DENON POA-3000RG Specifications Denon / Den On

DENON POA-3000RG
¥ 450,000 (around 1990)

Commentary

Stereo power amplifier using MOS super optical class A circuit.

The MOS super-optical class A circuit is a further development of Denon's original optical class A circuit. It achieves excellent sound quality and high efficiency by amplifying up to the level of general listening power as pure class A.
In the MOS super optical class A circuit, interference between the main signal system and the bias control circuit is eliminated by optical coupling which transmits the control signal from the bias control circuit to the bias circuit, and high speed bias control is achieved by optical element.

In the final stage, six large-capacity large-size power transistors of Pc130W are connected in parallel, so that there is enough space to supply current to the load.
MOS FET (Pc30W) and MOS Power FET (Pc100W) are connected in inverted Darlington configuration to drive the last stage with sufficient space. The Inverted Darlington driver stage with MOS Power FET allows 10 times more bias current than the conventional one, expands the pure A-class operation range of the driver stage by 10 times, improves the quality at small and medium output, and eliminates sound quality degradation at small output.

A differential 3-stage amplifier circuit is used for the voltage amplifier stage.
This circuit employs a low-noise, low-feedback capacitor FET selected by Denon's strict standards for the first stage differential amplifier circuit. The pre-driver stage employs a current-mirror differential amplifier to supply a high-level signal voltage to the output stage, and a parallel differential circuit to further improve the quality, resulting in a significant improvement in linearity.

The power supply section is equipped with a large toroidal transformer and a large-capacity acoustic power supply condenser. The power supply section supplies power to the power stage and pre-driver stage independently, and the left and right channels are completely independent to create a monaural layout structure. This allows the power supply section to be completely monaural construction through the power stage and pre-driver stage, eliminating the left and right interference caused by the power supply section.
In addition, the main signal system and power supply are completely separated via a large heat sink, and the left and right circuits are made into a symmetrical structure to eliminate characteristic differences.

The chassis structure employs a 5-point supporting high-rigidity chassis made of thick plate material, and the cabinet is firmly supported by a large heavy-weight foot based on sintered metal.

Epoxy glass composite boards with excellent strength and electrical performance are used for printed circuit boards.
In addition, high-quality parts such as acoustic resistance and condenser are adopted.

The POA 3000 rg can also be used as a monaural power amplifier by switching the switch.
High power is achieved by driving the left and right 2-channel amplifiers as positive and negative polarity amplifiers in monaural operation, and the balance input in monaural operation uses the direct balance input method.

There are two types of input jacks, an RCA pin jack and a cannon connector. Both unbalanced and balanced inputs are available.
The balance conversion circuit for monaural unbalanced input is equipped with Inverted Σ Balance circuit originally developed by Denon. In order to bring out the advantage of balance transmission system, all amplification elements are discrete configuration using high-performance and high-quality parts. This circuit realizes high power supply voltage, low distortion factor and high SN ratio.

The output terminal is a two system large speaker terminal for bi-wiring connection.

Equipped with an analog meter for peak output level display.
This meter is equipped with a meter switch that can turn on and off the lighting and operation.

Equipped with a newly developed protector circuit that can drive low-impedance speakers stably.

It is equipped with front operation input level control for stereo and monaural independently.

It uses an input level control knob using a briar and a real wood mirror finish cabinet with multi-layer coating.
In addition, a 20 mm thick glass window is used in the front.