This is a review and detailed measurements of the M-Audio Air Hub USB DAC and Headphone amplifier plus a USB hub (and hence the name). It was kindly purchased by a member and drop shipped to me. The Air Hub costs just US $69. So the question is, do we have a bargain jewel on our hand? Let's find out.
From controls point of view, the Aid Hub has a lovely, large volume control on top with excellent feel:
Sadly the large knob only controls line out. It has no impact on headphone out which has its own little volume control in the front.
I did not test the USB hub. You have see one, you have seen them all.
Here is the back panel connectivity:
There is a beefy 3 amp 5 volt adapter that powers the unit. Sadly, as the measurements showed later, it has nothing to do with the audio subsystem of the Air Hub! It is only there to power the USB-hub. The unit work without the power supply. I tested it with the supply plugged in but at the end, tested without and it made no difference whatsoever.
M-Audio provides an ASIO driver by itself which I appreciated. Windows also accepts the DAC without a driver. I used M-Audio ASIO for all of my tests.
DAC Measurements
As usual, we start with out dashboard with volume set to max. I only had one TRS to RCA cable for testing so I only tested one channel of the DAC:
I think this is one of the most broken dashboard views I have seen. For one, we can't even get 1 volt of output let alone nominal 2 volt that it should produce for unbalanced. As you see in the FFT spectrum display, our 1 kHz tone has given birth to tons of other spikes in addition to a broad "skirt" under our tone. These indicate severe clocking error. Indeed, I would see the Frequency counter jump up and down constantly. Maybe it uses synchronous USB and chases the poor USB clock for its DAC? If so, that is horrible as even $9 dongles run asynchronously these days.
SINAd which represents distortion+noise is in toilet as well:
Dynamic range is "OK" at 15 bits:
IMD test shows high noise and distortion levels:
The jitter test shows us the horror that was awaiting us:
The above test averages 16 runs to reduce noise so that we can see the spikes. If I reset the Air Hub and just capture the first instance I get a much cleaner output:
Don't mind the bottom as that is what goes away if you average 16 times. As you see there is zero jitter. Sadly if you let the DAC keep running, it then screws up its own clock, causing the jitter you see in the previous graph in blue.
I think we better stop here before depressing ourselves even more.
Headphone Out Measurements
For grins, I ran one test of power using 300 ohm load:
What? Just 1.5 milliwatts of power? Are these guys kidding? This is when I realized that the external power supply is not used. As a result of that, and poor implementation, the Air Hub simply doesn't have any power output.
Conclusions
The volume control on the M-Audio Air Hub is excellent. Sadly the good news ends there. It seems they took an obsolete laptop USB DAC chip ("CODEC") and stuffed in there and called it done. No effort was made to build a quality audio product. Shame. The M-Audio company that I know from back in 1990s was a high-end audio company. After changing hands twice, it seems to be building trash. Avoid at all costs.
Wait. There is one use for this device. Buy it, use the case and volume control to build your own DAC! Outside of that, I can't possibly recommend the M-Audio Air Hub.
What a poor way to end our year. Shame on you M-Audio!
------------
As always, questions, comments, recommendations, etc. are welcome.
It has been a great year folks. I hope you all have a fantastic new year. No need to send any money but if you insist, here is the link: : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
From controls point of view, the Aid Hub has a lovely, large volume control on top with excellent feel:
Sadly the large knob only controls line out. It has no impact on headphone out which has its own little volume control in the front.
I did not test the USB hub. You have see one, you have seen them all.
Here is the back panel connectivity:
There is a beefy 3 amp 5 volt adapter that powers the unit. Sadly, as the measurements showed later, it has nothing to do with the audio subsystem of the Air Hub! It is only there to power the USB-hub. The unit work without the power supply. I tested it with the supply plugged in but at the end, tested without and it made no difference whatsoever.
M-Audio provides an ASIO driver by itself which I appreciated. Windows also accepts the DAC without a driver. I used M-Audio ASIO for all of my tests.
DAC Measurements
As usual, we start with out dashboard with volume set to max. I only had one TRS to RCA cable for testing so I only tested one channel of the DAC:
I think this is one of the most broken dashboard views I have seen. For one, we can't even get 1 volt of output let alone nominal 2 volt that it should produce for unbalanced. As you see in the FFT spectrum display, our 1 kHz tone has given birth to tons of other spikes in addition to a broad "skirt" under our tone. These indicate severe clocking error. Indeed, I would see the Frequency counter jump up and down constantly. Maybe it uses synchronous USB and chases the poor USB clock for its DAC? If so, that is horrible as even $9 dongles run asynchronously these days.
SINAd which represents distortion+noise is in toilet as well:
Dynamic range is "OK" at 15 bits:
IMD test shows high noise and distortion levels:
The jitter test shows us the horror that was awaiting us:
The above test averages 16 runs to reduce noise so that we can see the spikes. If I reset the Air Hub and just capture the first instance I get a much cleaner output:
Don't mind the bottom as that is what goes away if you average 16 times. As you see there is zero jitter. Sadly if you let the DAC keep running, it then screws up its own clock, causing the jitter you see in the previous graph in blue.
I think we better stop here before depressing ourselves even more.
Headphone Out Measurements
For grins, I ran one test of power using 300 ohm load:
What? Just 1.5 milliwatts of power? Are these guys kidding? This is when I realized that the external power supply is not used. As a result of that, and poor implementation, the Air Hub simply doesn't have any power output.
Conclusions
The volume control on the M-Audio Air Hub is excellent. Sadly the good news ends there. It seems they took an obsolete laptop USB DAC chip ("CODEC") and stuffed in there and called it done. No effort was made to build a quality audio product. Shame. The M-Audio company that I know from back in 1990s was a high-end audio company. After changing hands twice, it seems to be building trash. Avoid at all costs.
Wait. There is one use for this device. Buy it, use the case and volume control to build your own DAC! Outside of that, I can't possibly recommend the M-Audio Air Hub.
What a poor way to end our year. Shame on you M-Audio!
------------
As always, questions, comments, recommendations, etc. are welcome.
It has been a great year folks. I hope you all have a fantastic new year. No need to send any money but if you insist, here is the link: : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Luxman L-85V
DSC_6689_z
