Denon PMA-250

Data

General

• Manufacturer: Denon
• Model: PMA-250'
• Year of manufacture: 1987
• Made in: Japan
• Color: Black, Silver,Copper
• Type: Analog
• Remote control: No
• Power consumption: 80 W
• Dimensions: 435 x 85 x 250 mm (WxHxD)
• Weight: 4.7 kg
• Original price approx.: 349-399,- DM
• Model variants:
  • E2 Europe
  • EK UK
  • EI Asia
  • EU USA
  • EC Canada
  • EA Australia

Ports

• Number of inputs:
  • Phono (2.5mV 47kOhm) (RIAA MM).

CD/CD direct (150mV 47kOhm)

• • Tuner (150mV 47kOhm)

Aux (150mV 47kOhm)

• • Tape IN (150mV 47kOhm).
• Number of outputs:
  • 1 speaker pair 4..16 Ohm
  • Headphones 6,3mm jack
  • Tape Record-Out

Technical Data

• Continuous power
  • 8 Ohm: 2x 25 W (1kHz THD 1%)
  • 4 Ohm: 2x 40 W (1kHz THD 1%)
• Dynamic power
  • 8 Ohm: n.a.
  • 4 Ohm: n.a.
• Total harmonic distortion: 0.05% (-3dB rated Output, 8 Ohm)
• Attenuation factor: n.a.
• Frequency response: 10 ... 40,000 Hz
• Signal to noise ratio: 72 dB, 96 dB
• Stereo channel separation: n.a.
• Tone control:
  • Bass: 100 Hz ± 10 dB

Treble: 10 kHz ± 10 dB Loudness: no

• • High Filter: no
  • Low Filter (Subsonic): no
  • Mute: no
  • Direct/Line-Straight: no

Special Features

• Balance control via double volume control on one axis
• red LED signals that the unit is switched on
• switch for tape monitor; tape playback is not provided via the source selector switch
• switch for CD-Direct, bypasses only the source switch and the tape monitor switch, but in principle passes through the tone control,
• Headphones switch off main speakers when plugged in; except U.K. model.
• Model variants USA, Canada and Asia have additional power connections
• Speaker clicks when switched off regardless of volume setting

Electronics

• Amplifier
  • discrete push-pull output stage with bipolar transistor pair 2SC3853/2SA1489 (conceivable European replacement types: TIP3055/TIP2955, TIP140/TIP145 (Darlington))
  • Fuse protection of the power amplifiers per channel by F4.0A fine-wire fuse on the motherboard

Adjustment of quiescent current setting rudimentary possible, exact adjustment requires disassembly down to PCB solder side

• • uPC1225H driver module

phono stage with OP M521BP

• • Tone control in feedback path between output power stage and input driver stage
  • Headphones connected via series resistor to output stage
• Power supply:
  • 2x 27VAC nominal voltage (center tap) ; 2x 32VAC idle.

1x bridge rectifier (MB2U)

• • 2x 8200uF filtering to ±36VDC -> supply output stage
  • 2x linear longitudinal regulation to ±16,5VDC -> supply phono stage
  • protection of the power side by T1,0A fine-wire fuse inside the unit

Circuit diagram can be found on the net under 'denon pma 250 service manual pdf'.

Listening test on Wharfedale Diamond 220 from 22 May 2021 Klaushuhn

Other equipment Bluesound Note 150

I have selected my music pieces under Al Di Meola, AC DC and Pat Metheny. A mix that should reveal sonic strengths and weaknesses.

With CD direct switching and without loudness, it quickly becomes apparent what the "little one" can do. can do.

An excellent neutrality. The most surprising thing is the excellent spatial representation. Wide and deep. Never intrusive, yet present.

Then there are the excellent large speaker terminals. to look at. For the reception of banana plugs. Clearly ahead of its class and time.

An absolute buy recommendation for speakers with medium to high efficiency.

Pictures