Misinterpreting subwoofer specs

Wharfedale Diamond 12 Series

prateekatasniya

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from soundstagesolo.com


By this measurement, the best subwoofer of the bunch was a slim, dual-10″ sealed model from Von Schweikert Audio, which I measured with a -3dB response down to 19Hz. The worst was a 15″ ported model from B&W (in the decades before and after the company spelled out Bowers & Wilkins), which had -3dB response down to just 30Hz. Yet in my blind tests, the panelists raved about the B&W’s deep bass extension and complained that the Von Schweikert didn’t have enough bottom end for action movies.

Baffled by this, I ran every standard test I could think of to explain the difference (including pulling the plate amps out and measuring those), and then I started concocting experimental measurements. I finally got my answer when I used an Audio Precision analyzer to measure the subs’ output in dB versus distortion, at 20, 40, 60, and 80Hz. This measurement lined up perfectly with the listener impressions—the chunky B&W delivered ample output at 10% total harmonic distortion at 20Hz, while the slim Von Schweikert was down about 15dB under the same conditions. It appeared the Von Schweikert sub had been EQ’d with a bass boost to make it flat down to 20Hz (still a common practice with small subs), but its amp and drivers didn’t have the physical capacity to deliver those low frequencies at a useful volume.

CTA-2010

The CTA-2010 standard eventually codified subwoofer output measurements, which have become a common component of subwoofer reviews for some publications. But that left a legacy of about two decades’ worth of subwoofer measurements that misrepresented the products’ capabilities—and we still see this misrepresentation on some subwoofer spec sheets.

I was trying to explain this since a long time ( which I learnt from my experience).. finally I found a source which people would take seriously. Hope this helps you choose better subs.
 
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DB1989

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Your explanation lines up with an opinion that a learned FM mentioned in one of the posts on the forum (can't precisely recollect who or where) that simply because measurements do not back up listening tests, it does not necessarily indicate that the listener is wrong or suffers from bias/subjective preference but could also be attributable to the correct variables not being measured, much like what Hans Beekhuyzen mentioned in his channel about MQA which was underscored by another learned FM in the relevant thread which is linked (not trying to start a war/discussion on MQA etc which can be directed to the relevant thread):

 
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