The Philips/Marantz DPM-7 Digital Processing pre-main amplifier prototype is a true treasure from the early eighties. Only 60 units were handbuilt by the skilled technicians at Philips in Eindhoven, The Netherlands. The DPM-7 was a showcase of the cutting-edge technology and innovation that Philips was capable of during this time.
Handbuilt prototype
This prototype was developed by the same group who were responsible for creating the Philips MFB speakers and later, the Philips DSS Digital Speakers. Unfortunately, Marantz did not share the same vision as Philips and ultimately decided not to produce the DPM-7 due to their commitment to "pure" sound and rejection of tone controls. Despite this setback, the knowledge and experience gained from this prototype played a crucial role in the advancement of digital audio technology.
From the (conceptual) manual
"The Marantz DPM-7 is an pre-main amplifier comprised of both a digital control amplifier and a 100W x2 high power amplifier. The digitalized control amplifier portion includes the world's first ASP (audio signal processor) developed exclusively for audio equipment. The functions of the control amplifier are processed digitally, thus totally eliminating any chance for diminished sound quality."
Digital sound processing
"Furthermore, the digital sound processing concept has been incorporated in every aspect of the control functions. The DPM-7 is equipped for a great variety of functions, including digital reverberation, a digital graphic equalizer, and many controls for creating the perfect sound field."
Specifications
ASP (Sound Signal Processor):
- Sampling frequency: 44.1kHz
- Quantization: 16-bit linear
Digital inputs: CD1, CD2/DAT 2, DAT 1
Digital Sound Processing:
- Reverberation: 1sec - 9sec
- Reverberation/Absoroption: 3 positions: hard/medium/soft
- Graphic equalizer: +/-12dB (2dB steps)
- Variable frequencies: 32Hz, 64Hz, 125Hz, 250Hz, 500Hz (1/3 octave from central frequency) 1kHz, 2kHz, 4kHz, 8kHz, 16kHz
- Dynamic range control: compression/expansion - release time: 3 positions long/medium/soft
- Special effects: 5 positions
- Acoustic memory: 4 memories
- Volume preset: 2 presets
Analog inputs: Phono (MM/MC), Tuner, Video/AUX
Power Amplifier Section
- Rated output: 100W x 2 (20Hz - 20kHz - 6ohm)
- Frequency response: 20Hz - 20kHz (+0, -0.3dB)
Dimensions: 420x146x334mm (wxhxd)
Weight: 14.5kg
