Marantz RV450PRO

Commentary

Surround processor with Dolby Pro Logic Decoder.

The Dolby Pro-Logic Surround System is a home-use surround system that reproduces the same effect as a movie theater by installing almost the same circuitry as the professional surround decoder developed by the Dolby Research Institute for movie theaters in order to clarify sound localization and realistic sensation.

In the Dolby surround sound recording, the front L/R component and the surround component that surrounds the person are recorded in a composite state, and the surround effect is realized by separating and playing back this component.
The RV450PRO is equipped with a directional enhancement circuit that improves the front-rear and left-right channel separation from the conventional 3 dB to more than 25 dB. In addition, the 3-channel L, R, and S (surround) playback is replaced with 4-channel L, R, C (center) and S playback to separate the sound image at the center and localizing it.

The surround channel is equipped with a digital delay circuit that outputs a signal 20 msec behind the front channel. This greatly reduces noise compared with the conventional analog method and makes sound localization clearer. The surround channel S/N ratio of 96 dB is achieved by using a noise reduction system in this circuit.

Equipped with three modes that can be freely selected according to the type and size of the speaker used for the center channel.
The normal mode is most suitable for the case where a small speaker is used for the center channel rather than the left and right speakers. The center speaker outputs a signal of 100 Hz or higher, and the signal of 100 Hz or lower, which has little influence on the direction localization, is distributed to the left and right channels.
Wide mode is used when the center channel speaker is equipped with a bookshelf type or higher speaker that can fully reproduce overtones. The output separated by the directional enhancement circuit is sent directly to the center channel.
Phantom mode is a mode in which no speaker is used for the center channel. The center channel signal is divided equally into left and right by the directional enhancement circuit.

In addition to the Dolby Pro Logic Surround mode, Hall Surround and Matrix Surround modes are also built-in.
Hall surround gives the sound as if you are listening in a hall, while matrix surround mode cancels out the signal located in the center of the left and right and emphasizes the indirect sound, so that you can play back more realistically, such as a during sport joint.

With a built-in test tone generation circuit, the test tone automatically circulates through each channel of L, R, C and S, and the level can be set according to the listening condition.

Equipped with a master level controller that can simultaneously control the volume of four channels : L, R, C, and S.
It is also equipped with center volume and surround volume that can adjust center output and surround output.

Model Rating

Type	Dolby Pro Logic Surround Processor
Maximum power output	25W (4 Ω)
Total harmonic distortion factor	0.03% (1 kHz, 20W)
Frequency characteristic	Front : 40 Hz ~ 30 kHz -3dB Surround : 60 hz - 6 khz -3dB Center : 60 Hz ~ 30 kHz -3dB
Input Sensitivity / Impedance	150mV/50k Ω
Delay time	20 msec (digital delay)
Signal-to-noise ratio	Front, center : 80 dB Surround : 96 dB
Maximum external dimensions	Width 420x Height 60x Depth 200 mm
Weight	3.3kg