Elektor Special Project Röhren 10 (May 2014)

Overview

This issue of Elektor Special Project Röhren (Tubes) marks the tenth edition, celebrating a decade of publications focused on vacuum tube technology. It serves as a valuable resource for DIY enthusiasts, educational institutions, and workshops, offering a wealth of construction guides and fundamental articles.

Key Articles and Projects

• The Tube Special Project Series Reaches Round Number 10

  Commemorating the tenth issue since its inception in December 2005, this section highlights the series' growth into a comprehensive archive for tube electronics enthusiasts.

• News from Tube Manufacturers

  This article provides an update on the latest developments, news, and product remakes from leading tube manufacturers, covering trends from 2013 and early 2014.

• Fundamentals: Cathode Feedback with Output Tubes via an Output Transformer Winding

  An exploration of the cathode feedback principle for output tubes, a technique that, though sometimes overlooked, offers significant advantages. This contribution examines the principle and its specific characteristics.

• Fundamentals: The Interstage Transformer

  Examining circuit concepts that utilize interstage transformers for coupling tube stages, a practice often associated with a distinctive sound. The article investigates the historical and physical aspects of this technique.

• Construction Guide: Single-Ended Class-A Output Stage with 4 x 6V6

  6V6 quattroSE - Serious Single-Ended with 16 W - Not Just for High-Efficiency Loudspeakers

  Description: This project presents an affordable single-ended amplifier delivering approximately 15-20 W with excellent sound quality and low operating costs. Its design minimizes wiring and maximizes construction reliability by eliminating the need for complex adjustments and utilizing a PCB layout.

  [Image Description: Photograph of a guitar amplifier showcasing its vacuum tubes.]

• Construction Guide: CD Preamplifier with CD Filter

  Discussion on the challenges of digital audio from CDs, particularly sampling frequencies and digital-to-analog conversion. This article introduces a preamplifier with a filter designed to overcome these issues, aiming to achieve sound quality comparable to analog records.

  [Image Description: Illustration of a CD filter's function, showing a digital signal being processed to produce a smoother analog waveform, resembling an analog record's sound.]

• Technical Article: Modern Hybrid Amplifier

  Definition of a hybrid amplifier as a circuit principle that combines transistor-based driver stages with tube-based output stages, or vice versa.

  [Image Description: Photograph of a modern hybrid amplifier module, combining transistors and tubes.]

• Technical Article: Electronic Hall Spiral - The Cathedral in the Matchbox

  Addressing the common issue of flat sound in electric guitars without reverb. This section discusses the traditional 'hall spiral' electromechanical reverb units and the advantages of modern semiconductor-based solutions for interference-free reverb, enabling easy retrofitting.

  [Image Description: Photograph of a guitar amplifier, likely demonstrating the use of vacuum tubes.]

• Construction Guide: UHF Mixer

  with the Double Triode ECC 2000 and the Triode/Pentode ECF 80

  Details the design of a mixer featuring a cascode input stage and a pentode mixer with a separate oscillator, emphasizing ease of construction and adjustment. It suggests using designs from Elektor Tube Special Issue 4 (September 2008) for subsequent FM intermediate frequency amplifiers and stereo decoders.

• Technical Article: Looking Inside the Tube

  An examination of the internal structure of electron tubes using X-ray computed tomography, allowing for detailed observation without damaging the tube.

• Technical Article: 6L6GC

  with best Regards from the United States of America

  An in-depth look at the 6L6GC vacuum tube, widely used in guitar amplifiers and audio equipment. The article covers its various versions, technical specifications, performance measurements, and user experiences.

  [Image Description: Photograph of a vacuum tube socket, a crucial component for connecting tubes.]

• Technical Article: Tube Socket

  Focuses on the components used to connect vacuum tubes in electronic circuits.

Information & Resources

• Foreword (Page 3)
• The Tube Special Project Series Reaches Round Number 10 (Page 6)
• Obituary: Jan Jurco, Founder of JJ Electronic (Page 41)
• Book Review (Page 85)
• Tube Data (Page 88)
• Advertisers Index (Page 90)
• Imprint (Page 90)

Downloads

Additional resources, including PCB layouts for the projects and a photo series for the UHF mixer construction, are available for download at: www.elektor.de/roehren-10.