EWA M-100 Turbo/Turbo S Power Amplifier

EWA M-100 Turbo/Turbo S Power Amplifier

Power is everything with control.

Big Boys (and Girls') Toys: The M-100 is all the power amplifier a sensible person would ever need, and then some. It has actually made a Krell KSA-150 cry...

But you're not here because you're sensible, are you?


Fully dual mono, dual differential bridged power amplifier. This is two completely independent mono amplifiers with their own discrete power supplies inside one stereo chassis.

The Turbo version is an upgraded version of the celebrated M-100, though capable of producing significantly more power  with its sophisticated and massively engineered power supply. It will dominate completely any loudspeaker you care to suggest.  Integrated DC blocking and mains control is standard, as are XLR balanced inputs.


Thirty Watts RMS of realistic class A operation means that you will hear just class A much of the time, but the transition to A/B transients is seamless and utterly undetectable. Smooth, clean controlled sound with perfect timbre and imaging (thanks to zero phase distortion) at almost limitless volume

These amplifiers produce some heat due to class A operation, but are actually incredibly efficient due to their sophisticated power supply, thermal management and dynamic biasing system. They barely get warm compared to valve designs or less resolved push-pull designs. At the tip of the heatsink fins they are barely ten degrees above ambient.

Turbo 'S' - or 'Sense'.

Sense is a unique innovation by Colin Wonfor, based on several methods of feed-forward error correction he used in applications that we really are not allowed to discuss publicly. ;) The following is an oversimplification:

In the case of the EWA M-100 Turbo S, 'Sense' is a feed-forward error correction system that compares the audio signal all the way from the loudspeaker terminals to the input of the amplifier, and dynamically corrects for any differences, losses, or phase shift detected. This includes back-effects from the loudspeaker.


(This means an additional set of wires needs to connect to the loudspeaker terminals and run back to a designated terminal on the amplifier. This is not bi-wiring, nor does it create a short circuit. Any signal wire can be used. No audio signal uses these additional wires.)

What is 'Sense' correcting? Starting with any losses on the loudspeaker cable itself , back EMF from the loudspeaker and various secondary effects of the crossover network all manifest themselves electrically in the loudspeaker - which the amplifier can now invert and cancel.

By comparing the the signal at the loudspeaker terminals with the input terminals at the amplifier, every difference (that isn't voltage or current) is corrected, in effect using the dual differential amplifier circuit itself to 'EQ' the signal in the analogue domain.

So what is the difference? You might expect it to be pretty minor, right?

Wrong. Sense really brings a new level of control and presence to the sound you hear. It can even be seen, on bass heavy material the output is clear, loud, extended - yet the loudspeaker bass drivers appear to move and oscillate less. You'll have to hear the difference, or more accurately feel the difference - in scale. I'm afraid there's not much to compare it to.

EWA M-100 Turbo 'Sense': Power is everything with control.

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