DENON PMA-850/II

Commentary

Pre-main amplifier, an improved version of PMA-850.

A symmetrical (fully complementary) push-pull circuit is used for each amplifier stage.
This system is composed of PNP and NPN bipolar transistors. Although the number of parts such as transistors is larger than that of the conventional system, transmission characteristics can be improved without depending on NFB. By this system, transmission characteristics are improved by symmetric push-pull circuit with excellent bare characteristics and negative feedback technology, and S/N, frequency characteristics, dynamic range, phase characteristics and transient intermodulation distortion are improved.

Pc100W EBT (Emitter Ballast Transistor), which exhibits high-speed switching characteristics, is used in parallel for the power transistor. By designing with sufficient margin, distortion can be reduced over a wide up to 4 Ω load.

Class A / Class B operation switching system is adopted for the power amplifier section.
This allows for a wide range of combinations from high efficiency speakers to low efficiency speakers.

The power supply uses a large toroidal transformer and a 10,000 μ Fx2 + 2 large block capacitor.

Equipped with a head amplifier exclusively for MC cartridge.
This amplifier achieves high S/N distortion rate with a 16-chip head amplifier with a low-noise bipolar transistor at the first stage.

The equalizer amplifier realizes 90 db S/N, high gain (42 db) and high output (25 v).
In addition to reducing distortion, the RIAA deviation is within ± 0.2 dB.

On the PMA 850 II, the control amplifier can be completely disconnected from the main circuit when the intermediate control section is not required, and the power amplifier can be driven directly by the output of the equalizer.
In the tone control circuit for both bass and treble, the indication of the knob becomes a complete flat amplifier at the Defeat position, and the sound quality can be adjusted by continuous variable at other indication positions.

When the power amplifier is driven directly by the output of the equalizer, a filter circuit can be inserted before the power amplifier if necessary.

The internal structure emphasizes phase characteristics and separation characteristics.

The volume is a continuously variable volume with high reliability and precision.

Gold-plated terminal is used for MC input terminal.

Model Rating

Type	Pre-main amplifier
Rated Output (Double-channel Drive, 20 Hz to 20 kHz, 0.01%)	Class A operation : 22W + 22W (8 Ω) Class B operation : 100W + 100W (8 Ω)
Output Bandwidth (IHF, 8 ω)	Class A : 5 Hz to 100 kHz (THD 0.02%) Class B : 5 Hz to 100 kHz (THD 0.05%)
Input Sensitivity / Impedance	Phono MM : 2.5mV/50k Ω Phono MC : 0.37 mV (Rs = 40 Ω) Tuner : 320mV/40k Ω Main in : 1V/50k Ω
SN Ratio / Allowable Input	Phono MM:90dB/200mV Phono MC : 74dB/30mV (Rs = 40 Ω) Tuner:105dB Main in:122dB/1V
Total harmonic distortion factor	MM-Rec out : 0.01% (at 25 V output) Tuner-Pre out : 0.003% at 3 V output
Frequency characteristic	RIAA deviation : 20 Hz to 20 kHz ± 0.2 dB Tuner-Pre out : 5 hz to 100 khz + 0 to 1 db Main-SP : DC ~ 100 kHz + 0 -1dB (0.5W, 8 Ω)
Tone control	Bass : ± 8 dB (100 Hz) Treble : ± 8 dB (10 kHz)
Filter characteristic	Subsonic filter : 20 Hz, 12dB/oct. High cut filter : 7 kHz, 6dB/oct.
Pwer	100 VAC, 50Hz/60Hz
Power consumption	250W (Electrical Appliance and Material Control Law)
External dimensions	Width 434x Height 164x Depth 400 mm (including leg, knob, terminal)
Weight	18kg