Understanding Loudspeaker Measurements, Part 1

S

shadyJ

Speaker of the House
Over the last couple of years, Audioholics’ speaker reviews have contained graphs that have prompted questions from many readers about the meaning and importance of the information displayed in them. Some readers have found the information in them confusing, and that is our fault for not recognizing how cryptic these sort of representations are for an average reader. It can be easy to take these sorts of data visualizations for granted when one spends so much time dealing with the minutiae of loudspeaker behavior, and that can sometimes lead us to assume too much knowledge on behalf of the reader, especially novices to the audio hobby. In this article, we explain frequency response and the set of frequency response curves known as the 'Spin-O-Rama' curves.


READ: Understanding Loudspeaker Measurements, Part 1
 
D

D Murphy

Junior Audioholic
That looks really interesting. Now I've just got to find time to give it a close read. Thanks Shady.
 
ryanosaur

ryanosaur

Audioholic Ninja
Definitely... Good work! I was lucky I think, I undersood most of this, somehow... it was Subwoofers and the Electronics that didn't make much sense.
Fortunately, I found this guy that made some amazing speakers, too! ;)
Thanks for another good write up, Shady!
 
Swerd

Swerd

Audioholic Spartan
Thanks shady. Your article goes about explaining what 2-dimension graphs can tell people. I've found that scientists or engineers are quite used looking at and understanding graphical presentations of data. But among non-scientists, many but not all, have limited experience with them. As a result, the graphs can get in the way, making it easy to loose their attention. Whenever I've talked to groups of people (on subjects other than audio) and used graphical data, I've noticed its easy to loose some people early on. Their eyes glaze over. They might be interested in the subject, but I've never been able to find another way of getting through to them without the graphs.

So I think its great that you're trying to reach this audience. It certainly fills a need. I hope it works well.
 
lovinthehd

lovinthehd

Audioholic Slumlord
Good job, am bookmarking this, as people ask these sort of questions about what to expect by looking at measurements fairly often and want a good starting point...
 
Verdinut

Verdinut

Audioholic Samurai
Clear and well explained Part 1. It was about time to have an expert who could explain the loudspeaker industry jargon for the common audiophile.

Looking forward to see the rest of the topic.
 
gene

gene

Audioholics Master Chief
Administrator
The waterfall plots and polar maps often seen in Audioholics' speaker reviews are colorful and visually interesting, but what can they really tell us about a loudspeaker's performance? In this article, we explain the meaning of these graphs. We try to help you understand what to look for in determining the sound character of speakers from the information displayed in these graphs, so you can use them to find the right speaker for your system.

polars.jpg

Read: Understanding Loudspeaker Review Measurements Part II
 
ryanosaur

ryanosaur

Audioholic Ninja
Super cool! Thank you guys!!! Please keep it coming. :)
 
D

D Murphy

Junior Audioholic
Great job Shady. I thought showing polar maps from various vantage points was particularly helpful.
 
G

Gonzaga_1

Audiophyte
I'm curious how to read a waterfall plot when measuring the sound absorption of sound panels in a room. One measurement without panels and one with. How does one compare the effectiveness?
 
S

shadyJ

Speaker of the House
I'm curious how to read a waterfall plot when measuring the sound absorption of sound panels in a room. One measurement without panels and one with. How does one compare the effectiveness?
It doesn't make much sense to talk about polar responses in room. The directivity of the speaker does not change. You can measure the effects of an acoustic panel, but it won't have any kind of directivity that would translate into a polar map.
 
gene

gene

Audioholics Master Chief
Administrator
In our subwoofer reviews, we post a very comprehensive set of measurements that illuminates the full range of a subwoofer's performance. We have noticed that one of the graph sets in our subwoofer reviews have been a bit cryptic for much of our readership, however, for those who understand what is being displayed, they are some of the most illuminating graphs in looking at how well the subwoofer maintains accuracy from low loudness levels to its maximum limits. In this article, we attempt to shed some light on these graphs so any reader can follow them to get a better understanding of what their subwoofer is actually doing.

sub.jpg


Read: Understanding Subwoofer Review Measurements Part III
 
Verdinut

Verdinut

Audioholic Samurai
Those are very comprehensive details of subwoofer behavior measurements. Good work Shady.
 
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S

SDX-LV

Audiophyte
Great article about Spinorama and also very good explanation of the other measurements. I personally prefer Spinorama as it is the format that tells you the most in a single graph.

As Audioholics.com and specifically James Larson is the number 1 source of independent Spinorama measurements on the Internet, I have included links to your work on the speakerdata2034.blogspot.com where people can find as many different Spinorama measurements as possible and also learn how to interpret them.
If anything, the data on the blog can be used for comparison and it is also scaled to allow for easy 1:1 comparisons.

Thank you for your measurements and articles!
 
S

shadyJ

Speaker of the House
Great article about Spinorama and also very good explanation of the other measurements. I personally prefer Spinorama as it is the format that tells you the most in a single graph.

As Audioholics.com and specifically James Larson is the number 1 source of independent Spinorama measurements on the Internet, I have included links to your work on the speakerdata2034.blogspot.com where people can find as many different Spinorama measurements as possible and also learn how to interpret them.
If anything, the data on the blog can be used for comparison and it is also scaled to allow for easy 1:1 comparisons.

Thank you for your measurements and articles!
Very cool site you have! Let's hope that spin-o-rama becomes more widely adapted so you are able to add more in the future. And thanks for the compliments!
 
S

SDX-LV

Audiophyte
Thanks James!

BTW, perhaps you or someone you know who is good with measurement data and familiar with Spinorama standard may be interested to post-process data from publicly available measurement data files?

There are 2 cases I most interested in but did not manage to crack the data myself:
  • For KEF Ci200RR-THX as well as KEF Ci3160RL-THX among the official specifications there is also EASE GLL data that can be exported to text/spreadsheet for most directivity measurements.
  • Then also Princeton 3D3A Lab offers everyne to download their database of anechoic measurements for a number of interesting speakers.
  • + there are some more interesting manufacturer measurements in EASE GLL or CLF formats that could be published in a nice way with the right tools.
For now this data is usable by really hardcore enthusiasts only :)
 
S

shadyJ

Speaker of the House
Thanks James!

BTW, perhaps you or someone you know who is good with measurement data and familiar with Spinorama standard may be interested to post-process data from publicly available measurement data files?

There are 2 cases I most interested in but did not manage to crack the data myself:
  • For KEF Ci200RR-THX as well as KEF Ci3160RL-THX among the official specifications there is also EASE GLL data that can be exported to text/spreadsheet for most directivity measurements.
  • Then also Princeton 3D3A Lab offers everyne to download their database of anechoic measurements for a number of interesting speakers.
  • + there are some more interesting manufacturer measurements in EASE GLL or CLF formats that could be published in a nice way with the right tools.
For now this data is usable by really hardcore enthusiasts only :)
If you are interested in developing spin-o-rama graphs from raw data, that can be done, but it would take a little work. If you wanted to do it, you need to refer to the CTA-2034 standard to see all the processing that needs to be done. There are a bunch of steps involved, so yeah, as you say, its for hardcore enthusiasts only.

If you are able to send me the data files in a csv format, I might be able to turn those files into spin-o-rama graphs, maybe.
 

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