You Can DIY! Passive Preamp: Transformer Implemented

In this article, Jack Elliano the founder and principal designer behind Electra-Print Audio, details a simple but very interesting concept of a line amplifier using step-up transformers plus a variable gain control, offering usable results from low impedance sources. The preamplifier project uses Electra-Print handcrafted transformers, which the company manufactures for its own high-fidelity tube audio components, directly from its home base in Las Vegas, NV. This article was originally published in audioXpress, January 2005.

Gary Galo reviews the Benchmark HPA4, a reference headphone/line amplifier designed to deliver amplification of analog sources for audio enthusiasts, mixing and mastering engineers. Resulting from Benchmark’s collaboration with THX, the HPA4 features a THX-888 headphone amplifier for an output signal with high voltage, current, and and power complemented by low distortion, noise, and crosstalk. This article was published in audioXpress, November 2019.

Benchmark Media Systems, introduced their new HPA4 headphone and line amplifier at CanJam Global SoCal, (LA, April 7-8) and will be showing it again at Axpona (Chicago, April 13-15.) where Benchmark will be conducting personal listening demonstrations. For this new development, Benchmark partnered with THX in order to incorporate the THX Achromatic Audio Amplifier (AAA) technology, which Benchmark had already explored for its flagship AHB2 power amplifier.

This design by Joseph Norwood Still is a control unit that the author described as offering “lifelike concert-hall performance for a modest cost”. A great tube-based amplifier for phono and line sources, featuring a very subtle bass enhancement control using negative feedback to enhance only selected frequencies, below 400Hz. As the author described, a great project for discriminating audiophiles.