Paul McGowan writes ....
On my recent visit to Japan, I was working with a high-end dealer who had a beautiful set of Dan D’Agastino’s monoblock amplifiers on display. He and I both wanted to pit the BHK monos against these copper-beauties which we did. Helping him disconnect the D’Agastinos from the wall I noticed the amps sported 20 amp IEC inputs that needed a special power cord. Tracing the cable back to the wall socket I had to laugh. An adapter was in use. A 20 amp to 15 amp “cheater plug” because the dealer hadn’t a bonafide 20 amp AC receptacle—not only defeating the purpose of the 20 amp inlet—and limiting power cable selection—but also adding an unwanted layer between the wall socket and amplifier.
The 20 amp connector does indeed permit greater current to flow into the amplifier. With a 15 amp connection, you can theoretically draw about 1800 watts, while a 20 amp connection affords about 2400 watts. Do we need that greater current? How many loudspeakers are using anywhere near the rated wattage available through a 20 amp connector, relative to the 15 amp?
I cannot think of many (actually any) loudspeaker systems that approach even the lower of the two numbers. So, I often wonder why 20 amp connections are used.
There are applications where it makes sense to me. Our newest Power Plant, the upcoming P20, is a good example. Here, we have a situation where multiple large power amplifiers might be plugged into this single P20 regenerator and the increased wattage potential offers greater headroom if nothing else.
How did we solve the practicality issue I reported from my Japan trip? By clever means. Our chief engineer, Bob Stadtherr, designed both a 15 amp and 20 amp IEC receptacle into the new P20. A foolproof door slides over the unused inlet so users can attach whichever power cable they wish.