[ProAudio] Microphones question

[Louis Judson]

Even the lowly Shure M-267 quoted -129…
<L>
Lou Judson * Intuitive Audio
415-271-8070 mobile

I'm just a simple sound engineer, nothing more, nothing less.
-- paraphrase of the Dalai Lama.

> On Jun 14, 2021, at 8:06 AM, Mike Rivers via ProAudio <proaudio at bach.pgm.com> wrote:
> 
> How about a little discussion on the value of knowing the EIN of a preamp and how the figure is useful to the designer? 
> 
> Here's why I ask:
> 
> When I was writing reviews regularly, EIN was (and still is) often quoted in the product's specs. The numbers ranged from -125 dBu (just a couple) to a majority being either -127 or -128 dBu. Manufacturers liked to tout it because it was a nice low number with "noise" in its name. And it was always measured at a level within a dB or so of clipping since that's it looked the best. 
> 
> But unless I missed the appropriate chapter, EIN is a calculated value - the measured noise level with the gain subtracted out. So a preamp with 60 dB of gain that advertised EIN=-128 dBu could be expected to put out -68 dBu of noise, measured, of course to the advantage of the marketing department with the appropriate input termination (0, 100, or 150 ohms usually) and output load.
> 
> So, among design engineers, what's the big deal about EIN? Is there a better way of measuring it that's more meaningful? And if you can squeeze another dB of EIN out of a design, how significant will this be to the user?  I
> 
> , know "it depends."
> 
> -- 
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