Features

Overview: The Blaupunkt GTA 270 DSP is a two-channel, Class AB amplifier designed to power a pair of speakers or a subwoofer in your vehicle. The amp has a built-in DSP (digital sound processor) for optimizing the sound of the connected speakers, and for filtering the preamp output to another amplifier. The amplifier outputs 70 watts RMS per channel into a 4 ohm load, or 100 watts RMS at 2 ohms. You can bridge the amplifier to a single 4-ohm load to get a 200 watt RMS output. The amp comes with a spare fuse, terminal tools, and mounting screws.

Digital Sound Processor (DSP): The GTA 270 DSP has a built-in 28/56-bit Analog Devices / Sigma DSP that lets you customize the sound settings for full range speakers and for a subwoofer, depending upon which speakers are connected. A series of controls are designated "Front" and let you adjust the sound of the speakers connected to the amplifier. Another series of controls, marked "Subwoofer" adjust the sound of the preamp outputs on the amp. These preouts can feed the signal to an active subwoofer, or to a separate amplifier that is driving a passive subwoofer. The amplifier has the following audio controls on the right side panel:

• Gain Control: The amp has a single gain control for matching the preamp output voltage of the connected head unit. The rotary control is continuously variable from 200mV to 5V.
• Crossover Switch: You can select the type of crossover you want, using the 3-way switch: Hi, Low, or Full. The Hi (high-pass) setting is for small to medium-sized speakers, and filters out low frequencies that might cause distortion. The Low (low-pass) setting filters out high frequencies that are undesirable if you are driving a subwoofer with the amp. The Full (full-range) setting disables the crossover, allowing the full frequency range to be amplified.
• X-over: The rotary "X-over" control lets you dial in the cutoff frequency of the crossover. The control is continuously variable between 50Hz and 5kHz (5000Hz). Only the frequencies above the cutoff frequency (if switch set to high-pass) or below the cutoff frequency (low-pass) are sent to the amplifier. If the crossover switch is set to Full, the X-over frequency control is disabled.
• Crossover Slope: The 3-way crossover slope selection switch (labeled "dB/Oct") lets you choose the slope of the crossover. You can choose from 18dB (Bessel filter), 24dB, or 48dB (Butterworth filters) per octave slope. A steep slope (48dB/oct) provides a strict separation of the blocked and forwarded frequencies. A soft slope (18dB/oct) gives you a more gradual transition from the blocked to the forwarded frequencies. If the crossover switch is set to Full, the crossover slope control is disabled.
• Subsonic Filter: The built-in Subsonic Filter is a variable high pass crossover that filters out extremely low frequencies that typically cause distortion and waste amplifier power. The Subsonic Filter control sets the lower frequency limit of the amp's output, and is continuously variable between 0 Hz and 80 Hz.
• DSP Subwoofer Controls (Preouts Only): If you are connecting an active subwoofer or another amplifier to drive subwoofers to the preamp outputs, you can adjust the signal sent to that sub or amp. The crossover control of the active subwoofer or second amplifier should be set to Full Range. The subwoofer controls include:
  • Phase Control: The Phase Control helps fine tune the subwoofer with the other loudspeakers. Out-of-phase speakers create mutually canceling frequencies that hurt the sound system's bass response. The variable Phase control lets you adjust the "attack" of the subwoofer between 0° and 180° until the bass sounds the best.
  • X-over and Subsonic: These two rotary controls let you set the upper limit (X-over 40Hz-200Hz) and lower limit (Subsonic 0Hz-80Hz) of the frequency range of the preamp output signal.
  • Crossover Slope: Like the Front Crossover Slope control, you can set the slope of the crossovers for the preamp outputs to 18dB, 24dB, or 48dB per octave.
• Compressor Switches: Two DIP switches are provided on the amp for Front Compressor and Sub Compressor. When the switches are in the On position, the output volume is reduced by 10dB. The Front and Sub Compressors feature separate switches.

Connections: The Blaupunkt GTA 270 DSP features set screw terminals for all bare wire connections. The set screws are tightened/loosened with the supplied 4mm and 2mm Allen wrenches. The amp terminals are as follows:

• Power/Ground: The power and ground connections use set screw terminals. The terminal openings are 0.316" in diameter, and 10-gauge power/ground wire is recommended. A 20A fuse should be placed on the power wire no more than 18" from the battery.
• Fuses: The amplifier has one 20A ATO (blade-type) fuse installed. A spare 20A fuse is included with the amp.
• Remote Turn-on: The set screw terminals for the remote turn-on lead is 0.15" in diameter. You can use 18-gauge or 16-gauge wire for the turn-on lead.
• Speaker Terminals: Two pairs of set screw terminals are provided, allowing you to connect two speakers to the amplifier. There are markings for left and right +/- terminals, plus the terminals to connect when bridging the amp (L+ and R-). The set screw terminals for the speakers are 0.15" in diameter, allowing you to use up to 16-gauge speaker wire.
• Line Level Input: One pair of stereo RCA jacks is provided for the input signal.
• Line Level Output: One pair of stereo RCA jacks is provided for the output signal to feed an active subwoofer or an amplifier driving passive subwoofers. (The RCA Input and Output jacks are mounted on the "control" side of the amplifier.)