Blog Posts | PURIFI

11 Articles

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Side effects of Passive Crossover Filters

PURIFI 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

0 16431

App Notes

The PURIFI Tweeter Project - Part 1

PURIFI 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

0 22855

Time/Phase Alignment, Acoustic Center, Lobing etc.

PURIFI 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

0 32051

SPK16 Reference Design

PURIFI ApS, Lars Risbo

SPK16 Reference Design

Note: SPK16 is now released as a kit with build description 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 w...

Ushindi

May 9, 2023

0 58164

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

0 24469

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

0 12737

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

0 14472

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

0 11822

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

0 7695

Doppler distortion vs IMD?

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

0 11372

Distortion, The Sound That Dare Not Speak Its Name

PURIFI ApS, Bruno Putzeys

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

0 12987