As I mentioned recently, we have recently invested several thousand dollars in new test equipment. Although Bruel & Kjaer has always been at the heart of our test set, we have not had the luxury of duplication across the various sites that I may need to measure speakers: on the production line, in the test bunker (for grading drive units), at the Old Dairy (open space for measuing) or The Stable (mini deadroom) or at home. I have made do with 'clone' amateur test equipment - especially microphones, and that has introduced a degree of uncertainly which has wasted valuable time.
So, back to B&K, the best, the most accurate, with traceable standards and a very long life. For example, here is the actual curve (also supplied as a mini-CD) for the best of the new microphone capsules we have just purchased from B&K Denmark http://www.bksv.com/.
As you can see from the curve below the yellow zone reresents +/- 1dB, and this specimen deviates from perfectly flat by a maximum of only about 0.5dB at the very highest frequencies and is, for all practical purpsoses, perfect. Bigger picture here: http://www.harbeth.co.uk/images/B&Krefmic640.png
An accurate microphone, a reliable and known acoustic space - even if not a perfelcty relection free one, and a flat amplifier (another sad story) are paramount should you wish to design quality speaker systems.
We now meet our ISO9001 obligations in this important area.