DENON PMA-630

Commentary

A pre-mounted power amplifier with a simple circuit configuration while focusing on disc playback.

The PMA 630 is a straight-type amplifier that combines two high-performance unit amplifiers. The input signal from the analog source is amplified by a high-gain equalizer amplifier and fed straight to the DC power amplifier, eliminating unnecessary coloring.
Since programs other than disc playback are directly connected to the DC power amplifier, there is no need to worry about noise pollution or distortion in the intermediate amplifier. Therefore, the power amplifier achieves high output power and high gain.

Both the power amplifier and the equalizer amplifier use a complimentary service push-pull circuit in which NPN and PNP transistors are symmetrically arranged, and excellent distortion characteristics and S/N are realized.

The gain of the equalizer amplifier section is large at 42 dB (1 kHz, 125 times) because it is directly connected to the DC power amplifier section.
To achieve a high S/N ratio and low distortion, parts and circuits have also been examined. An ultra-low noise transistor is used for the first input stage, and the noise level is -137dB below the input conversion ratio. In addition, a symmetrical class A push-pull circuit is used for the equalizer amplifier to reduce harmonic distortion to 0.003%, close to the measurement limit.

The power supply section uses a large transformer that is resistant to voltage fluctuation and takes into consideration magnetic flux leakage, and a newly developed low-impedance large-capacity block capacitor (18,000 μ Fx2).

The Rec out off function allows you to disconnect the tape deck from the main signal path even if the tape deck is connected to the Rec out jack, thereby eliminating any negative effects on sound quality.

The front panel is used for the front panel.

A relay drive system is used for speaker switching to reduce the output impedance and improve the damping factor.

The protection circuit is an electronic circuit that protects speakers and transistors and a double protection circuit that uses a power relay.

Equipped with Loudness control and 2-stage subsonic filter.

Model Rating

Type	Pre-main amplifier
Power Amplifier Unit
Circuit system	All-stage pure complimentary service push-pull circuit
Rated Output (Both Channels Driven, Sine Wave Continuous Output)	80W + 80W (8 Ω, 20 Hz to 20 kHz) 100W + 100W (4 Ω, 1 kHz)
Input Sensitivity / Impedance	320mV/100k Ω
Total harmonic distortion factor	0.01% or less
Intermodulation distortion factor (60 hz : 7 khz = 4 : 1)	0.005% or Less (at Rated Output Equivalent Amplitude Output) 0.005% or Less (Sine Wave 1W Equivalent Amplitude Output)
Output Bandwidth (IHF, both channel drives)	5 Hz ~ 100 kHz (THD 0.05%)
Frequency characteristic	DC ~ 100 kHz + 0 -1dB or less (at 1W output)
Signal-to-noise ratio (IHF-A)	112 dB (input short circuit)
Output impedance	0.09 Ω or less
Output terminal	Speakers A and B : 4 Ω ~ 16 Ω Speaker A + B : 8 Ω ~ 16 Ω Stereo headphone
Preamplifier Section (Equalizer Amplifier)
Input Sensitivity / Impedance	Disc1, 2 : 2.5mV/50k Ω Tuner, Aux, Tape : 320mV/30k Ω
Pre-out Output / Impedance	Maximum power : 25 V Rated output : 320 mV Load Resistance : 50k Ω (THD 0.01%)
Disc Maximum Allowable Input	200 mV or More (1 kHz)
RIAA deviation	20 Hz to 20 kHz ± 0.2 dB or less
SN ratio (IHF-A, input short circuit)	Disc : 86 dB or more Tuner, Aux, Tape : 112 dB or more
Total harmonic distortion factor	0.003% (at 10 v output)
Subsonic filter	20Hz/40Hz, 6dB/oct.
Loudness control	Low : + 9 dB (100 Hz) High frequency : + 5 dB (10 kHz)
<General>
Crosstalk (Disc in to SP out)	-60dB or less (20 Hz to 20 kHz)
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	190W (Electrical Appliance and Material Control Law)
External dimensions	Width 434x Height 145x Depth 390 mm (including leg, knob, terminal)
Weight	17kg