The 5002 Project: A DIY Mono Amp Block

I built this amplifier to run my Dynaudio X12 speakers. The X12s are not known for efficiency, but these little mono blocks run the accurate X12s with ease. Don’t be fooled by their low power output. The limiting factor is voltage, not their ability to drive a load. This article was published originally in audioXpress, February 2012.

November 2013 was the first issue of the redesigned audioXpress in its current form, featuring several new sections, including the first of its R&D Stories series, focusing on engineering and product development - independently of the audio application field. This article by Stuart Yaniger on QSC’s Flexible Amplifier Summing Technology (FAST) was a reference for many to follow.

Belgium-based brand StormAudio made its worldwide launch at CEDIA 2016 where the company unveiled its line of high-end immersive audio home theater processors and amplifiers. The Home Entertainment and Luxury Audio Division of Auro Technologies wants to push the boundaries of performance in audio electronics, introducing innovations in 3D audio processing and Immersive Sound, offering support for Dolby Atmos, DTS:X and Auro-3D immersive audio formats.

Danish company ICEpower, independent from Bang & Olufsen since May 2016, announced the decision to merge with Audio Bricks, and to acquire its holding company, Bolecano Holding AB, from Sweden. While ICEPower is highly recognized in the market as one of the leading brands in audio amplification, Audio Bricks is a relatively new company, created in 2014 by Patrik Boström and Lars Press Petersen, which have now become partners and shareholders of ICEpower, respectively holding the position of CTO, Amplification, and CTO, Research and SMPS in ICEpower.

In this often mentioned project published in audioXpress, April 2001, the author explores the advantages of composite amplifiers and provides a detailed description on how he built his 50W per channel unit. A composite amplifier (also called nested-feedback amplifiers) consists of two or more operational amplifiers cascaded together with a negative-feedback loop around the entire network. Read the complete article now available online.

In this article from audioXpress archives, originally published in July 2003, Charles Hansen describes four hybrid power amps that anyone might consider for their own designs. Starting from the idea that an op amp provides both a differential input stage and high overall gain in one package, Hansen explores the ramifications of using an op amp as a combined input and voltage amplifier stage in power amplifiers. As he writes, “I did not build the four amplifiers shown in this article, but I did run a SPICE simulation to verify that they did perform as audio amplifiers."

Based in Yorkshire, England, Ivor Drawmer’s company has a long history of audio processing innovation and brilliant audio circuits. In recent years, Drawmer has been working on some brilliant monitor controllers and monitor preamps for studio work. Complementing those new studio systems, Drawmer now introduced its high performance CPA-50 compact Class D amplifier, delivering 25W rms per channel into 8 ohms (50W rms per channel into 4 ohms) or working as a 100W rms into 8 ohms monoblock which allows bi-amped or bridged modes.

In 2008, Nelson Pass submitted an article on its new F5 power amplifier design to audioXpress. At the time, he wrote: “I feel that it’s important to support AudioXpress, a magazine with which I have a 35 year history, and which also serves as a mainstay for the DIY community. Lately they have kindly printed projects that I had already posted on the web, but I decided that they deserve a little better than that.” Effectively, the F5 project was published in May 2008 and had a huge impact on the global DIY community and certainly contributed for the fact that audioXpress is still around today.

Recently shown at InfoComm 2016, the all-new VMA Series mixer/amplifiers by JBL Commercial, have been developed specifically for global markets demanding cost-effective solutions for commercial audio installations. Perfect for applications that require quality equipment at an affordable price, VMA Series mixer/amplifiers feature both 4 ohm/8 ohm and 70V and 100V output with convenient features, including a Bluetooth and USB media player, independent bass and treble controls for each output channel; paging chime; and priority muting.

Responding directly to the needs of the installation market, Lab Gruppen unveiled two new amplifier families during InfoComm 2016. The new LUCIA amplifiers follow the highly successful launch of LUCIA 70 V output models during last year’s InfoComm show now with three new LUCIA 60 W power models, all with configurable DSP features. The company also expanded its D Series advanced install-dedicated amplifier platform with the introduction of three slimline models.