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Geoff Hill


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How To Accurately Measure Loudspeaker Drivers using your existing Microphones and Analysis Equipment.

Let's face it Loudspeaker Driver measurements are in a mess right now!

We have many standards, IEC 60268-5, JIS and now AES2-1-r in draft form... All of which in theory and in practice should give the industry throughout the world reliable and consistent measurement data - but do they? Actually they don't do this, as they parts either undefined or ill defined and open to individual interpretation.

All of them in effect demand a perfect measurement environment (typically an Anechoic Chamber) free from any undesirable effects over the full frequency range of 20Hz to 20kHz+: Which it could be argued can never exist. Even worse an Anechoic Chamber is primarily designed to allow reliable detection of very quiet sounds by excluding external influences and minimising internal reflection of any sound produced within - the quietest are very quiet -15dB below the threshold of hearing (0dB SPL re 20uPa) - great any one notice we are measuring "LOUDspeakers" at any where from 60dB to 100dB+!

We are mostly using Analysis Tools based upon, MLS, TDS, Log-Sweeps and other FFT techniques more than capable of "seeing" down through noise levels 80dB or more below the fundamental and certified to +/-0.05 dB (conservatively).

All this and still as an Industry we cannot reliably and consistently measure to +/-0.5dB, between any supplier to any customer and trust that measurements will be to this level or accuracy - more typically one can expect +/-2 to 3dB!

Sorry, but this is simply crazy! We have spent and are probably still spending Million of £/$/€ on large Anechoic Chambers) - typically a small one is the size of a house and this is to measure Loudspeaker Drivers inaccurately.

There has got to be a better way!!

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