Getting a grip on your AC connections
By Roy Gregory
Electrical connection is a big deal when it comes to high-performance audio. Collectively we expend considerable angst and even more money on connectors for signal cables and speaker leads, digital interconnects and bi-wire jumpers. But if there’s one lesson to be learnt from the constant procession of products that passes through a reviewer’s listening room, it’s that connector tolerances suck. “Variable” doesn’t even begin to cover it. From under (or over) sized RCAs to XLR connectors that won’t release, sloppy banana sockets to 75Ω BNCs that aren’t, the challenges when it comes to signal cables are legion. Yet they’re nothing compared to the worst offender…
We also spend money on power cables – in some cases a considerable amount. Yet the vast majority of those power leads are terminated with a standard C13 IEC connector. The connector body might be fancy, but the nose is more than likely an off-the-shelf item. The socket into which it’s inserted is almost certainly off-the-shelf, chassis mounted and more often than not, cheap as chips – ‘cos all it’s got to do is accept a kettle lead. The dismissive nickname says it all. That socket will definitely accept an IEC power cord; it just won’t necessarily welcome it with the close embrace that makes us audiophiles feel all warm and comfy!
This is one connection in the audio chain that too often slips below the radar, not least because doing anything about it involves safety standards, certification and potential liability.
At this point you might well be thinking “So what?” Given the ubiquitous nature of the IEC AC connection, surely it’s fit for purpose. Well, it’s definitely fit for boiling your kettle, but for the demands of a high-end audio system, maybe not so much. No matter how much energy a cable manufacturer expends on the termination of their power cords, how carefully they select their IEC plugs or how carefully those plug noses are manufactured, they have no control over the other half of the connection – the socket their cable gets plugged into.
Not all equipment manufacturers ignore the issue. Increasingly we see products, especially power amps, equipped with the high-current C20 IEC socket, designed to accept the larger, squared-off C19 plug. The higher current capability is welcome (and also suggestive) but the real benefit of the C19/C20 interface is its superior security. It just provides a way better fit. There are other alternatives too, like the superb Neutrik PowerCon connector, with its twist and lock action. But it suffers from being both more expensive and non-standard. Making your customer replace or re-terminate his/her potentially expensive power cords is perceived as a significant barrier to sale, meaning that the otherwise excellent PowerCon has struggled for acceptance.
Which leaves the vast majority of high-end audio products hooked up via C13 connectors. As end-users, that leaves our system’s performance prey to loose, wobbly or sagging plugs, compromised, unstable or inconsistent connections. As reviewers, who spend too much of our time with our heads shoved unceremoniously down the back of equipment racks, foraging through the tangle of cables we vainly refer to as “dressed”, it leaves us prey to inadvertently loosening or disconnecting power cords – with results that can vary from the irritating to the catastrophic. Disconnectiuon is one thing, but a loose connection is far more insidious. That lack of physical and electrical integrity can lead to increase AC source impedance, lower levels of contact and thus increased risk of surface contamination, higher levels of AC associated noise and even, in the worst cases, arcing within the AC connection! Throw in the physical challenge presented by the sheer weight of many heavy-duty, audiophile power cords and it makes matters considerably worse.
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