# Subwoofer testing methodology - what do you think is important?



## craigsub (Sep 9, 2006)

Hi all - This is an open thread to discuss subwoofer testing methodology. What is important when testing a subwoofer?

1. Frequency Response?
2. Max output at various frequencies?
3. Distortion at various frequencies and SPL levels?
4. Standard Features?

To get this started ... let's say this was proposed as a method for testing subwoofers, would everyone agree that this is the optimal approach?

Proposed testing method #1.

A. All subwoofers will be tested outdoors at one meter Groundplane.
B. Six different frequencies will be tested on each subwoofer at varied lengths of time, shown below. The purpose of using these test tones will be to find how much SPL, measured in dB, that each subwoofer can deliver at each frequency shown for the duration shown. 
C. 20 Hz will have a test tone which lasts 0.325 second.
D. 25 Hz will have a test tone which lasts 0.260 second.
E. 31.5 Hz will have a test tone which lasts 0.206 second.
F. 40 Hz will have a test tone which lasts 0.1625 second.
E. 50 Hz will have a test tone which lasts 0.130 second.
F. 63 Hz will have a test tone which lasts 0.103 second.
G. Each test tone will be delivered at increasing SPL until the subwoofer is exceeding 40% THD at a given frequency.
H. Bass below 20 Hz will not be measured.

This is proposal 1 for a subwoofer test methodology.

Please feel free to chime in with opinions on this.


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## Dale Rasco (Apr 11, 2009)

Are the different frequencies measured in a sweep or independent test tones generated one at a time?


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## craigsub (Sep 9, 2006)

Dale - This methodology would use independent test tones, not a sweep.

And for those who hate decimels ... .325 second is less than 1/3rd of a second. These tones range from about 1/3rd of a second for 20 Hz to about 1/10th of a second for 63 Hz.


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## Dale Rasco (Apr 11, 2009)

That's what I thought, just wanted to make sure.


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## craigsub (Sep 9, 2006)

For further clarification - There is a real lack of meaningful subwoofer testing being done now, and the home theater world could use some testing done which combines both measurements which reflect real world performance along with (as unbiased as is reasonably possible) listening tests.

I put up the methodology in the first post in order to give people a starting point for testing subs.

The first post is intended to get the members here to say "I think it's a great test, and here is why" ... or ... "I think it needs a lot of improvements, and here is why ... "

Let's see some opinions ...EVERYONE READING THIS is welcome to reply.


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## chashint (Jan 12, 2011)

I would prefer a down frequency sweep beginning at 200Hz and ending at 5Hz increasing in amplitude until the peak output is compressed 1dB (if 1dB is not adequate for audio testing then 3dB compressed).
I would also like to see distortion at 10Hz or 20Hz intervals along with 2nd and 3rd order harmonics.

I am really not all that concerned about burst mode, if the performance is there in swept mode it will be there in burst mode.


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## Dale Rasco (Apr 11, 2009)

I agree that we need to establish a better methodology for subwoofer testing that is not only indicative of real world results, but is also repeatable. I think this is a great starting point.


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## craigsub (Sep 9, 2006)

chashint said:


> I would prefer a down frequency sweep beginning at 200Hz and ending at 5Hz increasing in amplitude until the peak output is compressed 1dB (if 1dB is not adequate for audio testing then 3dB compressed).
> I would also like to see distortion at 10Hz or 20Hz intervals along with 2nd and 3rd order harmonics.
> 
> I am really not all that concerned about burst mode, if the performance is there in swept mode it will be there in burst mode.


This is the type of response that will make for a great thread. :T


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## drdoan (Aug 30, 2006)

Sounds like a great starting point. Have fun. Dennis


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## craigsub (Sep 9, 2006)

So far ... 78 views and one suggestion. No one has commented on the first criteria as posted.

I will offer up what I think is important ...

1. Max output using sinewaves (either sweep or individual) before audible distortion is detected by the tester, who should be several meters away from the subwoofer. 

2. Frequency response curves along with analysis of the posted response curve against maximum output curves. Why this analysis? Let's say we are looking at two sealed subwoofers. Subwoofer "A" is +/- 3 dB from 15 to 100 Hz while subwoofer "B" is down 9 dB at 15 Hz.

The first impression may well be that "A" is superior to "B". 

But then we have the max output sweeps ... and we see that "B" delivers, say, 100 dB at 15 Hz while "A" delivers only 91 dB.

We can conclude that "A" likely has more eq built into the response curve, and that "B" was designed with less eq, but more output. 

"B" is actually the more powerful, capable subwoofer.

Without analysis, people may miss this.

More later.


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## Dale Rasco (Apr 11, 2009)

If we are going to make this a real world test, there needs to be some sort of way to get an acurate measurement "in room" in order to let people know what they can expect out of the box without an EQ. Maybe a 10Hz-200Hz sweep from the center of the room directly from the sound card to the sub. Of course there would need to be a baseline or some sort of parameters established such as an untreated 15X20 room. It doesn't have to be pretty or incredibly detailed, it just needs to represent what one can expect to have to tame.

I know there are plenty of variables that have to be considered such as insulated walls versus hollow walls, carpet vs tile vs wood floors, 10'ceilings vs. 8' ceilings and so on, but I think it would be beneficial to see. I am not sure on how to go about it, I just think that there would be some benefit to it.


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## Dale Rasco (Apr 11, 2009)

Then again, if we are catering to the hard core such as ourselves, then an in room test as described wouldn't matter anyway.


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## craigsub (Sep 9, 2006)

Dale - Unfortunately, there is no way of doing an "in room response" test that could be meaningful in terms of raw data. However, listening tests are also important to add to the data. Let's say the reviewer in question has a 20x15x8 foot room. After the measurements, a series of listening tests in this room with each subwoofer being properly eq'ed according to its capacity to deliver bass should be done.

A smaller ported sub may only have useful output to 32 Hz, but it may be a terrific budget entry and sound good in this room. 

A larger sealed sub may well extend to 10 Hz in this room.

The reviewer needs to be able to properly eq each subwoofer in his room, while staying within the limits of each subwoofer. He/She then needs to report on sound quality, overall feel ... and describe what the subwoofer did with various movie and music scenes.

The reviewer is now setting a good objective and subjective criteria, which is (IMO), the proper combination of criteria.


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## Mike P. (Apr 6, 2007)

I'm not sure 1/3 or 1/4 duration tones are representative of demands made on subs in real world listening such as movies. A longer time frame perhaps? Bass below 20 Hz should be included as some designs do reach the lower frequencies.


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## craigsub (Sep 9, 2006)

Mike P. said:


> I'm not sure 1/3 or 1/4 duration tones are representative of demands made on subs in real world listening such as movies. A longer time frame perhaps? Bass below 20 Hz should be included as some designs do reach the lower frequencies.


Mike - You are onto something here. The opening criteria was posted with a specific reason in mind. I am curious how long it is until someone identifies the criteria as written.


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## Matman1970 (Jan 27, 2011)

I would have chimed in, but I am such a noob I would feel like I just got invited to NASA to help redesign the shuttle.:dumbcrazy:


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## Ricci (May 23, 2007)

Hey guys. Craig. I have recently started up a testing program. I completed the first round back in October. Or data hosting site just launched. We plan to do 2 or 3 rounds a year from here on out on just about anything I can get my hands on. Diy, pro sound, commercial ht, car audio raw drivers, whatever. The next round should be in May. Have a look at the tests I am doing under the "know how" section. We have another test or 2 to be added as well. This battery is way beyond what most tests will entail but hey you asked.


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## craigsub (Sep 9, 2006)

Ricci - It's nice to see you in this thread ... I clicked on the link, and there is a written "mission statement", but I could not find any data for the tests you already did. Am I missing something, or are you working on getting the results from last March on the site?

This looks intriguing - I also know of another prominent HTS member who is looking to start testing subwoofers.

I am not, in any way, trying to run how these tests should be done. What I hope to accomplish with this thread is helping to get a testing protocol which shows meaningful data, adds some subjective listening tests, and is thorough enough for the experienced diyer to read with confidence while also allowing the newbie, and even moderately experienced subwoofer shopper an understandable test.


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## Mike P. (Apr 6, 2007)

Under the Systems tab click on a individual System Name to go to the test.


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## Ricci (May 23, 2007)

Mike has it down. You can click on almost anything on the site linked in my sig and it will take you where you want to go. Also the graphs are active and will sort by the data column you have selected. We only have 9 systems tested as of now but we should be adding another 10-12 in May. We have been working on this for about 5 months now. Anyway under "know how" is a list of my equipment and the test program here.

http://www.data-bass.com/know-how. 

It is rigorous.


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## craigsub (Sep 9, 2006)

Strange ... The first link took me to the home page, but when clicking on the individual lcons, nothing happened. The second link works fine. That is a LOT of work. :T


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## kyle_k (Oct 10, 2007)

Its probably because you use ie7, it should be fixed now. if you're still have problems at this point let me know what browser and settings you're using! Explorer has major compatibility issues compared to all the other browser so its difficult to design around it.

http://www.data-bass.com/


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## dmanonlyone (Mar 5, 2009)

I was reading on another test page that the testers were using every capability of the sub to make it sound it's "best" then start the actual testing of the subwoofer and it's limits. By capability I mean if the sub had parametric eq or a similar function; since it is part of the subwoofer, then use it. 

This I think is getting closer to actual testing that is meaningful to a consumer. I realize there are many who just look at numbers, buy a sub, plop it down and turn it on without any regard for placement or tuning or equalization, but those folks are inherently wrong in the first place.

Ultimate standardization of the subs being measured in a home setting within the parameters of the sub will give the fairest actual useable results for comparison.


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## viccmw (Dec 15, 2010)

By no means am I knowledgeable in this area. I saw the chaps at Audioholics basing their subwoofer testing on the CEA 2010 Subwoofer testing, which I assume it's standard-based.

The link :
http://www.audioholics.com/education/loudspeaker-basics/2010-subwoofer-shootout

Seems, like your testing is on a similar approach?

At the end of the day, as a consumer, what I would like to see is an objective results that compares the woofers tested. Based on this, I think I can go with the methodology of the testing by Audioholics or yours...


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## kyle_k (Oct 10, 2007)

Object is important. I think they did a great job with the reviews at Audioholics but I think there are two points to take away from all that bashing. 1. They are being critical of the language used. If you write a lot, you'll probably upset someone if you're even remotely negative about a popular product. The second issue is they seem to have not tested the multiple modes that the subwoofer offers. Like Ilkka's tests of the SVS subs, when we come across systems that have more than one configuration, we'll run each test and produce the results. The only thing we will skip on it the room EQ feature sets. For example, we'll likely re-test the dual SW152 as we did not have the right amp.


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## chashint (Jan 12, 2011)

craigsub said:


> Mike - You are onto something here. The opening criteria was posted with a specific reason in mind. I am curious how long it is until someone identifies the criteria as written.


Oh Craig you are such a teaser :nono:
No sane person would think the CEA 2010 standard is a good way to test a subwoofer


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## Fatcat (Aug 17, 2008)

craigsub said:


> Hi all - This is an open thread to discuss subwoofer testing methodology. What is important when testing a subwoofer?
> 
> 1. Frequency Response?
> 2. Max output at various frequencies?
> ...


Just stumbled onto this thread.
WARNING, What I know about audio in relation to most of the posters here could probably fill a thimble but here it goes...
- Why would one not measure bass below 20 Hz in such a test? It seems like so many are looking for a sub's capability in this area.
- The length of the test tones seems really short. Wouldn't longer test tones give one more accurate results?
- Why only six frequencies within the listed range above? Wouldn't measuring at least twelve different frequency samples give you better granularity to the results.
- Is 40% distortion too high a figure? Can we not hear distortion from a sub at a lower percentage?

Thanks....Carlo.


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## Mike P. (Apr 6, 2007)

Subs should be measured below 20 hz if the design has the capabilities. I agree the tone time length is too short. An example would be the Klipsch RW-12d. It's notorious for port noise in a HT application, 1/3 of a second test tones won't show it.


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## Sirbrine (Sep 27, 2009)

craigsub said:


> So far ... 78 views and one suggestion. No one has commented on the first criteria as posted.
> 
> I will offer up what I think is important ...
> 
> ...


I am really just learning about sound quality and I understand that some people focus on raw output for maximum impact while others are more concerned about musicality. While I want both, I prefer musicality. That said, I guess I would agree that "B" is the more powerful subwoofer in the example above but I'm not sure it should necessarily be called the more capable unless I have misunderstood the meaning of the statement.


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## ISLAND1000 (May 2, 2007)

Ilkka's test are the gold standard. Anything less will produce less available information.
Add waterfalls covering the measured frequencies.
Test from 10-100 Hz. In my opinion that will include usable subs that fit/crossover with many mains and surrounds.


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## Stitch (Feb 26, 2011)

I have a totem thunder sub-any suggestions for home theater settings?


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## ISLAND1000 (May 2, 2007)

X-over @80Hz.


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## sickboy013 (Feb 28, 2009)

If an in-room listening test is done I think it may be a good idea to post what the trim settings were on the avr for the sub and what the gain on the sub was set to. 

I know it'll differ from avr to avr, but, it would be helpful to know how hard that particular sub was working to achieve the in-room results. Therefore someone reading the test results could gauge, within some degree, how the sub may work in their size room.

Forgive me if this is out in left field! onder:


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