> This is fantastic, John, Raimund, David, more.
> Finally, after years of "might be this or might be that", things
> "might" start to clear up.
Klas, I'm glad that to finally hear that :-)
> I cannot overlook the consequences of using a resistor load on a plug in =
power
> input, for example)
In my tests I always use a 150 ohms load for both the more professional rec=
orders with balanced XLR inputs and consumer-grade units with 3.5 mm TRS in=
puts.
I think this method is valid at least for those microphones that have an ou=
tput impedance of about 150 ohm (such as the widely used Sennnheiser K6/ME6=
x series with internal battery). Because these microphones do not use the p=
lug in power, I always switch off the PIP on the recorder.
This also means that my tests do not necessarily reveal the real performanc=
e 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 t=
o get meaningful EIN figures for that specific application. But I'm afraid =
that I cannot repeat all my measurements for that alternative load resistan=
ce...
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.c=
om/pro/index.php) and tried to look up the EIN figures. I found this specif=
ication 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 ba=
ndwidth that apply to this figure and they confused the unit (it should rea=
d -119 dBu, not -119 dbm). Assuming this figure applies to a termination re=
sistor 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. Ma=
ybe it's so poor that they decided to hide it?
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, whe=
n even well-respected manufacturers contribute to the confusion.
Happy Holidays,
Raimund
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