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Review and Measurements of Intona USB Isolator for Audio DACs

amirm

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#1
This is a review and measurement of Intona USB Isolator. In the last few years there has been a proliferation of USB filters, cleaners, regenerators, feeding on fear of audiophiles of noisy computer ports. Intona doesn't actually play in that market directly. They built this device for industrial control applications where strict isolation from the machine being controlled is required. Audiophiles however, have been interested in the unit just as they are in other devices in this category.

This unit is on a kind loan from a forum member. It retails for USD $229 plus $29 shipping to US. It comes in a nondescript, plastic box. No pretense of being a audio jewelry here. For this review I compared the Intona to Uptone Regen and TotalDAC D1. You can see the full collection here:

Intona USB Audio Isolator and Filter Picture.jpg


Interestingly the Intona works without any external power even though it is an active device. The Uptone Regen which is also active needs an external power supply which itself can be a source of noise (I used the iFi iPower supply that was recommended for it). I think the TotalDAC is passive but I am not sure. Either way, it doesn't need a power supply.

Let's get into measurements and see how they do. If you are not familiar with my tests, I suggest reading my tutorial on audio measurements here: https://www.audiosciencereview.com/forum/index.php?threads/understanding-audio-measurements.2351/.

Measurements
Wanting to get positive results, I reached out for a DAC that I know lets USB noise bleed into its output: the Schiit Modi 2 Uber. From past testing I know that J-test of jitter and noise is very revealing of what these devices do or don't. So I hooked up the Modi 2 Uber to my HP Z series Laptop, fired up Roon to play the J-Test signal to it and measured what comes out of the DAC. Anything other than the main tone at 12 kHz is unwanted:

Intona Isolator USB Filter DAC Jitter and Noise Measurement.png


Focusing on the naked Modi 2 Uber, we see that we picked right. The broad shoulder below and around our tone indicates low frequency, random jitter. In addition we see that it produces those spikes in yellow to the left.

The graph in red is with addition of Intona. We see that it nicely cleans up all the lower frequency distortion spikes. It does nothing for random jitter as that is likely created inside the Modi 2 DAC.

So objectively speaking, the Intona USB Isolator does its job, providing a cleaner signal to Modi 2 which in turn generates cleaner output.

Let's switch to Uptone Regen and see what it does:

Uptone Regen USB Filter DAC Jitter and Noise Measurement.png


That is a bummer. Not only does it not remove any distortion products, it adds its own at 8 and 16 kHz! The Regen has a USB hub in it and seemingly it allows the 8 Kbyte USB packet interval to become much stronger. We definitely took a step backward here. The Uptone Regen is $175 and the iFi Power supply is another $50 so the total cost is the same as Intona.

Next let's examine the TotalDAC D1. I have reviewed the totaldac D1 before. This is another take on it with our new setup here:

TotalDAC D1 USB Filter DAC Jitter and Noise Measurement.png


This is essentially the same outcome as Regen. Nothing is filtered and we have a new spike at 16 kHz. Seeing how this is the most expensive of the three at €390 or USD $480, this type of performance is super disappointing.

Enough with low-end DACs. Let's put the Intona in front of the RME ADI-2 DAC and see what happens:

Intona USB Filter RME ADI-2 DAC Jitter and Noise Measurement.png


As we see in yellow, there is nothing to be fixed and performance is at the limits of my measurements. The Intona adds a bit of noise to low frequencies. Not sure what it is about but it is extremely small.

Conclusions
The Internet is full of praise for these USB filters. The imagination works wonders here, equating USB and computers with noise, and assuming anything that filters it must make things sound better. That predisposition makes one perceive improvement even if it is not there.

Noise is easily measured as see above. So people should not assume a device is a true filter without seeing it actually measured as such. Based on this work, and confirmed by previous measurements I have performed, neither the Uptone Regen nor the TotalDAC D1 filter anything. Instead, they add their own noise components. Mind you, the addition while measureable, is not audible so no wonder no one is complaining about it. If you want to dismiss objective data on these products you can. But please go into any subjective review assuming that it could also do nothing versus "must be filtering."

It is in this context that I smile when I see the performance of the Intona USB Isolator. Finally a USB filter that actually filters! So congratulations to Intona for building a proper product that reproduces the USB bus cleanly.

Alas, as I have shown with RME ADI-2 DAC, you do not need USB filters. The solution to Modi 2 Uber noise and distortion is to buy a DAC at the same price or lower that doesn't have these issues. Schiit products seem to be sensitive to quality of USB power. Better designed DACs don't have that problem.

-----

As always, questions, comments, recommendations, etc. are welcome.

If you like this review, please consider donating funds for these types of hardware purchases using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
 

fredoamigo

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#4
again, the unitilities of these products are demonstrated...I think it would also be very interesting to test products like the w4s recovey that pretend to restore the original integrity of the USB signal and that embed clocks...I'm very doubtful but why not?https://wyred4sound.com/products/digital-converters/recovery
 
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#5
I can't wait to see all the glowing reviews of the yet to be released UpTone Ethernet ReGen.

I could write those reviews myself right now.

I think I could do the engineering with similar ease. :)

AFAIK under the covers the Uptone regen seems to be a degenerate form of a common USB hub with just one output port.

Regenerating the USB signal is usually a big part of how USB hubs work. They typically are based on a separate clock. For extra credit you can put in a standard USB galvanic isolation chip and a new 5 volt power supply.

You can duplicate the Uptone USB Regen this way with about $30 worth of little boxes, direct import from the Pacific Rim via ePacket ordering on eBay or AliExpress.

There is a legitimate use for these things that has nothing to do with high-end audio, and here is an example of a regular commercial solution:
http://www.analog.com/media/en/tech...-selector-card/2884.pdf?domain=www.linear.com

Moving back towards the topic of Ethernet, the moral equivalent of a USB hub for ethernet is simply an ethernet hub, with the added extra attraction that they usually don't provide DC power (that feature is called Power over Ethernet or POE) and they already, by convention pass signals through an itty-bitty transformer with galvanic isolation rated at about 3 KV.

So, since you can get a good working Ethernet hub for about $5, the asking price for the high end audio ethernet isolator should be about $500.00, more or less. :)

If one needed more evidence to support the theory that all of the glowing reviews for this stuff are 100% based on expectation and placebo effects...
 

Purité Audio

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#6
Fascinating Amir as always, we stocked the Intona and it did help with a couple of really poorly designed valve DACs, but with anything well designed I didn’t hear any difference.
Mattias from RME provided the eye pattern/ measurements I believe for Intona.
Keith
 
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#7
As we see in yellow, there is nothing to be fixed and performance is at the limits of my measurements. The Intona adds a bit of noise to low frequencies. Not sure what it is about but it is extremely small.

Conclusions
The Internet is full of praise for these USB filters. The imagination works wonders here, equating USB and computers with noise, and assuming anything that filters it must make things sound better. That predisposition makes one perceive improvement even if it is not there.

Noise is easily measured as see above. So people should not assume a device is a true filter without seeing it actually measured as such. Based on this work, and confirmed by previous measurements I have performed, neither the Uptone Regen nor the TotalDAC D1 filter anything. Instead, they add their own noise components. Mind you, the addition while measureable, is not audible so no wonder no one is complaining about it. If you want to dismiss objective data on these products you can. But please go into any subjective review assuming that it could also do nothing versus "must be filtering."

It is in this context that I smile when I see the performance of the Intona USB Isolator. Finally a USB filter that actually filters! So congratulations to Intona for building a proper product that reproduces the USB bus cleanly.

Alas, as I have shown with RME ADI-2 DAC, you do not need USB filters. The solution to Modi 2 Uber noise and distortion is to buy a DAC at the same price or lower that doesn't have these issues. Schiit products seem to be sensitive to quality of USB power. Better designed DACs don't have that problem.
Agreed.

I've been looking at schematics of USB DACs such as they are available to civilians and I see an obvious dividing point. Some products seem to connect the power for the signal handling chips directly to the 5-volt VCC bus from USB land with good old copper traces, and others that filter the 5 volt supply before using it. Some even re-regulate it. What a concept!

I found this habit of using raw power and non-band-passed data signals to be a pretty shocking lapse, especially for premium-priced gear. In the world I design audio gear in, everything that comes from the outside is automatically questionable and needs at minimum RF filtering if there is any RF susceptibility inside. Regulator chips are very effective and literally a buck a dozen and why not put them in the next time there is a jerk of one's knee? Ferrite beads can cost even less!

I suspect that one enabling technology for more newly developed USB DACs is the use of signal processing chips that are happy with 3.3 volt VCC, which leaves a little room for filtering and even low-dropout re-regulation.
 

Veri

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#8
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#9
Thank you for an interesting review. I own an Intona and this is my experience:

In my system I experienced serious USB noise when playing out of my laptop and into an Accuphase DAC 40. The noise was clearly audible and really disturbing from the listening position. My wife was asking: "what is that noise?". So no placebo here.

Running the laptop on battery made the problem vanish. I think it probably is a ground a ground loop issue.Running on battery is not practical so I ordered the Intona (industrial version), and it did its job completely. No noise anymore. I also ordered an IFI iUSB3.0 which reduced the noise, but did not remove it as the Intona did.

My issues were easy to identify. I guess a less noisy, but not quiet, USB is the reason for discussions on differences between streamers.
 
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fredoamigo

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#10
The reviews on that website nauseate me.
The best one is this one... my taste.
More sparks and more air. More depth and smooth sonics. More openness and more analog sound...... With the W4S Recovery I forget to analyze the sound, instead I enjoy the music.".

It's unstoppable!!!;)

but what's said here may be true before he has a measure that proves otherwise? however, without measures it is necessary to find the technical explanation of the improvement can be the internal clock?
 
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#11
Thank you for an interesting review. I own an Intona and this is my experience:

In my system I experienced serious USB noise when playing out of my laptop and into an Accuphase DAC 40. The noise was clearly audible and really disturbing from the listening position. My wife was asking: "what is that noise?". So no placebo here.

Running the laptop on battery made the problem vanish. I think it probably is a ground a ground loop issue.Running on battery is not practical so I ordered the Intona (industrial version), and it did its job completely. No noise anymore. I also ordered an IFI iUSB3.0 which reduced the noise, but did not remove it as the Intona did.

My issues were easy to identify. I guess a less noisy, but not quiet, USB is the reason for discussions on differences between streamers.

Ground loops are almost universally characterized by being a low frequency hum, sometimes remarkably pure power line frequency which is either 50 or 60 Hz in most parts of the world.

Hiss would usually be some kind of EMI whether from local gear or nearby broadcast including cell towers.

In general if being battery powered fixes the problem, you just take advantage of the fact that most higher quality battery powered gear has internal batteries and rthey can be recharged via a USB port. You can even find USB cables that provide separate USB plugs for signal and power for negligable money. You then hook a low-buck USB power supply up to keep the battery perpetually charged. Worked for me many times. Take the $100's you saved and invest it in what really makes having a great system worth it - more prerecorded media. Or chase something that really matters like room acoustics or start saving up for a good subwoofer if you don't have one! :)
 
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dir

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#12
thank you for investigation.
my question about sample rate of J-test.
why 48 kHz not 44.1 kHz? it would be interesting to evaluate the character of jitter in the same mode as music content.
 

Jimster480

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#13
Another wonderful review, I tested the audioquest USB filter and another similar passive USB filter.
Would be interesting if you could test the Schiit Wyrd, its similar to the other filters tested here.

There are some computers though with really poor noisy USB ports, my friend Hugo has this problem and he experienced the issue with his Korg DAC and then also with my SMSL M8. Which when tested here didn't exhibit these problems, so it means that some peoples computers really have so much noise in the usb signal that it will cause actual audible problems similar to what someone else here described.

But outside of possibly removing that sort of incredible power bleed.... it definitely won't do anything else for you. The reviews of these products are nothing less than a placebo or a feeling to need to make a comment and perceive a difference even if there isn't one.
 

garbulky

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#14
So if I get this straight if there are significant jitter/noise problems the Intona may help measurably. But if the DAC is already pretty good with that, the Intona may introduce more noise than it removes?
 
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#15
Ground loops are almost universally characterized by being a low frequency hum, sometimes remarkably pure power line frequency which is either 50 or 60 Hz in most parts of the world.

Hiss would usually be some kind of EMI whether from local gear or nearby broadcast including cell towers.

In general if being battery powered fixes the problem, you just take advantage of the fact that most higher quality battery powered gear has internal batteries and rthey can be recharged via a USB port. You can even find USB cables that provide separate USB plugs for signal and power for negligable money. You then hook a low-buck USB power supply up to keep the battery perpetually charged. Worked for me many times. Take the $100's you saved and invest it in what really makes having a great system worth it - more prerecorded media. Or chase something that really matters like room acoustics or start saving up for a good subwoofer if you don't have one! :)
To clarify: The noise is variable i both frequency and level. When touching the mousepad noise is heard in the loudspeakers.

A dark and squeaking sound at the same time. I do not have any noise problems when using a different laptop. I’ve ordered a new powersupply for the laptop to see if that`s the source of the problem.
 

DonH56

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#16
Ground loops including EMI from the notebook can cause a broad range of noises though a pure ground loop is usually dominated by 60/120 Hz noise as Arny said. Switch-mode power supplies (essentially universal in PCs) can put a lot of HF noise on the line. A new supply may or may not help depending upon how it isolates the wall outlet. I would would pick up a Hum-X or something like it and try that if you suspect the wall power as the source of the noise: https://smile.amazon.com/Ebtech-Hum...?ie=UTF8&qid=1523551072&sr=8-1&keywords=hum-x

USB isolation, also per Arny, is another avenue well worth exploring.
 

amirm

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#17
thank you for investigation.
my question about sample rate of J-test.
why 48 kHz not 44.1 kHz?
It is historical driven by the fact that some low-end vendors take shortcuts with 48 kHz sampling and produce more distortion there, than 44.1 kHz. I can switch to 44.1 kHz but it will then make it harder to do comparison with older measurements.

The other minor reason is that others measure 44.1 but no one measures 48. Given the advent of high-res download and popularity of 96 kHz sampling rate there, 48 kHz tests have value there.

I am open to suggestions for the future.
 

gvl

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#18
Ground loops are almost universally characterized by being a low frequency hum, sometimes remarkably pure power line frequency which is either 50 or 60 Hz in most parts of the world.

Hiss would usually be some kind of EMI whether from local gear or nearby broadcast including cell towers.
I had a HP laptop that used a 3-prong power plug which would produce a nasty HF buzz when used with grounded amps at the end of the chain, but no buzz with ungrounded amps. Fits a ground loop pattern, no?
 

dir

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#19
some low-end vendors take shortcuts with 48 kHz sampling and produce more distortion there, than 44.1 kHz.
but what is the practical benefit of this mode, which does not coincide with 99% of the music content? What does it describe?
Even if we look at the statistics of HDtracks.com, the prevailing format of all new rock / pop HD-albums will be 24 bit / 44.1 kHz not 24/96 or 192 kHz.
Often a low-budget device can have only one clock on the board. So maybe it will turn out that a nice music source with a 44.1 generator will give poor measurements in your J-test. Even worse, the converter with only one 48 kHz multimedia clock will seem fine in your J-test, but it turns out to be a bad musical performer with high jitter.
I suggest to establish measurements with TWO reference sampling frequencies. At least, we can detect the weak resampling inside DAC's.
 

Jimster480

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#20
but what is the practical benefit of this mode, which does not coincide with 99% of the music content? What does it describe?
Even if we look at the statistics of HDtracks.com, the prevailing format of all new rock / pop HD-albums will be 24 bit / 44.1 kHz not 24/96 or 192 kHz.
Often a low-budget device can have only one clock on the board. So maybe it will turn out that a nice music source with a 44.1 generator will give poor measurements in your J-test. Even worse, the converter with only one 48 kHz multimedia clock will seem fine in your J-test, but it turns out to be a bad musical performer with high jitter.
I suggest to establish measurements with TWO reference sampling frequencies. At least, we can detect the weak resampling inside DAC's.
That is actually not a bad recommendation, but it would cause amir to have more work than he already has...
 
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