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Optical input with zero gain (NH900)?

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etotheix

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When using the optical input, does anyone know what record level on the NH900 gives a neutral result -- no gain, no attenuation? (I definitely don't want to use AGC because I want to preserve the all dynamics of the original recording.)

Seems like this should be listed in the manual but I can't find anything. I tried 30 but got lots of clipping; so obviously 30 is not zero gain. I experimented with some other settings and got a fine recording, but I'd really like to know where zero gain is. Anybody?

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Oooh, so you're thinking AGC is 0db gain for optical-in? That would be great! I was thinking AGC was AGC and that for both optical & line-in, AGC would tweak levels as you record the same as with the mic-in AGC. Have you done very careful comparisons? Like using a source that varies levels a lot -- say a classical piece that is soft for a long time and then gets really loud?

Do you think that for analog line-in, AGC might be a constant 0db too? I kinda half remember doing some experiments that made me think is wasn't. But, if the analog line-in AGC was a constant 0db, then couldn't you use a mic with a preamp at line-in and never again have to worry about resetting the recorder to manual when recording live? That would be very good!

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  • 3 weeks later...

  etotheix said:
When using the optical input, does anyone know what record level on the NH900 gives a neutral result -- no gain, no attenuation? (I definitely don't want to use AGC because I want to preserve the all dynamics of the original recording.)

Seems like this should be listed in the manual but I can't find anything. I tried 30 but got lots of clipping; so obviously 30 is not zero gain. I experimented with some other settings and got a fine recording, but I'd really like to know where zero gain is. Anybody?

AGC is only done on the analog inputs. if you record from digital this means unity gain. they only didn't spend a own menu item for this. The manual level is only useful if you have a already digital signal from a weak source or if you want to fade out/in a digital recording. I've tried it with the spdif out from a digital mixer.

with "AGC", the levels were the same. with manual level i thought unity gain was at 15/30 and 30/30 is about +12db.

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How I figured out that 18/30 was "unity" [actually slightly below it]:

1) I played a loosely-calibrated -12dBfs signal [output by my sound card as -12dBVU] and matched the levels on the HiMD so that the hash mark on the scale was where -12 sat. I then repeated this with -6dBfs and 0dBfs signals to see how close it was. It's out by about -1.5dB at 18/30 according to my exquipment.

This would be more accurately done with a signal generator and oscilliscope, but alas, I have neither.

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