Boston Acoustics GT-50

5-channel car amplifier — 55 watts RMS x 4 + 250W x 1

  • Boston Acoustics GT-50


  • Boston Acoustics GT-50

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  • Boston Acoustics GT-50

  • Boston Acoustics GT-50

  • Boston Acoustics GT-50

  • Boston Acoustics GT-50

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Item #: 065GT50

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Our take on the Boston Acoustics GT-50

by Gabrielle Thorndyke

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

The GT-50 amplifier upholds Boston Acoustics' reputation for attention to detail. This compact amp puts out 55 watts of continuous power to 4 speakers, and up to 350 watts to a subwoofer. It can handle low-impedance loads that would destroy a lesser amp, giving you flexibility when putting together a system and allowing you to get maximum power.

Mounts in any position
A forced air cooling system, more efficient than a traditional amp heat sink, allows this amp to be be mounted in any position, even upside down, without fear of failure due to excessive heat. Adjustable mounting feet make it even easier to adapt the GT-50 to uneven surfaces found in your vehicle.

Read more

High- and low-pass crossovers
Boston Acoustic's Q-Tune feature allows you to get the best bass response from any type of speaker. Variable frequency filters allow you to send the right signals to the right places, reducing wear and tear on your speakers. You'll find all controls and connections on the front of the amp, making installation and adjustment as simple as possible.


  • 5-channel car amplifier
  • 14.4 volts:
    • at 4 ohms: 55 watts RMS x 4 at + 250 RMS watts x 1
    • at 2 ohms: 85 watts RMS x 4 + 350 watts x 1
  • 12.5 volts:
    • at 4 ohms: 45 watts RMS x 4 + 190 watts RMS x 1
    • at 2 ohms: 65 watts RMS x 4 + 250 watts x 1
  • variable high-pass (20-350 Hz at 12 dB per octave) and low-pass (50-350 Hz at 12 or 24 dB per octave) filters
  • preamp-level inputs
  • fuse rating: 3 x 30A
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • MOSFET output stages
  • Q-Tune technology for crossover adjustment
  • Dynamic Power System for higher efficiency and increased power output
  • fan-cooled with side cooling vents for more mounting positions
  • adjustable mounting feet
  • 21-9/16"W x 2-5/16"H x 8-13/16"D
  • warranty: 1 year
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
RMS Power Output (Watts x Channels) 55 x 4
400 x 1
Peak Power Output (Watts x Channels) N/A
Power at 2 Ohms (Watts x Channels) 85 x 4
Bridged Power (Watts x Channels) ---
Minimum Impedance Bridged ---
Minimum Impedance Unbridged 1
Best Frequency Response 10-95k Hz
THD at Rated RMS Power 1%
Signal to Noise Ratio 100 dB
Input Voltage 14.4v
Amplifier Class AB
Low-Pass Crossover Frequency 50-350 Hz
Low-Pass Slope (dB/octave) 12dB or 24dB
High-Pass Crossover Frequency 20-350 Hz
High-Pass Slope (dB/octave) 12dB
Bass Boost No
Bass Boost Frequency N/A
Fan Cooled Yes
Fuse Rating 30 x 3
Speaker Level Inputs No
Preamp Outputs No
Width (inches) 21-9/16
Height (inches) 2-5/16
Depth (inches) 8-13/16
Parts Warranty 1 Year
Labor Warranty 1 Year
Product Research
What's in the box?

Download owner's manual

  • 5-Channel amplifier
  • 6 Self-tapping Phillips-head screws (length=3/4")
  • Female quick-slide (0.25")
  • 2 Hex keys (2.5mm & 2mm)
  • Fuse puller
  • Owner's Manual
  • Warranty sheet
  • Product Registration card

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Input and Output Notes


Dual Mode Capable: The Boston Acoustics GT-50 offers excellent vocal sound quality with low distortion on front-end components, and at the same time provide high current performance for subwoofers. The amplifier is capable of handling very low impedances, allowing 1-ohm stereo or 2-ohm mono operation.

Low-Profile Design: The compact and low-profile design allows for installations in tight locations where other amplifiers will not fit. The GT-50 carries the same design as other GT-series amplifiers, which allows you to mount multiple GT-series amps side by side for a clean, professional look.

DPS (Dynamic Power System): This technology ensures high efficiency at the output stages, increased power with lower impedance and maximum dynamics and instantaneous response.

Forced Air Cooling: This advanced cooling system allows you to mount the amplifier in various positions. You can even mount the amplifier upside down. This design also offers reduced weight and increased cooling efficiency over traditional heat sinks. The amplifier is equipped with side and rear vents.

Note: The cooling vents must be kept clear of obstructions once the amp is installed. Failure to leave the vents unobstructed can lead to premature thermal shutdown or amplifier failure.

MOSFET Output Stages: The amplifier uses highly efficient MOSFET output stages for quick recovery under heavy transient conditions.

Q-Tune: This technology combines sophisticated crossover adjustments with Q-Control settings to seamlessly transition rear bass to the front sound stage.

Multi-Position Mounting Feet: The amplifier has six track-mounted mounting feet which are designed to slide in both directions to clear installation obstructions on the mounting surface.

Status LED Indicators: The LED indicators on the amplifier lets you know when you amp is on or when it is malfunctioning.

  • Green Indicates normal operating conditions.
  • The Green and Red Indicator light will come on when the amplifier is first turned on. The red will turn off after a few seconds.
  • When both Red and Green remain on, the amplifier is in thermal shutdown mode.
  • When only the Red LED is on, it indicates a fault condition.


Removable Control Cover: The GT-50 amplifier features a removable aluminum control cover that conceals all controls of the amp. The cover provides a cleaner look, and it prevents accidental adjustment of the settings once they are set. The cover is held in place by two screws, which can be loosened or tightened with a coin.

Input Sensitivity Controls: The amplifier features independent sensitivity control for the front, rear, and subwoofer channels. This control is used to match the incoming signal from your CD receiver and/or separate processor to the amplifier to give you the best overall sound quality. The Sensitivity range for each set of inputs is 0.2Volts (200mV) to 5 Volts.

Front and Rear High-pass Crossover Controls: The amp offers independent high-pass crossover controls for the front and rear speakers to allow you to filter out frequencies between 20Hz to 350Hz. Keeping certain bass frequencies from the full-range speakers will prevent distortion. You can independently turn the High-pass filters off for full range use.

Front and Rear Q Control: The "Q" Controls are active when the high-pass crossovers are engaged and are centered on the selected crossover point. The range of operation is 0.7 to 1.2. This control increases the bass information centered around the high-pass crossover point.

Rear Input Switch: You can choose to connect one or two pairs of RCA inputs for the front and rear channels. In the Stereo L-R position, the left and right inputs go to the rear L & R channels of the amplifier. In the Front L-R position, the inputs for the rear channels are derived from the Front channels and sent to the Rear L & R channels of the amplifier.

Subwoofer Low-pass Crossover Controls: The low-pass crossover control allow you to filter out frequencies above the crossover point so that only the desired bass frequencies reach your subwoofers. The frequency control is variable between 50Hz and 350Hz. The Low-pass Slope switch lets you choose a gentle slope of 12dB per octave, a sharper slope of 24dB per octave, or Off.

Subwoofer Level: The amplifier can be used with the optional GT-RSL wired subwoofer level controller (sold separately). The wire controller uses voltage control amplification to adjust subwoofer level, eliminating noise and phase error issues. The Subwoofer Level switched should be turned set to "Off" when not in use and set to "On" when in use. The connection for the GT-RSL controller is found on the front of the amplifier behind a removable plastic panel held in place by two small Phillips-head screws.

Subwoofer Mode Switch: If you have connected a third pair of RCAs, the Subwoofer Mode Switch should be placed in the Mono L-R position. If you use a single RCA to the sub input, the Switch should go in the L-Mono position. If you have no dedicated subwoofer RCAs, the Switch goes in the Non-Fading Mono position, and the subwoofer signal is derived from the front and rear channels.


Power Output: The GT-50 offers power specifications measured at input voltages of both 14.4VDC and 12.6VDC:

  • 14.4 Volts DC:
    • Multi-Channel Power @ 4 ohms: 4 x 55W, 1 x 250W
    • Multi-Channel Power @ 2 ohms: 4 x 85W, 1 x 350W
    • Mixed Operation Power @ 4 ohms, 2 ohms: 4 x 55W, 1 x 400W
  • 12.6 Volts DC:
    • Multi-Channel Power @ 4 ohms: 4 x 45W, 1 x 190W
    • Multi-Channel Power @ 2 ohms: 4 x 65W, 1 x 250W
    • Mixed Operation Power @ 4 ohms, 2 ohms: 4 x 45W, 1 x 300W

Input and Output Notes

Connections: All input and output connections are located on the front of the amplifier to make installation and wire management easier.

RCA Inputs: The amp includes three sets of recessed RCA inputs to connect from the RCA outputs of your head unit or processor. The recessed design provides added clearance in tight mounting locations.

Remote Inputs: The supplied female quick-connector can be used to connect the remote turn-on lead (not supplied) from the head unit to the amplifier. This lead turns the amplifier "On" when head unit is turned "On". The amplifier has separate remote turn-on inputs for the front, rear, and subwoofer channels. These remote leads are wired in parallel inside the amplifier so only one needs to be connected.

Power Connections: The amplifier accepts stripped bare wire into the dual power and ground terminals. All power and ground terminals can accept up to a 4-gauge wire. The set screws can be tightened with the supplied 2.5mm hex key.

Speaker Connections: The amplifier accepts stripped bare wire into the speaker terminal blocks. The speaker outputs accept up to an 8-gauge wire. The set screws can be tightened with the supplied 2mm hex wrench. In addition to the four front and rear speaker outputs, the amplifier offers dual subwoofer outputs. The subwoofer terminals are internally wired in parallel, allowing you to connect two 4-ohm subwoofers.

Subwoofer Level: Proprietary 9-pin connection for optional GT-RSL wired remote controller found behind plastic panel held in place by two Phillips-head screws.

Fuses: The amplifier accepts standard AT-style automotive blade fuses. It comes equipped with three 30A blade fuses.

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Boston Acoustics GT-50 Reviews

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5 out of 5

Best 5-ch amp in the price range

Written By Amped, Dallas, TX on Saturday, January 17, 2009
Crutchfield Customer Review (What's this?)
I purchased this amp to replace the dying Bose amp in my Audi A4. I already had Infinity Reference 5.25" components in the front and rear doors and 2 JL Audio 6w0 subs in the trunk. I decided to keep the factory head unit to preserve the OEM look.

One of the truly unique features about this amp, which helped out a lot during the installation, is the ability to mount it upside down. This allowed me to mount it to the underside of the rear deck without taking up much usable trunk space. The adjustable mounting feet helped out a lot in securing the amp to the not-so-flat underside of the rear deck.

I used a standard Scosche EFX 4 gauge wiring kit to power the amp, and everything seems to be fine with that. The amp has good adjustability, with a nice set of controls for each channel. This was helpful while tuning the system and trying to get the subs and mids to blend seamlessly. The amp is definitely the strong point in my system, and I have plenty of room to grow with my components and subs. At this point, everything sounds clean, and everything looks neat. What more could I ask for?
1 out of 1 people found this helpful
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5 out of 5


Written By Ryan, Mechanicsville MD on Monday, December 08, 2008
Are you kidding me? If you need an amp buy THIS ONE. This price is
absolutely a steal and the quality is top notch. The recessed inputs allow
for a super clean installl and the adjustments are easily made in the front
panel. The 24db LPF is also a great feature. This is a very nice amp..I feel
like I'm stealing!!
12 out of 13 people found this helpful
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5 out of 5

Above Outstanding

Written By JMO, Boston, mass on Saturday, October 25, 2008
There isn't a strong enough word to desribe this Amp. The sound quality that is produced from this amp is beyond outstanding. The music sounds like a studio recording, the vocals scream as if the artist was sitting in your car. I normally don't take the time out to write a review, but this is an exception. The sub channel is outstanding as well. I bought this at my local dealer for way more than this, but it's worth every penny. If you are serious about sound and quality or just happen to have nice taste, priced reasonably..you are on the right page.
60 out of 67 people found this helpful
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