Kenwood U737

The Kenwood U737 is a single-DIN receiver with a CD transport, a USB interface and an FM/AM tuner. It is the only single-DIN unit and the only USB-equipped unit in this archive. Mounting dimensions are 178 x 50 x 160 mm, half the height of the double-DIN models. The manual carries publication number B64-4055-00.

The CD transport reads CD media and decodes three compressed formats: MP3 to MPEG-1 and MPEG-2 Audio Layer-3, WMA to the Windows Media Audio standard, and AAC in AAC-LC form from .m4a files. The same three decoders are available over the USB interface, which conforms to USB 1.1 and 2.0 at full speed, supplies up to 500 mA and reads FAT16 and FAT32 file systems.

Conversion differs from the other Kenwood units recorded here. The U737 uses a 24-bit digital-to-analogue converter with an eight times oversampling digital filter, against the 1-bit converters fitted to the double-DIN MD and CD models. Its quoted signal-to-noise ratio of 110 dB at 1 kHz is the highest of any transport in this archive, with total harmonic distortion of 0.008 percent and dynamic range of 93 dB.

Audio control is a three-band arrangement fixed at 100 Hz, 1 kHz and 10 kHz, each adjustable across plus or minus 8 dB. There is no multi-band equaliser of the kind fitted to the DSP-equipped models. An auxiliary input accepts a maximum of 1200 mV at an input impedance of 100 kohm, with a response of 20 Hz -> 20 kHz within plus or minus 1 dB. The pre-out is specified at 2500 mV into 10 kohm when playing CD or CD changer sources, the highest pre-out level recorded here.

Output is rated at 30W x 4 into 4 ohms at 1 kHz and 10 percent THD or less, with a maximum of 50W x 4 and a stated speaker impedance range of 4 to 8 ohms. Supplied parts include a remote control, two AA cells and a Music Editor CD-ROM.

U737 SPECIFICATIONS
Media	CD with MP3 (MPEG-1/2 Audio Layer-3), WMA (Windows Media Audio) and AAC (AAC-LC .m4a) decoding, plus USB mass storage with the same three decoders
FM tuner	76.0 -> 90.0 MHz in 100 kHz steps. Usable sensitivity 9.3 dBf (0.8 uV/75 ohm), S/N 50 dB sensitivity 15.2 dBf (1.6 uV/75 ohm), frequency response 30 Hz -> 15 kHz (plus or minus 3.0 dB), S/N 70 dB mono, selectivity 80 dB or more (plus or minus 400 kHz), stereo separation 40 dB (1 kHz)
AM tuner	522 -> 1629 kHz in 9 kHz steps, sensitivity 28 dBu (25 uV)
CD section	GaAlAs laser diode, 8x oversampling digital filter, 24-bit D/A converter, 500 -> 200 rpm constant linear velocity, wow and flutter below measurable limits, frequency response 10 Hz -> 20 kHz (plus or minus 1 dB), THD 0.008% (1 kHz), S/N 110 dB (1 kHz), dynamic range 93 dB
USB interface	USB 1.1 and 2.0 at full speed, maximum supply current 500 mA, FAT16 and FAT32 file systems, MP3, WMA and AAC decoding
Audio section	Maximum output 50W x 4, rated output 30W x 4 (4 ohm, 1 kHz, 10% THD or less), speaker impedance 4 to 8 ohm, pre-out level 2500 mV/10 kohm (CD and CD changer), pre-out impedance 600 ohm or less
Audio control	Bass 100 Hz, middle 1 kHz, treble 10 kHz, each plus or minus 8 dB
Auxiliary input	Frequency response 20 Hz -> 20 kHz (plus or minus 1 dB), maximum input 1200 mV, input impedance 100 kohm
Supplied parts	Power harness, truss screws M5 x 6 mm (four), flat screws M5 x 7 mm (four), sems screw M4 x 8 mm (one), remote control, AA cells (two), Music Editor CD-ROM
Electrical	14.4V (11 -> 16V), maximum current draw 10A
Form factor	Single-DIN, mounting dimensions 178 x 50 x 160 mm, mass 1.20 kg
Source	Kenwood owner's manual, publication B64-4055-00