COLUMBIA PMA-350

Commentary

Pre-main amplifier using Darlington power transistor.

The PMA 350 uses the Darlington Power Transistor of Motorola Inc. in the United States. The power and driver transistors are contained in the same pellet for excellent temperature stability.
In addition, the symmetry of the push-pull circuit is enhanced by using the pure complimentary service configuration of PNP and NPN by this transistor.

The OCL circuit consists of a direct-coupled pure complimentary service 2 power supply OCL circuit.
The differential amplifier uses a hybrid IC with carefully selected transistors.

The equalizer amplifier section is designed with special emphasis on the dynamic range and equalizer characteristics. The circuit configuration is a 3-chip E-E feedback type using specially selected silicon transistors. The power supply voltage is approximately 40 v.

The tone amplifier section has a 3-chip configuration with an FET in the middle. The collector current of the in the first stage is reduced to operate in a region with low noise level. In addition, it is designed with a power supply voltage of 40 v like the preamplifier to obtain a wide dynamic range and excellent linearity.
Also, in consideration of connecting with a multi-amplifier circuit, an emitter follower is used to extract the tone control characteristics so that external loads do not affect them.
In addition, the tone control knob has an 11-position click stop.

Model Rating

Type	Pre-main amplifier
Circuit configuration	Differential-Amplified OCL circuit for all stages directly connected pure complimentary service 2 power supply system
Power Amplifier Unit
Rated output	Single-channel Operation : 47W/47W (8 Ω, 0.1% distortion factor) Both channels operating : 38W + 38W (8 Ω, 0.1% distortion factor) 46W + 46W (8 ohm, EIAJ, 5%)
Harmonic distortion factor	0.1% or Less (at Rated Output) 0.03% or Less (1 kHz at 0.3W ~ 30W output)
Cross modulation distortion factor	0.1% or Less (at Rated Output)
Frequency characteristic	8 Hz ~ 150 kHz + 0 -1dB at 1W Output
Input impedance	82k Ω or more
Damping factor	70 or More (1 Hz ~ 10 kHz) 50 or More (1 Hz to 50 kHz) 20(100kHz)
Input sensitivity	1 V (output 12 V)
Residual noise	0.1 μ W or Less (8 Ω)
Signal-to-noise ratio	90 dB or more
Preamplifier Section
Output (harmonic distortion rate 0.1% or less)	10V(100Hz) 10V(1kHz) 5V(10kHz)
Harmonic distortion factor (at output 1 V)	0.023%(100Hz) 0.024%(1kHz) 0.028%(10kHz)
Cross modulation distortion factor	Not more than 0.1%
Frequency characteristic	Aux : 15 Hz ~ 70 kHz (Power amp 8 Ω Load)
Input sensitivity	Phono1 : 2mV/60k Ω Phono2 : 8mV/60k Ω Aux1/2 : 100mV/100k Ω
Maximum Undistorted Allowable Input (1 kHz)	Phono1:200mV Phono2:600mV
Equalizer characteristic	RIAA deviation within ± 1 dB
Signal-to-noise ratio	Phono1 : 70 dB or more
Tone control	Bass : + 9.5 dB ~ -11dB (100 Hz) Treble : + 10 dB ~ -9dB at 10 kHz
Filter	Low Filter:-7dB(50Hz) High Filter:-6dB(7kHz)
<General>
Input terminal	Phono1/2, Aux1/2, Tape Play (RCA)
Output terminal	Rec out, Speaker out (2 systems), Pre amp out
Recording and reconnector	Rec/PB (DIN terminal) Input sensitivity : 100 mV Output level : 30 mv
Semiconductor used	Transistor : 21 Diode : 12 pcs IC : 1
AC outlet	Switched : one system Unswitched-One system total:350W
Power supply voltage	100 VAC, 50Hz/60Hz
Power supply fuse	2.3A
Power consumption	20W (no signal) 65W (at 1/3 rated output)
External dimensions	Width 370x Height 141x Depth 310 mm
Weight	8kg