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Author Topic: Mic specs --> gain starting points?  (Read 586 times)

George Reiswig

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Mic specs --> gain starting points?
« on: May 31, 2023, 12:07:08 PM »

Strange question that is more theoretical than anything. At one point, I got pretty compulsive about my vocal mic locker in particular, so I set up a measurement method where I could play white noise through a small speaker at about 90dB into a microphone, adjust the gain on my mixer appropriately, and recorded the gain setting I ended up with in a table so I could quickly reference a relatively equivalent setting for gain across my various microphones. It works pretty well.

But I got to wondering: is there a way to (at least within a manufacturer's own testing method) do something like this based on the specs? For example, if I have measured Mic A, which has an output spec of -49 dB @ 1 kHz, and recorded it's gain setting as 26dB, can I translate Mic B with a -52 dB @ 1 kHz spec to need 29dB of gain to be about equivalent? (52-49=3, so add 3dB to Mic B for an overall equivalent output)
« Last Edit: May 31, 2023, 12:18:08 PM by George Reiswig »
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Tim McCulloch

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Re: Mic specs --> gain starting points?
« Reply #1 on: May 31, 2023, 01:44:18 PM »

Yes, presuming the electrical output of the microphones are referenced to the same physical sound pressure and frequency spectrum.
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Brian Jojade

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Re: Mic specs --> gain starting points?
« Reply #2 on: May 31, 2023, 03:03:01 PM »

Yeah, you probably could go through all of that sort of effort, but what does it get you?  Final gain adjustment should be based on the actual source volume, which is going to vary far more than the different gain levels of most mics.  Also, a gain measurement at 1khz may or may not be relevant to the source material you're working with.

Generally speaking, no matter which mic I'm working with, the 'starting point' gain is somewhere in the +25/30 range, ish, which should be plenty to see signal lights on the mixer, then adjust as needed based on the source.  No spreadsheet or math needed at that point.
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Brian Jojade

George Reiswig

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Re: Mic specs --> gain starting points?
« Reply #3 on: May 31, 2023, 03:14:51 PM »

Yeah, you probably could go through all of that sort of effort, but what does it get you?  Final gain adjustment should be based on the actual source volume, which is going to vary far more than the different gain levels of most mics.  Also, a gain measurement at 1khz may or may not be relevant to the source material you're working with.

Generally speaking, no matter which mic I'm working with, the 'starting point' gain is somewhere in the +25/30 range, ish, which should be plenty to see signal lights on the mixer, then adjust as needed based on the source.  No spreadsheet or math needed at that point.

Totally get that. This is mainly to help me when I'm doing rehearsals, jams, etc. where I am the soundman...but also the lead vocalist and guitar player. Not only is that combination job only feasible if I'm an octopus, but just understanding a starting point for my own vocal given different mics is helpful, and I can't judge my own mic's volume relative to other singers when I'm running sound and singing at the same time but can't afford a real sound engineer.
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Tim McCulloch

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Re: Mic specs --> gain starting points?
« Reply #4 on: May 31, 2023, 05:17:12 PM »

Totally get that. This is mainly to help me when I'm doing rehearsals, jams, etc. where I am the soundman...but also the lead vocalist and guitar player. Not only is that combination job only feasible if I'm an octopus, but just understanding a starting point for my own vocal given different mics is helpful, and I can't judge my own mic's volume relative to other singers when I'm running sound and singing at the same time but can't afford a real sound engineer.

Ah, I see.  I don't think in a run-and-gun situation that +/- 3dB is a big deal so long as you're + or - in the right (or at least consistent) direction... ;)

It's probably more useful to note which mics in your collection have considerable differences from your most commonly used mic, say an SM-58 and how many dB of difference it is.  And also helpful is where, on individual channel metering, a "correct for this use, today, this gig" level is.  The idea is you don't have to PFL to see it...

With the X/M32 I have a tablet that is mostly used for displaying the meters screens, whether mixing on the desk or another tablet/computer.  If you've got room and a cooperative console/software, you might find it useful.

Edit ps:  years ago, working as a stage hand, I used a vendor supplied microphone calibrator to line check and mixerperson to set rough input trims.  I want to say it was Sennheiser (and all the labeling was in German), and it had a choice of 1kHz tone and pink noise.  I think the housing had been modified, but the idea was 'touch the grille of the calibrator to the foam wind screen on the mic, and wait until you hear "next" on the walkie.  We did a 60 input symphony show in under 30 minutes.
« Last Edit: May 31, 2023, 05:20:42 PM by Tim McCulloch »
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Brian Jojade

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Re: Mic specs --> gain starting points?
« Reply #5 on: June 01, 2023, 01:20:15 PM »

I can't judge my own mic's volume relative to other singers when I'm running sound and singing at the same time

At least you recognize this as fact!   But the problem lies in the fact that the gain of the particular mics is going to be within a few dB. The different level of each singer will vary much more than that.

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Brian Jojade

Rick Earl

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Re: Mic specs --> gain starting points?
« Reply #6 on: June 01, 2023, 05:04:29 PM »

Yes, presuming the electrical output of the microphones are referenced to the same physical sound pressure and frequency spectrum.

Exactly what Tim said

Here is an SM-58: Sensitivity (at 1,000 Hz Open Circuit Voltage)
54.5 dBV/Pa (1.85 mV)
1 Pa = 94 dB SPL

Here is a Sennheiser e835: Sensitivity (free field, no load) 2.7 mV/Pa

Neither specify all the parameters of the test,; temperature, frequency, distance, etc.  Also impedance load can make an impact too, as your mixer is different from others.    I think your method works and is probably easier.  I have done similar with a mic calibrator like Tim mentioned in another reply.
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Jeff M Hague

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Re: Mic specs --> gain starting points?
« Reply #7 on: June 02, 2023, 10:24:18 AM »

Strange question that is more theoretical than anything. At one point, I got pretty compulsive about my vocal mic locker in particular, so I set up a measurement method where I could play white noise through a small speaker at about 90dB into a microphone, adjust the gain on my mixer appropriately, and recorded the gain setting I ended up with in a table so I could quickly reference a relatively equivalent setting for gain across my various microphones. It works pretty well.

But I got to wondering: is there a way to (at least within a manufacturer's own testing method) do something like this based on the specs? For example, if I have measured Mic A, which has an output spec of -49 dB @ 1 kHz, and recorded it's gain setting as 26dB, can I translate Mic B with a -52 dB @ 1 kHz spec to need 29dB of gain to be about equivalent? (52-49=3, so add 3dB to Mic B for an overall equivalent output)

I'm not sure it would be possible working on manufacturer provided specs because they tend to post difeerent specs for their gear. Not unlike speaker system specs. However, I have starting points based on experience. For instance, at my house gig - X32, SD16s, Senn e945s for vox - I know a good starting point for gain is 20dB. On my rig - M32C, DL16s, Senn e945s for vox - 18dB is a good starting point. Using SM58s for vox, I find those are also good starting points although I find I usually have to bump them a couple dB once soundcheck starts.
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Jeff

ProSoundWeb Community

Re: Mic specs --> gain starting points?
« Reply #7 on: June 02, 2023, 10:24:18 AM »


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