Le 19/12/2024 à 13:41, kandoit7 via
groups.io a écrit?:
Thank
you for your response, Jerry.
?
Based
on the methods you provided, I will proceed to experiment with
impedance measurement.
?
The
experimental setup is as follows:Speaker
(Sine wave Signal Source)→ Mic → DI Box (high-precision
potentiometer) → Audio AnalyzerThe
DI box is equipped with a high-precision potentiometer, which
will be connected as a variable resistor
between
pins 2 and 3 of the XLR connection from the microphone.
Subsequently,
it will be connected to the audio analyzer via an XLR cable.
?
The
speaker emits sine wave signals at frequencies such as
100Hz, 200Hz, 400Hz, 1000Hz, 2000Hz, and 10000Hz.Initially,
the sound pressure level (SPL) at each frequency is measured
without connecting the DI box.
You can't do that, because you don't know the gain (or attenuation)
of the DI box.
What value is this potentiometer? Ideally it should be about 500
ohms.
You must do a measurement without a load, then another with the
potentiometer attached. These measurements don't need a DI box. In
addition, most DI boxes are unbalanced.
Another
method is to rent the MR-PRO device from NTi Audio.
According
to the NTi Audio website, this device is also used for
measuring speaker impedance. (However, I anticipate that
renting the device might be somewhat difficult...)
The MR-PRO does not provide phantom power. You would have to add
phantom power separately.
OTOH it would give more accurate results than the -6dB method, and
allow meaurements at different frequencies.
