• Registered: 2014-09-03
  • Posts: 3

Topic: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

Hi guys,

I tried a couple of searches but couldn't find any similar topics, so apologies if this has been addressed previously.

I've noticed that the level indicators in Totalmix for Analogue Inputs 1 + 2 are always changing. I currently have no cables connected to the inputs. Analogue Outs 1+2 are going to Yamaha HS7 monitors.

I took a screen capture of Totalmix to demonstrate the issue and posted it to youtube. Link below:

http://youtu.be/cZ7njUCdou4

Is this behaviour normal? Any idea what could be causing this?

I've also recently noticed that my monitors are emitting digital noise. When I unplug the XLR cables from the monitors the digital noise stops and all I can hear is a small bit of white noise. Do you think they two issues are related?

Thanks,

Stephen

RME Babyface
iMac: 2.8GHz i7, 8GB RAM.
OSX: 10.8.5

2 Reply by Timur Born (edited by Timur Born 2014-09-03 22:25:27)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

That's normal. What you see is the peak of the noise floor of the AD converters, and since noise is random in nature it's fluctuating. When you switch meters from peak to RMS you will see it settle down, because RMS is averaging the random levels out.

The noise you hear from your monitors should be unrelated to this. What you likely hear there likely is computer related noise, from changing CPU power states (moving the mouse) and especially heavy GPU load. This kind of noise travels over the ground of the cables from the computer to the interface and then the monitor speakers. There it creates an audible signal with the true 0 volt earth line of your powered speakers 3-prong plug. If that's what is happening for you then one way to get rid of it is to change the wiring of your XLR cables to lift the shield. There are some ready-made adapters and lots of images on the web showing how to wire the plugs.

  • Registered: 2014-09-03
  • Posts: 3

Re: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

Thank you for the speedy reply Timur. Would it be normal for the noise floor peaks to increase when an input is connected to a condenser mic without phantom power being active? I tend to leave a condenser connected to AN1 for convenience. I've noticed that the fluctuations are a lot higher when I have it connected.

RME Babyface
iMac: 2.8GHz i7, 8GB RAM.
OSX: 10.8.5
  • Registered: 2008-01-01
  • Posts: 3,025

Re: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

I edited the post: I meant wiring to lift the *shield* of the XLR cable, not the ground.

  • Registered: 2014-09-03
  • Posts: 3

Re: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

So I could insert something like this between the Babyface and the monitors?

http://www.sweetwater.com/store/detail/GLT255

RME Babyface
iMac: 2.8GHz i7, 8GB RAM.
OSX: 10.8.5

6 Reply by Timur Born (edited by Timur Born 2014-09-04 08:37:56)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: Babyface analogue input 1+2 have fluctuating meter values in Totalmix

If this adapter breaks pin 1, which is likely but not documented in the description, then it should help. Try the adapter on both sides (interface or speakers) and use what works best. Alternatively the adapter may introduce a capacitor, which may or may not work, depending on the frequency of the noise.

There are modules that physically decouple ground via winding instead, but these may alter the audio signal. Palmer offers both kinds, either as "Line Isolation Box" or as DI boxes. There are cheaper ones by Behringer and others available. But frankly, I'd just get rid of pin 1 and likely be good with it.

If you don't want to mess with cabling an alternative but more expensive solution is to use two interfaces. The first interface is connected to the computer and the second interface is connected to the speakers. In between the two interfaces you use an optical connection (ADAT or SPDIF), which by its very natures does not couples grounding between the devices. That's what I am using currently, also because it allows me to use the Babyface as a big volume know while using the UFX for everything else.

Your speaker noise problem likely is not an RF problem, but the computer mainboard producing noise on its ground lines. But the "cable/mic acting as an RF antenna" might be the source of your "mic without phantom power connected" observation. Others may know more about this than I do.

Here is a older post on Rane's web-site that explains the pin 1 shielding problem, including a mic example: http://www.rane.com/note165.html