DENON PMA-780D

Commentary

A pre-main amplifier with built-in digital multi-interface circuit for digital output.

The power transformer is equipped with a 400 VA rank, 6.2 kg large EI transformer.
A rectifier with a surge current of 200A/200V is used for rectification, and a total of 32,800 μ F electrolytic capacitors are installed to obtain a strong output current.
The electrolytic capacitor is a 2-2 system, which is the feature of pure dynamic power supply. Two types of electrolytic capacitors with different tan delta cut off power supply noise and provide high-purity energy supply capability.

The power amplifier section uses DENON's unique super non-feedback amplifier.
This amplifier has a simple circuit configuration in which the audio signal flow is unidirectional. Distortion components caused by active devices such as transistors are detected by a high-speed operational amplifier and only the distortion components are removed.
In theory, static distortion (harmonic distortion, intermodulation distortion) is canceled out, and dynamic distortion (transient distortion) does not occur. This circuit has high stability.
F for the last stage_TA power transistor of 20 MHz / Pc150W is used in a single push mode, and linear amplification characteristics are obtained from very low volume to very high volume.
The voltage amplification stage employs three differential amplification stages and the first stage employs an ultra-low noise FET to achieve low noise and DC configuration. The final stage of the push-pull circuit ensures good matching with the power amplification stage.
Further, f excellent in high-frequency characteristics is obtained._TBy adopting a new current mirror circuit using a 20 MHz high-speed transistor, a high spin rate of ± 350 V / μ sec between CD input and SP terminal has been obtained.

It is equipped with digital multi-interface for digital output.
The digital multi-interface section consists of "interface circuit" and "D/A converter circuit".
The interface circuit automatically identifies and corresponds to the sampling frequency, and is equipped with a linear phase digital filter.
The D/A converter circuit uses the "W Super Linear Converter" system, which has independent left and right channels. Since two D/A converters are used, there is no conversion error, excellent channel separation, and no time difference between left and right channels, even at large inputs.

The interface circuit and the D/A converter circuit are built on separate circuit boards and shielded between them. The interface circuit is equipped with a dedicated power supply that is independent from the secondary side of the transformer to prevent interference of digital signals, which are noise for analog signals.
In addition, the entire unit is covered with a shield case that also acts as a vibration absorber for the chassis and circuit board to prevent digital noise from leaking into other parts.

It is equipped with a source direct switch. When it is used, the control section is completely canceled and all input sources are directly connected to the power amplifier.

An equalizer amplifier composed of an ultra-low noise FET differential amplifier is mounted on the first stage.

It is equipped with a tape input Route 3, and with the Rec Out selector it is possible to record separately from the speaker playback.

The analog input system is equipped with a processor loop mechanism that can take advantage of sound creative devices such as surround processors and graphic equalizers.

The top cover is fixed at 8 points and fixed directly to the main chassis.
The bottom chassis has a two piece structure that separates the transformer and other parts. In addition, the vibration reduction effect is improved and vibration modes are dispersed by careful consideration of the appropriate setting of each dimension, the position of each screw, and the arrangement of insulators.

Equipped with a subsonic filter exclusively for Phono.

Equipped with a newly designed reset-type high-speed protection circuit.

Model Rating

Type	Stereo pre-main amplifier
Power Amplifier Unit
Rated Output (20 Hz ~ 20 kHz)	110W + 110W (8 Ω) 130W + 130W (6 Ω)
Input Sensitivity / Impedance	Processor loop input : 150mV/47k Ω
Total harmonic distortion factor	0.004% (20 Hz to 20 kHz, 55W, 8 Ω)
Cross modulation distortion factor	0.003% (equivalent to 110W, 8 Ω)
Dynamic Power	350W/2 Ω
TIM Distortion	Measurement limit value or less
Slew rate	± 350 V / μ sec
Output bandwidth	5 Hz to 100 kHz (55W, 0.5%, 8 Ω)
Line input frequency	4 Hz ~ 150 kHz, + 0 -3dB (1W, 8 Ω)
Output impedance	0.1 Ω or less
Output terminal	Speaker : AORb : 6 ~ 16 Ω, A + B : 12 ~ 16 Ω Headphone Jack Maximum Output : 430 mW (8 Ω), 8 ~ 400 Ω Compatible
<Digital Interface / DAC Part>
Digital Input Level / Impedance	0.5Vp-p/75 Ω Coaxial
Frequency response (0 dB)	5 Hz to 20 kHz ± 0.3 dB
Signal-to-noise ratio (vs. 0 db, 1 khz)	105dB
Dynamic Range (1 kHz)	96dB
Total harmonic distortion factor (0 dB, 1 kHz)	0.0025%
Channel Separation (0 dB, 1 kHz)	100dB
Preamplifier Section
Input Sensitivity / Impedance	Phono MM : 2.5mV/47k Ω Phono MC : 0.2mV/100 Ω CD, AUX, Tuner, Tape1, 2, 3 (DAT) : 150mV/47k Ω
Maximum Output / Rated Output	8V/150mV (including processor and loop output)
Total harmonic distortion factor	0.002% (1 khz, 8 v, processor loop output included)
Equalizer (RIAA) deviation	20 Hz to 100 kHz ± 0.3 dB (MC IN to processor loop output included)
<General>
SN ratio (input ratio (input short-circuit, auditory sense compensation A)	Phono MM:88dB Phono MC : 69 dB at 0.25 mV input CD, AUX, Tuner, Tape1, 2, 3 (DAT) : 108 dB
Tone control characteristics	Bass : ± 8 dB (100 Hz) Treble : ± 8 dB (10 kHz)
Subsonic Filter for Phono	16 Hz, -12dB/oct.
Loudness control characteristic	Low : + 4 dB (100 Hz) High frequency : + 4 dB (10 kHz)
Muting switch	-20dB
Power consumption (Electrical Appliance and Material Control Law)	216W
Pwer	100 VAC, 50Hz/60Hz
External dimensions (including foot, knob, terminal, etc.)	Width 434x Height 172x Depth 396 mm
Weight	15.6kg