>Raimund wrote:
>In my tests I always use a 150 ohms load for both the more
>professional recorders with balanced XLR inputs and consumer-grade
>units with 3.5 mm TRS inputs.
>
>I think this method is valid at least for those microphones that
>have an output impedance of about 150 ohm (such as the widely used
>Sennnheiser K6/ME6x series with internal battery). Because these
>microphones do not use the plug in power, I always switch off the
>PIP on the recorder.
Yes. That is correct!
>This also means that my tests do not necessarily reveal the real
>performance of the recorders in conjunction with PIP microphones,
>which usually have much higher output impedances. As far as I know,
>their impedance is in the range of 2 to 5 kOhm. So, one had to use a
>similar load resistor in order to get meaningful EIN figures for
>that specific application.
> But I'm afraid that I cannot repeat all my measurements for that
> alternative load resistance...
I fully accept that, your measurements are the only meaningful
anyway, to people using plug in power microphones.
My specific Telinga question is whether there is any use in driving
pip microphones from a separate battery and adding a source follower
with an output impedance of, say, 50 - 200 Ohms? For users of some
recorders I think it is, but not for others.
What makes a difference, when and why?
>Just another note on the high noise levels that you recently
>reported from a Nagra recorder. I just visited the Nagra website
>(http://www.nagraaudio.com/pro/index.php) and tried to look up the
>EIN figures. I found this specification for the Model Nagra VI:
>
>"Input noise with condenser mic : 0.88 =B5V (-119 dBm)"
>
>They unfortunately, they don't tell us the termination impedance and
>the bandwidth that apply to this figure and they confused the unit
>(it should read -119 dBu, not -119 dbm). Assuming this figure
>applies to a termination resistor of 150 ohms and a bandwidth from
>20 Hz to 20 kHz, this EIN would be still acceptable for most
>microphones, but not superior.
>
>Interestingly, they don't reveal the input noise for the model Nagra
>SD. Maybe it's so poor that they decided to hide it?
Just such a suspicion is horrifying!
>There are EIN figures for the models PICO and LINO are specifies as :
>
>"Microphone EIN : > 122 dB"
>
>But that figure does not make any sense to me. They probly meant
>-122 dBu, but who knows...
>
>So, I'm not surprised why customers are getting lost with these
>things, when even well-respected manufacturers contribute to the confusion=
.
I totally agree. And not only respected manufacturers, but strange
"debates" on the web, where parameters like mV/Pa are treated like
"opinions"...
I wish you happy holidays too, Raimund!
>------------------------------------
>
>"While a picture is worth a thousand words, a
>sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
>
>Yahoo! Groups Links
>
>
>
Telinga Microphones, Botarbo,
S-748 96 Tobo, Sweden.
Phone & fax int + 295 310 01
email:
website: www.telinga.com
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