One-ohm loads, grounding and switching supplies: Peter Foster on the Halcro Eclipse

Begin with the system around the cable

Asked for practical grounding advice in an RF-noisy environment, Peter Foster begins with grounded, shielded cables. He immediately limits the advice: noise depends on the particular system, so there is no single prescription that solves every installation.

That qualification matters because grounding problems can involve signal references, protective earth, cable shields, component topology and RF ingress. Shielded cables are a sensible starting point; protective earth and internal safety measures should remain untouched.

The one-ohm claim

Foster says the Eclipse is unusually insensitive to loudspeaker load. His example is a pair of Apogee Duettas whose impedance, he says, falls to around one ohm or slightly below. He reports driving them with a prototype Halcro amplifier and a separate linear supply without difficulty.

Distortion and the shape of a soundstage

Foster connects low intermodulation and crossover distortion with the absence of extra sum-and-difference products and with more stable spatial placement. He describes the subjective result as initially unfamiliar because artifacts a listener expects to hear are no longer present.

Why Halcro chose a switching supply

Foster’s case for the switching supply begins with power-factor correction. He says drawing mains current more nearly in phase with voltage allows greater continuous delivery than a conventional peak-rectified supply under demanding conditions. He also acknowledges the cost: switching creates physical and RF noise that must be managed.

Inside the Eclipse, a dedicated supply chamber, extensive filtering and damped cabling address that problem together. Halcro treats the switching supply and its noise control as one piece of the amplifier’s architecture.

Incremental work—and one open door

Foster expects much of Halcro’s near-term work to be implementation-led: extending the range, carrying technology to lower price points and exploring phono and digital products. He also mentions more radical topology ideas associated with Bruce Candy, while making clear that such a design would begin again from the ground up.

Taken together, the conversation shows where Halcro’s attention was directed: difficult loads, grounding, low distortion and supply architecture. The future products were still taking shape around those same engineering concerns.