1 Topic by Ellef (edited by Ellef 2020-01-08 01:33:32)

  • Ellef
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Topic: USB isolator for Babyface Pro

Hey there,

do you have experiences with USB isolators on RME devices?
I try to fix a ground loop between my Babyface Pro and my PC that emmits a lot of junk, especially when the system is under load.

There are some cheap adapters on eBay and Amazon. But I doubt that they can please the bandwith (only 12 mbit/s) and deliver clean and stable power without adding any serious distortion.

Has anyone tried the galvanically isolating high-speed models from Intona or ALLDAQ?
Are there cheaper alternatives to consider? Is iFi worth a look?

Looking forward to your comments.

Ellef

2 Reply by MC

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Re: USB isolator for Babyface Pro

This forum has a search function. Try 'Intona' etc. Everything is there.

Regards
Matthias Carstens
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Re: USB isolator for Babyface Pro

I am not sure how well this will work for your Baby Face, but I use the following on my Roland Boutique synths, that suffer from ground loop hum, if powered by USB and the audio signal is fed analog, into my Fireface 802.

https://hifimediy.com/high-speed-usb-isolator-480Mbps

This is one of the only ones that worked for me.  It is high speed (but also compatible with full and low speed) and is USB 3 compatible.

4 Reply by MC

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Re: USB isolator for Babyface Pro

A search will also reveal that I had zero luck with this specific adapter with RME interfaces.

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Matthias Carstens
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Re: USB isolator for Babyface Pro

MC wrote:

A search will also reveal that I had zero luck with this specific adapter with RME interfaces.

Yikes!  I just did a search and found exactly what you are talking about!  Although not using it on an RME device, I have been using it for 1.5 years with my Roland Boutique synth and so far, have not noticed any issues.  I am a little weary however, as you mentioned it was overvolting, which I had no way of knowing or checking.  My Roland Boutique IS bus powered however, so I hope I am ok and not in fact breaking the connected devices?!

6 Reply by MC

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Re: USB isolator for Babyface Pro

If it's bus powered then it draws some current and the voltage will be lower, so most probably not an issue for you.

Also it might be that meanwhile they have a newer generation shipping, with undisclosed fixes. But to know that I would have to order another one - not.

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Matthias Carstens
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Re: USB isolator for Babyface Pro

MC wrote:

If it's bus powered then it draws some current and the voltage will be lower, so most probably not an issue for you.

Also it might be that meanwhile they have a newer generation shipping, with undisclosed fixes. But to know that I would have to order another one - not.

Thanks so much for your continued input on this, I really appreciate the response.

Yes, I am using Bus powered devices, so the power should be lowered, because of this.  I highly doubt there is a new revision, to be honest.  I was actually waiting for this new version to come out and pre ordered it back then.  I received it late summer 2018, which is roughly when you said you got yours, so I bet they are one and the same.

Thanks again so much MC, glad to know I learned something about this and will start looking for alternative isolators for future purchases.

Hey, maybe you guys should come up with one?  With your expertise and products which can rely on this, I think it would be a great business expansion for you!  wink

8 Reply by MC

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Re: USB isolator for Babyface Pro

If we would come up with one it would be the Intona one. So no need to do that. I know it's not cheap, but you get what you pay for.

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Matthias Carstens
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Re: USB isolator for Babyface Pro

MC wrote:

If we would come up with one it would be the Intona one. So no need to do that. I know it's not cheap, but you get what you pay for.

Fair enough and thanks for your time, in sharing your wisdom and expertise.  I really appreciate it.

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Re: USB isolator for Babyface Pro

I tried the ALLDAQ ADQ-USB 3.0 today. Quite an expensive device but it practically solved all my noise issues I had with the balanced and especially unbalanced output of the BFP. However, the isolator needs an external power supply to be able to drive an audio interface which adds to cost and may introduce issues with stand-by when the computer is waking up.

Out of curiosity I just ordered an Intona 2.0 isolator (standard version). It is a bit cheaper and can supply up to 500 mA without external power. Hopefully it will run stable with my BFP.

I will do some RAA loopbacks and compare the performance of both devices soon.


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Ellef

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Re: USB isolator for Babyface Pro

Thanks for sharing Ellef.  I am curious and excited about your findings.  Please do share when you are ready and best of luck!

12 Reply by MC

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Re: USB isolator for Babyface Pro

The Alldaq works perfectly (as explained before), but uses an internal hub chip, which means you loose USB resources. That can become important if you have more USB devices than ports. The Intona is tranparent like a cable. Both units can not power a Babyface Pro by themself.

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Matthias Carstens
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13 Reply by Ellef (edited by Ellef 2020-01-12 13:03:24)

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Re: USB isolator for Babyface Pro

Could you explain how the internal hub chip of the ALLDAQ could interfere with the usb resources?

And did I understand it correctly that even the Intona will require a power supply to run the Babyface Pro?
Since the Intona 2.0 has no input for an external PSU itself, I would then have to connect a 12V supply directly to the interface. The ALLDAQ on the other hand has an input for an external PSU itself and does also apply filtering before handing the 5V over to the interface.

Have a nice day.
Ellef

14 Reply by MC

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Re: USB isolator for Babyface Pro

Every USB device requires USB resources. If you have too many of them Windows will show a message 'Not Enough USB Controller Resources”, Google it for details and fixes. As our multichannel USB audio interfaces require a lot of these resources, adding a hub based isolator can already be too much and then disables the audio interface completely. That's why I use the Alldaq on USB3 with a dedicated port, but use the Intona for everything else also behind hubs (as one is typically forced to do with USB 2).

Yes, you would have to use an external power supply for the BF Pro. Now this seems like a bit useless discussion. The Alldaq works for you, so why not continue using it? It's a fine product for both USB 2 and 3 and much cheaper than questionable others (won't mention names).

Regards
Matthias Carstens
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15 Reply by Ellef (edited by Ellef 2020-01-12 19:30:49)

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Re: USB isolator for Babyface Pro

I see, thanks for the hint! I actually encountered that issue yesterday one or two times when hooking up the adapter. Using the 3.0 port with its limited endpoints may have been the cause. I will switch to the 2.0 port once the error reappears.

Before making a final decision I want to test all possible setups, switching between the ALLDAQ, the Intona and an external USB hub I ordered. Maybe I can achieve the same effect for cheaper.
Spending 200 - 300 Euros for an USB isolator is still questionable imo. That is already the price range of a decent balanced DAC which I could feed with an optical signal and thus evade alle the noise introduced by the computer. So my expectations are quite high for an USB isolator of that price.

As to the power supply, is there anything special to consider when selecting a 12V PSU for the BFP? I just tried an old Telekom Speedport 12V / 2.5A adapter and it appears to work fine. Looking at the noise isolation properties, I wonder whether there will be any significant difference between a cheapish off-the-shelf supply and a higher quality supply approved for medical and engineering purposes. I do ask because I had some noise issues with a pair of very sensitive in ear microphones in the past which picked up hum at 50 Hz and 150 Hz. Recording an unbalanced loop with Rightmark's Audio Analyzer I can still see those 50 Hz and 150 Hz spikes in the noise spectrum. The ALLDAQ is fed by a cheap PSU too because I do not want to spend the extra 50 Euros just for the official accessory. Maybe I have to go fully battery powered to solve that issue as well hmm

Regards
Ellef

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Re: USB isolator for Babyface Pro

Did a few measurements today and noticed that the distortions have gone completely:

https://i.imgur.com/E32pGWX.png
RAA: 48 Khz, 24 Bit, 3/4 out to 3/4 in, -5dB

Had a ton of noise above 1 kHz and some spikes at 50 Hz and 150 Hz before. After reconfiguring the whole cabling of the system the spectrum is much cleaner. And the strange thing: even without the ALLDAQ in place! The graph above is basically the same with and without the isolator, which tells us that the ALLDAQ works transparent without introducing additional noise.
As for the noise measured before, I guess it was just a faulty cable somewhere in the setup.

So what's the point with the ALLDAQ?
The isolator comes into play when I connect other components to the Babyface Pro such as my active speakers. Without the isolator in place I hear very loud buzzing noises when connecting through unbalanced TRS. Going with balanced XLR is mostly clean. But there still appear to be some random spikes going through the chain that always trigger both speakers even when no signal is played back. Those issues have completely vanished with the isolator between the interface and the computer. Ground loop solved.

Looking at my in ear microphones I cannot hear or measure any difference between both configurations. I guess it is just a flaw of the capsules being very prone to EMI.


As for the playback, I consider to send the isolator back and go for an external DAC which I can supply with an optical signal. Like I said, those galvanic isolators come with a price of 200 to 300 Euros. That is already the scale of a Topping D50s, a Soncoz LA-QXD1 or a SMSL SU-8. Those would not only bypass the the ground connection but also add a few more INs and OUTs.

I'm still waiting for the Intona to arrive. But I don't think it will change anything with the observations described above.

Regards
Ellef

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Re: USB isolator for Babyface Pro

The Intona arrived today. Results as expected. It is a bit cheaper but does the same job.
Here are some of my final thoughts:

ALLDAQ ADQ-USB 3.0-ISO
+ 3.0 compatible
+ quality housing made of aluminum
+ filtered 5V Input
- pricy
- potential issues with USB resources (see MC's explination above)

Intona USB 2.0 Hi-Speed Isolator
+ a bit cheaper
+ same practical performance
- large plastic case
- no cable included

Both devices do not show any distortions in the RAA measurements. Both isolate all the noise for unbalanced connections and prevent voltage spikes that made the active speakers stand-by function trigger all the time.

I also compared two externally powered USB hubs (one from Anker, one from Primewire) and could not find any advantage in noise performance. The ground loop persists.

After all I am thinking about either keeping the ALLDAQ or buying an external DAC with optical input.
Or the cheapest: use an analog line isolator for the speakers.

Regards
Ellef

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Re: USB isolator for Babyface Pro

MC wrote:

... Try 'Intona' etc....

I love this forum!

I had managed to previously missed the galvanic isolation discussion - but driving two sets of studio monitors from my ADI-2 PRO - one via an unbalanced cable - I was getting some digital noise issues.

Installed Intona today - and completely silent.

Thanks MC & Ellef