JDS Synapse & Neutron V1 USB Isolators Review

[staticV3]

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.

DACs with isolated USB input are basically non-existent.

Isolators are not a crutch for poorly designed DACs.

They're a crutch for poorly designed computers and fundamentally flawed RCA interconnects.

 

[Lambda]

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.

The XLR connection is only as beneficial as the receiving devices CMRR...

 

[milosz]

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.

Even a $20,000 DAC can be affected by a ground loop. Isolators don't clean up the USB signal, they break the loop in the system ground.

 

[Roland301]

I think I've definitely gotten my money's worth out of my Topping HS01. I use a speaker power amp to drive everything in my system, including headphones, so noise problems are very evident. $60 isolator is a lot cheaper than buying different amps for all the transducers I want to drive.

 

[johny_2000]

Would it be just as smart to buy a quality DAC and avoid the $100 connector? I have never experienced any USB noise.

Here are my practical results - RME DAC has no noise with or without USB isolators.

 

[dmitrykos]

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.

When you connect multiple AC-powered devices then this interconnection has multiple ground paths (PC/TV/streamer has one path, powered DAC or connected Amplifier have another), this condition forms the Ground Loop. Then, due to different ground potential (different load, different conductor resistance) current is induced into this loop and starts flowing. This current is a sum of currents induced by EMI from different parts of connected devices (obviously they have different loads and handling different tasks), including AC frequency. Thus sum is actually the noise we see in the measurements. It can be harmless to digital parts of electronics (to some extent) but DAC is producing analog signal by amplifying it to the level we can hear. As a result such amplification will also amplify the noise circulating in the system.

It has nothing to do with a hw design of the DAC and its design can't be qualified as poor or good in relation to ground loop. But, stationary DAC producers could make USB port isolated for data and power paths as a simple countermeasure against the ground loop problem. Balanced connections help in rejection of the induced noise but can not fully solve it due to ground potential difference (if difference is low then of course noise effect will become same low but that is a matter of luck and combination of connected devices). 100% guarantee for absence of ground loop is physical disconnection of the grounds by USB isolator or optically (Toslink).

 

[amper42]

When you connect multiple AC-powered devices then this interconnection has multiple ground paths (PC/TV/streamer has one path, powered DAC or connected Amplifier have another), this condition forms the Ground Loop. Then, due to different ground potential (different load, different conductor resistance) current is induced into this loop and starts flowing. This current is a sum of currents induced by EMI from different parts of connected devices (obviously they have different loads and handling different tasks), including AC frequency. Thus sum is actually the noise we see in the measurements. It can be harmless to digital parts of electronics (to some extent) but DAC is producing analog signal by amplifying it to the level we can hear. As a result such amplification will also amplify the noise circulating in the system.

It has nothing to do with a hw design of the DAC and its design can't be qualified as poor or good in relation to ground loop. But, stationary DAC producers could make USB port isolated for data and power paths as a simple countermeasure against the ground loop problem. Balanced connections help in rejection of the induced noise but can not fully solve it due to ground potential difference (if difference is low then of course noise effect will become same low but that is a matter of luck and combination of connected devices). 100% guarantee for absence of ground loop is physical disconnection of the grounds by USB isolator or optically (Toslink).

MacBook Pro (Qobuz) -> USB -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any type of ground loop.
MacBook Pro (QoBuz) ->wifi UPnP -> Wiim mini -> Optical -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any type of ground loop.
MacBook Pro (QoBuz) ->wifi UPnP -> RPI4 (Moode)-> USB -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any ground loop.

Regardless of which MacBook Pro I use = NO audible ground loop. (2012, 2019, 2021)

Are there certain PC brands that typically require an isolator? Or is it other factors like a cable box or TV plugged into the same AC circuit?

Doesn't make much sense to buy an isolator when no audible issue is present.

 

[Roland68]

And this was Amir’s conclusion in his review of the intona



So I’m confused, do we need these things or not?

are there any known downsides?

This question is very easy to answer.
If you have heartburn, you need a remedy for heartburn. If you don't have heartburn, why should you take a remedy for it?

It's exactly the same with USB isolators. No problem, no USB isolator necessary.

However, good USB isolators, such as the Intona for USB 2.0, don't make anything worse.

 

[Jinjuku]

My $69 Behringer 204HD has balanced out and works just fine. I don't have a singled ended connection in my setups. Even my Headphones are TRSS.

 

[welwynnick]

Even my Headphones are TRSS.

TRRRS?

 

[Jinjuku]

TRRRS? View attachment 413353

Yeah, that one

 

[dmitrykos]

MacBook Pro (Qobuz) -> USB -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any type of ground loop.
MacBook Pro (QoBuz) ->wifi UPnP -> RPI4 (Moode)-> USB -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any ground loop.

Balanced connection (XLR in your case) rejects most of the noise caused by the ground loop, it has been mentioned in this thread multiple times as well as specified as one of countermeasures in cited Wikipedia article. Balanced connection does not break ground loop though but noise becomes severely mitigated. If MacBook is on battery then there won't be any ground loop. There is a teardown of MacBook's power adapter and it appears that it provides isolated DC power:


Source: https://www.righto.com/2015/11/macbook-charger-teardown-surprising.html

So basically your config is isolated on MacBook's end and that explains why you do not experience ground loop noise. It has been mentioned already here that USB isolator is solving the ground loop problem and if it does not exist then you do not need it. In your case even single-ended connection would not have any noise.

MacBook Pro (QoBuz) ->wifi UPnP -> Wiim mini -> Optical -> RME ADI-2 DAC FS -> XLR -> Purifi = Never any type of ground loop.

Besides aforementioned here you disconnect grounds with Optical connection. It is one of 2 available methods to disconnect grounds of connected devices.

Doesn't make much sense to buy an isolator when no audible issue is present.

Of course, although your config is isolated and you benefit from it. This thread mentions many cases where other configurations suffered from ground loop noise until a USB isolator was used to fix the problem.

 

[BrentW]

I'm excited about this from an ADC standpoint. For instance microphone or instrument levels can be very low and computer noise, when in shows up in these devices, is very annoying. My Line6 HX Stomp exhibits worse sound when plugged into my computer (has its own power supply) and I've never been able to debug this other than keeping it unplugged as much as possible.

 

[dmitrykos]

I'm excited about this from an ADC standpoint. For instance microphone or instrument levels can be very low and computer noise, when in shows up in these devices, is very annoying. My Line6 HX Stomp exhibits worse sound when plugged into my computer (has its own power supply) and I've never been able to debug this other than keeping it unplugged as much as possible.

Try connecting DSP processor to PC via the USB isolator, most likely you have ground loop noise discussed here as long as you hear difference in sound when PC gets plugged to your system.

 

[lini]

Thanks for a practical example!

You're welcome.

Greetings from Munich!

Manfred / lini

 

[GWolfman]

You're welcome.

Greetings from Munich!

Manfred / lini

Vielen dank

 

[L-Train]

The lower the pF value (coupling/parasitic capacitance) the better. Here is the same list from @192kbps sorted from best to worst by this parameter:

Neutron HiFi Isolator V1 20-22pF
DSD TECH SH-G01L 37 pF
Hifime High-Speed USB Isolator v2 71 pF
HS02 1 nF (1000 pF)

Excellent job on the Neutron HiFi V1 Isolator! The next time I'm in the market for another USB isolator I think it'll be at the top of my list.

I had purchased a Topping HS02 last year and while it's been working well I was a bit let down by the rather high isolation capacitance of its Mornsun VRB0505S-5WR3 DC-DC converter compared to other isolators. So I did a quick search on DigiKey to look for a better performing drop-in replacement and found the RECOM RS3-0505S/H3 which has an isolation capacitance of 30pF (max), isolation voltage of 3kVDC, and output ripple and noise of 50mVp-p (max), compared to 1000pF (typ), 1.5kVDC, and 150mVp-p (max) of the Mornsun.

Installed in the HS02:

Unfortunately I don't have the equipment to do any accurate isolation or noise measurements to quantify an improvement. In casual testing, powering a Khadas Tone Board appears to work fine. Of course, it doesn't make sense to buy an HS02, pay an additional ~$21 USD for the RECOM, and then spend the time to do the modification, since the Neutron isolator would be about the same cost with none of the hassle and with lower noise on the output voltage rail.

For those that have an HS02 and want to do the modification: after bending the RECOM's legs downward, the legs are only just long enough to be flush with the bottom of the PCB so it's best to solder it in from the top.

 

[Lambda]

Even a $20,000 DAC can be affected by a ground loop. Isolators don't clean up the USB signal, they break the loop in the system ground.

And a properly designed 20€ DAC can be Significantly less affected... This is why it needs to be tested.
Some DAC Have a low impedance from USB GND to Analog GND. Some Have Common mode filtering on input and output and seperated analog and digital grounds.

 

[Jarrett]

Excellent job on the Neutron HiFi V1 Isolator! The next time I'm in the market for another USB isolator I think it'll be at the top of my list.

I had purchased a Topping HS02 last year and while it's been working well I was a bit let down by the rather high isolation capacitance of its Mornsun VRB0505S-5WR3 DC-DC converter compared to other isolators. So I did a quick search on DigiKey to look for a better performing drop-in replacement and found the RECOM RS3-0505S/H3 which has an isolation capacitance of 30pF (max), isolation voltage of 3kVDC, and output ripple and noise of 50mVp-p (max), compared to 1000pF (typ), 1.5kVDC, and 150mVp-p (max) of the Mornsun.

Installed in the HS02:

View attachment 413537

Unfortunately I don't have the equipment to do any accurate isolation or noise measurements to quantify an improvement. In casual testing, powering a Khadas Tone Board appears to work fine. Of course, it doesn't make sense to buy an HS02, pay an additional ~$21 USD for the RECOM, and then spend the time to do the modification, since the Neutron isolator would be about the same cost with none of the hassle and with lower noise on the output voltage rail.

For those that have an HS02 and want to do the modification: after bending the RECOM's legs downward, the legs are only just long enough to be flush with the bottom of the PCB so it's best to solder it in from the top.

Do you happen to know if the design in the HS01 is similar and would it be worth upgrading?

@dmitrykos Why is lower pF value better? Do you know what it is for the HS01?

Thanks!

 

[Lambda]

My $69 Behringer 204HD has balanced out and works just fine. I don't have a singled ended connection in my setups. Even my Headphones are TRSS.

its not actually balanced.
One pin is just directly shorted to GND.

It's exactly the same with USB isolators. No problem, no USB isolator necessary.

How do you know you dont have any problem?
just because you don’t hear it?

But it is entirely possible (even likely) that you have some amount of "problem"
And this inaudible "problem "might degrade the performance of an 500€ dac with an SINAD of 120dB down to the Level of a 9€ dongle. with ab SINAD of 95dB.