Updated with reduced RF emissions and support for USB 3.0 - Dec. 2020
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 ensures the USB signal path is as RF isolated as possible.
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 from Roon, HQPlayer or other capable upsampling players. For owners of DX DACs, Dan recommends a final conversion from USB to DX using SRC•DX followed by DC•BLOCK isolation. This provides an even more transparent sound than from direct USB input.
12" (30cm) USB A Male to 3.5mm x 1.35mm DC Power Plug
*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.