Tech Notes | PURIFI

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

0 3923

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

0 9369

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

0 15312

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

0 18648

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

0 38672

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 6559

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

0 5430

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 7569

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

0 3960

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 5354

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 4980

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 8435

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