PURIFI Transducer Technology ApS, Lars Risbo Time/Phase Alignment, Acoustic Center, Lobing etc. Introduction There is widespread confusion regarding the terms phase and time-alignment of loudspeakers. Moreover, the fundamental concepts of latency, delay, phase-delay and group delay are often con... Ushindi Sep 22, 2023 Tech Notes
PURIFI Transducer Technology ApS, Lars Risbo SPK16 Reference Design SPK16 is a passive 2 way speaker system with a 6.5X-NAA alu cone woofer assisted by two passive radiators on the sides of the box combined with a prototype of the coming PTT 33mm long stroke dome twee... Ushindi May 9, 2023 Tech Notes
PURIFI ApS Low Distortion Filter for PTT6.5X04-NAA In the following, we show that not all methods of equalization are created equal. In particular, using a series notch reduces distortion, which does not happen with alternative methods. The proposed circuit results in an extremely clean low-pass response combined with low distortion... Ushindi Nov 16, 2022 App Notes
PURIFI ApS Some Speaker Problems That Needed Solving Some time ago we posted on our website a pair of sound demos that we thought were quite instructive. One showed that Doppler distortion was much less audible than an equivalent amount of amplitude modulation, thereby sinking a lot of “masking theory” based audio discourse... Ushindi Oct 14, 2021 Tech Notes
PURIFI ApS Combating Hysteresis Distortion (part 1: Amplifiers) Our blog post concerning hysteresis distortion got people asking what secret non-hysteretic material we were using then. What is it about our industry that programs people to look for unobtanium mater... Eigentakt May 13, 2020 Tech Notes
PURIFI ApS This Thing We Have About Hysteresis Distortion *Read any Purifi interview and someone is sure to mention hysteresis distortion (or iron distortion, same thing). What is it about and how serious is it?* Hysteresis happens in any coil that has a ma... Eigentakt Ushindi Apr 28, 2020 Tech Notes
PURIFI ApS Does negative feedback cause TIM? Actually, “TIM” is not so much a type of distortion as a test method to detect Slew Induced Distortion. Nobody calls it that though, and if I need to be pedantic, what we call the animal may not be th... Eigentakt Apr 20, 2020 Tech Notes
PURIFI ApS Low frequency harmonic distortion is almost inaudible. So what’s the point of low distortion drivers? Decades of research has shown that we’re not very sensitive to distortion at bass frequencies. I doubt if anything has happened to our species recently that would change that. Consider the science set... Ushindi Dec 12, 2019 Tech Notes
PURIFI ApS A fast driver needs a light cone. Or does it? Intuition can play us tricks. Take this simple example: how does a speaker cone move when you try to make it produce a “pulse”? I’m willing to bet quite a few of you will guess it will rapidly move fo... Ushindi Dec 10, 2019 Tech Notes
PURIFI ApS Doppler distortion vs IMD? Let’s get this out of the way first: Doppler distortion is a form of IMD. This is interesting because IMD in general tends to get little interest on loudspeaker forums, whereas Doppler distortion is o... Eigentakt Ushindi Dec 7, 2019 Tech Notes
PURIFI ApS Distortion, The Sound That Dare Not Speak Its Name Read any discussion about loudspeakers and you get the impression that distortion as a topic is eagerly avoided. If it is mentioned, it is done sotto voce, implicitly. For instance: “you can’t get goo... Ushindi May 2, 2019 Tech Notes
