PURIFI ApS, Bruno Putzeys Discrete Op Amps: When and Why It Actually Matters “Discrete is an old audiophile hobby horse,” said Lars. “It proves nothing. Consider writing a few words.” Yes, precisely. Doing things discretely has no inherent value. The normal procedure is that y... Eigentakt Jun 24, 2025 Tech Notes
PURIFI Transducer Technology ApS, Lars Risbo The PURIFI Tweeter Project - Part 2 Introduction In Part 1 we learned why we chose touse a hard dome as the radiator: the dome simply yields the best dispersion for a given size. A further advantage of a dome is that has high geometric ... Jan 31, 2025 Tech Notes
PURIFI Transducer Technology ApS, Lars Risbo Side effects of Passive Crossover Filters Introduction We use crossover filters to partition the frequency bands between drivers in a multiway speaker. In addition, the crossover filter may provide EQ such as baffle-step compensation. A passi... Ushindi Oct 8, 2024 App Notes
PURIFI Transducer Technology ApS, Lars Risbo The PURIFI Tweeter Project - Part 1 Introduction The tweeter project has been an intensive R&D effort for the last 3 years. Yes, we know, the long waiting time until it is released is painful for all of us. Since we are getting closer, ... Ushindi May 24, 2024 Tech Notes
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
