The Conrad-Johnson ET250S Power Amp

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Solid-state power amplifiers
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Conrad Johnson ET250S Power Amp
The Conrad-Johnson ET250S Power Amp

The ET in the product designation of this amplifier stands for Enhanced Triode, while the 250 is the rated output – Watts into 8 Ohms, naturally. But before the bearded triode brethren start getting all excited, the tubes in question are the 6922 twin-triodes used to provide the front-end of the hybrid circuit. That’s right – it uses a solid-state output stage, which is where all that power comes from, while truth be told, you are hard pressed to put your finger on those vacuum tubes’ contribution to the sonic picture as a whole.

The ET250S is a large, stereo amplifier built into c-j’s new “niche” casework, where the tubes peek from between semi-circular Perspex slats sitting in the forward facing alcove. Unlike the trio of pure tube designs that featured in Issue 52, the top-plate is barely perforated while the chassis sides comprise full depth heat sinks. In use the amp runs reasonably warm but not excessively so, making it a much better bet for enclosed installations than its valve brethren. Combine that with the high power output and you might start reaching a few conclusions regarding the ET250S’s target audience – but I couldn’t possibly comment. Facilities are as Spartan as ever, with a single pair of RCA/phono inputs and one pair of five-way binding posts per channel. The mains input is via a standard IEC socket, but watch out for the small dip-switch on the top right of the rear panel, which activates the remote trigger sensor. Knock it up by accident and you’ll be faced with a large and utterly unresponsive lump! In common with other c-j amps, the amplifier inverts absolute phase, meaning that you should reverse the polarity of your speaker leads in most cases, although not if using a c-j pre-amp. And therein lies a story, but I’ll get to that.

There’s no mistaking this amplifier’s power, headroom and transparency. Having spent three days sharing a room with it at the Denver Show, I can also vouch for its easy, relaxed sound quality, devoid of edge or hardness. In these two conflicting descriptions we find the core of a curate’s egg. In some respects the ET250S has all the classic qualities of a large solid-state amplifier. In others it’s more akin to a tube design. Does that make it the best of both worlds? Well, not exactly, and how well it sits with you will depend on your system and what you want from your music.

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