August 2022

What Do Measurements Reveal?
The latest computer design techniques and measuring equipment.
Editorial By Noel Keywood

  The Mission 770 loudspeaker was a ground breaker way back in the 1970s when most loudspeakers had paper or – at best – Bextrene cones. Think heavy, coloured sound – ponderous too. Then Mission appeared with their first product, the 770. Sporting a translucent drive unit pressed from polypropylene, it looked good and sounded good.

Using the very latest computer design techniques and measuring equipment – explained to me by designer Peter Comeau – this update aims to be even more accurate and revealing than the original. You can read about it on p10.

As regular readers know we rely on measurement to look at fundamental performance and I was pleased to see, when Peter Comeau showed me the 770's measured frequency response it was identical to ours. Since we use an industry standard measuring system (Clio), it was reassuring, since rooms and small anechoic chambers introduce complex errors not easily corrected.

There are various tricks however, such as gated pulses and fast chirps, that – I was surprised to find – are now available in free software Room Equalisation Wizard (REW). Reader Dan Grundy recommends – in Letters on p30 – a YouTube video showing REW and other equipment being used to measure guitar cabinets. Fascinating stuff, even just for all the work put into cabinets of so many shapes and sizes.

Measurement also reveals that, in spite of all the criticism on internet forums, Chinese built turntables are more speed stable than those of the past. The reason is they use modern, dedicated D.C. motors with servo-feedback control circuits, eliminating the speed wander of old A.C. synchronous motors. Couple this with a flat-ground belt rather than a cheap O ring, plus tightly machined bearing with no play in it, and wow has become a thing of the past, as we found with the Lenco LBT-188WA budget turntable you can read about on p71.

Modern computer based measuring systems and ever more sophisticated motors all play a part in helping improve the hi-fi products of today, as we show in this issue. I hope you find it interesting.

— Noel Keywood
Editor, HiFi World

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