MEASUREMENTS: Topping HS02 USB 2.0 isolator. (This works with the E1DA Cosmos ADC; and the Topping + Intona "double isolation" of DAC and ADC.)

Hey guys and gals, I must be a sucker for relatively inexpensive USB galvanic isolators. To be honest, this is mostly because I look for ways to lower noise on my measurement testbench, not that I'm concerned with the actual audiophile sound system these days! ;-)

Today, let's have a look at the recently released Topping HS02 USB2.0 isolator (currently ~US$100). This is an update to the previously reviewed HS01 last year. As you can see from the picture and specs, the box now has selectable USB-A/B connectors or USB-C. Isolation is not just applied to the in/out USB data connectors, but also the auxiliary power input with filtering which means the device could stay free of noise even if we plug in a power source with some noise in it. As usual, be mindful of power-hungry USB-powered devices which will require auxiliary power input.

Furthermore, Topping has improved compatibility now with the ability to negotiate USB2.0 low (1.5Mbps)/full (12Mbps)/high speeds (480Mbps). I can confirm that my low speed wireless keyboard dongle works fine.

The diagram showing the path of the data and power connections is relatively clear printed on top. Inside the box are a couple of pamphlets - the black one is the warranty card and Topping catalogue, and the white user manual. There's a short USB-A to USB-B cable in the plastic bag.

MEASUREMENTS: Intona 7055-C USB 3.0 SuperSpeed Isolator. And Darko & Lavorgna hear no difference with the Silent Angel ethernet switch. [Importance of open discussions.]

Over the last couple years, I've shown in my PC measurement system the benefit of using USB isolation to break ground loops when test devices are connected to the ADC. There was the ADuM4160 device which was limited to "Full Speed" (12Mbps). Then I posted on the Topping HS01 which operates at a fixed USB 2.0 "High Speed" (480Mbps).

Over the Christmas holidays, I got a hold of the Intona 7055-C USB Isolator which can run at USB 3.0 "SuperSpeed" (5Gbps), basically a pass-through device which provides galvanic isolation of the USB signal and ground lines, with the flexibility of being downward-compatible with 480Mbps (most important for USB audio), 12Mbps, and even Low Speed 1.5Mbps devices.

Although audiophiles have been talking about isolators like this for years used in home set-ups, they're really meant for industrial applications where devices with USB ports might be subjected to high-voltage surges and spikes. This "C" model is designed for protection up to a modest 1kV over 60 seconds. The more expensive 7055-D can handle up to 5kVrms over 60 seconds.

MEASUREMENTS: Topping HS01 - USB 2.0 Isolator & Ground Loop Eliminator (and a listen to Santana's "Blessings and Miracles")

Hey everyone, as you might be aware, I'm not a fan of USB "doohickeys" in general use. You know, all those USB boxes that are supposed to clean up your signal, or maybe reduce jitter, or "regenerate" this and that. Especially if you're not sure if you actually need it; some of these devices cost hundreds of dollars. On the lower price end, I had a look at the AudioQuest JitterBug FMJ last year which was a rather disappointing product.

Having said this, there are devices that can provide benefits like USB isolation for things like DACs. For example, the USB1 inexpensive ADuM4160 devices like this Nobsound ADuM4160. The problem is that this is only operating up to USB1 12Mbps "full speed". Furthermore, one would be limited to 24/96 performance even if the device is able to fall back and negotiate as USB Audio Class 1.

Enter the Topping HS01 (~US$70), a little black metal USB2.0 box advertised as providing galvanic isolation (to 1kVrms), for data and power lines with USB-B (to computer), and USB-A (to audio device) ends. Furthermore, there's a USB-C plug for devices that need extra power.

[Note: This device is not compatible with USB1.0/1.1. So don't be plugging in keyboards and mice to this. Non-audio devices like USB2 memory sticks and even my smart phone were fine. I have not tried plugging a USB2 hub up to this point so there might be issues there.]

MEASUREMENTS: USB Isolation with Nobsound ADuM4160 device and hi-res DAC. The world these days, and the audiophile microcosm.

 

After writing about very high resolution measurements with the E1DA Cosmos ADC last week and touching on basically "state of the art" fidelity like the Topping D90SE, for this week's post, I thought it would be good to talk about something more "fundamental". Often spoken of among audiophile tweakers but rarely have I seen evidence of actual value/effect for many of these devices.

Before I begin with this post or even show you anything, let me just say that I do not believe audiophiles need USB isolation for use with devices like DACs unless you know you have noise issues. I think we've all see indiscriminate suggestions that audiophiles need all kinds of noise filters and isolators (like this, or this). Sometimes these things cost quite a significant chunk of change compared to the downstream device (like DAC) itself!

Over the years, I have tried out a number of USB DACs with computers and simple streamer devices like the Raspberry Pi. With a normal set-up, I cannot say I have ever heard an issue with any of the various decent DACs I've tried. Likewise, measurements already suggest that in general there are no major noise issues with at least reasonable modern devices.

However, there are times when the system is complex enough where indeed you do see ground loops and noise like the 8kHz USB PHY noise pop through. A couple months back, I showed you some of this when we took the rather useless AudioQuest JitterBug FMJ for a spin in some of these situations! Today, let's look at the effect of that little inexpensive Nobsound ADuM4160 USB Isolator (typically can be purchased for <US$25) you see in the picture above.

MEASUREMENTS: Corning USB 3 Optical Cable, Ground Loops, and Noise.

Folks, remember, the "Linear Phase vs. Minimum Phase Digital Filter Test" is still running as I post this! Please give it a try and report back in the survey. I want data and hopefully an opportunity to report back on what the readership perceives (or not perceive).

I. Introduction

Indeed, "noise" can be an issue with audio systems. There's little worse that can happen to an audiophile after spending hundreds or even thousands of dollars on new equipment, plugging everything in as per "best practice", getting ready to play your first piece of music, and finding that for some reason, noise has seeped through to disturb the expectation of pristine, clean background silence from which music can blossom...

Before proceeding further, remember that noise can sometimes be subtle, and very importantly, ambient noise must be low in your sound room. It's quite possible that slight hum and low-level noise may not be significant from a normal listening distance if the ambient noise level is high (something we urban dwellers especially do have to consider!).