• From: Sweden
  • Registered: 2008-03-14
  • Posts: 149

Topic: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

Hi I have a problem with how the RME drivers report the recording level to logic.
I know there isn't any over 0 dBfs in digital audio recording but there must be some way to report this overloads.

Here's a picture of Totalmix reporting the overload while Logic stays at 0.0 dB

http://home.mac.se/makingsound/logicpro_se/over_test_rme.png

You can clearly see the overload in Totalmix but that will fade away after a second so there is no way of knowing
if the signal was recorded correctly or not. This would be super handy specially when I'm recording myself.
Logic is showing 0.0 dB, the same as in the Totalmix window BUT i don't get any overload warning.

Here's a picture of my MacBook Pro's internal card overloading using the internal microphone.

http://home.mac.se/makingsound/logicpro_se/over_test_internal.png

You can clearly see that Logic reports an overload of at least 6 dB. Better still, the numerical meter turns red and
will stay red until I click on that area.
It is now very easy to see that I have my Input gain to high and I can now mend it right away.

I know that the theory is that there is no such thing as OVER 0.0 dBfs but there should be a way for the Core Audio
driver to at least send an overload message to the host, in my case Logic. The amount of "dB over 0" is not required.
Clearly the internal internal interface manages to do that.

Is this an implementation that could be done in the future?

RME Fireface UFX
Mac Mini 2.6 GHz 16 GB Ram Areca RAID | MacBook Pro 2,2 GHz 16 GB Ram | OS 10.10.5

2 Reply by viper (edited by viper 2010-03-07 15:14:51)

  • viper
  • AES/EBU artist
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  • Registered: 2008-12-01
  • Posts: 134

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

Hi,
TotalMix at default settings shows possible overload if there are three consecutive 0dBFS samples (as you say in the digital domain there is nothing higher than 0dBFS, so you can't tell if its really an over).
This can be set differently in the "options" -> "Level meter setup" menu.

A more handy way would be using DigiCheck which also has a hold function and many more features.
You might want to check out the oversampling feature which detects inter-sample-peaks that will result in an overload during digital-analog conversion.

But even this feature won't help you when your analog input signal is overloaded.
I guess the reason why Logic shows 6dB in your picture is that the signal might get amplified (and therefore clipped) in the digital domain.

  • From: Italy
  • Registered: 2007-05-17
  • Posts: 94

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

Eric Bradley wrote:

Is this an implementation that could be done in the future?

This is a good idea!!

Fireface 800, MacBook Pro M1Pro, macOS15.1.1, Logic Pro 11.1
  • viper
  • AES/EBU artist
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  • Registered: 2008-12-01
  • Posts: 134

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

If I understand both of you right you would like to have a feature reporting any overload of the A/D-converter to the host...
To my knowledge such a feature would need significant amounts of development/costs and would give you only 0.1dB more SNR.

Right now, if you have a 0dBFS input signal you don't know if its overloaded or just scratching the maximum.
But if you set your maximum level to be not more than -0.1dBFS you are on the safe side (although I would allow some more dB headroom).

So the only plus for such a feature would be the additional 0.1dB in gain and therefore SNR.
Or did I get something wrong?

5 Reply by Eric Bradley (edited by Eric Bradley 2010-03-07 16:47:39)

  • From: Sweden
  • Registered: 2008-03-14
  • Posts: 149

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

viper wrote:

I guess the reason why Logic shows 6dB in your picture is that the signal might get amplified (and therefore clipped) in the digital domain.

Thank you for explaining this.
You are definitely right.
I just tried this with an external preamp connected to my Mac Pro's internal line in and I get the same behavior as in my first example, nothing over 0.0 dB.

It would however be nice if Totalmix could send those overload messages(depending on Totalmix's overload settings) to logic, making
it easier to see.

But maybe this is not possible...

viper wrote:

A more handy way would be using DigiCheck which also has a hold function and many more features.
You might want to check out the oversampling feature which detects inter-sample-peaks that will result in an overload during digital-analog conversion.

I would love to use DigiCheck for this but I'm not sure on how to use it.
Being a OS X user I have not been able to get my head around it.

It would be of great help if you could try to help me setting it up this way.

Thanks Again/ Eric.

RME Fireface UFX
Mac Mini 2.6 GHz 16 GB Ram Areca RAID | MacBook Pro 2,2 GHz 16 GB Ram | OS 10.10.5

6 Reply by Eric Bradley (edited by Eric Bradley 2010-03-07 16:40:40)

  • From: Sweden
  • Registered: 2008-03-14
  • Posts: 149

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

viper wrote:

(although I would allow some more dB headroom).

I usually go for -15 when tracking so it's not a big deal, but it would certainly make it easier to see when things go wrong.

RME Fireface UFX
Mac Mini 2.6 GHz 16 GB Ram Areca RAID | MacBook Pro 2,2 GHz 16 GB Ram | OS 10.10.5
  • viper
  • AES/EBU artist
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  • Registered: 2008-12-01
  • Posts: 134

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

Eric Bradley wrote:

It would however be nice if Totalmix could send those overload messages(depending on Totalmix's overload settings) to logic, making
it easier to see.

But maybe this is not possible...

Well - as the level is sent to your host - this is almost it. The only question is how the host handles possible overs.
But I agree, that it would be nice to have some kind of standard - as every tool seems to have it's own way to handle this.
Exactly this, and a lack of an oversampling feature forces me to use DC in parallel to WaveLab.


Eric Bradley wrote:

I would love to use DigiCheck for this but I'm not sure on how to use it.
Being a OS X user I have not been able to get my head around it.

It would be of great help if you could try to help me setting it up this way.

Unfortunately (at least for you wink) I don't have a Mac to check this out. As far as I know there are some features lacking in the Mac version of DC, but don't ask me which ones.

May be the "Windows way" helps you to set it up on your Mac as well:
- When DC is installed and running select "function" -> "4-Bar Level Meter" (or any other meter)
- Then set your inputs with "I/O" panel
- Now push the settings button (next to "I/O" or via "options" -> "settings" or F2 key). There you can select "infinite hold" to hold the maximum values, FSC for ovr to select the number of consecutive samples needed to show an overload or select the "OVS" button to turn the oversampling function on.

Regards, viper

  • rwil
  • rwil
  • S/Mux specialist
  • Offline
  • From: Montreal
  • Registered: 2007-05-01
  • Posts: 343

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

Looking to your pics I can see that your input is having an ambiance noise reduction enabled!? Maybe only that feature could reduce slightly the input post RME's input and explain the difference. Otherwise it is a well know behavior since every audio engine may have their way to perform the metering.
Try to disable any reduction feature into Logic, and adjust the FSC for ovr in Totlamix to adjust the number of consecutive samples until a good match. Still that I never drive as hot my RME inputs!

rw

Asus P8Z77-V LE Plus_i7-3770K-3.9GHz_DDR3-16GB_Win8.1-x64_TI FW PCI_1xUAD-2_Cubase 4&7

9 Reply by Eric Bradley (edited by Eric Bradley 2010-03-07 23:46:49)

  • From: Sweden
  • Registered: 2008-03-14
  • Posts: 149

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

viper wrote:

May be the "Windows way" helps you to set it up on your Mac as well:
- When DC is installed and running select "function" -> "4-Bar Level Meter" (or any other meter)
- Then set your inputs with "I/O" panel
- Now push the settings button (next to "I/O" or via "options" -> "settings" or F2 key). There you can select "infinite hold" to hold the maximum values, FSC for ovr to select the number of consecutive samples needed to show an overload or select the "OVS" button to turn the oversampling function on.

Regards, viper

Thanks for this.
It works really well actually.

DC even made me realize that one of my cables was faulty and was actually emitting too much noise.
I will use this method from now on.

RME Fireface UFX
Mac Mini 2.6 GHz 16 GB Ram Areca RAID | MacBook Pro 2,2 GHz 16 GB Ram | OS 10.10.5
  • From: Sweden
  • Registered: 2008-03-14
  • Posts: 149

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

rwil wrote:

Looking to your pics I can see that your input is having an ambiance noise reduction enabled!? Maybe only that feature could reduce slightly the input post RME's input and explain the difference. Otherwise it is a well know behavior since every audio engine may have their way to perform the metering.
Try to disable any reduction feature into Logic, and adjust the FSC for ovr in Totlamix to adjust the number of consecutive samples until a good match. Still that I never drive as hot my RME inputs!

rw

That was the picture of the internal MacBook Pro interface.
It will not matter if the ambient reduction is on. The meter will still show the over 0.0 dB.
I think viper nailed it when suggesting that the signal might get amplified in the digital domain.

RME Fireface UFX
Mac Mini 2.6 GHz 16 GB Ram Areca RAID | MacBook Pro 2,2 GHz 16 GB Ram | OS 10.10.5

11 Reply by MC

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

Re: Problem with dBfs over 0 in with Fireface 800 drivers and Logic.

I am not aware of any signal path to communicate level measurements to the Logic mixer so that they get displayed there. Same for any other program out there.

Regards
Matthias Carstens
RME

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