Yep, well known that several manufacturers bump up their ratings from what they really are. The other trick is to leave off the +/-db in the frequency response. However, there are many that tell the truth (ex. Revel, Paradigm, PSB). You just have to learn which ones or have enough experience in speaker design to know what's achievable.
???Why The HUGE Discrepancy in Sensitivity Ratings???
I'm shortlisting speakers & have noticed a HUGE difference in the sensitivity ratings provided by manufacturers & what they actually measure.For example the Martin Logan Motion 35XT is specd at 92db.sens.@1 watt & yet actually measured at 87db!At least 4 different pair of speakers on my list are the same,specd at 90db or better @1 watt yet NONE measured better than 87db so what gives?
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What bugs the crap out of me is that amplifier manufacturers used to do the same thing with power ratings.I don't know how this was changed but IMO it's high time the same pressure was brought to bear on speaker mans.to provide honest & accurate specs!that would certainly help but.............. i dont think there is a IEEE or AES or similar standard instituted by an industry institution. That leaves the door open to fudge specs. You confront the speaker manuf & he'll tell you that his speaker spec is correct because (for example) his spec sheets quotes in-room spec (but he's not obligated to put that in the spec notes so you are left guessing). There's nobody to enforce this spec. What we can do is educate ourselves & ask the right questions during purchasing. That'll let manuf know that they cant pull wool over our eyes. I still remember the marketing slogan from Syms Mens Clothing " An educated consumer is our best customer" - that's what we have to become.... |
With any panel speaker the measurement is done the same way as it is with a point source speaker. What happens is most of the sound made by the speaker is not picked up by the microphone. Examples of this are the Magnaplanars, Martin-Logans, and also mbls (which are omnis instead of planars). Its possible to correct for this and create a number that is the equivalent of 1 watt/ 1 meter or 2.83V/i meter. But usually the single-mic number is stated. This causes the speaker to look about 6 db less efficient or sensitive on paper than it really is. It sounds like Martin-Logan has corrected for the fact of their speakers being panels per the example given in the opening post. The adjusted number of 92 db is actually about right, although if you do the traditional measurement you get something more like 87db (which suggests that ML was being conservative). |
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