Audioholics Subwoofer Measurement Data Compilation & Report

By now you’ve seen the numerous subwoofer reviews we’ve published using our new Powered Subwoofer Test and Room Size Rating protocol. Audioholics.com has invested a great deal of resources measuring and analyzing subwoofers over the last few years.  As a result we have created the industry’s most comprehensive testing procedure and database of tabulated measurement results.  Our tests adhere to our strict testing methodology which is also compliant to the CEA-2010 Subwoofer Measurement Standard whenever practical.  

Audioholics CEA 2010 Subwoofer Measurement Data Excel Attachment

With each new subwoofer review published, we are now typically uploading an Excel spreadsheet of all subwoofers tested to that point.  This can be seen on the main page of this article and any recent subwoofer review towards the bottom of the site below the "Jump to" drop down bar.  You need Microsoft Excel to view it. If you have trouble finding the excel file, go to our forum thread and download the Zip file from the first post.  Also included on that thread is a PDF version of this spreadsheet for those that don't have Excel.

In this article, we will take you on a tour of our Excel Spreadsheet  measurement results called “Audioholics CEA-2010 Subwoofer Measurement Data”.   It is our hope that the reader can achieve a better understanding of what all the data means for a more informed purchasing decision by making objective apples-apples comparisons between various tested products. 

Output isn’t always everything as the laws of physics dictates BIGGER is BETTER if you want deep loud bass. But, how a sub behaves or more accurately termed “mis-behaves” gives a good indication of how it will perform in a real room using real program material.  This is why we stamp a room size rating on each subwoofer we review which will be discussed later in this article.

The Audioholics CEA-2010 Subwoofer Measurement Data Excel spreadsheet features 5 tabs each with different information collected for all the subwoofers we’ve tested over the last 5-6 years.  You can select one tab at a time by hitting the left mouse button with your cursor placed over the desired tab.  You will have to hit the right arrow key to shift the tabs over when you desire to view tab #5.

Tab 1:  Subwoofer General Data

This tab is rather self explanatory.  The brands are alphabetized and data such as price, dimensions, dimensional volume, weight, driver type, amplifier rating, system alignment, etc is tabulated in corresponding columns.  When a sub has multiple tuning modes it is listed as “yes”.  This means the manufacturer has provided a method for changing the tuning of their sub by either plugging ports or engaging different EQ settings, or a combination of both.  If the sub has an EQ on board we list it as “yes”.  Some subs even come with built in auto setup and room correction options which you can read about in their corresponding formal reviews.

Tab 1: Subwoofer General Data

We broke up the data collected by Josh Ricci in the top table for the first two tabs and data collected by other staff (myself included) in the bottom table for the first two tabs.  The reason for this is Josh is our primary reviewer testing per our new subwoofer measurement protocol which adheres to CEA-2010 testing.  Many of the reviews in the bottom tables were either done before we established our new measurement protocol or they were conducted by reviewers not setup on a CEA-2010 test rig.  Later on we discuss how to correlate the results done by different testers and methods as closely as possible.

Also notice that each brand/model# is hyperlinked to our formal review for that product.  If you want to dive into more detail on our tests or subjective impressions, just click the product and our review will open in a new browser.

Tab 2: CEA 2010 Output Results

Tabulated  CEA 2010 test results are located in this tab from 10Hz to 125Hz in 1/3^rd octave increments.  Our measurements are conducted at 2 meters using groundplane technique.  While the test program reports peak SPL data, we convert all of our data to RMS data at 2 meters which more closely resembles 1 meter 4pi (freespace).  Though it’s not as flattering to report 2 meter RMS data as it is to report 1 meter peak data to the manufacturers whose sole purpose may be a marketing slogan, we do this because it’s a more accurate way of representing actual product performance.

We always publish distortion data for all max output measurements done using CEA-2010 test signals.  This is the only way to determine pass/fall to ensure you have accurately achieved true maximum output of the product under test.  To get distortion data for a particular product, you will have to reference the formal review for that product.  In our reviews, you will find even more elaborate test results including frequency response, group delay, max long term compression tests, and much more.  Please reference our SVS PB13-Ultra and Velodyne DD18+ reviews as examples.

Some quick translations:

• For every doubling of distance you subtract 6dB (1 meter to 2 meter to 4 meter, ….)
• To convert Peak SPL to RMS SPL you subtract 3dB

Thus, to convert 1 meter peak to 2 meter RMS would involve you subtracting 9dB for every SPL measurement at each frequency. If you want to convert 2 meter RMS to 1 meter RMS you need to add 6dB for every SPL measurement at each frequency.  I can continue with more examples but just remember to always make sure you are comparing RMS or peak data when making SPL distance conversions.

Tab 2: of CEA 2010 Output Results

Bandwidth Uniformity (20-80Hz) - This a measure of how closely the subwoofer maintains a constant output across the entire frequency range.  If a sub maintains +-6dB that means it exhibits no more than a total swing of 12dB for the entire frequency range of 20Hz to 80Hz.  In most cases the tighter this number the better. In extreme cases, if a designer remains to focused on bandwidth linearity as a primary design goal, they can ultimately sacrifice too much output and/or extension.  In addition, employing a steep High Pass Filter (HPF) will cause the system to ring at its roll off points.  This can also result in a dramatic and sudden falloff of output below the subwoofers 3dB point which will nullify the advantage of picking up room gain at the lower frequencies. This type of behavior can be seen by closely inspecting the frequency response of the product and how steep the slope is on the High Pass Filter (HPF) employed.  We illustrate this in our formal reviews of the products via frequency response sweeps and also provide group delay measurements and engage in listening tests to determine if the product suffers from such sonic nasties. 

Frequency Range – This is a measure of the bandwidth the product is able to maintain its output with no more than +-3dB of variance. 

Tab 3: Sweep Output Results

Tabulated  test results are located in this tab from 20Hz to 125Hz in 1/3^rd octave increments using a continuous reverse sinewave sweep.  Our measurements are conducted at 2 meters using groundplane technique.  Distortion isn't measured during these sweep tests but levels are increased for each progressive sweep until compression is observed or mechanical or audible distortion is heard.  If mechanical noise or distortion is heard, the sweep is redone at a reduced level until the output sounds clean.  That level is then recorded as the maximum sustained sweep level for the product.

We do our best to correlate how CEA-2010 burst tests and reverse sinewave sweeps can directly compare but it’s far from a perfect translation. 

Tab 3: Sweep Output Results

What happens at low frequencies (driver limited output)?

What we’ve found is at low frequencies where the subwoofer is driver limited, the results between CEA-2010 test signals and continuous reverse sinewave sweeps usually correlate within 2-3dB (down to 20Hz) of each other.  The only exception is when a particular product has a very aggressive limiter which can either react too quickly causing it to prematurely limit output during continuous sweep tests or not react quickly enough resulting in excessively high distortion output using CEA-2010 test signals. 

What happens at high frequencies (amplifier limited output)?

We’ve found at frequencies where the subwoofer is amplifier limited, the results between CEA-2010 test signals and continuous reserve sinewave sweeps usually produce lower results for the reverse sinewave sweeps between 3-6dB (up to 80Hz) depending on how high the tester continued to power sweep the subwoofer beyond its low frequency compression point. 

There is no perfect translation between CEA-2010 and reverse sinewave sweep testing of subwoofers.  This is why it’s a good idea to look at both sets of data for each product or try to directly compare competing products tested using the same test signals and methodologies.

Bandwidth Uniformity & Frequency Range for these results is also listed and computed in the tabulated data in a similar fashion to how it was done for the CEA-2010 test results of Tab2.

Audioholics Subwoofer Measurement Data Compilation & Report P2

Tab 4: Bassaholic Room Size

Tab#4 provides our Room Size rating for the subwoofers tested based on their CEA-2010 or reverse sinewave sweep output in according to our Room Size Rating protocol.  We have found the room size rating to really be a function of how much output the particular subwoofer produces below 30Hz because most subwoofers simply start running out of gas at this point.  This means whether the sub was tested via CEA-2010 or reverse sinewave sweep test method, we can still approximate a room size rating with a good confidence using either testing method. 

Tab 4: Bassaholic Room Size Rating

The top table shows results based on CEA-2010 testing conducted by Josh Ricci.  The bottom table shows results using reverse sinewave sweep testing by reviewers other than Josh Ricci.

As a refresher, here is the breakdown of our room size rating.  The subwoofer must be able to product the minimum SPL#s shown below when their test data is translated to 4 meters 1/8^th space.

If the subwoofer you are considering receives a “Large” room size rating, that means it will likely be able to hit full playback reference levels without being overdriven in a 3,000ft^3 to 5,000ft^3 room assuming you corner load the subwoofer.  The room size criteria and reference levels are listed at the top of the tabulated results for your reference when making product comparisons.

Tab #5: CEA2010 Max Sweep Comparison

The final tab of our subwoofer measurement spreadsheet exists to study how closely CEA-2010 and reverse sinewave sweep data track each other for each product under test.  The subs in this data table are all tested by both methods and by the same reviewer, namely Josh Ricci. 

Tab 5: CEA2010 Max Sweep Comparison

The table features data for all commercial subs tested under both measurement signal types (CEA2010 and reverse sinewave sweeps). Positive values indicate higher output levels were achieved using CEA-2010 test signals while negative values indicate less output was recorded using CEA2010 test signals. 

Conclusion

We hope this guide gives you a better understanding of our tabulated measurement results for subwoofers we review and test.  It is always advisable to spend the time and read the full review of each product while carefully observing our measurement commentary and subjective impressions of the product.  Looking at data alone doesn’t give you the full picture of product performance.  How the product actually performs in real world listening conditions, especially how it integrates into a home theater system is of paramount importance. 

Don’t be too caught up in the numbers game.  If sub A produces 2dB less output than sub B, don’t blindly chose sub A over sub B.  It’s quite possible sub B offers better overall performance and features that may be critical for your application.  Also remember that it takes 6dB of output difference for a subwoofer to play twice as loud.  So a 1-2dB difference between subs is often academic at best. 

For reference, here is a bass loudness chart:

• +1 dB = 1.12X louder than baseline
• +2 dB = 1.26X louder than baseline
• +3 dB = 1.41X louder than baseline
• +4 dB = 1.58X louder than baseline
• +5 dB = 1.78X louder than baseline
• +6 dB = 2X louder than baseline
• +7 dB = 2.24X louder than baseline
• +8 dB = 2.51X louder than baseline
• +9 dB = 2.82X louder than baseline
• +10 dB = 3.16X louder than baseline
• +11 dB = 3.55X louder than baseline
• +12 dB = 4X louder than baseline

If a particular subwoofer is too costly or too large for your application, consider a smaller (but well performing) alternative with future intent on adding a second subwoofer to your system.  We always recommend running multiple subs whenever possible for two reasons:

• increased headroom (up to +3dB for every doubling of subs corner loaded but not collocated)
• Smoother bass response across a wider listening area

The excel spreadsheet accompanying this report will routinely be updated and reposted in this article as well as our Powered Subwoofer Measurement Protocol so check back regularly to see our latest test results.  Good luck in your quest for Bassaholic perfection!