To Doug Schneider,
I am interested in buying a pair of Reference 3A de Capo i loudspeakers to use with my Border Patrol SE300B amplifier. Reference 3A states the sensitivity as 93dB, and you did a feature on the BE model in 2014 where you provided a link to tests carried out on the speakers showing sensitivity of 86.7dB. Back in 2000, you published this Reference 3A MM de Capo sensitivity of 89dB.
I wrote to Reference 3A asking about this disparity, but so far I have not received a reply. Are you able to throw any light on the differences between the manufacturer’s claimed sensitivity and your own measurements? Any help here would be most welcome.
Regards,
Michael Lakeman
United Kingdom
I’ll start by stating this: In many cases, manufacturers publish the most optimistic sensitivity specifications they can generate. They usually don’t specify their methodology, but some publish in-room sensitivity (typically 3dB higher than anechoic sensitivity), and some appear to be publishing the maximum sensitivity instead of average sensitivity over a certain range. How do I know this? Because it occurs with most of the speakers we measure. Why do they do this? Usually, it’s to make their speaker seem compatible with more amplifiers than it is. This sort of thing happens with impedance, too -- ignoring impedance dips makes a speaker seem like an easier amplifier load than it is.
The problem with manufacturers publishing overly optimistic sensitivity figures is that it can lead to amplifier-compatibility problems, particularly with low-powered amplifiers, such as the one you have.
Insofar as the de Capo i and de Capo speakers we measured, you can see that we measured them in an anechoic chamber and used a 2.83V input (which, into 8 ohms, equals 1W). There are some SPL peaks with both models that exceed 90dB, so maybe they’re trying to use those high points for those claims. The problem is, those are simply peaks; the sensitivity at most frequencies is between 85 and 90dB. When you average a range, like we do (300Hz to 3kHz), you get much more realistic figures, which is what we publish and stand by. We feel ours are also the ones you should use to gauge the amplifier power you need.
As a result, because of the limited power-output of your amplifier and the only-average sensitivity of the speakers you are looking at, you have to exercise some caution before going forward with a purchase. Otherwise, you might overdrive your amplifier, which may damage not only the amplifier itself, but also the speakers. . . . Doug Schneider
