• Registered: 2011-08-19
  • Posts: 10

Topic: Noise on Babyface Balanced Outs

Hi,

I recently purchased a Babyface and I am very happy with it. However, upon connecting it to my AE22 active monitors, I heard a low level hum. It sounded very much like mains hum so I spent a while testing to try and eliminate any ground loops. After a while of doing this I happened to notice that the hum goes away if I unscrewed the breakout cable and wiggled it a bit. The hum seems to go away as long as the break out cable isn't plugged in too tightly. Has anyone else had a similar experience and found a fix? Could it be that I have a faulty Babyface or breakout cable?

Thanks,

David.

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

I found this post which seems like a similar symptom to mine. I have therefore got in touch with the dealer and they have taken it back to investigate the issue.

  • Registered: 2011-08-09
  • Posts: 17

Re: Noise on Babyface Balanced Outs

This seems a ground loop problem. Babyface analog inputs and outputs are not true isolated although balanced (servo balanced, no isolation transformers) therefore more or less affected by the ground loop problem depending on wiring conditions. If that happends, I would check whether all devices connected to Babyface are using the same power point (power supply with earth connection). those devices have no earth connection may need to be grounded externally (e.g. some laptop adapters have no earth connection but using switch mode adapters which has very high inductive voltage on their case!
The other things I would look at are whether the devices connected to Babyface have balanced outputs or inputs, if not, make sure thery are connected as the BFF manual and the impedances are matched. I've found even I've got everything right, unbalanced analog input to BFF would raise the noise foor as much as 10 dB to about -85dB. Adding a isolation transformer will see the noise level drop by that amount immediately.

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

Thanks for the advice. Whilst I was testing I reduced the setup right down to the following:
- iMac connected to Babyface with supplied USB cable
- Babyface connected to a single active monitor (AE22) via the breakout cable (without the extension) and a single balanced XLR lead
- Active monitor connected to the same dual power socket as the iMac

I tried disconnecting the ground at the AE22 end of the XLR lead.

It was when I decided to try with the extension cable that I noticed that "wiggling" the breakout cable could make the noise go away or come back again. When the noise is not there it is very quiet indeed.

  • From: Melbourne, Australia
  • Registered: 2007-05-16
  • Posts: 495

Re: Noise on Babyface Balanced Outs

I experienced similar issues from new with BabyFace connections via the breakout (mic ins and headphone out) when first used earlier this year.  It was more emphasised when using the extender.

Assuming possible contamination on the connector pins, I carefully inserted and removed the breakout several times, and the problem seemed to be reduced.  Main use of the BabyFace since has been with the ADAT connection and the on-board headphone socket, and the problem hasn't been observed since (I am continue to use the FF400 for most work) except for some apparent MIDI related low-level noise on the output (MIDI being used to control a Micstacy).

One possible cause may be that some inadvertent contamination of the plugs/sockets occurred in production (occurred straight out of the plastic wrapper), and judicious use of contact cleaner might solve the problem.

De gustibus - et sonus - non est disputandum
  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

A little update for those who are interested:

The dealer took the unit back and, at first, couldn't reproduce the fault. However with a bit of persistence they managed to experience the same intermittent hum. They therefore exchanged it for a new unit.

I have just picked it up and thought I would try it out straight away. I connected everything up and screwed the breakout cable in reasonably tightly. It all worked and sounded great with absolutely no hum.

However, just to be sure I tried wiggling the breakout cable a bit and, sure enough, I could get the hum to return. It is much better and it is harder to make the fault appear however it does still seem to me that there is something not quite right. Probably OK at the moment but I am worried about whether or not it will get worse. Such a shame, because when it works it sounds great.

It seems to me that there may be something about the design of the 9-way/breakout cable which is causing this issue so am wondering if it would be better to exchange the unit for something which doesn't use a breakout cable (maybe the RME Fireface UC or a similar product from another manufacturer).

  • Registered: 2011-08-09
  • Posts: 17

Re: Noise on Babyface Balanced Outs

I've seen in this forum that iMac seems to get the ground loop or interference problem more often. One way to prove this is if you can use a different PCs (power adapter must have a ground lead) just to power the BFF to see if the issue is resolved. Has your iMac got a ground lead ? Other alternative may be trying a quality active USB hub to power the BFF?

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

Thanks again for your advice. The iMac does have a ground on the power lead. One of my previous tests though was to power the Babyface from a USB power adaptor in order to take the iMac out of the equation. The noise issue was exactly the same.

What I don't understand is how the problem can be intermittent depending on the exact position of the breakout cable. Surely if it was a ground loop issue and all the connections are being made correctly then it would hum all the time?

9 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 25,599

Re: Noise on Babyface Balanced Outs

DavidDaly wrote:

The iMac does have a ground on the power lead. One of my previous tests though was to power the Babyface from a USB power adaptor in order to take the iMac out of the equation. The noise issue was exactly the same.

Sure, because you suffer from a simple ground loop, which does not get solved by using another power supply, only by breaking up the grounds. There is nothing wrong with the BF or the breakout cable. Remove the basic grounding problem and wiggling the breakout cable does no longer make a dfference...

>- Babyface connected to a single active monitor (AE22) via the breakout cable (without the extension) and a single balanced XLR lead

Here you have it: simply remove the ground connection on the XLR cable on one side - problem solved.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

Hi Matthias,

Thanks for the response. However please note what I posted earlier:

I tried disconnecting the ground at the AE22 end of the XLR lead.

I have already tried to break any possible ground loop by disconnecting the ground on the connection between the Babyface and my monitor.

  • Registered: 2011-07-20
  • Posts: 12

Re: Noise on Babyface Balanced Outs

I made a test ... only babyface + laptop (working with battery) --> http://www.rme-audio.de/forum/viewtopic … 711#p60711

Ground noise !!!!!!

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

OK - I've carried out a few more tests. I have setup the replacement Babyface and breakout cable. Screwing the breakout cable in to the Babyface reasonably tightly it seems that everything is fine. If I unscrew the BO cable and wiggle it I can get the noise to come back. However I think this was just because some pins were not always making contact as I moved (and, having checked the pin-outs and position of the cable when it happened this still makes sense).

So I now think that whilst the first Babyface/BO cable was almost certainly faulty (as that noise got worse when you tightened up the screws) I think this one is probably fine.

As a side note, I tried disconnecting the earth in the XLR again and this actually added quite a lot of noise.

13 Reply by MC

  • MC
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  • Registered: 2007-04-06
  • Posts: 25,599

Re: Noise on Babyface Balanced Outs

DavidDaly wrote:

Hi Matthias,

Thanks for the response. However please note what I posted earlier:

I tried disconnecting the ground at the AE22 end of the XLR lead.

I have already tried to break any possible ground loop by disconnecting the ground on the connection between the Babyface and my monitor.

Sorry, I missed that one.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2011-08-09
  • Posts: 17

Re: Noise on Babyface Balanced Outs

I'm thinking in order to isolate the problem, we may try to take the AE22 out of the equation first, instead, try a headphone to see if the problem still persists. AE22 has amplifiers in it and I believe it uses servo balance input as well, that adds the noise susceptibility.

The other issue is the BFF's power supply. Even you have used a active USB hub to power it, I still suspect the power is not clean. Is the power adapter for the hub 2 pin or 3 pin? some adapters even have 3 pins still emit switching noise so the best is to use a traditional transformer type regulated dc power supply or use a transformer only AC power supply for BFF.

When your hands touch or near the system and the noise level changes, that's a indication the whole ground is not wired properly.

  • Registered: 2011-08-19
  • Posts: 10

Re: Noise on Babyface Balanced Outs

Having spent a few days with the Babyface now I can confirm that this must have been a fault with the first unit (either the Babyface or the breakout cable). The replacement has not given me any issues and there is no low level hum.

Although I appreciate that many would suspect the original problem was a ground loop issue, the fact that this new unit has resolved it together with the fact that the dealer was able to reproduce the fault, makes me fairly certain it was a fault with the Babyface or breakout cable.

Anyway - now that it is working nicely I have to say it is brilliant. Very reliable, good sound quality and works really well at low latencies!

  • From: Germany
  • Registered: 2007-04-10
  • Posts: 9,778

Re: Noise on Babyface Balanced Outs

Thanks for the positive feedback.


Regards
Daniel Fuchs
RME

Regards
Daniel Fuchs
RME

RME Support's Website

17 Reply by ywan03 (edited by ywan03 2011-08-31 16:30:24)

  • Registered: 2011-08-09
  • Posts: 17

Re: Noise on Babyface Balanced Outs

Good to hear that.

Can RME verify that by changing the analog input from balance to unbalance, the noise floor (dynamic range) will raise by 10 dB.  With an isolation transformer connected in balance mode, I get as good as the theory calculated so BFF is perfect. But without the transformer, the signal source is unbalanced, I've got 10 dB worse off in dynamic range. I'm talking about very low noise(-90dbm) so may not be heard by ears but shown up on the instrument.