Thanks very much Eric. Most of your figures are way over my head but
I do appreciate your most knowledgeable input!
So if you think the Olympus ME9 could be -50 dBV/Pa, then what would
that figure be if written as mV/Pa?
That is interesting to have your confirmation that EM172 is fairly
flat response to 20KH. The slight lift at 6 kHz makes it good for
birdsong :-)
Vicki
On 21/11/2014, at 12:15 PM, Eric Benjamin
[naturerecordists] wrote:
>
>
> Vicki,
>
> An interesting question. In the case of microphone sensitivity,
> there have been two reference levels in use over the years. One of
> them is output level relative to 1 uBar, and the other one is output
> level relative to 1 Pa. But people usually think of sound level in
> terms of dB SPL. 1 Pa is 94 dB SPL and 1 uBar is 74 dB SPL. The
> voltage level on the output is either stated in dBu (or m), which is
> dB relative 10 .775 Volts, or in dBV, which is dB relative to 1
> Volt. So the acoustic levels are 20 dB apart and the voltage levels
> are 2.26 dB apart. Are we confused yet? A little arithmetic is
> necessary.
>
> The EM172 I know about. Its sensitivity is -28 dBV/Pa, meaning that
> it puts out -28 dBV when a sound level of 94 dB SPL is present. -28
> dBV is the same as 38 mV, as Rob wrote. The self noise is 14 dBA.
> This is a very sensitive microphone capsule and also a very quiet one.
>
> The sensitivity spec for the Olympus microphone was probably -68 dBu/
> uBar, because that was the way that many manufacturers did it in
> 1988. One dBu = -2.26 dBV, and 1 uBar = -20 dB/Pa. So the
> sensitivity of the Olympus me9 is probably -50 dBV/Pa. A very low
> sensitivity by more modern standards. There has been a lot of
> improvement in microphone performance over the last quarter century.
>
> As for frequency response, a typical EM172 is fairly flat from 20 Hz
> to 20 kHz, with about a 4 dB lift at 6 kHz and then down 3 dB at 20
> kHz. It's really, really good for the price.
>
>
> On Thursday, November 20, 2014 4:14 PM, "vickipowys
> [naturerecordists]" <> wrote:
>
>
> Back in 1988 I bought a brand new Sony Pro Walkman WM-D6C, a cassette
> recorder that many field recordists were using at the time.
>
> I also purchased two Olympus Pearlcorder ME9 microphones (omni,
> tieclip), and had them wired as a stereo pair, and went off happily
> recording sounds all around Australia.
>
> I would like to get a rough idea of the sound quality of the ME9 mics,
> compared to the newer Primo EM172 (omni electret) mics that are used
> today, by me and many others.
>
> All I have to go on are the ME9 specifications:
> Frequency response: 50-13,000Hz
> Mike sensitivity: -68dB
> (the mics were powered by small mercury batteries).
>
> How can I compare the ME9 specifications with the EM172 mics:
> Frequency response: 100-12,000Hz fairly flat, but also may go lower,
> and higher up to 20,000 with some drop off.
> Mic sensitivity: 14 dB(A) / 38 mV/Pa (as shown on a chart by Rob
> Danielson)
>
> i.e. can someone please tell me what -68dB is as millivolts per pascal
> (mV/Pa)? Or offer other comments?
>
> Many thanks!
>
> Vicki Powys
> Australia
>
>
>
>
>
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