JDS Synapse & Neutron V1 USB Isolators Review

[CedarX]

I think you've gone too deep with your nitpicking with these statements, and I hope I managed to clear the confusion

I am certainly nitpicking !!!

But I also read too much on say... Head-Fi: there is a very fine line between "Class 2"--this product is aimed at solving a problem, actually experienced by the user--and "Class 1"--this product improves some stuff or everything, but is an absolute must for audiophiles... Put it an another way, these products can easily become money-grabber, targeting the less tech-savy user.

 

[dmitrykos]

Put it an another way, these products can easily become money-grabber, targeting the less tech-savy user.

Aggressive marketing is everywhere because of aggressive competition, you can't sell if you can't show off, it is true for practically all consumer products, not just electronics. But for our given case, we have ASR forum and independent testing which demonstrates the real-life performance of the device. It is invaluable opportunity to look at the device without marketing fuss.

 

[Oldson]

following this review i have ordered a V1.
thanks Amirm

 

[JasonC331]

Aggressive marketing is everywhere because of aggressive competition, you can't sell if you can't show off, it is true for practically all consumer products, not just electronics. But for our given case, we have ASR forum and independent testing which demonstrates the real-life performance of the device. It is invaluable opportunity to look at the device without marketing fuss.

So do you feel this will be a better product than the Topping HS02?

 

[lini]

You could ask ifi/SilentPower, whether their HDMI Silencer is also supposed to work for audio data transfers. (...)

Oops, just noticed, that I forgot the "i" - i.e., the actual name of the thingy is HDMI iSilencer. Product page see there: https://www.silentpower.tech/products/hdmi-isilencer

Greetings from Munich!

Manfred / lini

 

[carsknivesbeer]

I have posted before about the Topping HS01. In the case of Mac mini > JDS Labs Atom + > Yamaha A-s501 there is a very audible reduction of the noise floor coming through the speakers. I can turn the volume up to 85-90% on the receiver without hearing any white noise/static. Without it, it is audible at 15-20% volume. This was true while using a Topping E30 II as well.

Since there is no longer an optical out on the Mac, this is a real working solution to a problem that exists for the use case and not "snake oil". I would trust JDS not to make some bullshit claims and their openness in posting their own measurements (closely resembling ASR measurements) and their interactions in this forum continue to point to this conclusion.

 

[michaelahess]

This is a review and detailed measurements of the JDS Labs Synapse and Neutron Hifi V1 USB isolators. They were both sends to me by the respected companies. Synapse costs US $69, and Neutron US $118.
View attachment 412507
As you see, the styles are very different. Synapse comes in a playful red color. Neutron in a more serious case, resembling a USB power supply.

Some background: USB bus carries data, power and ground. Data is used by all downstream devices naturally (e.g. DACs). Power may or may not be used. The ground however, is always used as the reference for both data and power. Being normally connected to an active and high power computing device, USB ground and power can both be quite polluted. As can the data lines. If you are using balanced output in your downstream device (again, such as DAC), there is little import to this. However, if you are using unbalanced RCA connection, the noise on the USB ground can travel through the DAC and manifest itself as noise and ground loop. How much this happens, and how audible it is, is complex and not predictable. Suffice it to say, once it becomes audible, you are kind of stuck, having to possibly change your computing device, DAC or other games to try to hopefully eliminate such noise. It can be quite frustrating.

A USB isolator such as the ones being reviewed here, have two USB connections: an input and and output. They are electrically isolated from each other so have the potential to solve the noise problem above. Some expensive DACs have an isolator inside but I would say 99% do not.

Both of these isolators also regenerate the USB power. In the case of Synapse, you are only provided 100 milliamps whereas Neutron V1 passes through 400 milliamps. Further, it accepts power over micro-USB which can augment what it can produce. To the extent you have USB powered devices, the Neutron may work better depending on power consumption of the device.

Testing such devices is difficult. I could create an artificial ground loop but that would not be representative of real life situations. Fortunately, I just reviewed the JDS Element IV DAC and HP Amp which due to inclusion of its own AC power adapter, objectively shows the noise transmitted over USB. So I am going to use that for analysis of how well these isolators work.

USB Isolator Measurements
Let's first look at the dashboard of Element IV with direct USB connection:
View attachment 412508
I can always tell leakage of computer noise in the dense spectrum it creates in the FFT spectrum, top right. That noise while unlikely to be audible, adds up to the same level as distortion specs so we don't want that. Please note that I am seeing this with my Audio Analyzer which has floating input, i.e. its "RCA" connection is not grounded. When faced with this situation, I usually resort to different ways of grounding the analyzer to device being tested. Unless the noise is internal to the device itself, I am usually able to reduce it fair bit as is the case here:

View attachment 412509
Notice how a lot of that hash is gone in high frequencies. But we still have a tilted up noise floor in lower frequencies. SINAD is improved by 2 or so dB.

Now let's connect JDS Sypanse inline with the USB connection (now without grounding):
View attachment 412510

We see complete clean up of the noise floor with SINAD elevating 2 to 3 dB yet again.

I replaced Synapse with Neutron V1 and performance improvement was the same (there are tiny run to run variations):
View attachment 412511

We can zoom into the noise floor without the signal present:
View attachment 412512

Please ignore the differences in mains noise. That is again, nature of the floating analyzer input. If I use both Synapse and grounding, that gets almost eliminated:
View attachment 412513

Conclusions
Of all the devices I test, I say around 5 to 10% of time I run into noise issues. Per my explanation above, I am usually able to reduce their impact to be negligible. But in a few cases, I have failed to do so. You might say that is significant but my analyzer is not 100% stand in for whatever amplifier you use. You may have bigger or smaller problem or none. When hit with that issue, you can use Toslink optical but that may not exist in your source. And at any rate, Toslink is usually limited to 96 kHz sampling. With either one of these isolators, you can get maximum performance using USB bus and eliminate any dependence on the source.

I am happy to recommend both JDS Synapse and Neutron V1 USB isolators. Both function very well and are reasonably priced.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I've built a few of these for ground loops in ungrounded solar systems that need to be fully isolated. Costs a few bucks. Even with the nice cases, these are absurdly overpriced. But they are not snake oil, so I guess, great?

 

[Lambda]

If you are using balanced output in your downstream device (again, such as DAC), there is little import to this.

Exactly how little is measured in CMRR. So the common mode rejection ratio of a device should be tested.

How much this happens, and how audible it is, is complex and not predictable.

As I advocate for since a long time, this is why exactly these cases should be tested. No one cares if a DAC has SINAD of 120 or 130dB on a clean USB feed.But how much of the ground loop's common mode noise from the USB would leak into the chain and how much would be suppressed is kind of important.

Some expensive DACs have an isolator inside but I would say 99% do not.

It does not have to have real galvanic isolation to have a significant effect of attenuating noise coming from the USB. The noise this isolator is addressing is common mode noise.A competent DAC with separated internal analog and digital grounds as well as input and output CMRR filters can make a huge difference, especially for the high-frequency noise.

And also the Cables would make a difference in this cases.

 

[GWolfman]

Most usually it's not one specific device causing a ground loop, but rather the combination of equipment and circumstances. For example, you might live in a multi-apartment building, in which the cable or satellite TV/radio outlet ground might have a slightly different potential than the power outlet safety ground in the apartments. Now, let's assume that you so far had no ground hum problem with your hifi system, as all of its components happen to be safety class II devices and only the tuner is connected to the cable/satellite outlet - but then you have the idea, that you finally want to add a PC, that happens to be safety class I (be it equipped with onboard sound hardware, an internal sound card or an external USB sound interface or DAC), and now you're getting a very fat ground loop hum due to the two different ground potentials. Before USB isolators were offered, you then only had two choices: You could either insert an antenna ground isolator (which might not work in case of satellite TV/radio, though) or a usually transformer-based isolator for the analogue audio connection. Whereas with a USB isolator you have a third option specifically for USB-attached audio devices.

Greetings from Munich!

Manfred / lini

Thanks for a practical example!

 

[amirm]

As I advocate for since a long time, this is why exactly these cases should be tested. No one cares if a DAC has SINAD of 120 or 130dB on a clean USB feed.

My usb feed is not clean as this review clearly shows.

 

[pablolie]

Now I am curious... those who have issues... are you plugging stuff into different wall outlets? Or. a shared "powerbank" that is common to all devices?
Genuinely curious, because even in power dirty California I haven't had a hum or noise issue ever, and I moved here over 25 years ago.
At first I was paranoid and got some $1k+ Audio Power Power Wedge super extra power. claiming magic dust etcetera.. 25 lbs of uselessness I found out. But made moderate investments otherwise to provide a common source.
And my computer systems at home and work also have had zero noise issues.

 

[dmitrykos]

So do you feel this will be a better product than the Topping HS02?

In relation to ground-loop noise affecting audio equipment - all USB isolators isolating data and power will do the trick. There are functional and design differences and it's up to you to decide how important the features offered are.

 

[dmitrykos]

Now I am curious... those who have issues... are you plugging stuff into different wall outlets?

In my case does not matter - I get it with PC and amp for external speakers sourcing AC from the same outlet, and in my other tests I had PC from the same outlet and Laptop powered from another distant outlet.

 

[Lambda]

My usb feed is not clean as this review clearly shows.

Is it? How mush Noise is on it and how typical is that? Whats the maximum allowable Noise on a USB port for it to be still in spec and or in EMC FCC limits?

"works for me in the lab." on a analyzer with where i you can chooses and tweak the grounding of the input.
is not representative of the real world performance in a Audio chain.

As you say yourself.

However, if you are using unbalanced RCA connection, the noise on the USB ground can travel through the DAC and manifest itself as noise and ground loop. How much this happens, and how audible it is, is complex and not predictable. Suffice it to say, once it becomes audible, you are kind of stuck, having to possibly change your computing device, DAC or other games to try to hopefully eliminate such noise. It can be quite frustrating.

This is a real problem in the real world.
In many cases, the noise from the USB is so strong users can actually hear it (unlike the distortion of a modern, good DAC).
These are the cases we hear about when users complain and ask for help.
But what is your reasoning to assume that this noise is only on the signal if it manifests itself so strongly that you can hear it?
Logically, there must be a lot more cases where there is noise, but it is inaudible yet still significant compared to the DAC's noise and distortion.

Noise on the USB ground can be strong, but this is not normal.
In the same way, users should not need to buy a power station to reduce noise on their AC lines.
A competent DAC should not need an external device for that.

To assume you’re safe if you don’t use RCA is also a bold claim, since with XLR you still rely on the input device’s CMRR (which is also unknown).
Here we are with a real phenomenon that has a real audible impact on sound quality in the real world.

But you say it’s too complicated to measure and quantify, so you hand-wave it away?

 

[amirm]

To assume you’re safe if you don’t use RCA is also a bold claim, since with XLR you still rely on the input device’s CMRR (which is also unknown).

With some rare exceptions, XLR is cleaner with respect to RCA leakage when I see the problem as I have tested hundreds of DACs. Even poor CMRR is far better than no CMRR that you get on RCA.

 

[amirm]

But what is your reasoning to assume that this noise is only on the signal if it manifests itself so strongly that you can hear it?

I didn't say that. Where are you getting that from? I have said that objective noise is there but whether it rises to level of audibility is another matter. Likely many RCA connections suffer from some level of ground currents. They only become audible when that leakage gets quite strong.

Folks need to use balanced XLR if they at all can. RCA unbalanced connections are fundamentally a broken design. If you are stuck with them and you get audible noise, then the products in this review are an effective tool.

 

[bboris77]

Now I am curious... those who have issues... are you plugging stuff into different wall outlets? Or. a shared "powerbank" that is common to all devices?
Genuinely curious, because even in power dirty California I haven't had a hum or noise issue ever, and I moved here over 25 years ago.
At first I was paranoid and got some $1k+ Audio Power Power Wedge super extra power. claiming magic dust etcetera.. 25 lbs of uselessness I found out. But made moderate investments otherwise to provide a common source.
And my computer systems at home and work also have had zero noise issues.

In my case, ground loop noise only exhibited itself when there were multiple paths to the ground between different devices that were interconnected. In other words, when two or more of these devices used three-pronged grounded electrical plugs. It made absolutely no difference whether they were plugged into the same outlet or not. The simplest example would be a grounded PC connected via USB to a DAC connected to a headphone amp with a 3-pronged power plug. At higher volumes, one could clearly hear the buzzing coil whine through the headphones as soon as there was any graphic card activity. When I switched to a headphone amp that used an ungrounded 2 prong transformer plug, the noise was gone. Inserting an USB isolator between the PC and the DAC also took care of the problem.

From my limited understanding of the situation, it has to do with the ground potential and some of the electrical current taking the path of least resistance and leaking back into the signal chain.

 

[dmitrykos]

it has to do with the ground potential and some of the electrical current taking the path of least resistance and leaking back into the signal chain.

There is good quick explanation on Wikipedia related to Ground Loop issue, it explains how noise is created/induced due to the ground potential difference:

"These ambient magnetic fields passing through the ground loop will induce a current in the loop by electromagnetic induction. The ground loop acts as a single-turn secondary winding of a transformer, the primary being the summation of all current-carrying conductors nearby. The amount of current induced will depend on the magnitude and proximity of nearby currents. "

Source:

Ground loop (electricity) - Wikipedia

en.wikipedia.org

There is also useful article from Reneseas related to communication protocol but still explaining the Ground Loop Difference: https://www.renesas.com/en/document/apn/an1980-ground-potential-differences-origin-and-remedies

 

[milosz]

I've had ground-loop issues where a PC was connected to my DAC via USB. I also had an issue where a PC was connected to the "control" USB port of a DSP in an A/V system where the audio was coming from the EARC of the TV. I needed to have that PC controlling the DSP in order to adjust the filters, etc. The DSP had digital input but analog output, and when I would plug the PC in via USB I got that familiar hummmbbbzzzz of a capacitively coupled ground loop.

In both cases, a USB isolater solved the issue.

I've also had ground loop issues when a cable box was part of the system- disconnect Comcast's coax from the input of the cable box and the ground loop went away. In this case, I got an RF isolator and put it in series with Comcast's signal coming into the cable box F connector. The ground (shield) on the Comcast RF coax caused a ground loop. Who knows where that shield was connected, some dodgy pole mounted distribution amp, no doubt. Cable TV plants are generally pretty sketchy- years ago they started out pretty tight, but over the years various techs installed who-knows-what and there you go.

 

[amper42]

Glad to know there is a device that helps clean up poorly designed DACs. Would it be just as smart to buy a quality DAC and avoid the $100 connector? I have never experienced any USB noise.