JDS Labs Synapse UAC2 Ground Loop Isolator – Filter The Noise, Purify The Signals
JDS Labs Synapse is a $69 USD Ground Loop Isolator, a type of noise filter one would use for a computer that produces audible background noise with their IEMS, Headphones, DACs and AMPs. Today we will review the Synapse and explore what effects it has on sound and whether it is a good purchase for most music listeners.
Introduction
JDS Labs is a popular brand producing DAC/AMPs, so it is a bit unusual to see them producing the synapse, a type of USB Filter that will remove unwanted noise from the signal of your computer. As an Amazon Influencer, I earn from qualifying purchases, and using the purchase links in my reviews helps me maintain this website and Youtube Channel. Huge thanks to JDS Labs for providing the sample for this review, in exchange for my honest opinion.
PROs – Really good performance with no degradation of the dynamic range or any other issue. Small and easy to implement in a setup, and affordable.
Cons – Can get a bit warm during usage, can introduce quantization in the sound.
Product Link
Official Link – https://jdslabs.com/product/synapse/
Amazon – https://amzn.to/3YDECoL
Build Quality/Aesthetics
Synapse is an UAC2 Compliant Galvanic Isolator, built to eliminate ground loop noise, while persevering the USB Sampling rate. The core of the device is an ISOUSB211, which cancels USB Signal Loss and optimizes the USB Timing diagram, providing a clean, isolated power to your DAC, mixer, interface or sound device. To connect to your device, Synapse uses two Type-C connectors, one for input and one for output, and it comes in two variants, one in a metallic CNC enclosure, and one in a 3D Printed Resin Enclosure, which is 20 USD cheaper.
JDS Labs includes all the needed accessories to use the Synapse in a setup. Synapse transmits equalized, Hi-Speed USB Data at 480 Mbps, enough for basically any audio stream. The highlight of how it works is by implementing Galvanic Isolation, supplying up to 100mA of Power to the USB device, through its low noise, transformer isolated LDO. As most devices connected to a computer will introduce a Ground Loop, and your signal will have this issue, Synapse eliminates this ground loop noise from peripherals like powered monitors, saving your sound. Physically, Synapse has a size of 10mm x 39mm x 59mm, and a weight of 28 grams for the CNC Metallic version.
The active component is the ISOUSB211 Chipset which acts in tandem with the TPS7A 5V LDO Output Regulator. This setup offers 2500 V Transformer Isolation and an ESD protection of 25 kV. If you connect a USB Device that requires more than 100mA, you won’t break that device, but the connection will not work. I have used FiiO KA15 with the Synapse, with no issues, although KA15 reports pulling over 150 mA from the USB port. I am not sure if the device was not supposed to work, if Synapse is bypassed in this situation, or if Ka15 reports just the output amperage, not necessarily what it eats up from the USB connection.
To explore the problem, I have compiled a short explanation from a large number of science forums, and papers on the USB Audio, of why you’d need the Synapse in the first place, and how it interacts with the DAC. To start with, USB audio has 4 connections – a differential data pair D+, D-, 5V Vcc and Ground. None of these connections are galvanically isolated or filtered so a mechanism exists whereby noise can be conducted from the sending device, for example your PC or streamer, into your audio system via the DAC. This noise can then be conducted via grounds into the rest of your system – which is why most of the USB filters and isolators are named Ground Loop isolators.
Whether you will hear it, and have any negative effects as result of this noise depends on the source device and your DAC. Noise from computer power supplies and USB interfaces can be coupled through the USB power and ground lines into your DAC. This noise rides on the audio output of the DAC. For example, I have almost 10 USB ports connected at the same time, including an external HDD, which has its own switching power supply, two keyboards, one mouse, a drawing tablet, three DACs, one external HDD and one microSD card reader. All of those can introduce an interference which will eventually be audible in the soundcard I am actively listening, and the PSU will also do that from time to time, and the GPU can do that too, and with RTX 4090 consuming up to 600W of power during gaming or work, you can see how a system will easily have noise.
Subjective Usage / Sound
The subjective usage is excellent, I can just plug in the Synapse in between the DAC and the computer, and most background noise disappears. Some DACs have an inherently higher noise floor, or random popping noise, when the GPU is processing more heavily, or for example I can hear a mini pop noise when someone turns on or off a light in the house, or when the heater turns on and off, which is on the same line as my computer. The effect Synapse has seems to be a quantization effect, it will quantize the noise, basically apply a random quantization pattern, so a pop noise will not be audible anymore and it is covered by a pattern that you will most likely not hear or notice.
The noise handling method is very different from the likes of iFi Audio USB purifiers, which seemed to kill the dynamic range of the device, and compress the sound as it was reported by both many readers I have and by me in multiple occasions, as the Synapse will not affect the information of the sound, nor change it in any way, except for reducing the noise and the problem. A ground loop noise sounds exactly like this, a click / pop sound or a 50 Hz / 60 Hz hum noise, both of which are audible with certain devices, and if your source has problems.
My computer also has other limitations, because for example, the USB ports at the front are not just not galvanically isolated, but if I connected two things at the same time, they will interfere with each other, for example a microSD reader and a keyboard, the keyboard lags or downright interrupts while I am copying files. Same happens with Audio, where the computer / motherboard cannot support all the USB ports and for cost saving will fuse some of them together, their groundings, resulting in audible noise in your DAC / AMP. JDS Labs actually has a very good explanation of what Ground Loop noise is and how to get rid of it, so I will copy it over adding my own personal notes.
Audible whine from speakers generally indicates high frequency ground loop noise. The noise may change with PC activity, such as moving your mouse or changing GPU loads. I actually have expeirenced this plenty of times myself. Synapse is generally not intended to be used with JDS Labs products in particular, as all current generation JDS Labs amplifiers and DACs are mains isolated and do not consume USB power. This means there is no chance of ground loop noise from an Atom DAC+, EL DAC II+, or Element III as long as you pair with other mains isolated equipment.
Audio equipment powered by a switching power supply is unlikely to be mains isolated. Ground loop noise becomes a possibility when connecting multiple non-isolated devices, such as:
PC Soundcards
PC USB Ports
Most Active Speakers
Breaking Ground Loop – If you happen to hear noise from your speakers, switch to Optical Input and disconnect the USB cable. This instantly eliminates the PC as a grounding pathway to the speakers. Optical performance is excellent in all current JDS Labs DACs. Here is where you can really improve things, and where Synapse will come in handy, as for those soundcards that do draw power from the USB socket, if you hear that whine / noise, you will be able to remove it using the Synapse. JDS Labs Synapse will effectively remove that noise and leave the audio signal intact, uncut and pleasing to the ear, being what I can consider the perfect USB Galvanic Isolator / Ground Loop Isolator, looking nice, working well, and not affecting the sonics of the setup negatively in any way.
Value and Conclusion
The price of a JDS Labs Synapse galvanic isolator is not high, but it offers an essential accessory for any setup where Galvanic isolation is not used by default, and does this for a $69 USD price tag, making the Synapse a great deal for a pricier system where the designers could not or decided to not include galvanic isolation for the USB input.
At the end of the day, I could quote many reliable sources, but USB Audio has 4 connections, and none of them are by default galvanically isolated, and can transmit noise and EMI, so a device like the Synapse has the potential to improve the sound across a vast number of DACs if the source has a noise problem, which it most likely has.
Product Link
Official Link – https://jdslabs.com/product/synapse/
Amazon – https://amzn.to/3YDECoL
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Full Playlist used for this review
We listened to more songs than those named in this playlist, but those are excellent for identifying a sonic signature. I recommend trying most of the songs from this playlist, especially if you’re searching for new music! The playlists are different for Spotify, Tidal and Youtube, and based on the songs I enjoy and are available on each!
https://www.youtube.com/playlist?list=PL_cjBXGmwSHSdGcwuc_bKbBDGHL4QvYBu
https://open.spotify.com/playlist/5J3oloz8Riy9LxEGenOjQ0?si=979ba4f082414be7
https://tidal.com/browse/playlist/330fd544-8e5b-4839-bd35-676b2edbb3d5
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