Blog Posts | PURIFI

The PURIFI Tweeter Project - Part 2

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

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Tech Notes

Side effects of Passive Crossover Filters

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

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App Notes

The PURIFI Tweeter Project - Part 1

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

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Tech Notes

Time/Phase Alignment, Acoustic Center, Lobing etc.

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

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Tech Notes

SPK16 Reference Design

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

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Tech Notes

Low Distortion Filter for PTT6.5X04-NAA

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

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App Notes

Some Speaker Problems That Needed Solving

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

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Tech Notes

Combating Hysteresis Distortion (part 1: Amplifiers)

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

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Tech Notes

This Thing We Have About Hysteresis Distortion

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

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Tech Notes

Does negative feedback cause TIM?

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

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Tech Notes

Low frequency harmonic distortion is almost inaudible. So what’s the point of low distortion drivers?

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

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Tech Notes

A fast driver needs a light cone. Or does it?

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

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