Review: Cutthroat Audio Copper John Power Cable

Yes, the Copper John might be expensive for a power cable, but you might find it money well spent that allows your amp to present its best self.
Publish date:
Cutthroat Audio Copper John

Cutthroat Audio Copper John

Idaho-based manufacturer Cutthroat Audio and its proprietor, Ron Westwood, might be better known in guitar circles for their reproductions of early ’60s brownface F-style combos, such as the Down Brownie

But for several years before segueing into hand-wired amp manufacturing, Cutthroat Audio specialized in high-end instrument, speaker and patch cables, and the Copper John Power Cable ($109 as reviewed, for a nine-foot cable) is the latest addition to that lineup of elite wire. 

Never mind that the moniker sounds like it came from the same place where Donald Fagen and Walter Becker found the band name Steely Dan; the premise is simple: replace your guitar amp’s generic, molded AC cable with a Copper John, and you’ll hear better tone!

Sure, the “power cable improves amplified sound” assertion is one of the audio world’s more snake-oil-infused claims, and Westwood tells GP he initially counted himself among the skeptics. But the aural proof showed him otherwise, and we were curious to test it ourselves. 

The premise is based on the fact that U.S. building codes require homes to be wired with a minimum of 14-AWG electrical cable, but most of us power up our amps - even our high-end, hand-wired, boutique tube amps - with generic 18-AWG cords with molded ends.

No, our guitar signal doesn’t pass through this cable, but the efficiency of the AC supply feeding the amplifier’s power transformer and related stages can, in theory, have an impact on an amp’s performance and, thus, its sound.

Each Copper John is handmade from Sommer SC-Rubberflex Titanex cable with a heavy-duty polychloroprene rubber jacket, into which three 13-AWG rubber-insulated copper conductors are fed. 

This is shielded further with a durable outer skin of red Techflex braided sleeving. Conductor ends are tinned with Cardas Audio four-percent silver solder, and audio-grade Wattgate connectors are attached at either end. The result is a formidable red snake of a cable that looks as serious as the results it intends to deliver.

Like Westwood, I approached this review as something of a power-cable skeptic - which is to say I was willing to believe an extremely cheap cable might impede an amp’s performance a little, but I didn’t expect this kind of overkill could actually yield better results than any average, decent-quality AC cable. I was wrong. 

I A/B tested the Copper John using a Marshall-esque 50-watt Friedman Small Box head and a 5E3 tweed Deluxe-style combo, swapping between it and a generic cable with molded ends. To my ears, the results were not dramatic, but I’ll attest they were significant, heard primarily in a fuller low end and a clearer sound overall.

Enhancements to note articulation and the immediacy of the pick attack were noteworthy, as was what I’d swear was a slight increase in volume from each amp with the Copper John in place. 

Of course, we all get used to what we hear from traditional generic cables and generally dial in our amps to “sound great” just as they are. But after switching between cables several times, I noticed that the amp sounded just a little slurred and woolly with the generic cable. 

Yes, the Copper John might be expensive for “a power cable,” but if your amp’s already in the $2,000-to-$3,000 range, you might find it money well spent that allows your amp to present its best self.


Copper John Power Cable
PRICE $89–$119 direct (depending on length, from 3 to 12 feet)

KUDOS A rugged, high-quality cable that enables optimal sonic clarity
CONCERNS Yeah, it’s pricey