DENON PMA-850

Commentary

This pre-main amplifier has been developed by integrating various technologies for the basic performance of audio players such as transmission characteristics, dynamic range, distortion, and crosstalk.

Each unit of the MC head amplifier, EQ amplifier, flat amplifier and power amplifier consists of a full complimentary service (complementary symmetry) circuit using both NPN and PNP transistors over all stages.
In each part, the first stage is a differential stage using high-gain NPN and PNP transistors, and the last stage is a push-pull stage. By using such a symmetrical circuit structure, even order harmonic distortion is cancelled out by each other and the total distortion is reduced.

The power amplifier uses a newly developed power transistor E. B. T (emitter ballast transistor).
F for E. B. T._TThe switch exhibits high-speed switching characteristics at around 100 MHz (10 times higher than conventional switches), thereby improving high-frequency distortion characteristics.
The power amplifier is composed of ICL and OCL DC amplifiers with excellent transient response and phase characteristics.

The power supply uses a 420 VA large-capacity toroidal transformer with independent windings for the left and right channels in one package. In addition, 20000 μ F large-capacity block capacitors are used for the left and right channels respectively, and dynamic crosstalk is suppressed by using independent rectifier circuits.
Since the toroidal transformer has excellent leakage flux characteristics, high S/N can be achieved.

In order to reduce noise, newly developed ultra-low noise transistors are used in the first stage of the MC head amplifier and equalizer amplifier. In addition, a toroidal type (with multiple shields made of silicon steel inside the case) is used to minimize the leakage flux of the power transformer, which causes a decrease in S/N. The S/N of the head amplifier and equalizer amplifier is improved.

The gain of the MC head amplifier of the PMA 850 is inversely proportional to the impedance of the connected cartridge depending on the construction principle of the circuit used.
Cartridge impedance and output voltage are almost directly proportional, and the output of the MC head amp is automatically equalized, eliminating the need for extensive volume adjustment for each cartridge.

The control amplifier section, including the tone control section, can be completely disconnected by the direct coupling switch, and the power amplifier can be directly driven by the output signal of the equalizer amplifier section.
This makes it possible to enjoy a simpler reproduction system.

The input terminal of Phono3 is gold-plated with high reliability.

To minimize and stabilize distortion, S/N, and crosstalk, a dual bus line is used for the power supply ground.

Model Rating

Type	Pre-main amplifier
Power Amplifier Unit
Circuit system	All-stage pure complimentary service push-pull circuit
Rated Output (Both channel drive)	85W + 85W (8 ohm, 20 hz ~ 20 khz, THD 0.01%) 110W + 110W (4 ω, 1 khz, THD 0.05%)
Total harmonic distortion factor	0.01% or less
Cross modulation distortion factor (60Hz:7kHz=4:1)	0.02% or Less (at Rated Output Equivalent Amplitude Output) 0.01% or Less (Sine Wave 1W Equivalent Amplitude Output)
Output bandwidth	5 Hz ~ 100 kHz (IHF, THD 0.1%)
Transmission Characteristics (at 1W output)	DC ~ 100 kHz + 0 -1dB
Input Sensitivity / Impedance	1V/50k Ω
Output impedance	0.16 Ω or less
Signal-to-noise ratio	122dB
Output terminal	Speaker AORb : 4 Ω ~ 16 Ω Speaker A + B : 8 Ω ~ 16 Ω Headphone port
Preamplifier Section
Output Level / Impedance	Pre out : 1 V (Rated), 20 V (Maximum Output at 50k Ω Load) Rec out : 320 mv (Rated), 20 v (Maximum Output, Load 50k Ω, THD 0.01%)
Total harmonic distortion factor	0.03% (at 3 V output)
Input Sensitivity / Impedance	Phono1, 2 mm : 2.5mV/50k Ω Phono3 mc : 0.37 mV (at cartridge impedance 40 Ω) Tuner, Aux, Tape : 320mv/40k Ω
Maximum Allowable Input (1 kHz)	MM:200mV MC : 30 mv (40 Ω)
RIAA deviation	20 Hz to 20 kHz ± 0.2 dB or less
Signal-to-noise ratio (IHF, A-network)	Phono MM : 89 dB or more (at input short-circuit) Phono MC : 74 dB or more (at input terminal 40 Ω) Tuner, Aux, Tape : 100 dB or more (when the input is short-circuited)
Frequency Response (Aux → Pre out)	5 Hz ~ 100 kHz + 0 -1dB at Tone Defeat
Tone Control Variable Range	Bass : ± 8 dB (100 Hz) Treble : ± 8 dB (10 kHz)
Filter characteristic	Subsonic filter : 20 Hz, 12dB/oct. High cut filter : 9 kHz, 12dB/oct.
Loudness control	Low frequency : + 7 dB (100 Hz) High frequency : + 6 dB (10 kHz)
Muting	-20dB
<General>
Power outlet	Switched : 1 system, 100W Unswitched-2, 250W (total)
Pwer	100 VAC, 50Hz/60Hz
Power consumption	215W (Electrical Appliance and Material Control Law)
External dimensions	Width 434x Height 164x Depth 400 mm (including leg, knob, terminal)
Weight	17kg