SECA class A

Here are pictures of the recently completed pre-production EWA SECA amplifier:



It's unbranded and unlabelled, and in a slightly smaller chassis than the production amplifier will be, but this is proof of concept of a very sophisticated piece of audio engineering.


It is 18W pure class A into 8 Ohms and a remarkable 34W into 4 Ohms. It's 24.6% efficient which is very good for single ended class A. Remarkable, in fact.


Featuring very nice thermal regulation from it's trick power supply; switched on from cold, the circuit provides extra power and heats up swiftly and it gets to operating temperature in fifteen minutes. The heatsinks rapidly warm, with a noticeable hotspot, which then spreads out to warm the entire chassis including the frontplate. As this happens the power backs off and settles at it's proper power output/draw. In a cold room it'll draw more power, a hot room it'll draw less - always ending up at the same temperature. It's much better than most class A amps in this respect.


The bandwidth of this amplifier is astounding, as is the speed of the bass and astonishing detail. Grip and control are unarguable.


You can actually DIY a variation of this amp, these circuit boards are at ABCaudio.biz for £120. Build cost will likely be around £800 plus chassis, and it will be 15% efficient. Colin likes to tweak as he goes, and has access to much better components. For example, the output devices used on the EWA SECA cost £38 each (four on each board) and are just gorgeous, such high performance, so the genuine EWA built item will always be superior.


The plans for the production amplifier are to have power output of 35W single ended class A into eight Ohms, which actually doubles into 4 Ohms. It will be an extraordinary machine, we want to bring it to market for under £3,500 which will make it (we think) the highest value class A amplifier available anywhere today. Amplifiers at four times the cost will not be able to compete on performance and sound quality.


How does this sound? I will leave that largely up to your imagination. In my view and experience (for what little that's worth) this amplifier is the measure of perfection (when used within it's performance envelope) that all other amplifiers must strive towards. The large EWA class A amplifiers are Push/Pull in their output - they are so much more practical, powerful and efficient and have extraordinary qualities. Comparing this SECA with an M-100 TS is an impossibility, as both do things so well and just miss out to the other in some things. The extra power the M-100 series has is alluring and compulsive, if only for that scale and presence at low levels - yet the utter purity of this SECA design is something where this amplifier stands alone.


Another triumph by Colin Wonfor. Several steps beyond anyone else.


This amplifier is available to pre-order for £3000 GBP. with a lead time of six weeks. Later in 2021 the chassis design may undergo some noticeable changes as seek UK manufacturing partners, which will likely see a price increase to £3,500.