The Sutherland Dos Locos is a monoblock transimpedance phonostage for low-output MC cartridges.
"There's no bling. I don't waste your money."
There are very few brands in high-end audio where a photo of the internals can be the hero image. Ron Sutherland creates such beautiful visual haikus with his circuit layouts that we can't help but stare, imagining the current flow as a pristine stream in a Kyoto temple garden.
Pictured above is the Dos Locos phonostage, the result of Ron Sutherland's personal carte blanche to take transimpedance design to its pinnacle. Dos Locos is a monoblock, so you need to buy a pair for a stereo cartridge. (This also means mono cartridge aficionados don't have to pay for a channel they won't use.)
But first, what's transimpedance? It's an underrepresented phonostage design idea that uses the cartridge as a current source rather than a voltage source. In regular designs, the phonostage offers the cartridge a resistive load across which voltage changes caused by the moving stylus are captured and amplified. A transimpedance phonostage presents the cartridge with a near-short circuit, so that the musical signal is derived from the current generated by the cartridge. This brings several benefits but also limitations. Most importantly, a transimpedance phonostage works only with low-output moving coil cartridges with a low internal impedance. No high-output MC, no MM, no moving iron, and no MC with an internal resistance over 20 ohms.
Benefits of Transimpedance
The contradiction with transimpedance is that a "low-output" cartridge might actually deliver a higher current. When a cartridge is described as low- or high-output, it refers to the output voltage. A lower-output-voltage design might, for example, use fewer turns of thicker wire, so its output current could be relatively high.
And because the transimpedance input presents the cartridge with a fixed virtual short, conventional cartridge-loading adjustments are no longer part of the setup. The cartridge's generated current also contributes to electrical damping, which can help control generator ringing and overshoot. The result is a cleaner, more controlled electrical interface between cartridge and phonostage. A well-matched transimpedance design delivers sharply defined transients, low apparent noise, and a strong sense of clarity and immediacy.
"I was floored," said Bob Gaines, a regular Upscale Audio customer, when he moved to a Sutherland transimpedance setup. "Groove noise was drastically reduced, and there was suddenly a presence in the music that I hadn't felt before."
The chassis cleverly hides that the Dos Locos is effectively a two-box design.
Frugal High-End Design
"There's no bling," says Ron Sutherland about his designs. "I don't waste your money."
Notice that while the Dos Locos chassis isn't particularly exotic, it effectively offers two boxes in one, with a wide airspace between the high-current power supply side on the left and the signal side on the right. Ron's beautiful circuit designs mean he can use very few of the very best components, gaining both the low-noise and low-cost benefits of short, simple signal paths. Ron stresses that signal purity drives the spare design and that he's not forcing the circuit to look a certain way.
Calling the Dos Locos "Ron's masterpiece that represents a new level in analog playback," Upscale Audio's analog specialist Bill Rudolph adds, "The Dos Locos has opened my eyes to current-based phono amps. The sound is so open and natural, able to render dynamics and weight to every instrument regardless of how loud they are in the mix."
The Sutherland Dos Locos will be featured in our main system at our August 1 event, Revolution 909. It costs $11,000 for the pair, but Sutherland has other transimpedance options, with the TZ Vibe selling for just $1,600. Don't attempt the transimpedance quest on your own! There are too many factors at play. Call and ask for one of our analog experts before starting on this fascinating and richly rewarding journey.
Browse the Revolution 909 collection.