• Registered: 2011-03-18
  • Posts: 5

Topic: OctaMic II max gain?

I have compared the mic preamps in my FF UC with my OctaMic II. Using two AKG 414s, and listening to a quiet sound source, I found that 60dB gain in the OctaMic corresponds to 50dB gain in the UC.

I switch the cables, tried different channels in the OctaMic but the difference was the same.
The OctaMic is connected via ADAT at 41,1kHz. As an extra check I also connected the OctaMic with a TRS-cable from line out to line-in in the UC. The level stayed the same (I'm using +4dB reference level on both the UC and the OctaMic).

So, who is telling the truth? Is max gain in the OctaMic really 50 dB or is max gain in the UC 70 dB? Or am I missing something? That would not be the first time…

Regards,
Stefan

2 Reply by MC

  • MC
  • MC
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  • From: Germany/Thailand
  • Registered: 2007-04-06
  • Posts: 24,813

Re: OctaMic II max gain?

The gain is defined in reference to either 0 dBFS (full level at the AD-conversion) or between analog input and output level. In the UC we use a chip with a defined gain, but the overall design (the adaptation to the ADC) makes the gain values different between units of different manufacturers.

'Gain' here is not based on a fixed input level, so your comparison is invalid. See more info in the Tech Specs within the manuals.

Regards
Matthias Carstens
RME

MC's Website

  • Registered: 2011-03-18
  • Posts: 5

Re: OctaMic II max gain?

Thank you Matthias. I understand, I think:
The digital level, as seen in TotalMix, depends not only on the size of the signal after the preamp  (input signal times gain) but also on the level at which the ADC reaches 0 dBFS. More headroom in the ADC equals less perceived signal gain.

Regards
Stefan