Industry & Product News
Loudspeaker Industry Sourcebook 2019 Edition is Now Online!
The Loudspeaker Industry Sourcebook (LIS) has been published every year for the past 23 years. Of course, many in the audio industry are now familiar with LIS in its online directory format, available at, which is fast becoming a year-round reference resource for everyone involved in R&D, manufacturing, technical support, marketing, or sales, in the loudspeaker, and related industries. Your annual subscription to Voice Coil or audioXpress or your status as a Loudspeaker Industry Sourcebook vendor includes a complimentary copy of the 2019 edition, which is now available at Check it out, there's so much more than the listings! Combining the editorial resources of our monthly publications, LIS 2019 contains cutting-edge articles from some of the finest industry leaders, interviews with audio professionals on trending industry topics, and industry reports about the state of the industry .    Check It Out
New Knowles AISonic Audio Edge Processor Optimized for High-Performance Mobile, Ear and Connected Devices
Knowles announced the IA8201, the latest product in its Knowles AISonic family of audio edge processors. The IA8201 offers robust voice activation and multi-microphone audio processing optimized for power-sensitive applications, and is the first processor specifically designed for advanced audio and machine learning applications, enhancing power-efficient intelligence and privacy at the network's edge. This processor has the compute power to perform advanced audio output, context awareness and gesture control .    Read More

Audinate Unveils New Dante-As-Software Products for Manufacturers and Developers
Supporting the AV industry's shift from purpose-built hardware to software-based solutions running on standardized hardware, Audinate announced two new software-based Dante networking products. Dante Embedded Platform enables manufacturers to add full Dante functionality in software running on Linux for x86 and ARM processors. The Dante Application Library allows software developers to seamlessly integrate Dante functionality directly into their PC and Mac applications. Early confirmed adopters include QSC, Zoom, and Analog Devices .    Read More

Røde Microphones Introduces TF-5 Premium Matched Pair Condenser Cardioid Microphones
Røde Microphones has introduced new TF-5 Premium Matched Pair Cardioid Microphones, designed in collaboration with legendary, Grammy Award-winning sound engineer Tony Faulkner. The TF-5 package includes the matched pair of microphones, stereo bar, and all the accessories needed for live sound or recording situations. According to the company, the TF-5 represents a new standard in small diaphragm condenser microphones, imagined and designed in collaboration with Tony Faulkner and manufactured at Røde's state-of-the-art facility in Sydney .    Read More

Bluesound Launches Professional Suite of Streaming Distributed Audio Products for Commercial Spaces at InfoComm 2019
Bluesound Professional is a new division of Lenbrook International, the home of brands such as NAD, PSB, and Bluesound, extending the group's reach from premium audio technologies for residential to commercial applications.  The new Bluesound Professional brand will be launching a raft of completely new products at InfoComm 2019, including multi-zone streamers, amplifiers, speakers, and controllers. The company aims to offer a versatile range of premium audio streaming solutions for commercial installers .    Read More

Klipsch Creates Premium Soundbar Line with Bluetooth and Wireless Subwoofers 
Klipsch announced the debut of two new premium, easy-to-use soundbars that are designed with quality materials and horn-loaded technology to look and sound like the brand's premium Reference speakers. The Klipsch BAR 48 and BAR 40 soundbars with wireless subwoofers are a true upgrade to television sound, enhancing movies and music with clarity and realism. The soundbars and subwoofers are made from wood like the brand's legendary, premium loudspeaker lines to deliver impressive acoustic performances .    Read More

Lectrosonics Introduces D Squared Digital Wireless Microphone System
Lectrosonics announced the introduction of its D Squared digital wireless microphone system, utilizing the Lectrosonics fourth-generation digital architecture that offers improved flexibility, ultra-fast setup, studio quality audio, and ultra-low latency. The system includes the DSQD four-channel digital receiver, DBu digital belt pack transmitter, and DHu digital handheld transmitter. System features include 24-bit, 48 kHz digital audio, two-way IR sync, three levels of encryption, and a tuning range from 470-608 MHz (470-614 MHz for export versions) .    Read More

Vesper Launches Ultra-High Acoustic Overload Point VM2020 Microphone for Smart Speakers
The world's first MEMS microphone designed for loud environments is here. Vesper, a developer of advanced piezoelectric sensors, has just introduced the VM2020, an ultra-high acoustic overload point (AOP) differential analog output piezoelectric MEMS microphone. This is the first consumer product-ready in mass production, able to work in extremely noisy environments without distortion. The VM2020 is available in a standard form factor and package, making it an ideal choice for demanding applications, from spatial recording arrays and acoustic monitoring systems to smart speakers .    Read More

Infineon to Acquire Cypress Semiconductor Aiming for Expanded Growth in Connectivity Technologies
Infineon Technologies AG and Cypress Semiconductor Corporation announced that the companies have signed a definitive agreement under which Infineon will acquire Cypress for $23.85 US per share in cash, corresponding to an enterprise value of €9.0 billion. The transaction is expected to yield €180 million in cost synergies per annum by 2022 and more than €1.5 billion annual revenue synergies in the long-term, the announcement states .    Read More

Editor's Desk
J. Martins

Purifi Audio
A Conversation About Amplifiers and Speakers

As audioXpress revealed a few weeks ago, a new Danish audio company, founded by Bruno Putzeys, Lars Risbo, and Peter Lyngdorf was recently announced. The name is Purifi Audio, and as you can guess from the founders involved, the venture promises Class-D amplifiers with record-breaking performance "unmatched by amplifiers of any operating class." But the new company will be doing more than amplifiers, since it also revealed a new 6.5" woofer with "magnitudes lower intermodulation distortion across frequency and SPL."

Purifi Audio was born out of the research work of Class-D pioneers Bruno Putzeys (of Philips, Hypex NCore and Kii Audio fame) and Lars Risbo, who pioneered direct switching PCM-PWM audio amplifiers as founder of Toccata Technology, later acquired by Texas Instruments (TI).  With these two founders, we also find the names of Claus Neesgaard, Søren Poulsen, and Kim Madsen, also coming from Texas Instruments and holding multiple audio patents in the domain.

On the loudspeaker side of the research we also find as co-owner the name of Carsten Tinggaard, the founder of PointSource Acoustics (2009), the most reputed Danish loudspeaker lab and prototype facilities, and a leading research company in motor design simulation and loudspeaker measurements. Carsten Tinggaard was previously the product manager for Danish Sound Technology (2003) and CTO of Tymphany Denmark (2005) and he is responsible for R&D for Peerless, Vifa and Scan-Speak brands.

Also now at Purifi is Morten Halvorsen, a Senior Acoustic Engineer at PointSource Acoustics. He co-developed both the loudspeakers and sound unit of the Montana by PointSource products and specialized in electromagnetic simulations, measurements, and procedure optimization. Halvorsen researched force factor modulation, and was responsible for much of the measurement equipment and simulation models developed at PointSource, which Purifi Audio is now expanding.

audioXpress had the privilege to meet the Purifi Audio just before the opening of another edition of the High End show in Munich, Germany, where the team was making its first public presentation to the industry. During the meeting, we had the chance to learn a little more about Purifi's first product, the 1ET400A, a Class-D single-channel, analog-input, amplifier module - based on the company's new "Eigentakt" self-clocking amplifier technology. We also discussed the PTT19-W02-03 ultra-low distortion 6.5" long-stroke woofer (Xmax ±14.7 mm), which we had the chance to hear.

The Purifi-Audio team (left to right): Bruno Putzeys, Lars Risbo, Claus Neesgaard, Morten Halvorsen, and Carsten Tinggaard.

The following are some of the topics regarding the team's projects on loudspeaker drivers and audio power amplifiers. We started by discussing the amplifier platform and its self-oscillating technology but we quickly understood that Purifi's research is deeply related with trying to solve the whole audio-chain equation and that their loudspeaker research was always coming up... because, as Lars Risbo explained, they continued to see " a mountain of problems, of speaker problems..."

Bruno Putzeys (BP) : We decided to split the amplifier and the speaker problems, because initially we were sort of trying to build a "clever amplifier" that also fixes the driver problems - and we know a lot about how to do that. I think the knowledge base that we have is probably the most mature when it comes to putting something like that together. But we decided - as a startup company - that we wouldn't be breaking the bank trying to design an IC for that, and we decided it was a better move to actually improve the driver just fundamentally as a mechanical item.

Lars Risbo (LR): And do a super amplifier. We will be able to scale a lot more power on this development platform easily over the next year.

Claus Neesgaard (CN): We put the amplifier to very vigorous testing and applied all the learning from doing IC-level design and taking that to market in automotive and consumer. So, it's pushed into extreme corners of operation - robustness matters as much as performance - and I don't think you see that widely in the industry, with people caring for all these levels.

BP: When I met these guys, I thought that they were completely crazy. The sort of testing that they subjected the amplifier to was unheard of. And with all respect to my previous employer... this was so way above anything that I've seen!
They would try to run the amplifier in its current limits continuously for half an hour or so, and they walked off and have a cup of coffee. When they came back - if it was still working - they would start applying shorts while it was cooking. They had this short box, with faster and long shorts timed differently...

LR: That's a lesson we learned at TI, when we were selling products in the millions... When we have a large customer and they have a problem, they would call the CEO, and that's not fun...

The new Purifi Audio 1ET400A amplifier module.

CN: If the performance is good, you can win a few customers and they can live with it. But we don't want to be just the highest performance high-end, addressing a few people's wishes and concerns, we want to really take this out and have everyone benefiting from it.

BP: It's the same as in live sound. If something is practical and portable, and if it's reliable, etc., only then will they choose the one that sounds best. But only after you've got all the other boxes ticked.

LR: We don't see ourselves as a high-end company in that sense. What we want is to do better sound that reaches out to all music lovers. We are not trying to do something that only works sometimes, or something that's based on these very special materials. We are trying to apply clever design, clever geometry, with industry standard materials and see how far we can get with that. 

BP: Actually, we can get further without applying "magical materials" to an industry standard design, which is what everyone else does.

CN: Our drivers are a very good example of that.

For a moment, we stopped the conversation to look at the driver's measurements... some of which are available online on Purifi's website.

BP: When you look at other driver manufacturers' datasheets, you will not see
these graphs. When we ask why don't they put distortion measurements in the datasheets, they say that is something that people measure for themselves. A) That's probably not true. B) If I want to buy a driver, I want all the data that allows me to actually select the one that I want without having to buy samples. There needs to be data that you can actually extrapolate. It's not just about data that shows "look what this baby can do!" It's about data that tells me what I can do with that baby!

CN: We also wanted to introduce a new level of measurements. We would like to tell everybody how we measure and why we measure, the detail of analyzing both harmonic differential tones and multitudes, complex signals, and find where it hurts... But for that, we also needed a new analyzer...

LR: When we started looking at motors we found a major distortion source that was flying under the radar. And it's not captured by the conventional graphs. We can have all these symmetrical plots and as part of that you can have loads of signal distortion. So there was obviously something that's not covered.

BP: In this specific case, the important information that you need to extract from the motor measurements is the inductance at all frequencies and all positions. And then suddenly you can discover a lot. That's something that we never see being done. Eventually we will see some sort of inductance at a certain position at an unknown frequency, and that doesn't actually tells us what the speaker will do when it sees a signal with one or two frequencies or whatever. So we've built our own analyzer for that and what we care is of course about the data that we needed to understand the problem. Many people will be gutted to ear that we are not going to sell the analyzer... Essentially, you mount the driver in a fixture like you would do with a Klippel analyzer and then you measure for two seconds and out pops all the data that a Klippel analyzer produces, plus the bit of data that we want.

CN: I guess it was the realization that in order to have that level of understanding and dig into the deepest corners, we needed to build our own machine...

BP: It was actually once that worked, once that level of detailed knowledge was in a mathematical model, we knew where to start looking to fix the problem. 

LR: And once you understand the problem, the solution almost presents itself... We are driven from an understanding in closing the loop between our model and measurements. 

CN: It's very far from the traditional trial and error. A lot of people talk about simulation, but simulation is also trial and error. This is way more about understanding the problems before you even try to do anything about it.

BP: And the understanding comes from the mathematical model. Not from the simulation. Usually, the simulation is actually more about catching writing errors in the mathematical derivation. Because once that's done on the simulation it just ends up exactly what the model already told me. 

CN: We go so far as to prove that the model was actually working, then we build the machine that actually could take the voice coil and move it against the magnet system, get all the data out, as a function of the position, frequency, and then we compare with our analyzer. That has been a constant. So when we have a question, we build, we measure, we compare, to see if there's something that is not matching, and the question will be there until we have solved it and the simulation is verified. So it is a kind of an adaptive signal processing where we are constantly in a loop, between simulation modeling, building, measuring, and listening, back and forth.

LR: The more you can condense a mathematical formulation, the more you can computerize the model. Because the mathematical model is so fast to evaluate, you can actually have a computerized optimization that takes a little more time than taking a cup of coffee.

BP: Exactly! It's exactly the same thing we did with the amplifier. We actually solved one of those things that was completely flying under the radar, but the bit that I am most proud of is that I finally figured it out how to make a sample data model of a PWM, away from 50%. That's the sort of thing I'm happy about. That in the end, the amplifier performed fantastically well. That I now have the whole thing... a unified model.

CN: Another strong thing that we have is that we can now take out all the different distortion components, because that's what we focused on. Getting the distortion down. Removing all the distortion components. In the driver, where you have the complex of the electromagnetic, mechanical movements, acoustic radiation, and again not knowing what comes from where. By putting it into a very sophisticated, not only static, but dynamic model, in just two-seconds of measurements, we can decompose all the distortion components and we can begin to see which one of those is.

Carsten Tinggaard proudly shows the team's first ultra-low distortion 6.5" long-stroke woofer, which is able to perform in a very controlled manner in the low end, without losing the details in the mid band.

AX: So, you have been working on the amplifier and on the driver. How do you connect both?

BP: It's quite simple. We have a technology company with two specific areas. One is doing the amplifier and the other doing drivers. Of course, it is the same team so we do the marketing together, but basically people can buy the driver or they can buy the amplifier, or if they want we can combine both. As soon as we decided not to mix the two problems in just one product, at that point we just said, OK let's market and sell them separately so that the people who just want to buy drivers from us can do that.

CN: Yes, they don't depend upon each other in any way. You get the full benefit of the amplifier as a standalone and you get the full benefit of the driver as a standalone, of course you can combine it and get something that's even better, because you are improving two layers or two parts of the signal chain. But there's no requirement in doing so.

AX: Bruno, but with KII Audio you were involved in a project where you designed an active system that involved precisely tuning all the aspects of the chain, including using DSP to help solving many of the problems you identified. There are currently manufacturers working on developing new drivers that are actually tied up to a dedicated amplifier and a sensor that helps counter nonlinearities...

BP: We have been looking at the sensor thing but actually it's more expensive and less effective than actually fixing the driver. Because for instance, motional feedback - there are no practical ways that you can make the loop band of a motional feedback system much better than a couple hundred hertz. Which means that if you have intermodulation distortion, that is not being corrected by the motional feedback system. So, if you want to fix that as well, actively, you can, but it means that at that point your DSP will have to contain that particular model, so that it can actually predict what that motor will do. Motional feedback with a simple sensor is kind of a dead-end. The sensor is useful in the case of where we have a model and there is a positional parameter in there and then it's a good idea to know the position within a half a millimeter or so... and to get rid of drift. But at that point that sensor is no longer really in the loop. It's only applied to that function of the model.
I see the point of selling a driver with an amplifier, because that's how we started this project. It's just that it turned out that it was cheaper to build a driver that didn't have all those distortions. I don't think that's necessarily the case that companies will be co-selling drivers and amplifiers. Of course, it just happens that we would be terrifically pleased to do exactly that. But at the moment...

LR: We don't rule out that at some moment we will have something with a sensor. But as long as the problem is actually cheaper to solve...

BP: Exactly. The combination of a sensor and the model, not for real motional feedback but simply using the sensor to inform the model roughly where the cone is - it doesn't even have to be accurate.

CN: At the end of the day, it is about solving problems where it makes sense. There were some obvious problems that it really made sense to solve in the driver, and at no extra cost. Not by using fancy materials, but something that we can apply to the entire market eventually.
We also have the experience of some things we have done in the past, where the more it becomes a "solution sell," where you have to change multiple things at a time, the longer the timeline you need to live with. Where is, if you can swap out individual things it is much faster and you get some feedback on the way and it's easier to shape.

LR: We were able to improve our understanding of the project... One thing that's bad is when you are trying to do a control of a system you don't understand.

As Bruno Putzeys confesses, the team pursued different routes in amplification "until we bumped into clear mathematical proof that a simple self-oscillating amplifier is a better way of going about it. I always thought that NCore would be my last amplifier of that sort..."

AX: But one thing that we see often in combination is the Class-D amplifier and the power supply. What is your opinion about that?

BP: Oh. It's just a matter of time until we do that as well. We designed the Class-D amplifier first and the power supply comes next. As a research company, we needed to get our fundamental IP in order because we started thinking about a product line-up. But I think quite clearly that amplifiers with a matching power supply bolted-on is a product proposition that's here to stay. 

CN: You will see that coming from us, in parallel with seeing the expanding product portfolio of modules, to get broader coverage. Higher power, higher current, higher voltage.

BP: It's simply a matter of practical experience. I was also there when Hypex started and if at that point we would have tried to do integrated modules, straight off the bat, then probably we would have gone bust before we could solve anything. You have to start selling what you have to the people who most want it. Clearly, our first module offering is something that we are mostly pitching at high-end audio companies, because that's a good way to start. But it's not our intention to restrict ourselves to that space. We definitely want to end up doing fully integrated power solutions.

AX: On the driver design. Can you expand the fundamental principles with different materials? 

CN: Yes, different sizes and different materials and we can accommodate different requirements. We are very well positioned to scale from where we are today.

Purifi Audio is now continuously updating its website, where we can find a lot of measurements that are not very common to find in product datasheets - as discussed - and there are also some relevant technical briefings, like a PDF named "Distortion, The Sound That Dare Not Speak Its Name." Very soon, we will expand this interview with a dedicated feature article in the printed edition of audioXpress .

R&D Stories
Future Shock. Powersoft Audio's Amplifier Technologies
By  Stuart Yaniger
Stuart Yaniger details the amplifier technologies developed and perfected by Powersoft Audio, the Italian company based in Scandicci, Florence. From the introduction of Class-D amplification to the unique company philosophy, Yaniger discusses how Powersoft strived to define the technological edge of its markets rather than follow trends. The article looks at some of its professional audio amplifiers, and examines the company's technologies involved, including how it approaches minimizing energy expenditure with low weight, heat management, and power factor management. It also provides a valuable perspective on Powersoft's own approaches to Power Factor Correction (PFC) technology integrated into switching mode power supplies and its Class-D Pulse Width Modulation (PWM) high-efficiency output stage. This article was originally published in audioXpress, August 2014 .   Read the Full Article Now Available Here

Voice  Coil Test Bench
The SB Acoustics SB29BNC-C000-4 Tweeter
By Vance Dickason
Here, we characterize the SB29BNC beryllium 29 mm dome tweeter from SB Acoustics. Test Bench has covered a number of SB Acoustics tweeters, and it's worth repeating that all the Sinar Baja (SB) transducers are developed by former Danish Vifa/Scan-Speak engineers Ulrik Schmidt and Frank Nielsen, co-owners of Danesian Audio. The SB29BNC-C000-4 is the second high-end 29 mm beryllium diaphragm neodymium dome sent by SB Acoustics for Test Bench. Features for this transducer include a small format 72 mm diameter injection-molded plastic faceplate, an 8 mm wide coated cloth surround, a 29 mm beryllium diaphragm, a copper cap on pole piece for reduced voice coil inductance and minimum phase shift, internal pressure equalization and flow resistor for non-resonant coupling of cavities, copper-clad aluminum wound voice coil wire, 0.25 mm Xmax, 95 dB sensitivity, a foam-mounting gasket, and gold-plated terminals. This article was originally published in Voice Coil, March 2019 .   Check it out here!

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