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SECA technology - an overview.


Single Ended Class A


EWA amplifiers will provide you with the ultimate experience in musicality and loudspeaker control. State of the art performance is guaranteed by Colin J Wonfor’s peerless experience in power supplies and class A amplification.

Colin Wonfor designed and built the largest ever Single Ended Class A audio amplifiers in the world (link): Class A all the way through from the input to the output terminals. The current generation of EWA amplifiers is based on this wonderful heritage. The Wonfor engineered SECA based circuits found in EWA designs brings exquisite class A amplification into our homes in a very efficient manner.

The driver stage of all EWA amplifiers operate in high speed SECA, Single Ended Class A.

This is part of a sophisticated approach to amplifier design: The grip, power, control and linearity of an elite A class P/P amplifier is in full evidence, but the only device adding gain in the circuit is a SECA driver. Therefore the full character of the amplifier is very much pure SECA.

Although EWA amplifiers appear complex, the actual signal path is deceptively simple, and elegant. Colin is a great believer that a designer should employ the K.I.S.S. mantra.


Designed and calibrated so the music signal sees zero negative feedback, EWA amplifiers utilise negative feedback purely as a DC servo control. The EWA SECA circuit also features such as an innovative dynamic bias system, meaning the amplifier can consume very little power at rest or low output. Depending upon frequency and amplitude, the amplifiers runs harder into class A as required across the frequency range - meaning you have the most advanced, most efficient class A amplification in the world, with an added benefit that this dynamic biasing system eliminates all crossover distortion at the output devices. EWA amps are conservatively rated for more than adequate RMS power (you will be shocked at what even the baby Q-20 can do)!


EWA amplifiers have very wide bandwidth, stunningly fast rise time and massive damping factor, meaning these amplifiers are in complete control of your loudspeaker. There is virtually zero non-linear phase shift within ten times the audio bandwidth, and every EWA amplifier is uniquely devoid of crossover distortion on the output. DC offset is impressively absent, under 10mV in all cases.

EWA pre-amplifiers are Single Ended, and electrically very quiet. The M-50-P contains a high performance MM/MC stage that holds it's own anywhere! They are superbly fast and detailed pre-amps, digging deep into every musical nuance. They are also equipped with excellent, high performance headphone amplifiers as standard.

SECA class amplifier DIY PCB available! Follow the 'Amplify' button below.

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All products are carefully cleaned with medical alcohol before packing and shipment. 

Home of the EWA cable system and SECA technology for amplifiers, by Colin Wonfor.  Contact us:  All text and images copyright 2021. ABCaudio, United Kingdom.