New CEA 2010 method for measuring true subwoofer performance

[Tom Vodhanel]

Hi all (I'm reposting this for those who may not have seen it the first time)

For those who haven't heard yet...ALMA and CEA have introduced a new method to gauge subwoofer performance. This is very good news indeed...as it will standardize things a bit and really levels the playing field for all manufacturers. A nice sidebar is that their test procedures(and the reasoning for them) closely parallel the methods of Nousaine and Mullen (and SVS) in determining the "clean" output capabilities of a subwoofer. The new 2010 standard does raise the standard 10% THD limit (in the deepest bass)...but this isn't a significant difference. Once you reach 10%, it (almost always) only takes another dB or two to raise the distortion levels to 25-35%(and often much higher). So if a subwoofer hits 100dB/20hz/10% THD...pushing it to 111-112dB will typically give you >30%. They test the subwoofer at 20,25,31,40,50,63hz. They then "score" it on "ultra low bass" and "low bass". The ultra low bass is the average of 20,25,31hz. The low bass is the average of 40,50,63hz. For each subwoofer, they will give you two "scores"...the Ultra low bass score...and the low bass score.

It will be a while before we get to see a large number of "scores" for subwoofers put through their paces in the new 2010 test...but here is how two of the most popular SVS models fair in our methods...which (imo) are close enough to the 2010 method to offer fair insight into what we can expect when these models are tested(using the new 2010 standard)

The differences are...

1)we currently use sine waves(the 2010 method specs a tone "burst"). In my experiences the tone burst method generally gives you a higher "score"..but not significantly so.

2)we measure output capabilities using 1/3/5/10/20% THD limits. The figures I'm listing here are with the 10% limit. Again, the 2010 method(which allows 25-35% THD down low) would give us another dB or so(on average)

3)we measure at 2m(ground plane). The 2010 method will convert everything to a "1m ground plane standard" So you would have to add 6dB to our readings to convert them to a 1m distance.

Based on these 3 differences. I have added approximately 8dB to all of our data. 1dB for #1, 1dB for #2m, and 6dB for #3. This may be a little conservative...but it should still be "in the ballpark" as they say..



SVS PB12plus/2(20hz)
20/112
25/118.3
31/121.4
40/126.6
50/127
63/124.8

Ultra Low Bass = 117.23
Low Bass = 126.13


SVS PB10
20/100.3
25/110.3
31/112.7
40/113.4
50/113.3
63/112.2

Ultra Low Bass = 107.76
Low Bass = 112.97

Remember, these are estimates only…but I think they will eventually prove to be surprisingly close. Since SVS has become the “target” for other manufacturers to shoot for with their “dream” products…let’s hope they have something that will approach CEA scores of 117/126 at $1199 and 108/113 at $429 for the consumer…someday.. If they cannot...I'm sure we will all hear how excessive distortion is something to strive for..

Tom V.
SVS

[Jack Gilvey]

If they cannot...I'm sure we will all hear how excessive distortion is something to strive for..

"I dunno, SVS subs always sound a little sterile and dry to me, lacking that palpable second-order presense that is oh so musicalish..."

[Chrisbee]

Jack Gilvey wrote:

"I dunno, SVS subs always sound a little sterile and dry to me, lacking that palpable second-order presense that is oh so musicalish..."

Did you forget the winking smiley, Jack?

Are you seriously suggesting that subwooofer distortion is desirable?

[Ed Mullen]

While the CEA standard does allow for a fairly high 2nd order harmonic (around 30% distortion IIRC) limit, under actual testing the upper order harmonics (which have much lower distortion limits) will cap-out the max SPL long before the 2nd order harmonic hits ~30% distortion.

It would be unusual to see a subwoofer generating 30% 2nd order distortion while also at the same time staying below the CEA limits for the upper order harmonics. I think the 2nd order CEA limit is artificially high in that respect, and will likely not be the limiting harmonic when doing max clean output tests per the CEA standards.

[khellandros66]

This is great news, this will give comsumers a way to not only understand what the product is capable of, but will also dilute the purchase to return ratio. As a retail salesman this is like a dream come true.

SVS is now gonna have off the rest on the industry (many of which will be jealous)

~Bob

[Ed Mullen]

The only problem I see with this standard is that it will labor under relative obscurity and the vast majority of b&m consumers will never see the data. And if they do happen to stumble across the odd OEM who actually pastes the data into their specs, there will likely be no frame of reference or database upon which to draw comparisons.

[caser85]

This is awesome... the standard should really help in comparing subwoofers.

Can you please tell me where to find scores for your other subwoofers, if available?

[Ed Mullen]

To the best of my knowledge, no subwoofer has actually been tested using this method as part/parcel to a professional review.

It will really be up to the OEMs to lead this charge and voluntarily publish the scores for their subwoofers so consumers can see the relative differences in audibly clean output between competing brands.

In the spirit of the standard, I'll be adopting a weighted THD metric to my reviews, but there are certainly differences between my test methods and the 2010 standard.

[lienly]

look forward to seeing your reviews with new 2010 std!

Ed Mullen wrote:

I'll be adopting a weighted THD metric to my reviews, but there are certainly differences between my test methods and the 2010 standard.