In 2019 the dream team of Bruno Putzeys, Lars Risbo, and Peter Lyngdorf announced an audio company named Purifi. A team with such beyond reproaches credentials and history of successes in both the commercial and academic sides of the HiFi industry bears watching. They announced breakthroughs in understanding hysteresis distortion resulting from iron and steel components applicable to both Class-D amplifiers and loudspeaker drivers. This led to the introduction in 2020 of the first Purifi woofers touted to “crack the extended-stroke code”. The “code” referenced is the fact known to loudspeaker engineers and advanced audiophiles that despite appearing on paper to have identical air moving capabilities in use traditional 12” and 15” short stroke woofers sounded better than 7” class long stroke woofers. The design and use case dilemma this created is that bass systems using 12 to 15 inch woofers require large refrigerator sized enclosures. Such mammoth boxes are welcomed, even celebrated, in dedicated single purpose listening rooms and home theaters. In more typical multi use spaces such outsized boxes are rejected as out of balance for harmonious living spaces. The “extended-stroke code” Purifi cracked is the complexly interrelated factors that kept long excursion drivers producing higher levels of inter-modulation distortion (IMD) when using their long stroke capability to make deep loud bass. In HiFi such claims of breakthrough are essentially a weekly occurrence. Given the credentials of the team at Purifi and their explanations of the multiple techniques brought to bear in early 2020 a shipment of first production PTT6.5 woofers and passive radiators were brought in for testing. From the first test boxes the results can be described as ‘gob smacked’ and ‘stunning’. The promised bass depth and volume is delivered, beyond that the reductions in distortions across the drivers’ entire operating range brings a clarity unique to the luxury woofer segment. For the next two years all our loudspeaker developments centered on extracting the maximum performance from this true break though driver.
