1 Topic by marioisaac (edited by marioisaac 2024-03-28 20:44:52)

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Topic: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

Hi guys, I bought an used Fireface UC and the Mic Input 1 does not receive signal from the microphone.

The Mic Input 2 does receive a signal from the mic, the input gain is set at 50, the noise level is at -48 dbfs, and the mic signal when talking or singing reaches -6dbfs, so that's a 42db signal to noise ratio.

Is this an expected SNR?

I have tried with a dynamic (Shure C606) and a condenser (Sonarworks) microphone, and I get similar results.

Is there something wrong with my mics, cables, or fireface UC, or is this expected behaviour?

2 Reply by ramses (edited by ramses 2024-03-28 21:03:52)

  • ramses
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

Sorry, but missing information.

> Hi guys, I bought an used Fireface UC and the Mic Input 1 does not receive signal from the microphone.

What mic?
Does it perhaps need phantom power (48V)?
Careful, some ribbon mics can be damaged by phantom power.

Could also be a routing issue, do both mic inputs route to the same output for monitoring?

BR Ramses - UFX III, 12Mic, XTC, ADI-2 Pro FS R BE, RayDAT, X10SRi-F, E5-1680v4, Win10Pro22H2, Cub14
  • Registered: 2024-03-28
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

I don't have both mic inputs occupied. I just tested mic1 with both microphones and it doesn't work; its just noise, it doesn't receive a signal. I guess this is faulty.

I am curious to know what is a decent SNR to be expected from a decent microphone/soundcard combo. Nothing fancy, just decent.

These are the microphones I am using:
Shure C606 (dynamic)
https://www.inta-audio.com/recording-c5 … hone-p2288

Sonarworks SoundID Reference Measurement Microphone (condenser)
https://store.sonarworks.com/products/s … microphone

For the dynamic mic phantom power is off; if I plug the condenser mic, I set the input gain down, plug the mic, and then turn on phantom power, then turn up the gain. To my knowledge it powers correctly the condenser mic.

Monitoring is off, the signal goes directly into DAW: Ableton, Bitwig, and Cubase.

The mics are connected via XLR cable.

  • waedi
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

You may provide a small MP3 from this recording ?

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

Sure, here is a mic recording file:
https://file.io/0hZKrw7BgQWb

6 Reply by waedi (edited by waedi 2024-03-28 23:57:29)

  • waedi
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

There is a repeating peak and the rumbling noise sounds like a washing machine.
Is there a washing machine near or a ventilator ?
This is input 2, right ?
And input 1 is all silent, no signal at all ?
What is the firmware number and the driver number ?


https://i.ibb.co/QFPrCDw/Bildschirmfoto-2024-03-28-um-23-46-21.png

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue

7 Reply by marioisaac (edited by marioisaac 2024-03-29 01:09:57)

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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

That was input2, and a ventilator was on.
Input1 is dead, just noisefloor, no mic signal at all, singing or talking on the mic does not even change the noisefloor level.
Input1 and Input2 gain levels are set at 50, and their noisefloor RMS reads -77 dbfs and peaks at -67 dbfs, WITHOUT any mic plugged in.

If a mic is plugged into input2 and the mic is OFF the noisefloor RMS reads -90 dbfs and peaks at -80 dbfs
If a mic is plugged into input2 and the mic is ON the noisefloor RMS reads -63 dbfs and peaks at -53 dbfs

Hardware revision: 127
Driver version: 1.249

Here are links for new recordings on input1 and input2:
https://file.io/2gpj58Ln2Tci

I want to add that any slight movement of the mics (dynamic or condenser) while recording results in sudden spikes in volume, maybe this is due to a cable? This is evident at the end of input2 recording.

By the way which software are you using to analyze the audio; those repeating peaks are pretty evident on that screenshot.

I appreciate your help on this.

Thank you

  • waedi
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

https://i.ibb.co/cNCzFMD/Bildschirmfoto-2024-03-29-um-01-52-45.png

It is in Reaper, I just use the Limiter with a lot of compression to see more details.
The noise-floor on input 2 seems to be something from outside, not produced by the interface.
There is again this repeated tick tack noise.
The noise from input 1 is more or less white noise without any pattern, could be a defective input.
And the cable obvious is in bad shape.
Did you bought the interface used for cheap ?

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

I turned off the ventilator so I have no idea what that tick tack noise could be.
So input 2 seems to be working well?
What SNR is decent for mic recording? When people mention SNR they refer to RMS signal ratio to RMS noise level ratio right?
I bought it for $750.

  • waedi
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

That price is a bit high but it's a very good interface and worth to maintain.
If it would be mine, I would contact service and ask for repair.
Email : support@rme-audio.com

M1-Sequoia, Madiface Pro, Digiface USB, Babyface silver and blue
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Re: Fireface UC Microphone Input Expected Signal-to-Noise Ratio

Thank you for your help Waedi, I'll contact support.