Hello everyone,
as a new member in this forum I want to contribute a very versatile circuit for SDC mics. Comments are welcome ;-)
The circuit was developed for old mics with MBHO capsules like Telefunken TC600 hifi, Dual MC312 and MBC500/MBC540 in order to
make them compatible with phantom power P48. All actually available MBHO capsules work also wery well.
Some technical data:
Supply current 2 mA @ 48 V DC phantom power via 2x 6K8 resistors
A-weighted noise level -120 dBV @ 33 pF capsule capacitance, -123 dBV @ 55 pF capsule capacitance
Polarisation voltage 39,5 V
Maximum output level 2 V rms (with 2x 1K5 AC-load on each signal pin to GND, nonlinear distortion < 0,5 %)
Nonlinear distortion 0,02 % @ 200 mV rms signal output
Input impedance 0,4 pF in parallel to 6 GOhm
Frequency response 20..20000 Hz -0,2 dB at the band edges
Signal amplification -0,3 dB
Common mode rejection ratio >60 dB @ 1 kHz, >44 dB @ 50 Hz
I have buildt 8 prototypes and they perform perfectly. Find attached the circuit diagram and the noise spectrogram
with 33 pF capacitor.
Enjoy!
as a new member in this forum I want to contribute a very versatile circuit for SDC mics. Comments are welcome ;-)
The circuit was developed for old mics with MBHO capsules like Telefunken TC600 hifi, Dual MC312 and MBC500/MBC540 in order to
make them compatible with phantom power P48. All actually available MBHO capsules work also wery well.
Some technical data:
Supply current 2 mA @ 48 V DC phantom power via 2x 6K8 resistors
A-weighted noise level -120 dBV @ 33 pF capsule capacitance, -123 dBV @ 55 pF capsule capacitance
Polarisation voltage 39,5 V
Maximum output level 2 V rms (with 2x 1K5 AC-load on each signal pin to GND, nonlinear distortion < 0,5 %)
Nonlinear distortion 0,02 % @ 200 mV rms signal output
Input impedance 0,4 pF in parallel to 6 GOhm
Frequency response 20..20000 Hz -0,2 dB at the band edges
Signal amplification -0,3 dB
Common mode rejection ratio >60 dB @ 1 kHz, >44 dB @ 50 Hz
I have buildt 8 prototypes and they perform perfectly. Find attached the circuit diagram and the noise spectrogram
with 33 pF capacitor.
Enjoy!