• Registered: 2018-08-14
  • Posts: 3

Topic: Implications of +13 and +19

Hi,

I have UFX III as well as ADI-2 pro and am not sure when to use +13 vs +19 (vs +24 ADI).  I'm not sure which is optimal from a SNR and distortion perspective.  Here are my primary use cases:
1.  Sending audio from DAW into 500 series gear and returning.  In this case I send out and return at +19dBU because the extra level really helps drive some of the analog gear the way I want it to so I suspect that is optimal
2.  Using clean outboard or onboard mic preamps I'm really not sure if I should use +13 or +19 for LDC/SDC/Dynamic mics

Here is my thinking ripe for correction.....  I don't know which ADC chips are used but many are ESS for example show ~3.2V for 0dBFS.  So if I'm set say to 19dBU that's about 7V (or do we lose 6dB if signal goes unbalanced?).  I think this means it is getting padded if I'm in the right ballpark with the ADC chip.  Since the output amplification stages of DAC are probably different it is likely really up to the implementation.  I guess the mic question will come down to the mic pre SNR at the required drive level and probably can't be easily answered...

Anyways, I'd love to understand more or at a minimum have a good rule of thumb smile

2 Reply by ramses (edited by ramses 2024-03-23 09:49:00)

  • ramses
  • DAW Mastermind
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  • Registered: 2012-10-14
  • Posts: 12,091

Re: Implications of +13 and +19

The goal is to send out a signal level (peak level) with high SNR and dynamics, but without overloading the analog input on the other side to avoid distortion.

When selecting the reference level, you must therefore be guided by the possibilities of the input on the other side.

Careful when connecting active monitors. Here you would need attenuators to fix "level mismatches" first.
https://forum.rme-audio.de/viewtopic.php?id=25399
Otherwise, the volume level would be much too loud if the output fader in TM FX is close or at 0 dB.
If you have no such attenuator, then choose on your active monitor the lowest sensitivity and on the recording interface level the lowest reference level. Even then, it is much likelier that you might need to turn down the output fader significantly.
More information, thoughts about this, see (*) below.

The data for SNR (dynamic range) per reference level can be found in the technical section of every RME manual.

Use Acrobat Reader's search function to look for certain keywords like "reference" or "level" or "+4" or "+19, then you will find the interesting sections automatically.

(*) Some active monitors have a potentiometer-controlled input sensitivity, which in the best case reduces the input volume a little more than the "consumer level". My monitors from Geithain (RL906) are an example of this. But even if I set the pots to the lowest input sensitivity, the volume is still too loud even at the lowest reference level of 0 dB.

Using the ADI-2 Pro with "auto ref level" activated, I operate the monitors for listening to music between -30 - -45 dB @+4 dBu reference level. Very quietly next to work as quiet background music. Dynamic loudness helps enormously here to prevent the music signal from flattening out too much.

When listening, I rarely use louder than -20 dB @+13 dBu, very rarely levels up to -14 dB @+19 dBu.

I could also use an attenuator on the active monitor here, but I'm not concerned about the few dB SNR when monitoring, the priority here is that ears and equipment remain intact. You can't achieve the highest SNR or the highest dynamic range anyway.

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub13