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The Boss 638UA/RDS638UA is a basic 1-DIN head unit for car audio systems.

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plenty of inputs available including USB, AUX, SD slot

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preamps are powerful and output a clean signal, allows external amps to perform their best

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installation and programming the unit is very easy, doesn't take a high degree of skill

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  • Only 3 words are allowed.

signal output without an amp is only about on par with a standard OEM stereo, not a significant quality increase

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owners manual isn't very detailed, need to play around with the unit to work out many of the functions

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CD player won't play burned CDs, despite in theory being capable of it

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backlighting is not consistent, brighter in some areas than others

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  • Only 3 words are allowed.


The Boss 638UA/RDS638UA is a basic 1-DIN head unit for car audio systems. This has all of the same functions as the Boss 642CA/RDS642CA, but has a monochrome display and different button panel layout. Audio output is run to the 4 channels at a full 60 watts each, and additional amplifiers can be attached through 5 volt preamp outputs. The tuner supports 24 station presets, and input through the front AUX port will work with iPods and other mobile devices. The CD drive will work with burned CDs as play MP3 files, and the display will show the contents of ID3 tags. Tone adjustment can be done through EQ presets, and separate control of the bass, treble, loudness, balance and fader are all available. A wireless remote control is also included.

  • Single DIN mounting
  • Full detachable front panel
  • 5 Volt preamp output
  • Active black mask display
  • Illuminated control buttons
  • PLL synthesized tuner with 24 Station presets
  • Switchable USA/Europe radio frequencies
  • Front panel auxiliary input
  • Compatible with audio output of iPod and other MP3 players
  • Quartz digital clock
  • CD mute function / Track repeat / Intro scan
  • 1 Bit D/A converter / 8X oversampling
  • ESP (anti-skip mechanism)
  • MP3/CD-R/CD-RW compatible
  • ID3-Tag display
  • Preset EQ response curves / Separate bass and treble
  • Loudness / Balance and fader controls
  • RCA outputs
  • Local/distance switches
  • Wireless remote control
  • Output power: 60W x 4 channels
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