CFA vs. VFA: A Short Primer For the Uninitiated
This article was written in 2014 in response to what can only be described as a vitriolic debate as to what constituted a CFA on diyAudio.com. At the time, many of the participants were struggling to grasp the fundamental differences between VFA’s and CFA’s, and even how to tell them apart. So, this document is […]
CFA Diamond Buffer IPS: Does it Operate in Class B or class A?
There is a persistent assertion by small group of amplifier design practitioners that the diamond buffer input stage of CFA audio amplifier operates in class B (or AB) mode wherein there is a hard ‘handover’ between each half of the diamond buffer input stage as the input signal passes through 0V. The most recent claim […]
Augmented Feedback Error Correction (AFEC)
AFEC is a simple technique that augments the feedback of an amplifier to dramatically improve the Large Signal Non-linearity (LSN) distortion performance by up to 20 dB across the audio band. Additionally, AFEC acts to remove any DC offsets and also improve PSRR significantly. Augmenting the feedback in a manner similar to that described in […]
The Alexander Amplifier
Mark Alexander’s eponymous creation was an early example of a high performance CFA amplifier and used an ADI integrated opamp and IGBT output devices in a novel circuit configuration that, at the time, yielded vanishingly low distortion and blistering speed. The ‘Alexander’ amplifier has been recycled by practitioners numerous times since its initial publication with […]
Hifisonix kx-amplifier now replaced with the new kx2-Amplifier
If you have purchased PCB’s and are still constructing your kx-Amplifier, I will continue to fully support your efforts as required, so do not worry. 114 PCB sets of the kx-Amplifier were sold, with as far as can be ascertained, a large proportion of them being built. Unfortunately 6 of the builders reported oscillation problems […]