UR22 Low freq. noise due to grounding design DIY solution

Amazon do not ship this product to Singapore so my friend purcased it and hand carried to me last night. The unit model serial number is UEUP01063.

I have done a silent/noise capture recording using Audacity (microphone slider to maximum) with no connection to UR22 at all except USB, +48V Off and with all knob set to minimum. I amplifier the recorded signal by 50 db using Adacity amplification and the noise level and waveform same as attached picture which was capture with input shorted. I check the noise spectrum using Audacity, noise level for frequency band above 60Hz is excellent at better than -90db, but there is a large noise level between 0 to 20Hz, it is as bad as -60db.

I have also done the test with all input shorted with no noticable inprovement.

Immediately I suspect that the USB power line may be not sufficient to drive the unit so I use a Y-USB cable to injet also a external USB power adapter to the unit and the noise level reduced by 9 db only ! ! ! So, it is not the solution!

Then, I decided to peel of a section of the USB cable outer rubble leyer, pull out the black (-) and red (+) power line, cut it off to stop the power supply from the PC and instead supply the UR22 directly (ONLY) by external USB adaptor.

Surprise ! ! ! I have the noise level dropped to below -90 db throught out the whole frequecy band !



Update: 01/05/2015 22:45

Further test shown that the noise level is not affected by the setting of Mix, Phone Output knobs setting, and adding the connection of output jack to my Yamaha DSP-A1000 power amplifier. However when I change the front pannel USB port to the rear USB port, the noise level worsen to -80db ! ! ! ? ? ?

With the good front panel USB port, two inputs not connected, two input gain knobs set to maximum, I can still get better than -85 db noise level. If I turn on the +48V without connecting the microphone, the noise level worsen to -75 db. I maydo a further test to add a resistor to simulate the microphone impedance to see what is happening, but it is not urgent as I do not plan to use condenser microphone and I do not worry about the +48V phantom power noise.

By the way the unit DO NOT LIKE USB3.0 port. It product broken audio playback very few seconds.

Since my test DID NOT involved other hardware outside the UR-22,based on two findings:
1- A split / external power supply eliminate the low frequency noise completely,
2- Different USB port give different noise performance.

It is obvious that inside UR-22, the analog ground (of all analog amplifier and ADC) and the digital group (of the USB circuitry) is poorly designed, NOT properly islolated / clearly split. Steinberg / Yamaha hardware engineers please check carefully and response.

Noise in 0 to 20 Hz specturm is not easily spot or audible by normal person but at -60db range certainly affecting audio clarity. Since I have found a work-around for issue, and its performance is excellent now, I am keeping the product.

Hi hgtan,
Thank you so much for your ingenious idea!
Yesterday, just one minute before I was about to return this humming and pulsating device, I took heart and assembled an adapter just as you suggested in your post. As a power supply, I used an old 5V USB-Hub power adaptor.
Now the noisefloor is totally acceptable!
It would be great, if an adaptor like this could be bought, but I think it’s to special…
Again, thanks a lot!!!
Oliver

In my own experience, If you are using speakers for you monitors (as opposed to headphones) the same grounding problem can be eliminated by using balanced cables from the unit to the speakers. Of course, you have to have monitors that have balanced inputs.

Ingenious idea! Portability is worthless, if performance suffers. I’d gladly pay extra for dedicated power supplies and premium jacks.

Hi Oliver,

I’m glad that you found the solution useful.
I wish Steinberg has learned from this lesson and make a better product in the future.

Regards,

HG

Hi Steve,

These are two different issues. It is more difficult to expect a better results in your example. In case of external USB audio box, since the computer communication to the external box only digitally and the box connected to amplifier only in analog way, a properly design (with good seperation of digital and analog ground, a quiet noise floor of below -100db is achievable.

If you’re using the product on the road to capture a band live for instance you wouldn’t have monitors connected - balanced or not! I think the only acceptable solution would be for a power adapter and cable to be designed and shipped for existing users (free) and the new units redesigned as outlined by the poster. I’ll remind you of Steinberg’s own marketing blurb for this product:- "Highlighting two industry-acclaimed D-PRE microphone preamps, class-leading 24-bit/192 kHz converters and a rock- solid metal housing, the UR22 audio and MIDI interface provides pure sound wherever you are. With a dedicated high- impedance switch, a separate headphones jack and phantom power supply, this portable 2-in/2-out device is the perfect choice for mobile musicians, touring DJs and everyone in between."

Note “portable” and “mobile” why would you be dragging a pair of balanced monitors around with you? Also note the claim of “pure sound” - pure it certainly isn’t with such a terrible noise floor in USB-only operation. Wouldn’t it be refreshing if manufacturers admit they’ve got it wrong occasionally and make good at their own expense?

When I have to do outdoor recording, I replace the power adaptor with a good quality high capacity power banK.

Good points, Peppapig

@peppapig I’m simply stating my experience, not defending or approving. People will find this thread through a web search, so it might help someone my post applies to.

hello hgtan,

thank you for posting and sharing how to solve this problem

question:
if i understand correctly
you cut 2 wires (+ and - ) on a USB2 cable between the computer and UR22
leaving only data wires to communicate since USB 2 has 4 wires

it is not clear to me how does UR get its power now ?

can you clear that out and do picture of your set
or draw a diagram of connecting UR22 (now without power comning from computer) to
-computer
-external USB hub

also

does this cutting regard USB 2 only?
as my computer is USB 3 …has 6 pins instead of 4
what would be the “cutting” scenario regarding USB 3
or
is it possible to use USB2 cable on USB3 lap top
and cut only 2 ( + and - ) of 4 existing wires
without any problems

thank you again for the post
it has brought a new perspective on importance of power supply
all good audio gear
has strong trafo’s

regards

4heli

Hi 4heli,

I’ve commitment during next few days, will provide what request in 10 days time.
As far as I know, UR22 driver do not like USB-3.

Regards,

HG

hi hgtan
been away for some time
thank your for this answer
and future info
all the best
4heli


Sorry my other urgent matter took longer than expected.
Here are two photos showing actual connection.

hi hgtan
thanks again

it is something steiberg might consider regarding future products
which rely solely on usb power from computer itself

i was always a bit susspicious regarding the amount of peak to peak voltage required from a mic per inside hardware
to react quickly and with enough power to complement transiens

this might look simple
but i think it is a very clever and thinked over improovement

regards and all the best
4heli

Hi 4heli,

USB port in general should be able to provide at least 5V 500mA supply.

The electek mic need to be biased by a +48V phantom supply with very low current. This is achieved by using a DC-DC converter.

To achieve a 0dbm (2.2Vpp on 600 ohm load) with sufficient headroom, said +3db, then the output amplifier should be powered by +/- 5V. This can also be achieved by using a DC-DC converter.

Actually UR-22 has done all these and my test proved that the USB 5V 500mA supply is sufficient.

The low frequency noise is due to poor grounding design - schematic circuit and /or PCB layout.

I’m really surprised that Steinberg / Yamahi is being so quiet on this matter!

Per this video, the problem can be solved with a hum eliminator. Do I need to buy one?

https://youtu.be/jSA2F1AwboU

Steinberg still hasn’t gotten back to me. It’s been three days.

Hello,

Since I have been reading with some attention the topic a question.

Would it be possible to use the UR22 only with a 5V USB PowerSupply and a USB cable, of which the datacables have been interrupted?? So not connected with a computer??

AL

PS I would also want to use the UR22 to only listen to what I am playing, or playing along with music, without recording it and MOST preferably, WITHOUT having to switch on my computer !!!