AX September: Speaker Special

Each year’s “speaker special” issue is a favorite among audioXpress members and clients. It features in-depth articles about speaker technologies and design projects, without completely ignoring other interesting topics (e.g., tube amps).

This year’s special speaker section features informative articles about a detailed loudspeaker design project and an intriguing electrostatic speaker experiment. We also included a third must-read speaker-related article, but it isn’t in the special section because it focuses on enclosures rather than speaker design. Let’s review each article.

On page 23, George Ntanavaras shares his Horizon loudspeaker design. Inspired by Siegfried Linkwitz’s work, Ntanavaras designed an open-baffle active loudspeaker featuring two woofers connected in series used as dipoles, a woofer/midrange used as a dipole, and a dome tweeter used as a monopole. He details everything from the baffle cabinet design to frequency response adjustments.

George Ntanavaras’s Horizon loudspeaker with front grilles (a) and without front grilles (b).

The Horizon loudspeaker’s dimensions

Turn to page 36 to read about Richard Mains’s excellent electrostatic loudspeaker (ESL) project. Although he started experimenting with hybrid electrostatic speakers about two decades ago, Mains hasn’t lost his passion for them. His article covers techniques relating to ESL fabrication, and includes the materials needed to complete your own project.

Richard Mains experimented with electrostatic loudspeakers. This image shows the diaphragm and stator contacts on the back of the cell (a) and on the front of the cell (b).

The third speaker-related article is about enclosures (p. 8). Mike Klasco and Steve Tatarunis cover the practical uses for enclosures, as well as wood alternatives and experimental design techniques.

The rest of the issue’s content is a nice mix of past and present audio technology. We feature an interesting turntable redesign project and the second part of a series on tube sound.

In the article “A Vintage Turntable Revisited,” Ron Tipton explains recent modifications he made to a 2011 turntable restoration project (p. 12). He describes lengthening the tone arm and why he used carbon fiber tubing.

Ron Tipton completed a second Netronics 350D rebuild. The only remaining original parts are the direct-drive DC motor, the platter, the aluminum nameplate with switches, and the 33-1/3 and 45 RPM speed control.

If you’re into tube sound, flip to page 18 for Richard Honeycutt’s insight on distortion. He covers topics such as distortion signatures and testing.

 

Audio Crossword Answers (September 2012)

The answers to the crossword puzzle published in audioXpress September 2012 are below. The issue is now available

Across

2.     BOOMY—A type of vibration that occurs if the speaker is not well damped by either the amps output circuit or the particular installation

5.     CONECRY—Notes or tones that are higher or lower in frequency than the intended note [two words]

6.     PI—The name Robert Nance Dee gave the pre-amplifier interface design in his audioXpress article (August 2012)

10.   AGGRESSIVE—Usually indicative of a lightweight, low-mass cone structure and a large magnet

11.   SCANSPEAK—In recent months, columnist Vance Dickason has put a number of high-end audio drivers from this Danish company to the test [two words]

14.   CASPER—This audioXpress contributor shared an easy-to-build amplifier for computer speakers in the November 2011 issue

16.   PRESENCENOTCH—The major fundamental resonance of a loudspeaker, which is mainly determined by the spider and the mass of the cone [two words]

17.   BREAKUP—Comb filtering and other anomalies that create the texture of the overall sound

18.   NEODYMIUM—A material used for the rare-earth magnets

19.   RAREFACTION—That phase of a sound wave during which the air pressure is below the normal atmospheric pressure

20.   PASS—In the January 2012 issue of audioXpress, this contributor described his modification to the JBL L300 loudspeakers

Down

1.     HONKING—A peaked 800 to 1200 Hz midrange that is up several decibels from the low end

3.     OUTPUTTRANSISTORS—In his October 2011 audioXpress article, “Upgrading the Phase Linear 200 Amplifier,” Patrick Brunner recommended changing these for higher gain [two words]

4.     ELECTROSTATIC—The “unique beam-splitter bass cabinet” was the twist in Charlie Mimbs’ construction of this type of hybrid-style loudspeakers (audioXpress, April 2012).

7.     VOICECOILRUB—Usually occurs after too much power is applied to a speaker for too long [three words]

8.     BELLMODES—The many minor resonances and new frequencies that result in response to the input signal when the speaker cone vibrates [two words]

9.     LIS—Our annual directory, which provides information on industry trends, speaker parts, and resources as well as components, software, and test equipment

12.   SURROUND—The area out at the periphery of the cone that usually has one to three corrugations

13.   THEPANHEADS—In the March 2012 issue of audioXpress, David Pellegrene shared this innovative speaker design that resembles a Harley-Davidson engine [two words]

15.   GAPENERGY—Measured by the Gaussmeter [two words]