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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 class A performance is guaranteed by Colin J Wonfor’s peerless experience in power supplies and audio engineering. 

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 SECA derived circuits, available only in EWA amplifiers, is based on this wonderful heritage. The Wonfor engineered SECA circuit 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, pure class A between 3 and 5 Watts. Smaller amplifiers in the range then output class A/B to the loudspeaker. The larger amplifiers output class A Push/Pull. 

The Wonfor SECA circuit features 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 run harder into class A as required across the frequency range - meaning you have the most advanced, most efficient true class A amplification in the world, with an added benefit that the dynamic biasing eliminates all crossover distortion at the output devices.

This can be described as a quasi hybrid approach, as the grip, power, control and efficiency of an A class P/P amplifier is in full evidence, but the full character of the sound is very much pure SECA. All EWA amplifiers feature vanishingly low THD due to Colin's expertise. 

Designed and calibrated with low levels of negative feedback, EWA amplifiers are quite 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. They are superbly fast and detailed, 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 2020. ABCaudio.