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Time/Phase Alignment, Acoustic Center, Lobing etc.
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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 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 Tech Notes
Low Distortion Filter for PTT6.5X04-NAA
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
Some Speaker Problems That Needed Solving
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
Combating Hysteresis Distortion (part 1: Amplifiers)
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
This Thing We Have About Hysteresis Distortion
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
Does negative feedback cause TIM?
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
Low frequency harmonic distortion is almost inaudible. So what’s the point of low distortion drivers?
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
A fast driver needs a light cone. Or does it?
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
Doppler distortion vs IMD?
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
Distortion, The Sound That Dare Not Speak Its Name
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
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