All items in category Project Articles
You Can DIY!: A High-Performance 60-Watt Class A Amplifier - Part 2 Power Supply and Measurements
by Andrew C. Russell

You Can DIY!: A High-Performance 60-Watt Class A Amplifier - Part 2 Power Supply and Measurements

The continuation of this 60-Watt Class A amplifier project, named the ax-Amplifier, this design uses Augmented Feedback Error Correction (AFEC) to achieve ultra-low distortion and improve key audio performance parameters without adding too much complexity and cost. The first part of this article described the amplifier design in detail. This second part details the power supply system and conclusion with measurements. This article was originally published in audioXpress, May 2024.
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You Can DIY!: A High-Performance 60-Watt Class A Amplifier - Part 1 Amplifier Design
by Andrew C. Russell

You Can DIY!: A High-Performance 60-Watt Class A Amplifier - Part 1 Amplifier Design

From the experienced hands of Andrew C. Russell, of Hifisonix fame, comes the ax-Amplifier, a Class A design that uses Augmented Feedback Error Correction (AFEC) to achieve ultra-low distortion and improve key audio performance parameters without adding too much complexity and cost. Published in two parts, the first article addresses the amplifier design in detail, with Part 2 detailing the power supply system and conclusion with measurements. This article was originally published in audioXpress, April 2024.
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From the Vault: The Borbely Preamp
by Erno Borbely

From the Vault: The Borbely Preamp

"Designing a preamp is probably the most challenging engineering task in the audio chain, and many designers have invested a lot of time and effort in it," wrote Erno Borbely in this original 1985 article for the Audio Amateur. "My reason for designing this preamp is quite simple: I wanted to have a top-quality preamp without paying megabucks for a Levinson or Accuphase unit. It is up to you to decide whether or not I have succeeded in achieving the same quality." This article was originally published in The Audio Amateur Issue 4, 1985, and is still frequently referenced.
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Pure Acourate Sound Project: Greater Than the Sum of Its Parts
by Jan Didden

Pure Acourate Sound Project: Greater Than the Sum of Its Parts

audioXpress traveled to Germany to learn about the Pure Acourate Sound Project, which aims to create the lowest distortion sound in a listening room. The initiators of the Pure Acourate Sound project are Ulrich Brüggemann, Markus Grelka, and Ralf Höllmann. The partners involved in this unique system are Purifi Audio, Okto Research, GIK Acoustics, Klippel, Roon, AudioVero, Rose Handwerk, and Joachim Gerhard. Ahead of the presentation at the May 2024 Munich High-End show, audioXpress offers a preview of the project.
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You Can DIY! eDD - A Direct-Drive Amplifier for Electrostatic Speakers
by Jan Didden

You Can DIY! eDD - A Direct-Drive Amplifier for Electrostatic Speakers

This article details a lifetime project from audioXpress' technical editor Jan Didden. After a successful restoration project of a pair of precious ESL-63 Quad electrostatic speakers, he opted to design and build the eDD, a well-performing high voltage amplifier to directly drive electrostatic speakers. This challenging but successful DIY project with a design goal of 1500V RMS at 20mA RMS over the full audio band, took a while to complete but was a success. This article shares every step of the construction.
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Optimizing Variable-Frequency Tone Controls
by Douglas Self

Optimizing Variable-Frequency Tone Controls

This article describes bass and treble tone control circuits where the frequency at which control begins in each band is variable over a 16 to 1 range, making it much more useful for correcting speaker deficiencies or room anomalies. Something that very few manufacturers have offered. This article was originally published in audioXpress, December 2023.
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A FINE Circle Speaker Design Tutorial. Part 3 — The Crossover
by Peter Larsen

A FINE Circle Speaker Design Tutorial. Part 3 — The Crossover

This article is the final part of Peter Larsen's tutorial for the design of a complete loudspeaker from transducer to final product. The first two parts of this Loudsoft simulation software system design tutorial series demonstrated the development of a 6.5" woofer and vented enclosure along with a 1" silk dome tweeter. The final step is an appropriate passive network design, which is where FINE X-over software comes to the rescue.
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A FINE Circle Speaker Design Tutorial. Part 2 — The Tweeter
by Peter Larsen

A FINE Circle Speaker Design Tutorial. Part 2 — The Tweeter

This is the second part of Peter Larsen's tutorial for the design of a complete loudspeaker from transducer to final product. The target design is a two-way speaker with a 6.5" woofer and a 1" dome tweeter. Having previously explained the woofer design, in this second article, Peter Larsen explains the process for a 1" silk dome tweeter.
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A FINE Circle Speaker Design Tutorial. Part 1 — The Design
by Peter Larsen

A FINE Circle Speaker Design Tutorial. Part 1 — The Design

For Voice Coil, Peter Larsen developed a tutorial for the design of a complete loudspeaker from transducer to final product. A great way to gain a practical perspective of the whole family of Loudsoft software tools. The target design will be a two-way speaker with a 6.5" woofer and a 1" dome tweeter, and this issue contains part one of this valuable exercise.
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You Can DIY! Build the Popping P Filter
by Ethan Winer

You Can DIY! Build the Popping P Filter

This original circuit effectively removes the low-frequency impulses caused by air blasts from a person speaking or singing into a microphone, as well as "plosives." This analog circuit removes these irritating sounds in real time, directly at the source by applying a 24-stage all-pass filter to delay only the lower frequencies of the main audio stream. This original circuit for non-commercial use is available for licensing for commercial manufacture. This article was originally published in audioXpress, October 2023.
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