2013, 07:30:33 am »

Sure, but both of these sets of graphs show the data I would look to see.  They show the peaks and valleys in the response clearly.  Taking this graph and showing anything that looks "flat" would simply be bogus.
so except for your own measurements-how many manufacturers are showing data that looks anything like unsmoothed data?

It all depends on what the particular person is looking for.  For a designer-there is a lot to be gained from unsmoothed data.

For the casual buyer-the unsmoothed data would turn them away-since they want something that is "smoother" sounding.  Even though they have no idea what they are really looking at.
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Ivan Beaver
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Scott Bolt

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Re: Understanding speaker specs
« Reply #26 on: January 30, 2013, 09:29:03 pm »

so except for your own measurements-how many manufacturers are showing data that looks anything like unsmoothed data?

It all depends on what the particular person is looking for.  For a designer-there is a lot to be gained from unsmoothed data.

For the casual buyer-the unsmoothed data would turn them away-since they want something that is "smoother" sounding.  Even though they have no idea what they are really looking at.

... [chuckles]...

You are making my point for me.  So there is no mathematical explanation for the frequency response graphs most manufacturers show.  It is just another marketing tool much like how many "watts" a powered speaker has  :o

You are correct that few would understand the graph and how it may or may not translate into a good sounding speaker.... but that is still no reason to "fake" the plot to get a more marketing friendly response curve.

I would just assume that any data being trumpeted as "engineering data" actually be real engineering data.  While I am an engineer, I suspect that any sound professional would also prefer that the data be based on real readings instead of marketing's dream of what they wished the data looked like ;)
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Tim McCulloch

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Re: Understanding speaker specs
« Reply #27 on: January 31, 2013, 12:03:53 am »

... [chuckles]...

You are making my point for me.  So there is no mathematical explanation for the frequency response graphs most manufacturers show.  It is just another marketing tool much like how many "watts" a powered speaker has  :o

You are correct that few would understand the graph and how it may or may not translate into a good sounding speaker.... but that is still no reason to "fake" the plot to get a more marketing friendly response curve.

I would just assume that any data being trumpeted as "engineering data" actually be real engineering data.  While I am an engineer, I suspect that any sound professional would also prefer that the data be based on real readings instead of marketing's dream of what they wished the data looked like ;)

I think the issue is "how much information is useful"?  Looking at the higher resolution data shows you a lot more, but to the "average" buyer (and a number of presumably more sophisticated ones) the extra data points will be misinterpreted or given far too much importance.

It's very easy to make bad sounding systems by applying too much correction to too many data points, particularly if that data is from a single test sample and not the unit in situ.  Don't ask me how I know.  ;)

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Ivan Beaver

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Re: Understanding speaker specs
« Reply #28 on: January 31, 2013, 07:32:58 am »


I would just assume that any data being trumpeted as "engineering data" actually be real engineering data.  While I am an engineer, I suspect that any sound professional would also prefer that the data be based on real readings instead of marketing's dream of what they wished the data looked like ;)
But a real engineer will not want to look at the full freq response in an unsmoothed format.

When doing real engineering-you will zoom in on particular areas unsmoothed to get a better idea what is going on.  Not the whole thing.

Look at it this way-look at the door in your room-it doesn't matter.  Now step up to it and put your eye as close as you can to it-does it look different?  Now let's take a magnifying glass and look at it.  How about an electron microscope?

If you want the REAL data-then the electronmicroscope is the way to go...

But what if the question is -"Have I sanded the door smooth enough to to paint?".

If you look closely you will still see ALL KINDS of imperfections-and you will never get them out.  But for the intended purposes-eyeballing it several feet away is just fine.

HOWEVER-if you are a paint engineer and are looking at the surface to see how well different formulations of paint will stick to different surfaces-then looking a lot closer is important-but not to the average person.

There is a thing as to much data.

As the old saying goes "What are we here to do?".  What do we really need to see?
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Ivan Beaver
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Brad Weber

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Re: Understanding speaker specs
« Reply #29 on: January 31, 2013, 09:28:24 am »

I would just assume that any data being trumpeted as "engineering data" actually be real engineering data.  While I am an engineer, I suspect that any sound professional would also prefer that the data be based on real readings instead of marketing's dream of what they wished the data looked like ;)
A real Engineer is also going to be looking at polars or balloon data, going to want better information about maximum power (and possibly ask for voltage and current information rather than Watts), will want to see sensitivity versus frequency, will want to see phase data and possibly other technical factors that probably don't matter to or may even discourage the average purchaser.  That has always been the dilemma, providing technical data that is complete and accurate enough for some but not overwhelming or intimidating for others.
 
I think what Tim was referencing was something it took me a while to understand (and that I still am learning) and that is differentiating what is important from what is not.  I have certainly been guilty of spending hours worrying about some little anomaly in the response that probably had no practical impact - and all too often at the expense of issues that did matter.
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