1 Topic by ARNK (edited by ARNK 2018-01-20 22:35:47)

  • ARNK
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Topic: Input Sensitivity Settings - Rear Analog Inputs

From RME Fireface UFX Manual, page 22 section 8.6 Analog Recording

"The input sensitivity of the rear inputs can be changed in three steps in TotalMix (Input Channel Settings, Level), assuring the highest signal to noise ratio will be achieved. A further optimization can be achieved by adjusting the source itself. Raise the source’s output level until the peak level meters in TotalMix reach about –3 dB."

Sorry for the daft question, but with regard to "Input Channel Settings, Level"...

I'm using a Dave Smith Pro 2 synthesizer with the volume knob set to max.

Questions:

1. The only way to reach about -3 dB is to adjust the volume knob on the synthesizer on a per patch basis (that is, per factory patch). I have an easier time for most patches reaching -3 dB using the +4dBu level. That being said, even after I adjust the volume knob on the synthesizer, the signal according to the RME interface clips starting closer to -7 dB? I don't see the meters go below -6 dB at all. Why might the meters go into the red when I'm nowhere close to 0 dB?

2. With the level in TotalMix set to "Lo Gain", patches certainly clip/distort less overall even with volume on the synth set to 100%, sounds come nowhere near -3 dB. They range from say -25 dB to around -7dB (again depending on the factory patch played). Is it common practice to leave the level knob on your source to max volume, or in general are you always adjusting it for the proper input level depending on the sounds you're working with?

Kind regards,
ARNK

2 Reply by MC

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Re: Input Sensitivity Settings - Rear Analog Inputs

I am a bit confused as you not clearyl tell where you get the level information. Let's look at the input level meters of TotalMix, and the channel where the Pro 2 comes in (which channel)?

> the signal according to the RME interface clips starting closer to -7 dB?

That sounds like you look at RMS meter levels, wich are like an average level. Peaks included are much higher. In TotalMix you see both simultaneously, and can change the text above the level meters to show the current RMS or peak value.

Regards
Matthias Carstens
RME

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3 Reply by ARNK (edited by ARNK 2018-01-21 04:30:32)

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Re: Input Sensitivity Settings - Rear Analog Inputs

MC wrote:

I am a bit confused as you not clearyl tell where you get the level information. Let's look at the input level meters of TotalMix, and the channel where the Pro 2 comes in (which channel)?

> the signal according to the RME interface clips starting closer to -7 dB?

That sounds like you look at RMS meter levels, wich are like an average level. Peaks included are much higher. In TotalMix you see both simultaneously, and can change the text above the level meters to show the current RMS or peak value.

Hi MC, thank you for taking the time to respond.

If you have moment, please either Open or Download the following screenshot:

https://ln.sync.com/dl/b3d599540/bjjgr7 … j-tzqrmdb8

It's a rather large/wide picture so you may need to zoom in around 175% or 200% to clearly see the details.

Quick overview of the picture:

  • Here I am using Cubase Pro 9.5

  • A DSI Pro 2 Synthesizer set to max volume

  • DIGICheck (4-Bar Level Meter)

  • TotalMix FX

  • Cubase Level Meter + Cubase Full Mixer Level View

  • iZotope INSIGHT

1. As you can see starting at the far left channel, Stereo Input for Pro 2 > Pro 2 Channel > Cubase Stereo Out.

2. Next to that, you'll see the DIGICheck meters, the TotalMix FX Interface and then the Main Level Meter in Cubase.

3. On the right side of the image, you'll see the full mixer in Cubase again and an instance of iZotope INSIGHT next to it.

Then while this audio was playing, I took a few snaps of what was happening with the meters on the RME Fireface UFX at the same time:

https://ln.sync.com/dl/a5ebfa590/rwxck4 … m-smdmmtyj
https://ln.sync.com/dl/a4154bbb0/btr4ps … u-pfr9bwgg
https://ln.sync.com/dl/6d102d390/d4h7pm … p-fs29wi43

As you can see, the meters on the interface change from solid yellow to red, whereas in Cubase, DIGICheck and TotalMix there's no clipping or peaks touching 0 dB at any point.

PLEASE NOTE: Clearly I'm just starting out on my path to understanding proper recording levels, gain staging and metering. I fully expect to be told I'm going about this or that the wrong way, or am looking at things the wrong way.

For instance:

  • At first glance, does the input level in Cubase appear relatively normal? The other meters?

  • Is it preferable to simply adjust the main volume on the sound source when things get too hot?

  • Why is the main volume level from the source the only way to tame the meters on the RME interface itself?

  • While bringing down the fader on the input channel in Cubase changes the meter from red to green on the Analog Out (bottom of the screen), it does nothing to change the clipping of the Audio input level (top of the screen). The only way for the Analog In meter to change from red to green on the interface is to turn down the volume from the source instrument.

That should do for a start. I appreciate any guidance/insight you might have to offer.

Best,
ARNK

4 Reply by MC

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Re: Input Sensitivity Settings - Rear Analog Inputs

- Basically all your level meters show the same levels in Peak and RMS values.

- The threshold for color red is not defined. It will change differently per device and meter. Sometimes the threshold is  adjustable (DIGICheck). So don't look at red, look at the levels. The peaks on the interface also don't reach 0.

- The input level is quite hot, but still ok if this is the hottest patch that you can generate. Otherwise you do need to lower the synth's output volume a bit for some headroom.

> Why is the main volume level from the source the only way to tame the meters on the RME interface itself?

These are hardware level meters that show the input level. The only way to 'tame' them is by changing the hardware ref level to one that fits, or by adjusting the source. Should be quite logical. Any too hot level distorts the ADC. Once distorted you cannot fix the corrupted digital signal by lowering it digitally.

> While bringing down the fader on the input channel in Cubase changes the meter from red to green on the Analog Out (bottom of the screen), it does nothing to change the clipping of the Audio input level (top of the screen). The only way for the Analog In meter to change from red to green on the interface is to turn down the volume from the source instrument.

Yes, and fully logical. Think again... wink

Regards
Matthias Carstens
RME

MC's Website

  • ARNK
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Re: Input Sensitivity Settings - Rear Analog Inputs

Definitely, that's clear now. I appreciate you taking the time out to respond.