Audio Database

A dedicated phono equalizer unit that enables the playback of analog records on the C-250.
It is possible to play back records by adding from the rear panel side.

The AD 250 is equipped with a gold-plated glass substrate printed circuit board and a dedicated input circuit to match each MM/MC cartridge.
In the MM input mode, it is matched to the high output impedance of the cartridge to provide a high S/N FET configuration.
In addition, since the MC input receives small signals with low impedance, a differential input circuit with low noise elements is constructed. By reducing the impedance of the NFB loop, low-noise reproduction is possible.

The MC input impedance selection of 10, 30 and 100 Ω and a subsonic filter for cutting ultra-low frequency noise are installed inside.
These functions can be set with switches in the printed circuit board before installing the AD 250.

Model Rating
(when connected to C-250)
Type Phono equalizer unit exclusively for C-250
Frequency characteristic AD Input : 20 Hz to 20 kHz ± 0.2 dB
Total harmonic distortion factor 0.005%
Input Sensitivity / Impedance
(Rated Output / 0.5 v Output)
AD MM : 8.0mV/2.0mV/47k Ω
AD MC : 0.25mV/0.063mV/10 Ω, 30 Ω, 100 Ω
Input short circuit, IEC-A compensation (at rated input) AD MM:95dB
AD MC:79dB
AD MC:85dB
Input conversion noise (input short, IEC-A correction) AD MM:-137dBV
AD MC:-151dBV
AD Maximum Input Voltage (1 kHz, 0.005% Distortion) MM:250mV
Gain AD MM Input → Balanced/Unbalanced Output : 48 dB
AD MM Input → Rec Output : 30 dB
AD MC Input → Balanced/Unbalanced Output : 78 dB
AD MC Input → Rec Output : 60 dB
Subsonic filter 25 Hz, -12dB/oct.
(set by AD-250 internal DIP switch)