Project Spotlight: Electronics + Wood Fab Speakers

MIT graduate student David Mellis is interested in how designers are combining high-tech parts like microcontrollers with low-tech materials in clever ways. Yesterday, I pointed everyone to Mellis’s inspiring 3-D Printed Mouse project. Now let’s look at another creative design—Fab Speakers.

Whether you’re a microcontroller fanatic, professional engineer, audiophile, musician, or all of the aforementioned, this open-source Fab Speakers project will surely inspire you to customize your own. I’d love to see how others tackle a similar DIY project!

Fab Speakers (Source: D. Mellis)

Mellis writes:

These portable speakers are made from laser-cut wood, fabric, veneer, and electronics. They are powered by three AAA batteries and compatible with any standard audio jack (e.g. on an iPhone, iPod, or laptop).

The speakers are an experiment in open-source hardware applied to consumer electronics. By making their original design files freely available online, in a way that’s easy for others to modify, I hope to encourage people to make and modify them. In particular, I’d love to see changes or additions that I didn’t think about and to have those changes shared publicly for others to use or continue to modify. The speakers have been designed to be relatively simple and cheap in the hopes of facilitating their production by others …

Use 6mm (1/4″) plywood. For the veneer, 1 9/16″ edging backed with an iron-on adhesive is ideal (like this one from Rockler), but anything should work if you cut it to that width. Pick whatever fabric you like. For the electronic components, see the bill-of-materials above. You’ll also need two-conductor speaker wire, available at Radio Shack… There’s also a wall-mounted, oval-shaped variation on the design. It uses the same circuit board, but combines both speakers into a single unit that can hang on a nail or screw in the wall. You’ll want to replace the batteries with a 5V power supply (included in the bill of materials); just cut off the connector and solder the wires directly into the + and – holes for the battery holder. You’ll also want to omit the power switch and just solder together the holes where it would have gone.

The design's battery holder (Source: D. Mellis)

Mellis gave me permission to write about the projects and post some of the photos from his website.

Click here to check out all the files for this project.

Hollow-State Amps & Frequency Response

“Glass audio” has been growing in popularity among average audio enthusiasts for the past decade. Music-loving consumers worldwide enjoy the look and sound (i.e., the “warmth”) of tube amps, and innovative companies are creating demand by selling systems featuring tubes, iPod/MP3 hookups, and futuristic-looking enclosures. I suspect hybrid modern/retro designs will continue to gain popularity.

Many serious audiophiles enjoy incorporating glass tubes in their custom audio designs to create the sounds and audio system aesthetics to match their tastes. If you’re a DIYer of this sort, you’ll benefit from knowing how amps work and understanding topics such as frequency responses. In the April 2012 issue of audioXpress, columnist Richard Honeycutt details just that in his article titled “The Frequency Response of Hollow-State Amplifiers.”

Below is an excerpt from Honeycutt’s article. Click the link at the bottom of this post to read the entire article.

Early electronic devices were intended mainly for speech amplification and reproduction. By the 1930s, however, musical program material gained importance, and an extended frequency response became a commercial necessity. This emphasis grew until, in the 1950s and 1960s, the Harmon Kardon Citation audio amplifier claimed frequency response from 1 to 100,000 Hz flat within a decibel or better. Although today, other performance metrics have surpassed frequency response in advertising emphasis—in part because wide, flat frequency response is now easier to obtain with modern circuitry—frequency response remains a very important parameter …

Just which factors determine the low- and high-frequency limitations of vacuum tube amplifiers? In order to examine these factors, we need to discuss a bit of electric circuit theory. If a voltage source—AC or DC, it doesn’t matter—is connected to a resistance, the resulting current is given by Ohm’s Law: I = V/R. If the voltage source is of the AC variety, and the resistor is replaced by a capacitor or inductor, the current is given by: I = V/X where X is the reactance of the capacitor or inductor. Reactance limits current flow by means of temporary energy storage: capacitive reactance XC does so via the electric field, and inductive reactance XL stores energy in the magnetic field.

Figure 1 - The values of reactance provided by a 0.1-μF capacitor and a 254-mH inductor, for a frequency range of 10 to 30,000 Hz (Source: R. Honeycutt, AX April 2012)

Figure 1 shows the values of reactance provided by a 0.1 μF capacitor and a 254 mH inductor, for a frequency range of 10 to 30,000 Hz. Notice that capacitive reactance decreases with frequency; whereas, inductive reactance increases as frequency increases.

Click here to read the entire article.

audioXpress is an Elektor group publication.



Weekly Elektor Wrap Up: Preamplifier 2012, Pico C, & a Webshop Hunt

It’s time for our Friday Elektor wrap up. Our Elektor colleagues were hard at work during this first week of April. Here’s quick review.

Elektor Preamplifier 2012: The Sound of Silence

Elektor has a 40-year history of high-end audio (tube and solid state) coverage: projects, books, circuit boards, and even DVDs. The latest project is the Preamplifier 2012, which was designed by renowned audio specialist Douglas Self, with Elektor audio staffer Ton Giesberts doing the board designs and testing on Elektor’s $50,000 audio precision analyzer! It achieves incredibly low noise figures using low impedance design techniques throughout, but still based on an affordable and easy-to-find opamp: the NE5532. The Preamplifier 2012’s most notable characteristics are its ultra low noise MC/MD section (get out your vinyl records) and the remarkably low-value pots in the Baxandall tone control (like 1-kΩ).Douglas Self and Elektor Audio Labs already stunned the audio community with their NE5532 Op-amplifier a while ago with 32 NE5532 op-amps basically paralleled on a board producing 10 W of extremely high-quality sound. Simply put: they know what they’re doing!You can read about the seven-board design in the April 2012 edition. In fact, why not follow the series?

Part 1:

Part 2:

Part 3: currently in editing for June 2012 edition.

NE5532 Opamplifier:

Pico C Webinar Announcement

Elektor announced this week that it will run a new webinar via element14 on the Elektor Pico C meter, which was featured in the April 2011 editions. The Pico C meter can measure small capacitances. In February 2012 the device was upgraded with new firmware.

According to an Elektor news item, UK-based author/designer Jon Drury will run the webinar slated for Thursday, April 19, 2012. He’ll cover a unique way of giving the original instrument a much wider range while also extending its functionality, all with new software and practically no changes to the existing Pico C hardware. Microcontroller fans, including AVR enthusiasts, can also learn how to adapt the software for different calibration capacitors. Elektor staffers are reporting that Jon may also give a sneak preview of his PicoLO oscilloscope and Pico DDS generator.  You can register at element14.

“E” Hunt!

In other news, Elektor is challenging you to find hidden Easter eggs in its webshop. Find eggs, get a discount. Click here to get started.



FPGA-Based VisualSonic Design Project

The VisualSonic Studio project on display at Design West last week was as innovative as it was fun to watch in operation. The design—which included an Altera DE2-115 FPGA development kit and a Terasic 5-megapixel CMOS Sensor (D5M)—used interactive tokens to control computer-generated music.

at Design West 2012 in San Jose, CA (Photo: Circuit Cellar)

I spoke with Allen Houng, Strategic Marketing Manager for Terasic, about the project developed by students from National Taiwan University. He described the overall design, and let me see the Altera kit and Terasic sensor installation.

A view of the kit and sensor (Photo: Circuit Cellar)

Houng also he also showed me the design in action. To operate the sound system, you simply move the tokens to create the sound effects of your choosing. Below is a video of the project in operation (Source: Terasic’s YouTube channel).

Design West Update: Intel’s Computer-Controlled Orchestra

It wasn’t the Blue Man Group making music by shooting small rubber balls at pipes, xylophones, vibraphones, cymbals, and various other sound-making instruments at Design West in San Jose, CA, this week. It was Intel and its collaborator Sisu Devices.

Intel's "Industrial Controller in Concert" at Design West, San Jose

The innovative Industrial Controller in Concert system on display featured seven Atom processors, four operating systems, 36 paint ball hoppers, and 2300 rubber balls, a video camera for motion sensing, a digital synthesizer, a multi-touch display, and more. PVC tubes connect the various instruments.

Intel's "Industrial Controller in Concert" features seven Atom processors 2300

Once running, the $160,000 system played a 2,372-note song and captivated the Design West audience. The nearby photo shows the system on the conference floor.

Click here learn more and watch a video of the computer-controlled orchestra in action.