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Old March 11th, 2014, 04:39 PM   #1
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A question about unity gain.

Hi everyone.

I was wondering if you would ever set input (Master) faders to anything other than unity? What is the purpose of an adjustable input fader other than to get to the desired 0 dB setting, which is consistently consistent on any given mixer. I know that good pre-amps like on a Sound Devices unit has something like this.

Sorry if this is really basic, but just had me wondering.

Jonathan
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Old March 11th, 2014, 05:37 PM   #2
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Re: A question about unity gain.

Unity is typically no channel amplification or attenuation (aka, boost or cut) to the signal) and used for initial preamp gain/trim adjustment / gain staging. It also could be looked at as a course (preamp gain) and fine (channel fader) adjustment. Some preamps/mixers have Unity notated as 'U', others as '0'.
In the absence of such notation, most would set the fader at around 75% up.
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Old March 11th, 2014, 06:09 PM   #3
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Re: A question about unity gain.

I'll go above Unity if I NEED the extra gain but that is most often my last attempt at getting more volume.

My Master fader normally sits at Unity, Channel fader in question SHOULD be operated between 30 and 70% of full range, depending on loudness required and channel input trim set to facilitate the above setting of Channel gain.

Again, this is a quick-and-dirty explanation based on TYPICAL applications.
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Old March 12th, 2014, 02:35 PM   #4
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Re: A question about unity gain.

Thanks Rick and Shaun.

I was just curious as to why there is even a knob to adjust when it seems like this could be something that is set and calibrated internally at a constant. In other words, why have something that you can adjust when you seldom need to adjust.

I do see your points however.

Just curious.

Jonathan
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Old March 12th, 2014, 03:40 PM   #5
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Re: A question about unity gain.

If you are mixing multiple mikes---say, for a band recording -- it is a useful feature. My procedure -- which may or may not be right for you -- set the mike lnput level to give a good (-12 to -6) level on each source when the fader for that channel is set to unity. This insures enough "meat" to the signal to record well. I then use the individual faders to balance the sources against each other ---- this is a creative use and not a technical one. Say I want the vocalist to stand out and the bass line to be less intrusive .... cut the fader to the bassist and, maybe, the drum mix somewhere below unity. Just for example.
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Old March 12th, 2014, 05:09 PM   #6
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Re: A question about unity gain.

Quote:
Originally Posted by Jonathan Levin View Post
Thanks Rick and Shaun.

I was just curious as to why there is even a knob to adjust when it seems like this could be something that is set and calibrated internally at a constant. In other words, why have something that you can adjust when you seldom need to adjust.

I do see your points however.

Just curious.

Jonathan
Jonathan, Some mixers don't have a Master gain pot like My Wendt X5 field mixer. They decided people wanted a fifth input and adapted the Wendt X4 which does have a Master input. Same box with different feature set. I miss the Master gain sometimes but not much. There are times you would want to increase the gain of everything with the Master if you are already pushing the input volume as high as it can go, and like the mix or you want to send a signal to something which needs more signal. Not all audio equipment accept standard input volumes to get a good signal and boosting the Master on our output may be the better solution. For instance some cameras don't have enough input sensitivity to get good record levels from some mixers.
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Old March 19th, 2014, 07:58 PM   #7
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Re: A question about unity gain.

Thanks Daniel!
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Old March 20th, 2014, 09:38 AM   #8
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Re: A question about unity gain.

The SD 302 does not have a master fader either. However the main XLR outputs can be attenuated down to -56dB (low mic level) or anywhere in-between via the software menu. The internal oscillator level can be adjusted for calibration though. Additionally the L&R returns can be switched to unbalanced line inputs.
I don't recall ever seeing a console type mixer w/o main masters.
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