OPTO•USB Optical Isolation for USB DACs

OPTO•USB™ is a USB optical isolator that provides RF isolated transmission of high-resolution digital audio from source to a USB DAC. OPTO•USB is better than any inline isolator, exotic USB cable or alternative USB-over-optical solution* that uses an embedded copper wire in the optical fiber. OPTO•USB uses all-dielectric multimode optical fiber for total RF isolation: there is no galvanic connection and no tethered wire antenna to emit or absorb radiated RF. 

OPTO•USB consists of a transmitter/receiver pair with USB signal connection on pigtail leads. A male USB 'A' at the transmitter plugs directly into a USB source. A female USB ‘A’ at the receiver supports cables or adapters for ‘B’ or ‘micro B’ DAC inputs. The transmitter is USB powered; the receiver requires a supplemental 5V input for optical demodulation. Optical fibre is standard OM2+ 50/125 multimode on LC connectors - widely available online. 

Operation with Windows, macOS or Linux is plug-and-play; no driver is required. OPTO•USB supports up to 32-bit PCM@1536kHz or DSD1024 playback. For owners of DX DACs, Dan recommends using OPTO•DX for the lowest RF noise. Alternatively, use OPTO•USB with a final conversion from USB to DX using SRC•DX followed by DC•BLOCK isolation.

*Monoprice Slimrun USB and Corning Optical USB provide 5V power from source to the client device via a thin copper wire inside the cable jacket. These 'active' solutions defeat the optical isolation with a galvanic connection. Even if the 5V power is injected from an external supply, the length of wire acts as an antenna to increase RF noise radiation and absorption.