Your basket is currently empty!
Articles
Welcome to our articles page, where you’ll find a wealth of information on everything audio-related. Our articles cover various topics that will appeal to audiophiles of all levels.
-
Hifisonix Accurate Inverse RIAA Network
The diagram above summarizes the interaction of the cutting head response (purple) and the playback EQ (red) which produces the final flat response (green). Note that the cutting head and the phono pickup (cartridge) are velocity transducers and therefore the cartridge output rises at 20 dB/decade if the record groove is cut at constant amplitude.…
-
Using the QuantAsylum QA401 for accurate Audio Measurements
The QA 401 from QuantAsylum (superseded by the QA403) has emerged as a popular, comprehensive audio test instrument in the DIY audio fraternity and the go to instrument in many cases for commercial production testing. It combines a first rate DAC and ADC with a simple user friendly PC interface to realize a fully integrated…
-
Building Quiet Audio Power Amplifiers Requires Best Wiring and Layout Practices
There is a misconception that noise pickup is reduced by placing the input RCA connectors (and similarly XLR input connectors in a fully balanced system) on opposite sides of the amplifier rear panel and then running short wires to the amplifier modules. This arrangement is the worst of all worlds. The internal loop areas available…
-
So Just How Quiet is Your Phono Stage?
You may be in for a surprise: actually not that quiet! The reason of course is that the cartridge inductance and resistance dominate the noise in any decent phono amp. To get the best in terms of noise performance, you really need to keep the input referred noise voltage and noise current to a minimum.…
-
Fast Recovery Transimpedance aka Voltage Amplifier Stages for Audio Power Amplifiers
Here is a quick look at some of the problems that can occur when the VAS (aka TIS) in an audio amplifier is driven into saturation without considering the effects of base charge storage – a phenomenon all bipolar transistors suffer from.
-
RIAA Equalizer Amplifier Design
This article explores the fundamental’s of phono amplifier design, culminating in a few practical designs. Special emphasis is placed on overload margins (critical if you want good sonics from your EQ amp), driving the EQ network adequately and noise. RIAA Equalization Amplifiers V2.0 Below is the RIAA Calculator Excel spread sheet. Please read the article above,…
-
Ground Loops
Updated with new material 7th January 2019 This set of c. 70 slides is the culmination of my experience over a period of about 25 years building power amplifiers and preamplifiers. I first started out in audio around 1975 or 76 as a teenager. Some of my creations were reasonably quiet – through pure luck…
-
MC Head Amp Circuit Compendium
Here is the new updated moving coil head amp designs compendium – updated 31 July 2019. The first file is a PDF compendium of about 28 different circuits with noise, distortion and current consumption details. All the LTspice sim files are zipped in the second file. What is immediately apparent from this is that having…
-
Hifisonix Ripple Eater PSU for the sx and kx-Amplifiers
The PCB’s are through hole plated and silk screened and are available from Jim’s Audio here: Ripple Eater PSU for kx and sx Amplifiers (please note these PCB’s are not available from the Hifisonix Shop) Here is an Excel file with the BOM:  Ripple Eater PSU BOM The BOM is provided for assistance – always…
-
How to wire-up a Dual Mono Bloc Amplifier
A few people have asked about wiring up a dual mono amp aka dual mono bloc. In a dual mono bloc there are separate power supplies and lots of opportunity for cross channel ground loops and ordinary ‘classic’ ground loops as well. This wiring scheme addresses the situation were unbalanced connections between the source equipment…