I just discovered this board, and am excited that it contains people who have the information that I need.
I’m trying to work out a statistical approximation of the SPL level at the mic position on stage for various instruments.
Since you all are good at setting preamp levels to be well above noise floor and not clipping, that is already quite close, in a statistical sense…
And if I know the mic model and the mic preamp gain, I can infer the expected peak level from the mic specs, using simple maths.
What I’m looking for is as much data as possible that ties preamp gain value to specific mic model to type of musical instrument.
Your mix files all contain the head-amp gain, and I presume that some of you have other records and channel sheets that tie the other two items of info to these values.
The more spreadsheet cells I can get on this, the better my statistics overlords like it, so I would love to be flooded with data at dr -dot tonmeister -at gmail -dot com
I promise to keep it all confidential and not be judgmental about any choices made.
What is it that you are hoping to do with this information?
I can tell you right now that any data I have will be of no relevance as I set my gain structure quite differently depending on the equipment I’m using and the music I’m reinforcing. I would think that it would be hard to create anything that’s accurate since everyone runs their equipment differently, not to mention how incredibly varied the equipment itself is, along with all the sources.
Well, for example, lets just take the idea of an SM 57 on a guitar amp. The level will obviously vary by the style of music, by the venue, and by the mood of the gig. And it will vary because some people will set preamp gain for max SNR and then move the faders to taste, and some will put the faders in the best position and adjust the gain to an appropriate mix level for that source.
But if I get 50 independent examples of mic on guitar-amp, I can make a graph that has a bell-shaped curve that shows the average and standard deviation of the amount of level that people thought necessary at that position. It’s helpful to know that, say 80 percent of the time people in similar situations will be within 15dB of value x. (factoring in mic sensitivity and gain)
This is partly for education, partly for justification of what gain range is appropriate on cheap vs midrange vs expensive mic preamps. Do you really need 70dB of gain on every preamp, if you don’t do ribbon mics on quiet instruments that often? Or if you love that Sennheiser MKH on snare, can you turn the preamp down far enough?
I’ve noticed at festivals that even before the band arrives many monitor mixers witll have the gain-knob dialled to something. When I ask, they say, “well, it’s a sax and a KSM32, so that level will probably be close enough. If it isn’t I can change it, if it is then I can worry about more important things”. I guess I’m trying to document this more formally. On some things the bell curve will be way wide, because of the variations above, but on things like brass instruments I suspect it might be more narrow. If I get enough data then I suspect breaking things out by musical style might give a smaller range of answers.
I’m not sure as well if the data collected will be of so much value, as you state yourself, that it may be within a corridor of perhaps 15dB - what is quite a lot?
but anyway, why not: if you take a look at my “OpenMixTools” it will give you the gain values
save the OpenMix file to disk and access “ad.@gain” of the <channel> nodes
keep in mind that on files from a PM5D (not RH) the gain may be wrong.