Adlib Audio Launches AA Install Speaker Range

adlib-speakersLiverpool based Adlib Audio launches a new specialist division – Adlib Speakers – to manufacture and market its AA brand of speakers, which are very proudly made in Liverpool, England. Hand-crafted and designed to perfection by a dedicated team of individuals who know their audio, using quality components, precision engineering and innovation, the AA series intends to be the ultimate ‘boutique’ brand for those who understand that their sound really matters. Adlib has been making, installing and using the AA range very successfully for the last 15 years, primarily for its own installations and projects, and now they believe the time has come to step up and make the AA series available for re-sale worldwide.

Currently there are four products available for re-sale in the AA range – the AA61, AA81 and AA121 – containing 6, 8 and 12 inch drivers respectively, complete with a dedicated AA12HL 12 inch sub. All the AA series cabinets are constructed from premium birch ply sourced in Finland, and are available with a hard-wearing textured paint exterior for installs. A huge amount of quality engineering and detail goes into manufacturing the AA range all featuring the best components, custom speaker chassis, compression drivers and Adlib’s own custom crossover networks.

Doing It Differently

Time moves quickly. We are already feeling the aftermath of 2014’s first two major industry shows. This is also a year when audioXpress is completing its transition to an expanded publication that addresses the needs of the audio engineering community—not only for those who have fun listening to music (there are plenty of magazines doing that) but mainly for those who imagine, create, and work with audio technology.

This year began with the 2014 International Consumer Electronics Show (CES) in Las Vegas, NV, introducing innovations on all fronts. It was also the largest CES in show history. While some companies introduced products based on users’ needs, it appears many consumer electronics companies still prefer to throw hundreds of new ideas at the wall to see what sticks. I guess a major electronics show like the CES is the ideal place to test those ideas, but sometimes we have to wonder why the successful companies that only introduce market-ready products don’t even need to attend the CES.

Yes, we miss seeing Apple at trade shows and we miss the inspiring clear vision of the late Steve Jobs. Apple is one those companies with products that are the perfect combination of state-of-the-art technology and innovation that are available for purchase exactly as advertised. And while the company was not in attendance, Apple’s products still dominated the 2014 International CES. It is no surprise that many great ideas and reference designs were designed to complement the iPad, the iPhone, and even the new Apple Mac Pro workstation.

IK Multimedia promoted its iRing wireless sensors to control music apps (or any other apps) using only gestures. We’ve also seen great photography peripherals for the iPhone and many new charging and home-automation solutions. There are even iOS-device-controlled robots and drones. And of course, no audio company could ignore the huge market created for wireless speakers and headphones. Many were especially designed for Apple’s mobile devices, leveraging Apple’s push for Bluetooth Smart 4.0 and AirPlay technologies. Apple also effectively revitalized the worldwide home audio market.

Wireless speakers, headphones, soundbars, integrated A/V receivers and audio systems are experiencing impressive growth rates, according to recently published market reports. Bluetooth products, in particular, continue to bolster the wireless speaker market, offering the convenience of portability, while multi-room audio based on Wi-Fi is also on the rise. Among the 20,000-some products introduced at the 2014 International CES, there were a significant number of new headphones and earphones.

After every CES, we should also acknowledge those sparks of inspiration from obscure companies and the truly exciting technology announcements. For example, cars connected to mobile networks—actually talking and seamlessly interfacing with our mobile devices.

It’s always difficult to understand why, but clearly, in the middle of all the Internet-connected toothbrushes and forks, speech-recognition watches, and curved television screens, some innovations make complete sense and leave us asking ourselves “why did it take so long?”

João Martins

The January 2014 Edition of audioXpress is Now Available Online!

Our first issue for the New Year highlights the main technologies and product launches at the 135th Audio Engineering Society (AES) Convention, one of the best audio engineering-related events in the US. While there, AES celebrated its 65th anniversary. And, of course, the convention was also a special event for us, marking the official presentation of the redesigned and reenergized audioXpress magazine!

In our What’s News section, we discuss HARMAN’s acquisition of Duran Audio, which was announced during the 135th AES Convention, and we detail the Dutch company’s valuable technologies and its history.

Our review for the month reveals a great stereo compressor in a 500-series format from the Polish company IGS Audio. Miguel Marques enjoyed his examination of the S-Type 500 VCA compressor and details the features and circuitry of this remake of a classic.

AX_012014Jan_360pxIn the final article of our three-part series “Tips to Resurrect a Classic Speaker or Design a New System,” Thomas Perazella confirms that a new woofer and a few DSP corrections can significantly improve the original Heil air motion transformer’s sound quality.

And for those who enjoy DIY audio, we have The Twin-T Oscillator, an audio oscillator and stereo VU meter design by Larry Cicchinelli. The easy-to-use unit combines a calibrated audio source with a level display.

In our Standards Review column, we discuss the new AES67-2013 Networked Audio-Over-IP (AoIP) Interoperability Standard and all the implications for the audio industry.

The issue also includes the third article in the series “The Lowdown on Woofers, Subwoofers, and Bass Shakers,” in which Mike Klasco and Steve Tatarunis look inside a few drivers and compare subwoofers and woofers.

For those audiophiles who follow Richard Honeycutt’s column, Sound Control, you will be glad to know that he addresses the difficult question of “Sound Isolation” and discusses the options when acousticians are asked the cost to “soundproof” a certain room.

Richard Honeycutt also begins a new series of articles dedicated to “The Development of Tube Guitar Amplifiers” in his respected Hollow-State Electronics column.

Finally, our own Shannon Becker interviews entrepreneurs Jason Lucash and Mike Szymczak, founders of OrigAudio, a really interesting company with great concepts for “foldable” speakers and other unique ideas.

Check it out at: or visit for information on how you can receive a monthly copy wherever you go.

From Broadcast to Home Recording to Digital Networks—Where the New audioXpress is Going

AXCover_122013Dec_120pxFor readers seeing this “second” issue of audioXpress since we introduced our new format and layout last month, I feel I should explain the concept a little more. Our target deadline for this relaunch was decided some time ago and I couldn’t think of a better place to introduce our “new” magazine than the AES convention in New York City!

I can summarize our concept in a few words: more (of what our readers expect), electronics (our roots), and audio innovation (our focus).

We are proud of our heritage as Audio Amateur, Audio Electronics, Glass Audio, and Speaker Builder magazines. Those titles were born in a time when amateur radio was still developing hand-in-hand with electronics and radio technology. And that is precisely why audioXpress is a part of the electronics publication portfolio of Elektor International Media (EIM).

But you may be wondering about audioXpress’s evolution and what to expect in the future.

It’s important to clarify that we will not continue to be a “home electronics” or consumer application-focused publication. We believe we should share the most interesting audio stories in the industry, independent of their application areas—consumer or professional, music or broadcast oriented. Hence, the innovation focus.

The most important consumer technologies often start with those developed for professionals. So, we will follow audio electronics innovations, together with the all-important disciplines of electroacoustics (and, needless to say, software, digital audio, networking protocols, and audio synthesis).

We believe that a publication such as audioXpress cannot focus only on the “home approach,” which still appeals to many enthusiasts and hobbyists. Some of us clearly remember the 1960s, when live concerts used “consumer” amps and speakers, before there were guitar amps and large speakers. At Woodstock, there were McIntosh amps (now a purely home audio brand) and the PAs were early versions of the JBL speakers (today both a pro and a consumer brand). Five years later, all the big “pro audio” brands in live sound, such as Electro-Voice and JBL, dominated that market (in the US at least). During this time, things were different in the recording studios. There, technology was first “borrowed” from radio and TV broadcasting. This is long before we had “home studios” using computers. And where exactly did that come from?

In the era of the Internet, blogs, and social networks, many magazines have disappeared. But we know a magazine can flourish. In addition to its content and its readers, a magazine must also have a purpose. It must provide a sense of community. More importantly, it needs to offer readers content they can’t find elsewhere. It does not matter if our readers are professionals, students, or enthusiasts. Our common interest unites us, whatever the platform: print, online, Facebook, Twitter, e-mail newsletters, or mobile apps.

We want to build a better audioXpress with more content, representing the common interests of the audio community while also reflecting the industry.

João Martins

Q&A: Daniel Weiss – Audio Engineer Focuses on the “Masters”

Daniel Weiss founded Weiss Engineering in 1985. The company designs and manufactures digital audio equipment for mastering studios.

Daniel Weiss founded Weiss Engineering in 1985. The company designs and manufactures digital audio equipment for mastering studios.

SHANNON BECKER: Tell us a little about your background and where you live.

DANIEL WEISS: I live in Uster, a small city close to Zurich in Switzerland. In the 1970s and 1980s, I played music in a band, first as a violin player and later as the bass guitarist, which seemed preferable to the other band members. I also built various synthesizers, amplifiers, and speakers. I did a four-year apprenticeship as an electronics technician and during that time two friends and I formed a company called “White Amplifiers.” We built amplifiers and speakers for musicians in our spare time. After the apprenticeship, I studied electronics engineering and eventually graduated with a BSEE.

SHANNON: In 1979, you joined Studer-Revox as an electronics engineer working in the digital audio lab. Can you share details regarding your work on the sampling frequency converter design?

DANIEL: In 1979, Willi Studer decided to enter the digital audio era and established the “PCM laboratory” with almost all the lab members being newly recruited engineers and technicians. We were kind of an isolated group as the other labs were slightly suspicious of digital audio technology. We also had a hard time (at least it seemed to me) defining digital audio products that would make sense in a mainly analog world.

There were several digital audio recorders around at the beginning of the 1980s (e.g., Sony, 3M, Soundstream, JVC, Mitsubishi, etc.). There wasn’t much standardization back then so the sampling rates and interface formats greatly varied. Thus, it made sense to create a universal sampling rate converter with custom wired interfaces. This became the SFC16, and I did most of the hardware design. It was a 6HU/19” unit with digital filters built in so-called distributed arithmetic. It is a very clever architecture that avoids the need for DSP or multiplier chips. For most of the units sold—I think 30 of them were manufactured—I also did custom interfaces.

One of the largest setups of a 102 Series system was used at Sony Music in New York in the form of the IBIS digital mixing console.

One of the largest setups of a 102 Series system was used at Sony Music in New York in the form of the IBIS digital mixing console.

SHANNON: What other types of audio products did you design? Can you share some of the challenges involved with the design(s)?

DANIEL: My colleagues at the PCM lab pursued various other projects, such as A/D and D/A design, analog reconstruction filter design (I also was involved), research in de-noising, and a preview unit for the delay required in vinyl cutting. This resulted in a A/D and D/A 6HU box, with enough memory to do the delay. It was not a simple task back then.

As Studer was mainly a tape recorder company, the design of a digital tape recorder was inevitable. The first model was an eight-channel unit using the newly established Digital Audio Stationary Head (DASH) format, which enabled you to interchange tapes with ones recorded on other DASH recorders. I did the audio processing unit for that eight-channel recorder, which was required for interpolation in case the data read from the tape could not be reconstructed via the error correction scheme employed.

Those were interesting times at Studer, as we were pioneers in the pulse code modulation (PCM) audio field. We did many side projects, such as a digital sine generator for measuring purposes (Audio Precision did not exist back then) or a study on TIM measurements with a new approach or a PWM-based analog track on the digital tape and so forth.

SHANNON: In 1985 you founded your own company, Weiss Engineering ( Initially, your company focused solely on designing and manufacturing digital audio equipment for mastering studios. How and why did you select that specific market niche?

DANIEL: One day in 1984, when I still was at Studer, a customer came to our lab and asked for an interface between a Sony F1 portable digital audio recorder and a Sony 1610 digital audio recorder. The F1 did not have any digital I/O, so it had to be a custom made interface box. Studer does not do such custom work, so I made that interface for the customer in my spare time. The customer was Ben Bernfeld, a recording and mastering engineer from Harmonia Mundi Acustica in Germany. He knew exactly what was required in terms of equipment for CD mastering (or pre-mastering to be exact). So we decided to build a modular digital audio system to interface and process digital audio. I did the design and manufacturing while he organized the sales. CD pre-mastering was popular in the US mainly, so we concentrated on that market.

SHANNON: Tell us about Weiss’s first product. Is it still being sold today?

The potential of a Weiss Engineering Mastering Studio “Mastering Mansion Madrid” uses  Weiss Gambit Series equipment, which are the white faceplate units on the left.

The potential of a Weiss Engineering Mastering Studio “Mastering Mansion Madrid” uses Weiss Gambit Series equipment, which are the white faceplate units on the left.

DANIEL: The first system became the Harmonia Mundi Acustica BW-102 unit, starting with modules for F1, 1610 interfacing, a digital high-pass filter for DC offset elimination, a digital de-emphasis and a digital level control module.

Over the years, dozens of modules were added. We even did digital mixing consoles based on the BW-102. The largest one was a 32-channel console with four auxiliary buses. Another one was a 24-channel configuration with GML fader automation used by Sony Classical in New York. Those consoles were a bit awkward in terms of hardware requirements, because the BW-102 initially was designed for two-channel applications. Later, we also upgraded most of the modules to handle 96 kHz. Quite a few customers still use the BW-102, we even occasionally sell modules. Technically it is still up-to-date with 96/24 capability and 32-bit floating point processing.

After the BW-102, we started the Gambit Series with 19” units (e.g., analog to digital, digital to analog, parametric equalizer, dynamics processor, de-noiser/de-clicker, sampling rate converter, and more).

SHANNON: In 2000, Weiss entered the high-end consumer audio market with a new product line. What was the impetus behind that decision?

DANIEL: We thought that our DAC1 DAC could find a market within the high-end community. So we built the Medea DAC, based on the DAC1, to test the waters. The Medea became a huge success and it did not take long for customers to ask for more. So we built the Jason CD transport to complement the Medea. Other high-end products followed, up to the latest one, the MAN301 network player.

SHANNON: With the two separate aspects of your company—professional equipment for mastering studios and high-end consumer products—you are in the unique position of controlling, in part, the “production” of the masters and their reproductions. Do you think there is a direct correlation between the two “worlds?”

The Weiss 102 Series consists of digital audio processing modules suited for CD mastering, mixing, and digital audio signal processing. You can configure a system according to your requirements.

The Weiss 102 Series consists of digital audio processing modules suited for CD mastering, mixing, and digital audio signal processing. You can configure a system according to your requirements.

DANIEL: Correlation maybe in that both mastering engineers and audiophiles are interested in getting topnotch sonic quality and ergonomics. We can use our design philosophy—with the utmost transparency—with both markets. But in the end, we simply supply tools. The mastering engineer needs to know how to use them properly.

SHANNON: To what do you attribute your company’s continuing success?

DANIEL: At first, it was the fact that we built the right product at the right time (i.e., when the CD took off there was a huge demand for decent audio processing in the digital domain). In the consumer market, I think our customers like our “no bull” approach. I don’t hold back with my opinions about $1,000 mains cords, gold-plated fuses, small wood blocks for acoustics treatment, or CD demagnetizing, and so forth. I wrote some white papers firmly based on the laws of physics on various audio topics in an attempt to fight the snake oil with facts. This is something I like about the pro audio people, they are down-to-earth guys.

SHANNON: Tell us about your favorite high-end consumer product? What makes it different from other products on the market today?

DANIEL: One of my favorites is the MAN301 network player—from our product line, of course. It is an incredibly versatile unit for CD playback and ripping, and metadata tagging/artwork. It uses the Gracenote database and this is hardly seen on any other high-end network player. It also includes file playback (including DSD), DAC, preamplifier functions, and so forth. I use one at home and enjoy it every day. We continue to develop additional software for the MAN301 (e.g., for room equalization, creative equalization, vinyl simulation, and so on).

I also like to listen to as many different speakers as possible to explore the various philosophies and designs. I think the speaker/room system has, by far, the greatest potential for improvement of the whole audio chain. Audiophiles should acknowledge that and stop messing around with mains cords. The industry still has a long way to go when it comes to speaker/room optimization.

SHANNON: Could you share your opinion on mastering for digital file distribution and, in particular, the mastering for iTunes initiative?

DANIEL: If it is mastering for an uncompressed format, then the procedure should not be different from a standard CD mastering—except maybe if the format is at a higher sampling rate and/or word length than for a CD.

Mastering for iTunes is different, as it means mastering for a lossy format (for the time being at least). But I think the best thing about that initiative is Apple imposes specific criteria on the technical quality of the supplied music, in particular that the music must not be clipped. There are also a number of recommendations available at

The Weiss-designed MAN301 network player’s front boasts a sleek design. It is a versatile unit that uses the Gracenote database.

The Weiss-designed MAN301 network player’s front boasts a sleek design. It is a versatile unit that uses the Gracenote database.

SHANNON: Where do you see the audio market headed in the next five years? Do you think we will eventually evolve to “high-end” streaming audio services rather than downloading files?

DANIEL: There always will be both variants. Many people like to “own” the music so they can play it anytime and anywhere. And, I think the emotional relationship to the music is different if you’ve got it “on file” and not just via a stream.

Streaming services are great to check out new music. They should have a “buy” button on their websites though. Streaming during travel can get expensive and/or can be annoying when the stream gets disrupted in the tunnel or because of too many people try to get streams on a train, for instance.

Also it seems that for artists streaming services are far from lucrative. That could be changed maybe if they would simplify the buying process right from the streaming site.

In any case, the majority of high-end playback systems will use computer-based playback devices because it is so much more convenient and easily enables people to discover new music from streaming services or even in their own libraries.

Expanding horizons. Expanding a common passion.

AXCover_112013Nov_120xWelcome to a new audioXpress.

Having followed the audio market and visited the world’s major trade shows for the last 20 years or more, I gained a broad perspective about how exciting and innovative the audio industry is. In particular, I recall the enlightening perspective you can receive from any Audio Engineering Society (AES) convention. The convention provides a place where industry veterans can share their experiences in engineering and communications. We chose to unveil the redesign of audioXpress at the 135th AES Convention.

In the early 1990s, I was fortunate enough to be responsible for a licensed electronics magazine. I quickly learned that the audience of such practical and project-oriented publications was a combination of students, enthusiasts, and industry professionals. They all share a passion for that field, are involved in many different areas, and use their spare time to pursue electronics-related hobbies—the most popular of which is audio electronics.

Since then, I have started several publications addressing the informational needs of professionals in the broadcasting, professional audio, and installation/systems integration markets. I also learned how the evolution of technology from analog to digital and the convergence with IT platforms and IP infrastructure was changing the market landscape at an exponential pace.

During this time, Edward T. Dell, Jr. (1923–2013) was devoting his life to people with a passion for audio electronics and creating magazines including Audio Amateur (rebranded as Audio Electronics in 1996), Glass Audio, Speaker Builder, and later, in 2000, audioXpress. In 2011, Ed Dell sold his company to Elektor International Media (EIM) and retired.

Much in the same spirit of the original Audio Amateur—and with the support of a worldwide organization deeply involved in the electronics industry—we believe that audioXpress will blossom into a fascinating publication that follows the latest audio innovation trends, independent of the application field, and shares a common audience of engineers, consultants, and enthusiasts in the electronics and audio fields, most of whom are involved in R&D.

Although it was deeply rooted in the US, audioXpress—together with its sister publications Voice Coil and the Loudspeaker Industry Sourcebook—reached professionals around the world (e.g., Europe, China, India, and Brazil). It has gained more of a global presence since its acquisition by EIM, which also publishes some of the best technical books in the electronics industry.

I am really excited to bring the “new” audioXpress to a wider global audience, knowing that we can build on the tradition of the original publication and its diversified audience. We are working to create a magazine you will enjoy and anticipate reading every month.

João Martins

2013 Loudspeaker Industry Sourcebook Now Available

Whether you’re an audio executive or simply an audio fan, you’ll find everything thing you need to make informed purchasing decisions in the 2013 Loudspeaker Industry Sourcebook,our annual publication that lists speaker-related companies and their products and services.

It’s the most comprehensive loudspeaker industry guide available.

The Loudspeaker Industry Sourcebook introduces you to the Bowers & Wilkins CI 800 Series speakers, featured in a custom theater display at a recent ISE 2013 exhibit.

The sourcebook is an excellent reference to keep on hand at your office or lab. You can also research its broad array of audio resources online. Click here to purchase a hard copy of the 114-page guide (at a discount) or view it for free online.

Roughy 230 companies and their products and services are included in the user-friendly

charts of this year’s sourcebook. And it’s easy to contact a manufacturer, consultant, or

This Monitor Audio system is one of several explored in the article “Trends in Loudspeaker Integration,” featured in the 2013 Loudspeaker Industry Sourcebook.

distributor directly by referring to the sourcebook’s extensive list of company executives, addresses, websites, and phone and fax numbers.

Also, this year’s sourcebook is much more than an extensive resource for everything from design software and manufacturing equipment, to test equipment, drivers, micro speakers, microphones, and enclosures. We are featuring more articles from experts on where the industry is headed in 2013 and beyond.

For example, one manufacturer examines the popularity of soundbars and how its engineers designed a soundbar-component-system intended to achieve surround-sound quality. Another article discusses the development of speakers that aesthetically integrate into your home’s architecture without sacrificing audio quality.

Another example of an integrated loudspeaker discussed in this year’s Loudspeaker Industry Sourcebook.

Those of you who like to test, measure, and simulate the performance of audio devices will find some interesting reading in this year’s sourcebook. Since today’s loudspeakers are small, portable, and widely used with smartphones, the sourcebook offers advice on how to use simulation software to optimize the output and tuning of microspeaker systems. And while you may know that impedance is a standard test measurement for loudspeakers, do you know how to construct and use an impedance test circuit? The sourcebook includes an article explaining how.

There is even more helpful information inside. So jump right in.


Q&A: Ron Tipton

Ron Tipton

Photo 1: Ron Tipton tackles a project in his home work space.

SHANNON BECKER: Tell us a little about your background and where you live.

RON TIPTON: I was born in Chicago, IL, and by the age of eight, I was spending many Saturdays haunting the exhibits at the Museum of Science and Industry with friends. I suppose that was an indication of where my main interests lay. We moved to Kansas City, MO, when I was 10, and I had to content myself with scientific books and magazines: no science museums. I moved to Las Cruces, NM, in 1956 to attend what was then the New Mexico College of Agriculture and Mechanic Arts as a junior in the Electrical Engineering department. (The college became New Mexico State University in 1960.) I did pick up a couple of EE degrees, but I didn’t complete my doctorate because of business. I started Testronic Development Laboratory (TDL) in 1957. Except for a few years in northwest Arkansas (more about that later) and back in Kansas City for a while, I’ve lived in the Las Cruces area since 1956.

SHANNON: Describe your career as an electrical engineer and your job at White Sands Missile Range.

RON: In the early 1960s, the telemetry (radio transmission of data from an air- or space-borne vehicle back to the ground) band was around 220 MHz. There were a number of reasons, including smaller antennas, to move the band to 2,200 MHz. I was part of the project to accomplish this move. These were the days of vacuum tubes, so designing and building a transmitter was a big challenge because any vibration in the missile (there was a lot of it) vibrated the tube grids causing frequency modulation of the output, which had to be very low to be acceptable. Several contractors tried and failed but one, Microdot, was successful. It was a big day when we flight tested the transmitter on a missile and it worked fine. Now, of course, the transmitters and receivers are all solid-state and reliable operation is taken for granted.

Most of my other work was with various passive tracking systems. Unlike radar, which is an active tracking system, passive systems use the emissions from the vehicle, usually the telemetry transmitter, to perform the tracking. This usually requires a ground-based antenna field, because they are phase and phase-difference measuring systems, so they benefited from the smaller antennas at 2,200 MHz. By knowing the antenna spacing and the telemetry transmitter carrier frequency, data was collected that was later converted to a track by computer analysis. I retired in 1995, so with the increases in computer performance real-time tracking is probably used today.

The telemetry transmitter’s carrier had to be very stable for this to work. The various detection oscillators in the ground-based receiver were set so the output to the tracking system was usually 5 kHz. The usual phase detectors were period counters. The track data 5 kHz started a high-frequency counter and the reference 5 kHz stopped it so there was some ambiguity in the count. I designed and built a very precise 5-kHz autocorrelation phasemeter using a Motorola DSP56156 digital signal processor. This resulted in 1,700 samples per cycle with a phase measurement resolution of 0.212° with a corresponding lower tracking error. I have never followed up on it, but this technique could be used to design a very precise audio phasemeter.

SHANNON: How did you become interested in audio electronics?

RON: I think it was a result of my love for music. In the early 1950s, I bought an inexpensive 33-1/3/45-rpm turntable, and I needed a preamplifier and power amp to use it. I decided to build them so I found a combination preamp, low-power amplifier in some book. I bought all the parts from Burstein-Applebee in Kansas City, built it, and it worked fine. It used vacuum tubes, of course. I was hooked.

SHANNON: Can you tell us about your work with active filters and pseudo-random noise generators? Do the models you used then still function today?

RON: By the mid 1960s, useful op-amps were available—in particular the LM741 general purpose, the LM301A for better performance, and the higher frequency NE531. It was practical to design and build active filters using either the voltage follower or multi negative feedback topology. I built them in potted modules and as plug-in cards. I had several orders for sets of third-octave bandfilter cards that exactly fit a Hewlett-Packard audio spectrum analyzer. I sold them for less than the HP price! I still have a few of the potted module filters and they work just as they did 50 years ago. Two 50-year-old active filter modules are shown in Photo 2.

Photo 2

Photo 2: Ron built these two active filter modules 50 years ago. The left-hand unpotted module is a tunable low-pass filter as part of the GMS piano tuning aid.

The left-hand unpotted module is a tunable low-pass filter mentioned in the next question as part of the GMS piano tuning aid. It is 2” square to give you an idea of its size. The six gold-plated brass terminal pins extend about 0.2” out of the epoxy potting material to make the electrical connections to the circuit.

The first pseudo-random (P-R) noise generator I designed and built, the model 105, used RTL logic. This was an early logic family in standard DIP packages. I didn’t sell even one of them but it was an interesting learning experience! Next came the model 108, which used 7800 series TTL logic. The 108 and its variants (i.e., the 108-M4, 108-M5, 109, and 111) all sold fairly well.

Perhaps I should mention that P-R noise is just random noise within each sequence but the sequences exactly repeat with the sequence length dependent on the shift-register length and the clock frequency. Thus, we have a random signal with a known period just like a sine or square wave. My article: “Audio Testing With Noise,” Voice Coil, December 2010, discusses P-R noise details.

The 108-M4 and 108-M5 were both “gated” generators. They could put out a noise burst with the duration and repetition rate set on the front panel or triggered by a pulse from a remote location. These were both custom models designed to meet the customer’s needs. This was economical for the customer because the 108-series all used the same size plug-in circuit cards with each card performing a certain function: clock generation, shift-register, gate generator, and so forth. The cards could be “mixed” to provide the required performance. You can find more on this topic, including photos, in the Voice Coil article mentioned earlier.

Photo 3

Photo 3: A typical plug-in card is used to perform a certain function (e.g., clock generation, shift-register, gate generator, etc.)

Photo 3 shows a typical plug-in card. They measure 4.6” wide by 4.7” high.

SHANNON: What kind of audio products did you build for GMS? Can you share some of the challenges involved with the designs?

RON:  I designed two lines of guitar amplifiers for GMS and both were marketed by Gretsch. The lower-cost line was the Broadkasters about which I don’t remember much or have any documentation. The premium line was the Nashville series, which included the Pro-Lead, Pro-Steel, and the Pro-Keyboard models. These were rather straight-forward designs with a few exceptions.

The reverb units were mechanical springs in a metal housing with a small loudspeaker without a cone driver at one end and an inductive pickup coil at the other end. I needed some power to drive it because there was quite a bit of loss in the spring, which was about 10” in length. I designed a small power amplifier in a potted module with an aluminum baseplate to transfer the heat to the amplifier’s chassis. A circuit diagram and photo can be found at

The Pro-Lead model had a tremolo circuit, which was also built as a potted module because Gretsch wanted to keep the circuit under wraps. It had rate and intensity controls on the front panel, a foot-switch jack to turn it on and off, and an LED that illuminated when it was on. I thought it was a rather clever design at the time. Details can also be found on my website.

The Pro-Keyboard had what we called an Accent module which was controlled by a three-pedal footswitch which enabled the musician to instantly change the volume. I though this design was rather innovative because I used the three pedals to get five levels of volume change by sensing how deeply the pedal was depressed. This circuit was also built as a module to hide the design. It used a 4066 analog switch to change the gain of an LM301A op-amp. The other logic chips just decoded the foot pedal positions to control the 4066. The circuit diagram for this design can also be found on my website.

In addition to the guitar amps, I designed a digital piano-tuning aid for the Baldwin grand piano manufacturing plant in Conway, AR. It was a box that produced the 88 piano notes through a built-in 6” speaker. The note to be played was selected by a row of 12-note push buttons and a row of eight octave push buttons or by a two-pedal foot switch, one pedal for the octave and the other for the note. There was also a front panel rotary switch for the normal equally tempered scale, a quarter semitone high or a half semitone high. (Pianos were often tuned slightly high so the structure could settle into the proper tuning.)

The heart of the piano-tuning aid was a 4059 programmable frequency divider, also called a divide by N divider where N was an integer number and the output frequency was the clock frequency divided by N. The integer numbers, N, were read from a PROM. The 4059 output was a square wave which contained too many harmonics to be useful in tuning a piano. (The person doing the tuning matched the output of the piano-tuning aid to the piano note by tightening or loosening the tuning pin.) So I needed to low-pass filter the output. I did this with a frequency-to-voltage converter whose DC output voltage controlled the cut-off frequency of a voltage tunable low-pass filter. The output was a sine wave because the filter’s cut-off frequency tracked the output frequency. I considered this one of my more interesting designs! (The F to V converter and the tunable low-pass filter were potted modules to conserve space and all of the logic chips used were RCA 4000-series CMOS because RCA was a major supplier to the Baldwin Piano and Organ at that time.)

SHANNON: You have been TDL’s founder and principal designer for many years. What has been your best experience?

RON: I think the most interesting task was designing the “Hot Strings” guitar for Chet Atkins. (It was marketed by Gretsch as the “Chet Atkins Super Axe.”)  This project is fully described in my article: “Designing the ‘Hot Strings’ Guitar for Chet Atkins” (Multi Media Manufacturer, May/June 2006). But I’ll recount some of the highlights.

Chet heard about my modules in the piano-tuning aid so he came to the GMS plant in the fall of 1975 to discuss the idea of putting some effects modules inside the guitar body. We finally settled on a compressor (2” × 2” × 0.5”) and a phaser (2” × 3” × 0.5”). By the end of August 1976, I had an assembled guitar ready for trial. Chet came to Prairie Grove about mid-September to give it a try. He was generally pleased with the performance, but he wanted a couple of changes. This was also the time he picked the “Hot Strings” name. We made the changes and my final set of drawings is dated January 19, 1977. I’ve never seen a production Super Axe, but I do have several photos.

The rear cover of RCA Records LP APL1-2786 (1978), “Chet Atkins and Les Paul: Guitar Monsters” shows 12 photos of Chet and Les. This guitar can be clearly seen in five of them.

Through the years, I’ve heard from several owners of a Super Axe and replacement modules are now available from the TDL website.

SHANNON: What was your first personal project? Why did you build it? Is it still in use?

RON: My first personal project was the mono phono preamp/power amp I mentioned previously. No, it’s not still in use, and I have no idea what happened to it.

SHANNON: You wrote an article, “A Vintage Turntable Revisited,” in audioXpress, September 2012. Why did you think it was important to revisit it?

RON: The revisit was important because of the carbon fiber tube tone arm which let me lengthen it and thus, reduce the tracking error. While it is true that this resulted in a rather large turntable, I think it was worth it. It is still much in use because it sounds very nice.

SHANNON: Can you share the details on some other personal audio projects?

RON: I usually have quite a few projects going at the same time, but I’ll talk about two of them that may be of interest.

I’m building a stereo pair of three-way speakers, that is, three inputs: base, mid-range and upper frequencies (see Photo 4).

Photo 4

Photo 4: This will be a stereo pair of three-way speakers. The three inputs will be: base, midrange, and upper frequencies, once Ron completes the project.

These will be sealed enclosures and you can see the internal bracing in the photo. The front and rear panels are 13-ply Baltic birch with 0.75” MDF for the sides, top, bottom, and braces. The box was computer designed for all Dayton (Parts Express) drivers. The top and bottom “holes” are for the 8” reference-shielded woofers (295-366), the next two holes toward the center are for the 2” dome midrange (285-020), and the center hole is for the 0.75” neodymium dome tweeter (275-035). The tweeter is rear-mount, but I have solved that construction problem! The seams are caulked, the black patches on the inside walls are barium-filled vinyl for sound absorption, and the woofer and midrange drivers have T-nuts installed for their mounting screws.

I have built active crossovers, each with the required three outputs, but a Behringer DCX2496 can also be used. The performance comparison will be interesting. Yes, it does require six power amplifiers, but that’s not such a big deal these days even though it would be best if they were all the same type. The simulated overall frequency response looks good.

Some of my projects are studies and they are difficult to describe or to photograph until finished. It’s also difficult to photograph a construction project for which I have all the material, but I haven’t started putting it together yet. So I’ll just tell you what it’s about.

As some of you may know, my company, TDL Technology builds audio equipment for sale. We do a 100-hour burn-in for quality control so our failure rate is nearly zero. But I’ve wondered about doing more. What about bad solder joints or microphonic parts (rare, but possible even with solid-state parts)? It occurred to me that a vibration test might be useful but commercial shake tables are out of my budget. So, what about building one?

The top surface to which the device under test will be fastened is a piece of 20” × 12” × 0.5” thick piece of ceramic tile cemented to a 20” × 12” sheet of 0.75” 13-ply Baltic birch plywood. On the underside of the plywood, two Aura Pro Bass Shakers (Parts Express 299-028) are mounted and wired in series. This composite platform will be supported above its heavy base at its four corners by 0.25” diameter rods and neoprene vibration isolators (McMaster-Carr 94955K31). The device under test will be attached to the top surface with cotton webbing belts fitted with ladder-lock buckles. Accelerometers (Measurement Specialties ACH-01) will be cemented to the top surface and mechanically attached to the device under test to monitor the vibration level.

The Shakers have a frequency response of 20 to 80 Hz so a low-pass filter will be used at the output of the noise generator. I expect white or pink noise will be the most useful. It’s possible that it would also be a useful subwoofer!

SHANNON: You have done a lot of work with audio restoration. Why do you think it is important?

RON: Personal (home) restoration is important because it’s fun and because the music needs to be saved. Record companies have released a tremendous number of records in the past 100-plus years and a few have been remastered and rereleased—a very few. Record archives do their best at restoration but many collections are very large and funds are always limited. I think it’s up to amateur restorers to do as much as possible.

SHANNON: We went from vinyl to cassette to CD to DVD to music servers. What do you think the next audio format will be?

RON: I hope the next big breakthrough will be holographic recording—but we’ll have to wait and see.

SHANNON: What do you see as some of the greatest audio innovations of your time?

RON: The invention of solid-state electronics is at the top of the list. It changed our world. And, I don’t mean just the transistor. LEDs and solid-state lasers made possible so many innovative audio products.

SHANNON: Do you have any advice for audioXpress readers who are thinking of building their own sound systems?

RON: I’ve been building most of my own audio equipment for more than 60 years so it’s possible that I’m prejudiced. As I sit here writing this I can see 10 different power amps and three different phono preamps that I’ve built. Getting into building your own can be addictive so beware! But if you have the inclination and the means, go for it! You will also learn a lot in the process, not only about audio techniques but also how to properly do the construction.

Q&A: Andrew Spitz (Sound + Interaction Designer)

Andrew Spitz is a Copenhagen, Denmark-based sound designer, interaction designer, programmer, and blogger studying toward a Master’s interaction design at the Copenhagen Institute of Interaction Design (CIID). Among his various innovative projects is the Arduino-based Skube music player, which is an innovative design that enables users to find and share music.

The Arduino-based Skube

Spitz worked on the design with Andrew Nip, Ruben van der Vleuten, and Malthe Borch. Check out the video to see the Skube in action.

On his blog, Spitz writes:

It is a fully working prototype through the combination of using ArduinoMax/MSP and an XBee wireless network. We access the API to populate the Skube with tracks and scrobble, and using their algorithms to find similar music when in Discover mode.

The following is an abridged  version of an interview that appears in the December 2012 issue of audioXpress magazine.

SHANNON BECKER: Tell us a little about your background and where you live.

Andrew Spitz: I’m half French, half South African. I grew up in France, but my parents are South African so when I was 17, I moved to South Africa. Last year, I decided to go back to school, and I’m now based in Copenhagen, Denmark where I’m earning a master’s degree at the Copenhagen Institute of Interaction Design (CID).

SHANNON: How did you become interested in sound design? Tell us about some of your initial projects.

Andrew: From the age of 16, I was a skydiving cameraman and I was obsessed with filming. So when it was time to do my undergraduate work, I decided to study film. I went to film school thinking that I would be doing cinematography, but I’m color blind and it turned out to be a bigger problem than I had hoped. At the same time, we had a lecturer in sound design named Jahn Beukes who was incredibly inspiring, and I discovered a passion for sound that has stayed with me.

Shannon: What do your interaction design studies at CIID entail? What do you plan to do with the additional education?

Andrew: CIID is focused on a user-centered approach to design, which involves finding intuitive solutions for products, software, and services using mostly technology as our medium. What this means in reality is that we spend a lot of time playing, hacking, prototyping, and basically building interactive things and experiences of some sort.

I’ve really committed to the shift from sound design to interaction design and it’s now my main focus. That said, I feel like I look at design from the lens of a sound designer as this is my background and what has formed me. Many designers around me are very visual, and I feel like my background gives me not only a different approach to the work but also enables me to see opportunities using sound as the catalyst for interactive experiences. Lots of my recent projects have been set in the intersection among technology, sound, and people.

SHANNON: You have worked as a sound effects recordist and editor, location recordist and sound designer for commercials, feature films, and documentaries. Tell us about some of these experiences?

ANDREW: I love all aspects of sound for different reasons. Because I do a lot of things and don’t focus on one, I end up having more of a general set of skills than going deep with one—this fits my personality very well. By doing different jobs within sound, I was able to have lots of different experiences, which I loved! nLocation recording enabled me to see really interesting things—from blowing up armored vehicles with rocket-propelled grenades (RPGs) to interviewing famous artists and presidents. And, documentaries enabled me to travel to amazing places such as Rwanda, Liberia, Mexico, and Nigeria. As a sound effects recordist on Jock of the Bushvelt, a 3-D animation, I recorded animals such as lions, baboons, and leopards in the South African bush. With Bakgat 2, I spent my time recording and editing rugby sounds to create a sound effects library. This time in my life has been a huge highlight, but I couldn’t see myself doing this forever. I love technology and design, which is why I made the move...

SHANNON: Where did the idea for Skube originate?

Andrew: Skube came out of the Tangible User Interface (TUI) class at CIID where we were tasked to rethink audio in the home context. So understanding how and where people share music was the jumping-off point for creating Skube.

We realized that as we move more toward a digital and online music listening experience, current portable music players are not adapted for this environment. Sharing music in communal spaces is neither convenient nor easy, especially when we all have such different taste in music.

The result of our exploration was Skube. It is a music player that enables you to discover and share music and facilitates the decision process of picking tracks when in a communal setting.

audioXpress is an Elektor International Media publication.

AX December: Speaker Design, Interactive Sound, Power, & More

audioXpress is all about range—range, in the sense of content diversity. Our international team publishes insightful articles on a wide variety of topics such as speaker design, sound analysis, glass audio projects, and hi-fi product reviews. This month we deliver once again.

First, I suggest you check out the interview with innovative sound designer Andrew Spitz (p. 38). Much of his current work focuses on “interactive experiences.”

Interested in speaker design? We’ve got you covered. Consider starting with the first part of Richard Honeycutt’s series, “Speaker Design School.”

Then  turn to page 8 for the second part of the series “Ribbon and Planar Magnetic Loudspeakers.” Finally, flip to page 14 for the conclusion to Ton Giesberts’s series on his active loudspeaker system project.

The completed PCB for the subwoofer is attached to its heatsink

Ready for a comprehensive transducer test? You can always rely on Vance Dickason’s expert analysis. This month he presents the results of tests he ran on a Morel TiCW 634Nd (p. 30).

The Morel TiCW 634Nd

Once you’ve had your fill of speaker articles, read what Gary Galo thinks about remastered editions of David Hancock’s 1967 recording of the Dallas Symphony’s presentation of Rachmaninoff’s Symphonic Dances (p. 24). What would you choose: vinyl, digital, or both?

If you’re a glass audio enthusiast, head to page 35 to refresh your understanding of power supplies for hollow-state electronics. Transformers and rectifiers are covered in detail.
Lastly, note that the long-awaited amp test page referenced in Richard Honeycutt’s audioXpress November 2012 article—“Differences in Amp Sound: What’s the Truth?”—is now available at