Introducing JDS Labs Synapse – Next Gen USB Isolator

Today, we’re excited to introduce JDS Labs Synapse, a UAC2 compliant galvanic isolator that’s anything but audiophile nonsense. Synapse is based on new isolation technology from TI, enabling a new generation of High-speed (480mbps) capable USB isolators. Synapse eliminates ground loop noise without limiting USB sampling rate. In fact, Synapse tends to improve DAC performance. Synapse features USB C inputs and outputs and a sleek glass top in a compact CNC’ed enclosure. And for those looking to save more, Synapse can be built in a 3D printed enclosure.

Why Now?

A customer last year described hearing ground loop noise from his powered monitors. He was well aware that the ground loop could be eliminated by using optical input instead of USB, but being a knowledgeable audiophile, he was frustrated and asked if we had considered galvanic isolation.

Around the same time, our new 47 kW solar array went live on the roof of our facility, injecting 3-phase power into our building via four large inverters. Our amplifiers measured normally on our ApX555 analyzer, but I was surprised to occasionally see high frequency noise from some audio equipment. The solar noise varied by test PC, even from DACs which did not consume USB power. This noise never would have been noticeable by ear–I’m talking a few spurious tones near 20 kHz and below -120 dBFS. But it was a surprise nevertheless.

We first prototyped discrete isolation at the I2C level (the digital stream between the USB receiver and the DAC chip itself). Few components were capable of handling the master clock signals used in our current DACs, and I suspected that such a quick solution would introduce more uncertainty than it solved. Experiences from 2012 reminded me that isolation is not always perfect–costly UAC1 isolators had led to a number of audio glitches back then.

TI’s fascinating new ISOUSB211 appeared on my radar while in preorder status. All sorts of USB isolators, reclockers, and jitter fixers have appeared on the market over the past decade, ranging from decent UAC1 solutions to ground lifters, to seriously questionable boxes of magic. TI’s evaluation board immediately eliminated noise from our building’s solar array. Great! And better yet, it pushed DAC measurements slightly higher. Alas, the chips remained on backorder for nearly a year. Samples finally landed on my desk in February.

Solving Ground Loop

When you connect a PC via USB to an isolated amp/DAC, feeding a set of externally powered speakers or monitors, you may encounter ground loop noise. Such ground loop may be audible as 60Hz hum, or you may hear annoying capacitor whine from your GPU or PC power supply. Eliminating ground loop is easy if you have an optical port, but we understand this is not always an option.

Every current JDS Labs amplifier and DAC is mains isolated, meaning ground loop cannot originate at your JDS Labs DAC. When other factors in your signal chain introduce ground loop, Synapse kills the noise without compromise.

Problematic USB Ports?

We sent samples of Synapse to several customers throughout the year, each with unusual USB issues. One owner described distortion from a specific USB port; another customer found a specific USB port which would not recognize his DAC. Most companies would say, “Okay, use a different port.” A USB port on my office PC has a bad internal connection, causing thumb drives to drop out several times per minute. Synapse solved each of these misbehaving USB port mysteries.

Hardware Overview

Since JDS Labs DACs do not consume USB power, Synapse is optimized for minimum size. The host side USB port feeds a power transformer rated for 2500 V of isolation at up to 100 mA. In other words, you may connect any USB device rated below 100 mA. No harm is possible if you accidentally connect a USB device which needs more than 100 mA of current.

The transformer output is post filtered by a TPS7A series LDO, which powers the galvanic isolator to provide clean, equalized USB data signals.

Each USB C port is protected from ESD events up to +/- 25 kV. In fact, Synapse flew through compliance testing. Ed, our longtime partner for FCC/CE testing, mentioned, “emissions are so low that I couldn’t see any radiated tones, even with 26 dB of gain on the antenna.”

By the way, we’ve elected to build Synapse as a standalone accessory for a couple reasons. Implementing the same technology into every Atom DAC 2 would noticeably raise the price for every customer, yet we know that a rather low percentage of customers encounter ground loop noise. Producing Synapse as a separate device keeps DACs more affordable for those dedicated to headphone listening. We’ve also learned to avoid long lead time parts as much as possible–these galvanic isolators have an 18 week lead time.

Enclosure and Accessories

Synapse is built in a red, CNC’ed Al 6061 enclosure with a tinted glass top surface. Or, you may opt for a 3D printed enclosure at a discount:

 

For your convenience, Synapse ships with a 10” (25 cm) USB C-to-C cable along with a pair of adapters for converting to or from USB C. This set of accessories covers almost any connection scenario you may encounter.

Synapse is in stock and ships today!