Alpine MDA-W955J

The Alpine MDA-W955J is a double-DIN unit with MiniDisc and CD transports and an FM/AM tuner. It is documented in a manual shared with the MDA-W977J above it and the MDA-W933J below it, and several entries are model-specific. Mounting dimensions are 178 x 100 x 160 mm with a mass of 2.5 kg.

The CD section is specified as an optical pickup with 1-bit quantisation across 5 -> 20,000 Hz within plus or minus 1 dB, dynamic range of 93 dB or more, signal-to-noise of 105 dB or more and channel separation of 86 dB or more at 1 kHz. The MiniDisc section covers 20 -> 20,000 Hz within plus or minus 0.5 dB with dynamic range of 90 dB or more and signal-to-noise of 105 dB or more.

Equalisation is model-specific. The MDA-W955J and MDA-W933J carry a seven-band graphic equaliser at 63, 160, 400 Hz and 1, 2.5, 6.3 and 16 kHz. The MDA-W977J instead carries a five-band parametric equaliser with 31 selectable frequency points. Maximum output is 45W x 4 on this model and the MDA-W933J, against 60W x 4 on the MDA-W977J.

An active dividing network operates ahead of the amplifiers, switchable between two-way and three-way on a rear panel switch. Crossover points are set in third-octave steps across 20 -> 200 Hz for the low range and 20 Hz -> 20 kHz for mid and high ranges, with slopes of flat, 6, 12, 18 or 24 dB per octave and level adjustment from 0 to minus 12 dB per band. The manual states that engaging the divider, or setting the rear switch to three-way, disables the surround modes and the surround level and time adjustments.

Time correction on this model is manual, across six channels covering front left and right, rear left and right and subwoofer left and right, adjustable from 0.0 to 20.0 with three stored presets. The automatic time correction routine using the supplied measurement microphone is documented for the MDA-W977J only.

A Customized Sound Database holds approximately 230 Japanese vehicle models. The setup sequence asks for the vehicle, the front speaker type, whether separate tweeters are fitted, whether a subwoofer is fitted, and whether the seats are cloth or leather, then configures the cabin acoustics from those answers. Alpine's DHE processor provides five settings, three bass modes, a vocal mode and an all-round mode, which the manual notes is particularly applicable to MiniDisc because of its compression. Surround modes are Normal, Dance, Hall and Stadium with level and time adjustable across plus or minus 4, and listening position offers All, Front-All, Front-Left and Front-Right.

MDA-W955J SPECIFICATIONS
Media	MiniDisc and CD, including CD-R and CD-RW. No MP3 decoding listed
FM tuner	76.0 -> 90.0 MHz. Usable sensitivity 0.8 uV (75 ohm) at 9.3 dBf (new IHF), stereo separation 45 dB or more, S/N 80 dB or more, frequency response 30 -> 15,000 Hz, image rejection 80 dB or more, IF rejection 80 dB or more
AM tuner	522 -> 1,629 kHz, usable sensitivity 22.5 uV
CD section	Optical pickup, 1-bit quantisation, 2 channels stereo, frequency response 5 -> 20,000 Hz (plus or minus 1 dB), dynamic range 93 dB or more (1 kHz), S/N 105 dB or more (1 kHz), channel separation 86 dB or more (1 kHz), wow and flutter below measurable limits
MD section	Frequency response 20 -> 20,000 Hz (plus or minus 0.5 dB), dynamic range 90 dB or more (1 kHz), S/N 105 dB or more (1 kHz), wow and flutter below measurable limits
Audio section	Maximum output 45W x 4 (60W x 4 on the MDA-W977J), front and rear pre-outs at 500 mV/10 kohm
Equaliser	Seven-band graphic at 63, 160, 400 Hz, 1, 2.5, 6.3, 16 kHz. The MDA-W977J instead carries a five-band parametric with 31 frequency points
Dividing network	Active, ahead of the amplifiers, two-way or three-way on a rear switch. Crossover in third-octave steps, 20 -> 200 Hz low range and 20 Hz -> 20 kHz mid and high, slopes flat, 6, 12, 18 or 24 dB/oct, level 0 to minus 12 dB per band. Engaging the divider disables the surround modes
Time correction	Manual, six channels (front left and right, rear left and right, subwoofer left and right), 0.0 to 20.0, three stored presets. Automatic time correction by microphone is listed for the MDA-W977J only
Sound processing	DHE Digital Harmonics Enhancer with three bass modes, a vocal mode and an all-round mode. Surround modes Normal, Dance, Hall and Stadium with level and time plus or minus 4. Listening position All, Front-All, Front-Left, Front-Right. Six user presets
Customized Sound Database	Approximately 230 Japanese vehicle models, with settings for front speaker type, separate tweeters, subwoofer and seat material
Expansion	Ai-NET bus for CD and MD changers and Ai-NET televisions, subwoofer output, auto volume, external RCA input via the optional KCA-121B Ai-RCA adapter or KCA-410C Versatile Link Terminal
Remote control	Supplied on the MDA-W977J and MDA-W955J. DC 1.5V x 2 (UM-4), 42 x 121 x 23 mm, 50 g excluding cells
Electrical	DC 14.4V (operating range 11 -> 16V), negative earth
Form factor	Double-DIN, 178 x 100 x 160 mm, mass 2.5 kg
Source	Alpine owner's manual covering MDA-W977J, MDA-W955J and MDA-W933J