The ax-Amp: a 60W RMS class A Current Feedback Amplifier

Click this link to order 2 off ax- Amplifier PCB’s https://hifisonix.com/shop/2-off-ax-amplifier-module-pcb/ Part 2 of the ax-Amplifier has just been published in audioXpress, 15th April, covering the power supply, power control, mechanical assembly and wiring, followed by detailed measurements. Here is a short synopsis provided from the AX website:- Click on the link to visit audioXpress […]

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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, […]

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Solid State Feedback Amplifiers: A Short History

“Why, sometimes I’ve believed as many as six impossible things before breakfast.” ― Lewis Carroll, Alice in Wonderland     A Future Without Feedback by Martin Colloms There is no mysticism in amplifier design, just serious science. —Andrey A. Danilov Introduction You will recall from the The Theory of TIM by Matti Otala elsewhere on this site, […]

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Ovation e-Amp: A 180 Watt Class AB VFA Featuring Ultra Low Distortion

The e-Amp is a 180 Watt RMS (very conservatively rated into 8 Ω ) fully balanced symmetrical (‘FBS’) amplifier featuring an emitter follower triple (EFT) bipolar output stage and beta enhanced VAS stage. The amplifier can be configured using jumpers for TMC (Transitional Miller Compensation) or straight Miller compensation (MC). The VAS can be lightly […]

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Audio Power Amplifier Design – Peter J Baxandall

In this 6 part series of articles published from January 1978 in the now defunct Wireless World magazine, Peter Baxandall takes the reader through some of the fundamentals of audio amplifier design as they were understood at the time.   Baxandall_Audio Power Amplifier Design In 1978  there was still much discussion about feedback and how […]

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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 […]

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